ORCID Profile
0000-0001-6370-6623
Current Organisations
University of Queensland - Gatton Campus
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Meat and Livestock Australia
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Publisher: CSIRO Publishing
Date: 2014
DOI: 10.1071/AN14270
Abstract: Reducing methane emissions from cattle in Australia will be dependent upon finding a strategy that can be readily adopted by its northern beef industry. The majority of the herd are located in this region and they graze low-quality tropical (C4) pastures, resulting in high methane output. There are few mitigation options that can be readily applied to extensively grazed cattle. The addition of nitrate to the diet of cattle has been shown to reduce methane production and may be an applicable strategy in northern Australia. Nitrogen is often the primary limiting nutrient in low-quality tropical pastures and it is common practice by industry to supplement with urea. Supplying an equivalent dose of nitrogen using nitrate as an alternative to urea has been demonstrated in cattle without adverse impacts upon animal productivity or health. These findings may not be directly applicable to grazing cattle in northern Australian because the diets and feeding management are not representative of the region. Nitrite toxicity can result from feeding nitrates to livestock and there is evidence that the composition of the total diet and feeding pattern influences the risk of toxicity. If nitrate supplementation in grazing beef cattle in northern Australia can be demonstrated to reduce methane and be applied safely, adoption rates will still depend on carbon market pricing. Current modelling suggests that the cost of supplementing beef cows with nitrate in northern Australia would be at least double the cost of urea supplementation.
Publisher: Public Library of Science (PLoS)
Date: 30-04-2019
Publisher: CSIRO Publishing
Date: 2021
DOI: 10.1071/AN20434
Abstract: Context Separation of a calf from its dam at weaning can cause stress behaviours such as excessive walking and vocalising. These behaviours combined with poor dry matter and water intakes during weaning can cause bodyweight loss in calves. We questioned whether adding a social facilitator cow to pens of calves weaned on pasture would decrease calf walking behaviours and prevent a loss in bodyweight. Aims We tested the hypothesis that a social facilitator (SF) cow at weaning would reduce the walking behaviours of calves and increase calf bodyweight. Methods Eighty Simmental × Angus heifer calves were allocated to four replications. In each replication, 20 heifer calves were randomly assigned to either the SF (n = 10) treatment in which calves were abruptly weaned and placed on pasture with a SF cow on the day of weaning (day 0), or to the control (CON, n = 10) treatment in which calves were abruptly weaned and placed on pasture without a SF cow. All calves had their bodyweight recorded and were blood s led on Days 0, 1, 7, and 14 for non-esterified fatty acids and β-hydroxybutyrate concentration. To quantify and evaluate walking behaviours, all calves were fitted with an in idual global positioning system collar that recorded calf location every 10 s for a 24-h period on Days 0, 7, and 14. Key results There was no effect for time spent walking (P = 0.07) or distance walked (P = 0.08), although the SF calves spent numerically less time walking and walked shorter distances on the day of weaning compared with the CON calves. There were no differences observed for calf bodyweight or average daily gain. Conclusion The results of this study indicate that the addition of a SF animal at weaning does not affect the distance walked on the day of weaning or the time calves devote to walking. Implications It is unlikely that a SF cow will decrease the distance and time spent walking by calves enough to improve calf bodyweight.
Publisher: Springer Science and Business Media LLC
Date: 07-01-2021
Publisher: Elsevier BV
Date: 08-2016
DOI: 10.1016/J.ANIREPROSCI.2016.06.003
Abstract: This study aimed to evaluate the reproductive response of anoestrous goats that were either hormonally treated and/or supplemented with maize for 9days to determine which treatment combination was the most effective in enhancing follicular development and ovulation rate, and whether these responses were associated with increases in metabolic hormones. The experiment was carried out using 28 does, using a 2×2 factorial design with seven does in each group to test the effect of synchronisation of oestrus, supplementation with maize and their interactions. Synchronisation of oestrous cycles (P 0.05) increased the number of codominant follicles, the diameter of the largest follicle on Day 9 and growth rate of follicles during the period of supplementation. Compared with non-supplemented animals, supplementation with maize increased the total number of follicles observed between Days 7 and 9 (P=0.039). In addition, nutritional supplementation with maize in combination with synchronisation of oestrus increased the ovulation rate by 43% (P=0.074). Interactions between time and supplementation with maize showed that plasma concentrations of insulin, leptin and IGF-1 were greater in does supplemented with maize compared with non-supplemented does (P<0.001). The findings show that hormonal synchronisation had the most influence on modifying follicular development and ovulation in anoestrous goats. Supplementation with maize increased the concentrations of insulin, leptin and IGF-1, which could potentially modify the sensitivity of follicles to gonadotrophins and reduce rates of atresia.
Publisher: Wiley
Date: 05-05-2008
Publisher: Public Library of Science (PLoS)
Date: 30-07-2021
DOI: 10.1371/JOURNAL.PONE.0249323
Abstract: In mammals, including sheep and mice, lactation attenuates the hypothalamo-pituitary-adrenal axis and plasma cortisol concentration. Oxytocin, one neuropeptide present in the blood during lactation, may contribute to such stress attenuation. Providing oxytocin intra-nasally increases plasma oxytocin concentration in cattle and can be used in non-lactating cows to mirror plasma oxytocin concentration of lactating cows. Therefore, our hypothesis was that there would be no difference in plasma cortisol between non-lactating beef cows intra-nasally administered oxytocin and lactating beef cows intra-nasally treated with saline. Twenty Bos taurus cows were randomly allocated by lactational status to one of four treatments, in a 2×2 factorial arrangement: 1) Non-lactating, saline (NL-S n = 5) 2) Non-lactating, oxytocin (NL-OXT n = 5) 3) Lactating, saline (L-S n = 5) and 4) Lactating, oxytocin (L-OXT n = 5). Two hours pre-treatment, cows were catheterized, moved to their appropriate chute and baseline blood s les were collected at -60, -45, -30, and 0 minutes before treatments were administered. Directly following the 0-minute s le, cows were administered their intra-nasal treatment via a mucosal atomization device. Subsequently, blood was collected at 2, 4, 6, 8, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, and 120 minutes. Non-lactating cows had greater ( P = 0.02) plasma cortisol concentration compared with lactating cows. There was no lactation by treatment interactions for either plasma cortisol ( P = 0.55) or oxytocin ( P = 0.89) concentration. Although a treatment by time interaction was identified for oxytocin ( P 0.0001), there was no main effect of lactation on plasma oxytocin concentration ( P = 0.34). Similar oxytocin and dissimilar cortisol concentration in lactating and non-lactating cows indicate that oxytocin alone cannot be responsible for reduced plasma cortisol in lactating ruminants. Further investigations are needed to elucidate alternative mechanisms that may be involved in the stress hypo-responsive condition of lactating mammals.
Publisher: CSIRO Publishing
Date: 2016
DOI: 10.1071/AN14632
Abstract: Twelve Bos indicus bulls were allocated to one of two treatment groups: rumen transfaunation (n = 6) given 10 kg of rumen fluid after transport or Control (n = 6), given 10 kg of deionised water after transport. Glycogen concentrations of the M. semimembranosus, M. semitendinosis and M. longisimus dorsi were measured before transport on Day –7 and after transport on Day 0, Day 1, Day 4 and Day 9. Feed intake, liveweight gain, plasma metabolites and electrolytes were recorded on the s ling days. Rumen transfaunation increased the dry matter intake of treated bulls compared with the bulls treated with deionised water. Rumen transfaunation had no effect on glycogen concentrations of the M. semimembranosus, M. semitendinosis and M. longisimus dorsi compared with the bulls treated with deionised water. The M. semimembranosus and the M. semitendinosis decreased in glycogen concentration immediately after transport on Day 0 but repleted to pre-transportation concentrations within 1 day. However, the M. longisimus dorsi demonstrated no change in glycogen concentration between the pre-transportation s le on Day –7 and Day 0 or Day 1 after transportation. The M. longisimus dorsi of the bulls increased in glycogen concentration between Day 1 and Day 4 after transportation. The bulls in this experiment demonstrated that muscle glycogen, as measured at the M. longissimus dorsi, cannot recover to sufficient concentrations (40–45 µmol of glycogen concentration per gram muscle) to ensure normal meat quality until between 1 and 4 days of rest when feeding Rhodes grass hay ad libitum.
Publisher: Wiley
Date: 22-07-2019
DOI: 10.1111/AVJ.12851
Abstract: The availability of safe, commercially prepared stock feed for production animals is an important step in ensuring animal health and welfare and the safety of food animal products for human consumption. Animal feed quality assurance programs include microbiological monitoring of raw materials, mill equipment and finished feed. Over a period of 16 years, 23,963 s les for Salmonella culture and serotyping were collected from 22 stock feed mills. A multivariable generalized linear mixed model (GLMM) was used to identify mill and s le type factors that increase the odds of detecting Salmonella. The odds of detecting a Salmonella positive s le was greatest in s les from raw materials and in mills that processed restricted animal material (RAM). The percentage of positive s les ranged from 7.2% in 2003 to 2.8% in 2017. Of the 1,069 positive s les, 976 were serotyped with 61 different Salmonella serotypes isolated. The serotype most frequently isolated from raw materials was S. Agona, (n = 108) whilst S. Anatum was the serotype most frequently isolated from equipment and finished feed (n = 156). The ersity of Salmonella serotypes differed between mills and different stages of the production line. Microbiological monitoring in the commercial preparation of animal feed in Australian stock feed mills guides the implementation of quality control measures and risk mitigation strategies thereby reducing the prevalence and ersity of potentially zoonotic bacteria such as Salmonella, enhancing food safety for both animal and consumer.
Publisher: CSIRO Publishing
Date: 2017
DOI: 10.1071/AN16079
Abstract: Temperature is a crucial factor in mammalian spermatogenesis. The scrotum, p iniform plexus, and cremaster and dartos muscles in mammals are specific adaptations to ensure sperm production in a regulated environment 4−6°C below internal body temperature. However, the limited endogenous antioxidant systems inherent in mammalian spermatozoa compounded by the loss of cytosolic repair mechanisms during spermatogenesis, make the DNA in these cells particularly vulnerable to oxidative damage. Boar sperm is likely to be more susceptible to the effects of heat stress and thus oxidative damage due to the relatively high unsaturated fatty acids in the plasma membrane, low antioxidant capacity in boar seminal plasma, and the boar’s non-pendulous scrotum. Heat stress has a significant negative impact on reproductive performance in piggeries, which manifests as summer infertility and results in productivity losses that amount to millions of dollars. This problem is particularly prevalent in tropical and subtropical regions where ambient temperatures rise beyond the animal’s zone of thermal comfort. Based on preliminary studies in the pig and other species, this article discusses whether heat stress could induce sufficient DNA damage in boar sperm to significantly contribute to the high rates of embryo loss and pregnancy failure observed in the sow during summer infertility. Heat stress-induced damage to sperm DNA can lead to disrupted expression of key developmental genes essential for the differentiation of early cell lineages, such as the trophectoderm, and can distort the timely formation of the blastocyst resulting in a failure of implantation and ultimately pregnancy loss. Confirming such a link would prompt greater emphasis on boar management and strategies to mitigate summer infertility during periods of heat stress.
Publisher: CSIRO Publishing
Date: 2017
DOI: 10.1071/AN15860
Abstract: Serum and liver retinol concentrations and blood β-carotene concentrations were studied in 30 Bos indicus heifers rendered deficient of vitamin A over 180 days and then given treatments of access to algae-based lick blocks (n = 10), injectable retinyl palmitate and molasses-based lick blocks (n = 10), or a negative control given access to molasses-based lick blocks only (n = 10). All heifers became deficient in blood and liver vitamin A, as well as blood β-carotene by 180 days. There was no treatment effect on bodyweight (P = 0.347). However, a highly significant effect of time (P = 0.001) was detected where all heifers achieved an average daily gain of 0.74 kg/day throughout the depletion phase of the study but lost 0.150 kg/day during the repletion phase. The concentrations of serum and liver retinol and blood β-carotene were not different between treatment groups (P = 0.362, P = 0.535 and P = 0.839) during the depletion or repletion phases of the study. All heifers continued to be rendered deficient in the concentrations of serum and liver retinol and blood β-carotene throughout the experiment demonstrating a highly significant effect of time (P = 0.001). Injectable retinyl palmitate (818 100 IU retinol) or access to algal lick blocks (4180 IU retinol) did not elevate blood or liver retinol concentrations in heifers rendered deficient of vitamin A. It is speculated that the protein-deficient diet fed to the heifers had an adverse effect on the blood retinol transport proteins.
Publisher: CSIRO Publishing
Date: 2016
DOI: 10.1071/AN14793
Abstract: This study aimed to survey farmers’ knowledge and practices on the management of pastures, stocking rates and markets of meat goat-producing enterprises within New South Wales and Queensland, Australia. An interview-based questionnaire was conducted on properties that derived a significant proportion of their income from goats. The survey covered 31 landholders with a total land area of 567 177 ha and a reported total of 160 010 goats. A total of 55% (17/31) of producers were involved in both ‘opportunistic harvesting’ and commercial goat operations, and 45% (14/31) were specialised seedstock producers. Goats were the most important livestock enterprise on 55% (17/31) of surveyed properties. Stocking rate varied considerably (0.3–9.3 goats/ha) within and across surveyed properties and was found to be negatively associated with property size and positively associated with rainfall. Overall, 81% (25/31) of producers reported that the purpose of running goats on their properties was to target international markets. Producers also cited the importance of targeting markets as a way to increase profitability. Fifty-three percent of producers were located over 600 km from a processing plant and the high cost of freight can limit the continuity of goats supplied to abattoirs. Fencing was an important issue for goat farmers, with many producers acknowledging this could potentially add to capital costs associated with better goat management and production. Producers in the pastoral regions appear to have a low investment in pasture development and opportunistic goat harvesting appears to be an important source of income.
Publisher: CSIRO Publishing
Date: 2016
DOI: 10.1071/AN14794
Abstract: An interview-based questionnaire survey was conducted on 31 goat properties in New South Wales and Queensland in 2013. This study has gathered information on goat herd management, reproductive performance and animal health, and has identified constraints that may limit goat productivity. Producers from high-rainfall regions reported having full blood Boer goats for stud breeding. In contrast, producers from pastoral regions had rangeland goats and Boer-cross goats. Overall, 87% of the producers identified a natural breeding season in goats and 61% separated kids from their mothers at weaning. The weaning age varied between 3.0 and 6.0 months. A total of 52% of producers castrated male kids. Only 10% of producers used ultrasound to conduct pregnancy diagnosis on their goats. The reported pregnancy rate was 60% for the pastoral regions and 94% for the high-rainfall regions. The average prolificacy was 1.4 kids/doe and the kidding interval was 12 months. Overall, 68% of producers fed their goat herd with supplements, with the exception that most producers from western New South Wales and south-western Queensland did not use supplements. Producers considered gastrointestinal parasites (61%) and body lice (48%) as the main diseases associated with their goat herds, although only 52% mentioned drenching the animals with anthelmintics. In general, properties in the pastoral regions showed low pregnancy and kidding rates, early age at first mating, high mortality rates, poor performance of Boer bucks and lower weights and weight gain compared with properties in the high-rainfall regions. The survey has highlighted areas that require further study to validate the observations of producers, for instance, factors that may be limiting the fertility of Boer goats in rangeland environments, the incidence of diseases, the use of Kidplan and management activities to improve goat productivity.
Publisher: Elsevier BV
Date: 03-2021
Publisher: Oxford University Press (OUP)
Date: 10-2021
DOI: 10.1093/TAS/TXAB191
Abstract: The purpose of this study was to evaluate the effect of intranasal oxytocin administered at abrupt weaning on weaning behaviors such as walking distance and time devoted to walking, calf body weight, and plasma non-esterified fatty acids (NEFAs), β-hydroxybutyrate (β-HB), and cortisol. Twenty Simmental × Angus heifer calves were randomly assigned to one of two treatments: intranasal oxytocin (OXT n = 10) or intranasal saline (CON n = 10). All calves were given the respective intranasal treatment on the day of weaning (day 0) and then placed on pasture together. Calves were weighed and a blood s le was obtained on days 0, 1, 7, and 14 postweaning. Blood s les were subsequently used to quantify plasma NEFA, β-HB, and cortisol concentrations. All calves in both treatment groups were fitted with an in idual global positioning system that recorded calf location every 10 s for a 16-h period on days 0, 7, and 14 to quantify and evaluate walking behaviors. There was no treatment × day effect for distance walked (P = 0.82), walking time (P = 0.80), non-walking time (P = 0.88), area utilization index (P = 0.84), calf body weight (P = 0.82), average daily gain (P = 0.54), NEFA (P = 0.22), or cortisol concentrations (P = 0.32). There was a tendency for a treatment × day effect observed for average walking speed (P = 0.09) and β-HB (P = 0.10), such that calves in the CON treatment tended to have lesser average walking speeds on day 14 and tended to have greater β-HB concentration after weaning. There was a treatment effect (P = 0.02) for NEFA concentrations, with the CON calves having a greater plasma NEFA concentration throughout the study compared with OXT calves. These data imply that OXT calves may have had differing metabolic responses immediately after weaning that could have altered the mobilization of NEFA, but this change was not substantial enough to impact body weights or walking behaviors.
Publisher: Oxford University Press (OUP)
Date: 29-06-2021
DOI: 10.1093/TAS/TXAB113
Abstract: The objective of this experiment was to evaluate the impact of protein supplementation and pasture contamination with gastrointestinal nematodes on the mitigation of parasitic infection in grazing lambs. We hypothesized that there would be no difference between protein supplementation and newly sown pasture in evaluating lamb growth and health parameters associated with parasitism. Furthermore, we questioned if there would be an interaction between protein supplementation and pasture type. A total of 192, 60-d-old lambs (28.3 ± 5.1 kg) were randomly assigned to one of four treatments: 1) new pasture without supplementation (NN) 2) new pasture with supplementation (NS) 3) established pasture without supplementation (EN) and 4) established pasture with supplementation (ES) and grazed for 112 d. Lambs were supplemented at a rate of 1% body weight/d. Supplemented lambs had greater body weight (BW) and average daily gain (ADG) when compared with non-supplemented lambs (P & 0.04). Additionally, lambs on newly sown pasture demonstrated greater BW and ADG when compared with lambs grazing on established pasture (P & 0.05). For lamb health, lambs in the EN treatment group had the greatest FAMACHA eye scores and lowest packed cell volume (PCV) over the course of the 112-d grazing period (P & 0.05). Moreover, NS and ES treatment lambs demonstrated similar FAMACHA eye scores when compared with NN treatment lambs however, NN treatment lambs showed lower PCV when compared with NS and ES treatment lambs (P & 0.05). In evaluating fecal egg counts (FEC), lambs on new pasture or given supplement demonstrated lesser FEC when compared with those lambs on established pasture or not given supplement (P & 0.05). Sixty-four lambs were harvested to evaluate total abomasum nematode counts which demonstrated that Haemonchus contortus represented approximately 80% of total nematodes. Furthermore, based upon gross margin analysis, lambs given a protein rich supplement on pasture had a 9.3 kg increase in lamb BW whereas newly sown pasture had a 1.3 kg increase in lamb BW. A protein rich supplement given to lambs grazing pastures contaminated primarily with H. contortus or placing lambs on newly sown pasture increases lamb BW and improves parasite resiliency. Selection of parasite management strategies may be influenced by cost of production and market opportunities.
Publisher: Oxford University Press (OUP)
Date: 05-02-2022
DOI: 10.1093/JAS/SKAC032
Abstract: The objective of the present experiment was to evaluate the effect of maternal supplementation with fatty acids (FAs) and methionine (Met) during late gestation on offspring growth, energy metabolism, plasma resolvin (RvD1) concentration, carcass characteristics, and hepatic mRNA expression. Ewes (5 pens/treatment 3 ewes en) blocked by body weight (BW) were assigned to one of four treatments from day 100 of gestation until lambing. The treatments were: basal diet (NS) without FAs or Met supplementation FA supplementation (FS 1.01 % of Ca salts, containing n-3 FA) Met supplementation (MS 0.1 % of rumen-protected methionine) and FS and MS (FS-MS). At birth (day 0), ewes and lambs were placed in a common pen. On day 60, lambs were weaned, sorted by sex, blocked by BW, and placed on a common finishing diet for 54 d (FP). A lamb per pen was used for a glucose tolerance test (GTT) after the FP. Carcass characteristics were recorded on day 56. Lamb data were analyzed as a randomized complete block design with a 2 × 2 × 2 factorial arrangement, with repeated measurements when needed (SAS 9.4). At weaning, lambs born to MS- or FS-fed ewes were heavier than lambs born from FS-MS ewes (FS × MS × Time P = 0.02). A marginal significant FS × MS interaction (P = 0.09) was also observed on RvD1 lambs born to ewes in the NS and FS-MS treatments showed a lower RvD1 plasma concentration when compared with lambs born to FS- or MS-fed ewes. Lambs born to dams fed FA showed an increase (P = 0.05) in liver COX-2 mRNA relative expression. Lambs born to ewes supplemented with Met showed an increase (P = 0.03) in liver FABP4 mRNA expression. An FS × MS × Time interaction (P = 0.07) was observed in plasma glucose during the GTT lambs born from FS-fed ewes showed lower plasma glucose concentration than lambs born to Met-supplemented ewes at 2 min after bolus administration. During the GTT, a marginal significant effect (P = 0.06) was observed for the lamb average insulin concentration due to maternal Met supplementation during late gestation, where these lambs had the lowest plasma concentration. Contrary to our hypothesis, the interaction of FA and Met supplementation during late gestation did not show a greater positive effect on offspring postnatal growth and metabolism. However, the in idual supplementation of each nutrient has an effect on offspring development with a concomitant change in markers involved in the inflammatory response and energy metabolism.
Publisher: Elsevier BV
Date: 04-2020
Publisher: Oxford University Press (OUP)
Date: 04-2022
DOI: 10.1093/TAS/TXAC045
Abstract: Mud increases net energy requirements for cattle because mud and precipitation compromise the ability of the hair coat to insulate and maintain core body temperature of the cow. The increase in energy required for a gestating cow to compensate for a muddy environment is unknown. The objective of this study was to evaluate effects of muddy conditions on cow body weight (BW) and fetal growth during late gestation. Sixteen multiparous Angus cows (n = 8/treatment) were paired based on initial BW and one cow from each pair was randomly allocated to either the mud (MUD) or control (CON) treatment on day 213 of gestation. Pens in the CON group were bedded with wood chips, while pens in the MUD group were designed to create a muddy lot (average depth of 23.6 ± 5.8 cm). Cows were housed outdoors in idually and fed the same diet that consisted of a limit-fed total mixed ration. Each pair was fed to meet energy and protein requirements for maintenance and gestation. From day 213 to 269 of gestation, cows were weighed and s led for blood metabolites weekly. Data were analyzed as a randomized complete block design with repeated measurements (SAS 9.4). Though cows consumed the same amount of dry matter, cows in the MUD treatment weighed 37.4 kg less than cows in the CON treatment (P & 0.01) by day 269 of gestation. Cows in the MUD treatment decreased approximately half a body condition score (BCS), while cows in the CON treatment gained approximately 1 BCS during the treatment period (P & 0.01). There was no evidence of a treatment × day of gestation effect for 12th rib back fat (P = 0.85), rump fat (P = 0.48), total plasma protein concentrations (P = 0.85), or plasma 3-methylhistidine (P = 0.84) however, there was a marginally significant treatment × day of gestation effect for plasma non-esterified fatty acid concentration (P = 0.09). Despite differences in cow BW at the end of the treatment period, calf birth weight (P = 0.66) and calf total plasma protein (P = 0.27) were not different however, the ergence in cow BW remained marginally significant at parturition (P = 0.06). These results indicate that mud increased net energy requirements for cows in the MUD treatment, as calf birth weight was not different but maternal BW was decreased compared with cows in the CON treatment.
Publisher: CSIRO Publishing
Date: 2018
DOI: 10.1071/AN16162
Abstract: The objective of this study was to investigate the effects of nitrate treatment on the arterial blood gas and haemoglobin fractions from Bos indicus steers after exercise. Bos indicus steers (n = 12 mean bodyweight ± s.e.m., 397 kg ± 10.84 kg) were used in this experiment to investigate the effects of three dose rates of nitrate salts (0, 30 or 50 g of nitrate/day) on arterial blood gases, methaemoglobin concentration, carboxyhaemoglobin concentration, oxyhaemoglobin concentration, total haemoglobin concentration, haematocrit, heart rate, and respiratory rate after exercise. Increasing the dose rate of nitrate resulted in a decrease in the partial pressure of oxygen (P = 0.004) in blood. Steers treated with 50 g nitrate/day had a decrease in oxyhaemoglobin concentration (P = 0.001) and a concomitant increase in methaemoglobin (P = 0.001) and carboxyhaemoglobin (P = 0.001) compared with steers treated with 0 or 30 g nitrate/day. Steers dosed with 50 g of nitrate had greater heart rates immediately after the exercise regimen compared with the steers dosed with 30 g of nitrate (P = 0.043) or no nitrate (P = 0.018). There was no difference between treatments for respiratory rate (P = 0.673) or rectal temperature (P = 0.207) after the exercise regimen. Feeding nitrate to Bos indicus cattle results in a decrease in the oxygen carrying capacity of their blood. It is likely that doses of nitrate greater than 50 g per day for this class of animal could induce hypoxaemic trauma if cattle have exercise imposed after consuming a nitrate supplement.
Publisher: CSIRO Publishing
Date: 2021
DOI: 10.1071/AN20389
Abstract: Context The Australian government has approved a greenhouse gas (GHG) offset method that requires cattle to consume nitrate in the form of a lick block. Field studies demonstrating the effectiveness of this methodology have not been previously reported. Aims This experiment was conducted to determine the effects on productivity and health when nitrate lick blocks were provided as a supplement to grazing beef cattle. We hypothesised that beef cattle given access to nitrate lick blocks would have similar productivity compared with cattle offered urea lick blocks. Methods Bos indicus breeding cows (n = 76) grazed a 467-ha paddock near Charters Towers, Queensland, between May and November 2014. A two-way remote automatic drafting system enabled allocation of cattle to different treatments while grazing in a common paddock. Treatments were 30% urea lick blocks (30U), or molasses nitrate lick blocks (MNB). At monthly intervals liveweight (LW), body condition score (BCS), and blood methaemoglobin concentration were recorded. Estimates of in idual supplement intake were made on three separate occasions using a lithium marker technique. Results Mean daily supplement intake (±s.e.m.) of 30U (122 ± 13 g) was greater (P & 0.001) than MNB (67 ± 8 g). Lesser MNB intake was associated with greater variability for in idual supplement intake, a greater proportion of non-consumers of supplement during July (P & 0.05) and reduced voluntary supplement intake until October (P & 0.001). Increasing MNB consumption during October and November was accompanied by elevated blood methaemoglobin concentration (P & 0.001). It was estimated that cattle offered MNB had insufficient supplementary nitrogen intake throughout the study to resolve rumen degradable nitrogen deficiency from grazed forage. Consequently, cattle provided access to MNB demonstrated conceptus free liveweight loss and lesser BCS compared with cattle treated with 30U (P & 0.001). Conclusion Nitrate lick blocks were ineffective as a dual-purpose non-protein nitrogen supplement and methane mitigant for beef cattle grazing poor quality forage. Further field experiments are required to determine if there may be situations where this GHG offset methodology is efficacious. Implications Caution is advised in implementing GHG mitigation methods that involve the use of nitrate lick blocks.
Publisher: CSIRO Publishing
Date: 08-07-2021
DOI: 10.1071/AN20148
Abstract: Context Nitrate salts can be utilised by the rumen bacteria as a nitrogen source. Nitrate salts can induce a methaemoglobinaemia in cattle if consumed in sufficient quantities. Methaemoglobinaemia is the principal factor that leads to the onset of clinical signs for nitrate toxicity in cattle. A methaemoglobin concentration ≥20% is considered unsafe for cattle. There are, however, limited studies on the longer-term effects of nitrate supplementation on methaemoglobin formation in Bos indicus steers consuming forage that is reflective of northern Australia’s poor quality, native pasture in the dry season. Aims We hypothesised that the Australian government’s recommended daily dose of nitrate salts given to Bos indicus cattle would not cause a methaemoglobinaemia in the blood % throughout a 70 day treatment period. Methods A 70 day study was conducted to determine the methaemoglobin, carboxyhaemoglobin, total haemoglobin, growth rate and forage intakes of cattle supplemented with a non-protein-nitrogen treatment containing nitrate (6.48 g NO3/kg dry matter intake (DMI) or no nitrate and consuming a chaffed Flinders grass hay (Iseilema spp.), a C4 species. The dose rate of nitrate was selected to match the Australian government guidelines. Ten 3-year-old fistulated Bos indicus steers (mean liveweight ± s.d., 400.7 ± 26.2 kg) were randomly allocated into two groups (n = 5). Blood s les were collected at 0, 2, 4 and 6 h after treatment with nitrate or no nitrate on days 10, 30, 50 and 70 to measure haemoglobin fractions in the blood. Key Results Nitrate treatment caused the mean methaemoglobin (P 0.001), peak methaemoglobin (P 0.001) and carboxyhaemoglobin (P = 0.008) concentration to be greater in the blood of steers compared with steers given no nitrate. Nitrate treatment had no general effect on the total haemoglobin, DMI or bodyweight of steers. Conclusions Bos indicus steers treated with 6.48 g NO3/kg DMI develop a methaemoglobinaemia that does not exceed 20% of total haemoglobin for 70 days. This data supports the Australian government’s recommended feeding rate of nitrate to sedentary Bos indicus steers. Implications The Australian government’s method for feeding nitrate to cattle is safe under the conditions of this study.
Publisher: Public Library of Science (PLoS)
Date: 09-09-2020
Publisher: Wiley
Date: 27-02-2017
DOI: 10.1111/AVJ.12560
Abstract: Vitamin A deficiency was diagnosed in a herd of 97 19-month-old Braford heifers in the Mitchell Grass Downs (Astrebla spp.) bioregion of Hughenden in north-western Queensland during November 2015. Two heifers died after a 48-h history of sternal recumbency and of the 19 that had neurological signs, 7 were blind. Histological changes in the optic nerves of the two necropsied cattle were consistent with vitamin A deficiency. This diagnosis was supported by vitamin A concentrations in fresh liver s les of 5 and 6 mg/kg wet tissue (reference range, 100-175 mg/kg) despite treatment of the cattle with twice the recommended dose of parenteral vitamin A 3 weeks prior to s ling. Rainfall on the property during the 2 years before the outbreak was less than the annual rainfall average of 464 mm, with a total of 281 mm in 2014 and 117 mm from January to November in 2015, most of this falling in January. Plant assays for both β-carotene and crude protein concentrations in dry matter (DM) were less than the recommended dietary requirements for beef cattle (0.30 mg/kg DM and 56 g/kg, respectively).
Publisher: Oxford University Press (OUP)
Date: 2023
DOI: 10.1093/JAS/SKAC319
Abstract: Changes in the environment, including nutritional changes, can influence fetal and postnatal development of the offspring, which can result in differences in growth, metabolism, reproduction, and health later in life. In beef cattle research on energy and protein restriction during late gestation appears to be contradictory. Therefore, in this review, we will examine the nutrient requirements recommended for this period. We are summarizing contradictory data on effects on offspring performance with possible explanations of the reason for why the data seems contradictory. We will finish by discussing some areas that we consider important for further research to increase the knowledge on how maternal nutrition influences offspring development. In particular, suggestions are provided on the need for more accurately measuring nutrient and energy supply and use and the impact on subsequent epigenetic effects. This will improve understanding of nutritional effects during gestation on offspring performance.
Publisher: Oxford University Press (OUP)
Date: 13-07-2022
DOI: 10.1093/JAS/SKAC239
Abstract: Sixty Angus × SimAngus-crossbred steers (body weight [BW] 279 ± 16 kg) were used to evaluate the effect of calcium salts of palm oil inclusion (CPO) and the amount of feed offered (AFO) on plasma glucose-dependent insulinotropic polypeptide (GIP) concentration and its association with energy metabolism and marbling score (MS) in feedlot steers. Steers were blocked by BW and gain to feed (G:F) and randomly assigned to in idual feedlot pens. Treatments (2 × 2 factorial) consisted of ad libitum-fed steers without (ANF) or with (AWF) the inclusion of CPO or restricted-fed steers (85% of the ad libitum intake of ANF) without (RNF) or with the inclusion of CPO (RWF). After weaning, steers were adapted to in idual pens and fed a corn silage-based diet for 30 d and subsequently placed in a ground corn (GC)–based diet. Diets were given ad libitum or at 85% of the ANF intake and with or without CPO. After 59 d on the finishing diet, all steers had ad libitum access to the finishing diet until harvest. Measurements of CO2 emission and O2 consumption to estimate respiratory quotient (RQ) were taken (n = 9/treatment). Correlations between plasma GIP and insulin concentrations and RQ were analyzed. A linear regression was performed to evaluate the association of plasma GIP and MS. All data were analyzed using the PROC MIXED procedure of SAS. During the first 103 d of the trial, there were AFO × CPO interactions (P ≤ 0.01) for BW, dry matter intake (DMI), average daily gain (ADG), and net energy for maintenance (NEm) intake. Ad libitum-fed steers without CPO presented the greatest DMI among dietary treatments and had greater BW and ADG compared with steers in the RWF and RNF treatments. After all steers had ad libitum access to dietary treatments, steers that were previously restricted showed a 30% and 19% increase (P ≤ 0.01) in ADG and G:F, respectively. There was a three-way interaction time × CPO × AFO (P = 0.04) for plasma GIP concentration. There was no correlation (P = 0.96) of GIP with RQ, whereas insulin demonstrated marginal significance for a positive (P = 0.07) and negative (P = 0.08) correlation with plasma GIP and RQ, respectively. There was no association (P = 0.30) between GIP and MS. These data indicate that GIP secretion results from an interaction between CPO and energy intake depending on the time relative to feed intake that GIP might indirectly regulate energy metabolism through insulin secretion, and that GIP does not appear to be associated with MS.
Publisher: Elsevier BV
Date: 2008
DOI: 10.1016/J.PHYTOCHEM.2007.08.017
Abstract: Plants have been used throughout history for their medicinal properties. This use has often focused on human health but plants have also been, and still are, applied in ethnoveterinary practice and animal health management. In recent times, the use of synthetic chemicals has become prevalent. Public awareness of the potential environmental and health risks associated with heavy chemical use has also increased. This has put pressure on regulatory bodies to reduce the use of chemicals in agriculture. The most striking ex le is the 2006 banning of antibiotics in animal feed by the European Union. Moves such as this have increased the drive to find alternatives to synthetic chemicals and research has again turned to the use of plant bioactives as a means of improving animal health. Current scientific evidence suggests there is significant potential to use plants to enhance animal health in general and that of ruminants (cattle, deer, sheep, etc.) in particular. Active areas of research for plant bioactives (particularly saponin and tannin containing plants) include reproductive efficiency, milk and meat quality improvement, foam production/bloat control and methane production. Nematode control is also a significant area of research and the evidence suggests a much broader range of phytochemicals may be effective. This review presents a summary of the literature and examines international research efforts towards the development of plant bioactives for animal health.
Publisher: Elsevier BV
Date: 2022
DOI: 10.1016/J.PREVETMED.2021.105546
Abstract: Salmonella contamination of livestock feed is a serious veterinary and public health issue. In this study we used a systematic review to assess the prevalence and characterization of Salmonella isolates detected in raw feed components, feed milling equipment and finished feed from 97 studies published from 1955 to 2020 across seven global regions. Eighty-five studies were included in a meta-analyses to estimate the combined prevalence of Salmonella detection and to compare the risk of contamination associated with different s le types. We found the overall combined prevalence estimate of Salmonella detection was 0.14 with a prevalence of 0.18 in raw feed components, 0.09 in finished feed and 0.08 in feed milling equipment. Animal based raw feed components were 3.9 times more likely to be contaminated with Salmonella than plant based raw feed components. Differences between studies accounted for 99 % of the variance in the prevalence estimate for all s le types and there was no effect of region on the prevalence estimates. The combined prevalence of Salmonella detection in raw feed components decreased from 0.25 in 1955 to 0.11 in 2019. The proportion of Salmonella isolates that were resistant to antimicrobials was largest for amikacin (0.20), tetracycline (0.18) streptomycin (0.17), cefotaxime (0.14) and sulfisoxazole (0.11). The prevalence of Salmonella contamination of animal feed varies widely between in idual studies and is an ongoing challenge for the commercial feed industry. Control relies on the vigilant monitoring and control of Salmonella in each in idual mill.
Publisher: Elsevier BV
Date: 04-2020
DOI: 10.1016/J.DOMANIEND.2019.106387
Abstract: Providing the neuropeptides oxytocin and vasopressin intranasally increased concentrations in plasma and cerebral spinal fluid in humans and primates, respectively. This is of interest because of the documented anxiolytic effects of oxytocin observed in humans and rodents. To date, a transnasal approach of hormone administration has not been investigated in beef cattle. Defining the pharmacokinetics of intranasal oxytocin in cattle is necessary for determining optimum s ling and dosing timelines for future investigations. Five, weaned Bos taurus steers were used in a 3 × 3 Latin square design. Treatments included 1) 0.33 IU oxytocin/kg BW (A, n = 5), 2) 0.66 IU oxytocin/kg BW (B, n = 5), and 3) 1.32 IU oxytocin/kg BW (C, n = 5). Steers were acclimated to handling and restraint procedures for 4 wk leading up to the start of the experiment. Frequent blood collection occurred every 2 min for the first 30 min and every 5 min for the second 30 min, relative to administration of intranasal treatment. No treatment by time interaction was detected however, there was an effect of time (P < 0.001) and treatment (P = 0.002) on oxytocin concentrations over time. Pharmacokinetic parameters, determined by PKSolver excel add-in, demonstrated an average maximum concentration (C
Publisher: CSIRO Publishing
Date: 2016
DOI: 10.1071/AN14886
Abstract: Twelve Bos indicus steers (liveweight ± s.d., 317.8 ± 28.5) kg were used in an experiment to examine two factors: daily nitrate dose (0, 30, 40 or 50 g of nitrate/day) and feeding frequency (once or twice a day) on methaemoglobin concentration, daily peak methaemoglobin concentration, rate of incline for methaemoglobin concentration, carboxyhaemoglobin concentration, oxyhaemoglobin concentration, total haemoglobin concentration, haematocrit and dry matter intake of Flinders grass hay. Increasing the dose rate of nitrate increased the fraction of methaemoglobin in the blood of steers (P = 0.014). A highly significant effect was demonstrated for the interaction of dose rate × day (P 0.001). For once a day intake of nitrate, the dose rates of 40 and 50 g per day showed a greater increase in mean methaemoglobin values than for the 0 and 30 g of nitrate per day. Increasing the dose rate of nitrate also increased the daily peak methaemoglobin fraction and the rate of incline to peak methaemoglobin values for both once and twice a day feeding of the nitrate supplements. However, increasing the dose of nitrate had no significant overall effect on total haemoglobin, deoxyhaemoglobin, carboxyhaemoglobin, haematocrit or dry matter intake. Twice a day feeding of nitrate decreased the formation of methaemoglobin in the blood of Bos indicus steers. This study demonstrates that caution should be exercised when feeding nitrates as a non-protein nitrogen source to cattle grazing low quality pastures in northern Australia.
Publisher: Elsevier BV
Date: 11-2021
Publisher: CSIRO Publishing
Date: 2018
DOI: 10.1071/AN16002
Abstract: This experiment has quantified the methane abatement potential of nitrate in the context of extensively managed cattle. The experimental protocol consisted of two, 4 × 4 Latin square design using eight rumen fistulated Bos indicus steers fed Flinders grass (Iseilema spp.) hay ad libitum. The treatments were Control (nil nitrogen supplement), urea (32.5 g/day urea) and two levels of calcium nitrate: CaN1 and CaN2 (to provide 4.6 g and 7.9 g NO3/kg DM equivalent to ~0.46% and 0.80% of DM, respectively). Complete supplement intake was ensured by dosing any supplement that had not been voluntarily consumed, through the rumen fistula, 1 h after feeding. Enteric methane production was measured using open circuit respiration chambers. Methane yield (g/kg DM intake) from the CaN2 treatment tended to be lower (P 0.07) than either the Control or urea treatments. There were no significant differences in methane yield between Control, urea or CaN1 treatments. Mean blood methaemoglobin concentrations were significantly (P 0.001) higher for CaN2 animals compared with the Control, urea or CaN1 treatments. In addition, a significant time effect after dosing (P 0.001) and a significant interaction between treatment and time after dosing (P 0.001) was apparent. Overall mean total volatile fatty acid concentration was 74.0 ± 1.53 mM with no significant treatment effect, but a significant effect for both time of s ling (3 h vs 6 h) within days and among 7 s ling days. The inclusion of calcium nitrate as a non-protein-N source significantly reduced the molar proportions of butyrate (P 0.001), iso-butyrate (P 0.05) and iso-valerate (P 0.001) compared with the Control. The provision of nitrate supplements, providing both a NPN and an alternative sink for H that would otherwise support enteric methanogenesis, has some potential. In extensive grazing systems effective methane abatement strategies are required. The elevated concentration of MetHb using CaN2 suggests that the strategy of replacing urea with nitrate in supplements fed to extensively managed cattle in the northern rangelands may be inappropriate where supplement intake cannot be controlled on an in idual animal basis and forage quality is seasonally variable.
Publisher: CSIRO Publishing
Date: 2011
DOI: 10.1071/AN10266
Abstract: Assessing the differences in gross margins for a north-western Queensland beef-production system was undertaken using herd-budgeting software. The analysis reviewed the viability of producing beef for the domestic market from either a steer or bull production system. A hypothetical herd of 1200 breeders was created for the case study evaluation. An integrated beef production system from breeding to feedlot finishing was found to be less profitable for bull beef production than for steers at the current market prices. Although bull production was more profitable than steer production during the feedlot phase, the production of bulls in this phase failed to compensate for the earlier economic losses in the weaning phase of –AU$24.04 per adult equivalent for bulls. During the feedlot phase, bull production systems had lower break-even sale prices than did steer production systems. In reviewing two pricing scenarios for bulls, it was found that marketing bulls at the same price as steers was the most profitable production system. We conclude that the production of bull beef from a north-western Queensland production system can be profitable only if bulls can be sold without discount relative to steers.
Publisher: Elsevier BV
Date: 2020
DOI: 10.1016/J.DOMANIEND.2019.07.007
Abstract: Changes in the physiological, psychological, and behavioral manifestations of stress have been observed in association with increases in circulating oxytocin (OXT). Providing OXT intranasally has been shown to attenuate stressor-induced hypothalamo-pituitary-adrenal (HPA) axis activation in humans and rodents however, anxiolytic effects may be context and species specific. The present study aimed to investigate the effect of intranasal OXT supplementation on stressor-induced activation of the HPA axis in beef cattle. We hypothesized that OXT would attenuate activation of the HPA axis, ultimately decreasing plasma cortisol and adrenocorticotropic hormone (ACTH). Twenty-eight Bos taurus heifers were blocked by bodyweight and randomly allocated to one of four treatment groups, in a 2 × 2 factorial arrangement: (1) saline, isolated, standing, and unrestrained (S-isolation stress [IS], 0.015 mL/kg BW 0.9% isotonic saline, n = 7) (2) saline, isolated, and restrained (S-restraint and isolation stress [RIS] 0.015 mL/kg BW 0.9% isotonic saline n = 7) (3) OXT, IS (OXT-IS, 0.3 IU/kg BW oxytocin n = 7) and (4) OXT and RIS (OXT-RIS, 0.3 IU/kg BW oxytocin n = 7). Oxytocin and saline were administered intranasally. Intranasal treatments were given followed by a waiting time of 30 min when each of the stress treatments was applied for 2 h. Blood s les were collected via jugular catheters directly after stressor application and every 10 min thereafter, for 2 h. Cortisol concentrations increased over time in animals exposed to RIS (P < 0.01) and decreased over time in animals exposed to IS (P < 0.01). Concentrations of ACTH decreased over time for the IS-treated heifers but remained elevated for the RIS-treated heifers (P < 0.01). Under the conditions of the present study, OXT treatment did not affect measured indicators of HPA axis activation. A treatment × time interaction (P < 0.01) was detected for OXT, such that OXT heifers exhibited greater initial OXT concentrations followed by a decline saline-treated heifers had consistently stable oxytocin concentrations. The RIS-treated heifers increased their glucose (P < 0.01) and lactate (P < 0.01) concentrations throughout the application of the stressors compared with the IS-treated heifers. Overall, restraint stress increased cortisol and oxytocin in B taurus heifers compared with heifers subjected only to isolation. Finding a more intermediate stress model may better allow for detection of the effects of oxytocin on the stress response.
Publisher: Elsevier BV
Date: 04-2015
Publisher: Elsevier BV
Date: 04-2015
Publisher: CSIRO Publishing
Date: 2009
DOI: 10.1071/AN09019
Abstract: A technique for the safe s ling of blood from cattle during transportation is described. The technique was validated using four 2.5-year-old Bos indicus steers held in stalls on a stationary body truck for 2 h, transported for 4 h and then held on a stationary truck for a further 2 h. The length of time required to take a blood s le from one animal using this technique was 30 s. Information gathered using this technique will be helpful in understanding the physiological reactions of cattle to transportation.
Publisher: Public Library of Science (PLoS)
Date: 19-07-2022
DOI: 10.1371/JOURNAL.PONE.0271673
Abstract: Glucose tolerance tests (GTT) are commonly performed in beef cattle to evaluate the glucose-insulin signaling pathway. Blood s les are obtained via a catheter and then transferred back to the laboratory for further analysis. A hand-held glucometer used chute-side can make performing GTT’s and quantifying blood glucose concentration much easier and faster for research purposes. The purpose of this study was to evaluate the agreement between a hand-held electronic glucometer (Precision Xtra Abbott Diabetes Care Inc., Mississauga, ON, Canada) for chute-side use in beef cattle compared with a colorimetric assay in the laboratory (Stanbio Glucose LiquiColor Stanbio Laboratory, Boerne, TX, USA). A GTT was performed on 13 Simmental × Angus steers during the growing phase. Blood s les were obtained via a jugular catheter. Glucometer readings were taken immediately after blood was s led from the jugular with no preservative, and laboratory measurements were conducted on plasma preserved with sodium fluoride. A paired t-test ( P = 0.40), Pearson’s correlation ( P 0.001 r = 0.95), Bland-Altman plot, and Lin’s concordance correlation coefficient (LCCC = 0.90) were completed to evaluate the performance of the glucometer relative to the results from the laboratory assay. Based on the results, we conclude that the glucometer is an acceptable method for measuring blood glucose concentration in beef cattle under field conditions.
Publisher: Wiley
Date: 09-02-2018
DOI: 10.1111/JPN.12877
Abstract: The effects on rumen kinetics after feed and water had been deprived for 72 hr were studied using four fistulated Bos indicus steers. The animals were assigned in a 2 × 4 crossover design with two treatments: feed and water ad libitum (control) and no feed and water for 72 hr (deprived) with four steers per treatment over two time periods. Feed and water deprivation caused decreases in the numbers of cellulolytic bacteria (1.4 vs. 0.4 cfu × 10
Publisher: Oxford University Press (OUP)
Date: 11-2007
DOI: 10.2527/JAS.2006-193
Abstract: The physiological and metabolic effects of prophylactic treatment with osmolytes were investigated using twenty-four 2.5-yr-old Bos indicus steers. Animals were allocated to 1 of 4 treatment groups: 1) control, feed and water deprived for 48 h (n = 6) 2) transported, transported for 48 h (n = 6) 3) glycerol, dosed with glycerol (2 g/kg of BW) and then transported for 48 h (n = 6) and 4) betaine, dosed with betaine (0.25 g/kg of BW) then transported for 48 h (n = 6). Body water, electrolytes, blood pH and gases, plasma lactate, glucose, albumin, total protein, anion gap, strong ion difference, total weak acids, and BW were determined at the conclusion of 24 and 48 h of transportation. The glycerol group had greater body water volumes than the control (P = 0.05) and transported (P = 0.02) groups. The glycerol, transported, and betaine groups had lower (P = 0.02) plasma Mg concentrations than the control group at 24 h, whereas the glycerol group maintained lower (P = 0.04) plasma concentrations of Ca than the control group. The betaine group had lower (P = 0.04) hematocrit than the control group at 24 and 48 h. Plasma bicarbonate and pCO2 were 13 and 17% greater (P = 0.01 and 0.04, respectively) in the glycerol group at 24 h compared with control and transported groups. However, the ratio of [HCO3]/[CO2] in the glycerol group did not differ from the other groups and thereby maintained pH. The glycerol group maintained a 30% greater (P < 0.001) plasma concentration of glucose than the control group, and 14% greater (P = 0.05) than the transported and betaine groups. In contrast, betaine had little effect on increasing blood glucose compared with glycerol. Glycerol-linked hyperhydration at 24 h may not only help to conserve water loss during long distance transportation, but the increased blood glucose may have an important protein-sparing effect due, in part, to greater insulin concentrations inhibiting the breakdown of muscle proteins, thus, countering the amino-acid mobilizing effect of cortisol after 24 h. Therefore, the osmolyte glycerol shows promise as a prophylactic treatment for attenuating the effects of long distance transportation by maintaining body water, decreasing the energy deficit, and preserving health and muscle quality.
Publisher: CSIRO Publishing
Date: 2019
DOI: 10.1071/RD18159
Abstract: Summer infertility continues to undermine pig productivity, costing the pig industry millions in annual losses. The boar’s inefficient capacity to sweat, non-pendulous scrotum and the extensive use of European breeds in tropical conditions, can make the boar particularly vulnerable to the effects of heat stress however, the link between summer heat stress and boar sperm DNA damage has not yet been demonstrated. Semen from five Large White boars was collected and evaluated during the early dry, late dry and peak wet seasons to determine the effect of seasonal heat stress on the quality and DNA integrity of boar spermatozoa. DNA damage in spermatozoa during the peak wet was 16-fold greater than during the early dry and nearly 9-fold greater than during the late dry season. Sperm concentration was 1.6-fold lower in the peak wet than early dry whereas no difference was found across several motility parameters as determined by computer-assisted sperm analysis. These results demonstrate that tropical summer (peak wet season) induces DNA damage and reduces concentration without depressing motility in boar spermatozoa, suggesting that traditional methods of evaluating sperm motility may not detect inherently compromised spermatozoa. Boar management strategies (such as antioxidant supplementation) need to be developed to specifically mitigate this problem.
Publisher: Oxford University Press (OUP)
Date: 2021
DOI: 10.1093/TAS/TXAA233
Abstract: Weaning and transport represent a high stress time for calves. Preconditioning (PC) by weaning before the transport separate these stressors. The stressors generate oxidative stress, which can be reduced by mineral and vitamin supplementation (MVS) with an antioxidant capacity. Our objective was to evaluate the effect of PC and MVS on performance of steers. The experiment used a 2 × 2 factorial arrangement design, considering a 26-d PC treatment from weaning to transport to the feedlot (day 0), and injectable MVS on days −45, −26, and 0. The MVS consisted of Cu, Zn, Mn, Se, vitamin E (0.2, 0.8, 0.2, 0.1, and 1 mg/kg body weight [BW], respectively), and vitamin A (1,190 IU/kg). Sixty Angus-crossbred steers (186.4 ± 27.6 kg) were randomly assigned to the four treatments (MVS+PC N+PC MVS+N N+N n = 15 per treatment). BW was recorded on days −45, −26, 0, 8, 15, and 29. On day 0, an additional BW was taken 30 min after the 5-h transportation (day 0.5). Between days 0 and 29, dry matter intake (DMI) and average daily gain (ADG) to DMI ratio (G:F) were measured. Between days −26 and 29 plasma concentrations of glucose, nonesterified fatty acids (NEFA), cortisol, insulin, total antioxidant status (TAS), and thiobarbituric acid-reactive substances were evaluated. Data were analyzed using the MIXED procedure of SAS with repeated measures, using treatment, time, and treatment × time as fixed effects and steer as a random effect. Between days −26 and 0, there was an interaction of MVS × PC (P ˂ 0.01) for ADG. From days −26 to 0, N+N and N+PC had the greatest and lesser ADG, respectively. On day 0.5, no-PC steers tended to lose BW, whereas the PC steers tended to gain BW (P = 0.09). In the period days 0 to 8, there were no differences (P ≥ 0.27) in DMI, but the PC steers had greater G:F and ADG (P & 0.01) compared with no-PC steers. Plasma NEFA concentration on day 0 was affected by MVS × PC (P & 0.01) because MVS decreased plasma NEFA concentration in no-PC steers, but it increased in the PC steers. Plasma concentrations of glucose, insulin, and cortisol did not differ among treatments (P ≥ 0.23). There was an MVS × PC interaction (P = 0.09) for TAS on day 0 N+N had the greatest TAS concentrations and MVS+N had the lowest TAS concentrations. In conclusion, a 26-d PC decreased steers BW compared with no-PC steers. The BW loss during PC was not recovered 29 d after feedlot entry. Despite this BW loss, MVS treatment decreased BW loss in the steers allocated to PC treatment on the day of transport.
Publisher: CSIRO Publishing
Date: 22-12-0001
DOI: 10.1071/AN20393
Abstract: Context Transportation, a common practice in cattle production, activates the hypothalamo-pituitary-adrenal (HPA) axis, ultimately increasing glucocorticoids and altering the cellular immune system in cattle. Oxytocin attenuates the HPA axis in mammals. Intra-nasal oxytocin supplementation has been investigated in human and rodent models, revealing anxiolytic effects. The aim of this study was to assess the ability of exogenous oxytocin to mitigate stress and inflammatory responses in transported cattle. Aims We hypothesised that Bos indicus cattle treated with intra-nasal oxytocin would demonstrate more stable cortisol and inflammatory responses when subjected to handling and 6 h of road transportation compared with cattle treated with intra-nasal saline. Methods Thirty, Bos indicus steers were allocated to one of three treatments: (1) intra-nasal sterile saline and held in the yard for 6 h (S-NT n = 10), (2) intra-nasal sterile saline and transported for 6 h (S-T n = 10), and (3) intra-nasal oxytocin (0.3 IU/kg bodyweight) and transported for 6 h (OXT-T n = 10). Blood was collected at 0, 6, 48, and 72 h and analysed for haematological parameters, cortisol, glucose and lactate. Key results A treatment × time effect (P 0.05) was detected for lymphocytes and basophils, such that oxytocin helped maintain baseline counts. A treatment × time effect was detected for neutrophils and eosinophils such that counts were greater and lesser, respectively, directly following transport (P 0.01) for transported treatments. Total leukocyte counts were not different between treatments (P = 0.96). No differences were observed between treatments or over time for plasma cortisol concentration (P = 0.46). A treatment × time interaction (P 0.03) was detected for bodyweight such that transportation, independent of intra-nasal treatment, resulted in increased weight loss compared with the non-transported treatment. Conclusion Oxytocin altered circulating basophils in Bos indicus cattle exposed to short-duration transport. Although no effect on the HPA axis was detected via changes in cortisol concentration, road transport induced some signs of an acute inflammatory response directly following transportation. Implications Providing exogenous oxytocin improved the maintenance and recovery of some cellular immune system parameters in Bos indicus steers subject to short duration transport and more research is needed to explicate a more comprehensive understanding of such effects.
Publisher: Wiley
Date: 10-2006
Publisher: Elsevier BV
Date: 02-2017
DOI: 10.1016/J.THERIOGENOLOGY.2016.10.014
Abstract: This study aimed to evaluate ovarian follicular dynamics in goats submitted to synchronization of estrus and supplemented with diets that differed in the metabolizable energy source and amount of energy. The experiment was carried out using 42 does allocated into three treatments, fed for 9 days with a ration providing 1.0 times maintenance containing maize (1 MM, n = 14) or without maize (1 M, n = 14) or a ration providing 1.5 times maintenance containing maize (1.5 MM, n = 14). Estrus was synchronized with two injections of cloprostenol given 7 days apart. Does were also treated with intravaginal progesterone inserts and eCG. The number of ovulations and size of the follicles were measured using ultrasonography on Days 10, 11, and 12 after the start of the dietary treatment. The interval to estrus and duration of estrus did not differ between treatments (P = 0.382). Does fed with 1 and 1.5 MM had a similar number of ovulations but a greater number of ovulations than goats fed with 1 M (P = 0.028). The mean number of small, medium, large, and total number of follicles on Days 10 to 12 of ultrasound evaluations did not differ (P = 0.204) between treatments, but mean numbers changed over time (P 0.258) by any of the treatments. In summary, the inclusion of maize in the ration can stimulate ovulation rate at maintenance level. Similar results between groups fed diets that included maize and provided metabolizable energy at 1.0 and 1.5 maintenance demonstrate that to increase the ovulation rate when synchronizing estrous cycles in does, dietary supplementation with maize can be restricted to provide a maintenance level of metabolizable energy only, which would reduce dietary costs.
No related grants have been discovered for Anthony Parker.