ORCID Profile
0000-0003-3458-3091
Current Organisations
Queensland Department of Agriculture Fisheries and Forestry
,
Papua New Guinea University of Technology
,
Charles Sturt University - Wagga Wagga Campus
,
University of New England
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Publisher: CSIRO Publishing
Date: 2023
DOI: 10.1071/ZO22046
Publisher: CSIRO Publishing
Date: 21-04-2021
DOI: 10.1071/AN19139
Abstract: Context Dual-purpose crops (for grazing and grain) are an important part of the feedbase in mixed farming systems in the medium-rainfall zone of southern Australia. On these farms, non-wool sheep breeds such as the Dorper may provide an opportunity to increase lamb production while reducing labour costs compared with traditional sheep breeds. Aims This study was designed to compare lamb production systems based on White Dorper and Merino ewes joined to a terminal sire, while exploiting a feedbase that included dual-purpose crops. Methods Two experiments were conducted at Wagga Wagga, New South Wales, during 2013 (Expt 1) and 2014 (Expt 2). In February in both experiments, White Dorper ewes were joined to either White Dorper or White Suffolk rams (lambs designated DD and WSD, respectively), and Merino ewes were joined to White Suffolk rams (lambs designated WSM). In Expt 1 a dual-purpose wheat (Triticum aestivum L.) crop was established and the paddock sub ided into nine plots (0.93 ha each). Pregnant ewes were allocated to plots on the basis of genotype (DD, WSD or WSM grazing separate plots) after blocking for number of fetuses identified at mid-pregnancy scanning, with three replicates based on genotype. Lambing commenced on 28 June, and ewes grazed the crop from 27 June to 14 August and then continued to graze in the same groups on a lucerne (Medicago sativa L.)–clover (Trifolium spp.) pasture sub ided into nine plots (2.1 ha), maintaining the same replicates until weaning on 2 October. In Expt 2, the cropping paddock was sub ided into six plots (1.86 ha each) sown to either dual-purpose wheat or canola (Brassica napus L.), with three replicates. Lambing commenced on 13 July. Merino and White Dorper ewes grazed the crops concurrently from 19 June to 12 August, and then lucerne–clover pasture until weaning on 29 September. In both experiments a mineral supplement was fed to ewes grazing wheat during the crop-grazing period. Key results Feed on offer was low (0.33 t/ha) in dual-purpose wheat crops at the start of grazing in Expt 1 and did not differ among genotypes at the cessation of grazing crops. Feed on offer was higher in wheat than canola at the commencement of grazing in Expt 2 (2.6 vs 2.3 t/ha P = 0.009), and a higher stocking rate was maintained on wheat than canola from the start of lambing. White Dorper ewes maintained a higher body condition score than Merino ewes throughout both experiments. In Expt 2, some ewes had serum magnesium and calcium levels below the normal range, and a high number of ewes (20%) required assistance at lambing. Number of lambs weaned per ewe scanned pregnant was similar among genotypes in both experiments. WSD lambs were heaviest (P 0.05) at weaning and DD lambs had greatest (P 0.05) fat depth over the eye muscle at weaning. Conclusions and implications When grazed on a feedbase typical of mixed farms in the medium-rainfall zone of southern NSW, White Dorper ewes were in higher body condition than Merino ewes however, reproductive rates were similar. Joining White Dorper ewes to a terminal sire may increase weaning weight of lambs compared with joining to a White Dorper ram, or a Merino maternal system.
Publisher: Oxford University Press (OUP)
Date: 10-2022
DOI: 10.1093/TAS/TXAC141
Abstract: The feeding value for ruminants of green hemp biomass, from the low Δ9-tetrahydrocannabinol (Δ9-THC) variety of Cannabis sativa L., is unknown. Twelve Merino ewes were in idually penned and randomly allocated on a stratified liveweight basis to one of two pelleted dietary treatments, control (0% hemp, n = 6) or hemp (42% green hemp biomass, n = 6) that delivered a diet meeting the nutrient requirements of the animals. The experimental period consisted of 17 d dietary and housing adaptation, followed by 7 d total urine and feces collection for determination of apparent nutrient digestibility. A ruminal fluid s le was collected on day 27 and assessed for pH, ammonia, volatile fatty acid (VFA), and cannabinoid concentrations. A blood s le from the jugular vein and incisional subcutaneous fat biopsy from an area around the base of the tail were collected on day 28 with additional fat biopsies taken 35 d and 140 d post-feeding to measure cannabinoids. The dry matter (DM), organic matter (OM), and crude protein (CP) digestibilities, along with total VFA concentration did not differ (P = 0.713) between the two diets however, acid detergent fiber (ADF) and neutral detergent fiber (NDF) digestibilities (P & 0.001), water intake (P = 0.023), and fecal water output (P & 0.001) were significantly lower for the sheep-fed Hemp. Rumen pH did not vary (P = 0.256) between diets, but ruminal ammonia concentration was significantly lower (P = 0.024) for sheep consuming Hemp. Sheep-fed Hemp had significantly greater molar proportions of butyric (P = 0.039) and hexanoic (P = 0.012) acids and lower molar proportions of propionic acid (P = 0.003). There were no differences between diets for N intake (P = 0.175), fecal N output (P = 0.253), and N balance (P = 0.695), with all sheep in positive N balance however, there was significantly lower (P = 0.001) urinary N output for sheep-fed Hemp. Cannabidiolic acid (CBDA) and tetrahydrocannabinolic acid (THCA) were detected in plasma of all sheep-fed Hemp. ∆9-tetrahydrocannabinol was present in the subcutaneous fat of four of the six sheep on the final day of being fed Hemp, and in all (six) sheep 35 d post-feeding and one sheep 140 d post-feeding Hemp. No cannabinoids were detected in the corresponding s les taken from the sheep-fed Control. Thus, despite green hemp biomass being nutritionally a suitable feed for ruminants, under current Food Standards in Australia, the presence of these cannabinoid residues restricts its use in ruminant diets.
Location: Australia
No related grants have been discovered for Gaye Krebs.