ORCID Profile
0000-0002-6773-4450
Current Organisations
Universidade de São Paulo -USP
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Universidade de São Paulo
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Publisher: Elsevier BV
Date: 08-2011
DOI: 10.1016/J.THERIOGENOLOGY.2011.02.022
Abstract: The objective was to evaluate the effect of estrus occurrence (based on removal of tail-head marks) on ovarian responses and pregnancy per AI (P/AI 30 d after AI) in suckled Bos indicus beef cows submitted to timed AI (TAI) protocols. Cows received an intravaginal device containing 1.0 g progesterone, and 2.0 mg estradiol benzoate im 8 d later, the intravaginal device was removed, and they were given PGF(2α) (0.25 mg of cloprostenol sodium) and 300 IU of eCG, with TAI 48 to 52 h later. In Experiment 1, cows were assigned to receive one of three treatments: 1 mg of estradiol cypionate (ECP) im at progesterone (P4) device removal (N = 178) 10 μg of GnRH im at TAI (N = 190) or both treatments (N = 172). In cows given estradiol (ECP or ECP + GnRH), more displayed estrus (P = 0.002) and became pregnant (P < 0.0001) compared with those receiving only GnRH. In Experiment 2, the effect of the occurrence of estrus on ovarian responses was evaluated in cows (N = 53) synchronized using ECP at device removal. Cows that displayed estrus had a greater diameter of the largest follicle (LF) at device removal (P < 0.0001), a greater diameter at TAI (P < 0.0001), a greater ovulation rate (P = 0.02), a larger CL (P = 0.02), and a greater P4 concentration (P < 0.0001) than cows that did not display estrus. In Experiment 3, the effect of GnRH treatment on P/AI at TAI was evaluated in cows that received ECP at device removal, and either displayed, or did not display, estrus (N = 726). There was no estrus by GnRH interaction (P = 0.22) the P/AI was greater (P < 0.0001) in cows that displayed estrus (61.9%) than cows that did not display estrus (41.4%). However, GnRH did not improve (P = 0.81) P/AI (GnRH = 53.7% vs. no GnRH = 52.6%). In conclusion, exogenous estradiol at device removal increased both the proportion of suckled Bos indicus cows that displayed estrus and P/AI. Cows that displayed estrus had better ovarian responses (i.e., larger follicles at TAI, a greater ovulation rate, larger CL, and greater P4 concentrations) following an estradiol/P4-based synchronization protocol. Although occurrence of estrus improved pregnancy outcomes, GnRH at TAI did not improve P/AI in suckled Bos indicus cows treated with ECP, regardless of estrus occurrence.
Publisher: Elsevier BV
Date: 07-2014
DOI: 10.1016/J.THERIOGENOLOGY.2014.03.018
Abstract: The present study investigated the effect of Holstein donor category (cows vs. heifers) and climate variation (hot vs. cooler season) on the efficiency of in vivo embryo production programs as well as embryo survival after transferred to Holstein recipient cows. A total of 1562 multiple ovulation (MO) procedures (cows: n = 609, and heifers: n = 953) and 4076 embryo transfers (ETs) performed in two dairy herds were evaluated. Donor cows had greater number of CLs (10.6 ± 0.6 vs. 7.5 ± 0.4 P < 0.0001) and ova/embryos recovered (7.6 ± 0.6 vs. 4.6 ± 0.4 P < 0.0001) compared with donor heifers. However, fertilization rate (47.9 vs. 82.4% P < 0.0001) and proportion of transferable embryos (31.5 vs. 67.4% P < 0.0001) were lower in donor cows than heifers, respectively. Regardless of donor category, the proportion of freezable embryos was less (P < 0.001) during hot season than in cooler season (21.4 vs. 32.8%). However, greater decline in the proportion of freezable embryos during the hot season was observed in cows (21.7 vs. 10.7%) compared with heifers (46.2 vs. 38.1% P = 0.01). In contrast, the season on which the embryo was produced (hot or cool) did not affect pregnancy rate on Day 31 (30.5 vs. 31.7% P = 0.45) and 45 (25.3 vs. 25.1% P = 0.64) of pregnancy. Regardless of the season in which the embryos were produced, embryonic survival after transferring embryos retrieved from donor cows was greater on Days 31 (36.0 vs. 30.7% P = 0.001) and 45 (28.3 vs. 23.1% P = 0.001) of pregnancy when compared with embryos from donor heifers. In conclusion, MO embryo production efficiency decreased during the hot seasons both in cows and heifers however, the decline was more pronounced in donor cows. Regardless of the embryo source, similar pregnancy rate was observed in the recipient that received embryos produced during the hot and cooler seasons. Curiously, embryos originating from donor cows had higher embryonic survival when transferred to recipient cows than embryos originating from heifers.
Publisher: MDPI AG
Date: 13-07-2020
DOI: 10.3390/ANI10071185
Abstract: Reproductive efficiency plays a major role in the long-term sustainability of livestock industries and can be improved through genetic and genomic selection. This study aimed to estimate genetic parameters (heritability and genetic correlation) and identify genomic regions and candidate genes associated with anti-Müllerian hormone levels (AMH) and antral follicle populations measured after estrous synchronization (AFP) in Nellore cattle. The datasets included phenotypic records for 1099 and 289 Nellore females for AFP and AMH, respectively, high-density single nucleotide polymorphism (SNP) genotypes for 944 animals, and 4129 in iduals in the pedigree. The heritability estimates for AMH and AFP were 0.28 ± 0.07 and 0.30 ± 0.09, and the traits were highly and positively genetically correlated (rG = 0.81 ± 0.02). These findings indicated that these traits can be improved through selective breeding, and substantial indirect genetic gains are expected by selecting for only one of the two traits. A total of 31 genomic regions were shown to be associated with AMH or AFP, and two genomic regions located on BTA1 (64.9–65.0 Mb and 109.1–109.2 Mb) overlapped between the traits. Various candidate genes were identified to be potentially linked to important biological processes such as ovulation, tissue remodeling, and the immune system. Our findings support the use of AMH and AFP as indicator traits to genetically improve fertility rates in Nellore cattle and identify better oocyte donors.
Publisher: Frontiers Media SA
Date: 02-03-2018
Publisher: Elsevier BV
Date: 07-2010
DOI: 10.1016/J.ANIREPROSCI.2010.03.007
Abstract: The objectives of the present study were to evaluate factors associated with estrous synchronization responses and pregnancy per insemination (P/AI) in Bos indicus beef cows submitted to progesterone-based fixed-time artificial insemination (FTAI) protocols. A total of 2388 cows (1869 Nellore and 519 crossbred NellorexAngus) from 10 commercial farms were evaluated to determine the relationships among breed, body condition score (BCS) on the first day of the FTAI protocol, the occurrence of estrus between progesterone device removal and FTAI, and diameter of largest ovarian follicle (LF) at FTAI on estrous synchronization responses and P/AI. Cows (n=412 primiparous 1976 multiparous) received an intravaginal device containing progesterone or an ear implant containing norgestomet (a progestin), and an injection of estradiol at the beginning of the estrous synchronization protocol. Body condition was scored using a 1-5 scale on the first day of the FTAI protocol and at 30-60 days postpartum. Females received 300IU of equine chorionic gonadotropin (eCG) and PGF(2alpha) on the day the progesterone device/implant was removed and were inseminated 48-60h later. At insemination, cows (n=2388) were submitted to an ultrasonographic exam to determine the diameter of the LF. Follicles were classified into four categories based on mean and standard deviation (SD) of the LF (LF1=two SD below the mean LF2=mean minus one SD LF3=mean plus one SD LF4=two SD above the mean). Ovulation rate was determined in a subset of cows (n=813) by three consecutive ultrasonographic exams: (1) at time of progesterone device/implant removal, (2) at time of FTAI and (3) 48h after FTAI. Ovulation was defined as the disappearance of a large follicle (>or=8.0mm) that was previously recorded. Estrus was determined in a subset of the cows (n=445) by the activation of a detection of estrous patch placed on the tail head on the day of progesterone device/implant removal. Pregnancy was diagnosed 30 days after FTAI. Pregnancy was influenced (P=0.001) by follicle diameter [LF1=27.5% (81/295), LF2=46.6% (328/705), LF3=57.9% (647/1118), LF4=63.3% (171/270)] and the occurrence of estrus [estrus=67.7% (174/257) and no estrus=36.2% (68/188)]. Follicle diameter at FTAI influenced ovulation rate [LF1=42.5% (34/80), LF2=73.9% (161/218), LF3=95.8% (407/425), LF4=97.8% (88/90)], the occurrence of estrus [LF1=54.8% (51/93), LF2=33.6% (43/128), LF3=68.9% (126/183), LF4=90.2% (37/41)] and P/AI among cows that had ovulations [LF1=32.4% (11/34), LF2=50.3% (81/161), LF3=60.0% (244/407), LF4=68.2% (60/88)]. Improving estrous responses between progesterone device withdrawal and FTAI and increasing the diameter of the LF at FTAI may be important aspects to achieve improved estrous synchronization responses and P/AI following progesterone rogestin and estradiol based FTAI protocols in suckled Bos indicus cows.
Publisher: Elsevier BV
Date: 2021
Publisher: American Dairy Science Association
Date: 10-2011
Abstract: Two experiments evaluated the effects of the first GnRH injection of the 5-d timed artificial insemination (AI) program on ovarian responses and pregnancy per AI (P/AI), and the effect of timing of the final GnRH to induce ovulation relative to AI on P/AI. In experiment 1, 605 Holstein heifers were synchronized for their second insemination and assigned randomly to receive GnRH on study d 0 (n = 298) or to remain as untreated controls (n = 307). Ovaries were scanned on study d 0 and 5. All heifers received a controlled internal drug-release (CIDR) insert containing progesterone on d 0, a single injection of PGF(2α) and removal of the CIDR on d 5, and GnRH concurrent with timed AI on d 8. Blood was analyzed for progesterone at AI. Pregnancy was diagnosed on d 32 and 60 after AI. Ovulation on study d 0 was greater for GnRH than control (35.4 vs. 10.6%). Presence of a new corpus luteum (CL) at PGF(2α) injection was greater for GnRH than for control (43.1 vs. 20.8%), although the proportion of heifers with a CL at PGF(2α) did not differ between treatments and averaged 87.1%. Progesterone on the day of AI was greater for GnRH than control (0.50 ± 0.07 vs. 0.28 ± 0.07 ng/mL). The proportion of heifers at AI with progesterone <0.5 ng/mL was less for GnRH than for control (73.8 vs. 88.2%). The proportion of heifers in estrus at AI did not differ between treatments and averaged 66.8%. Pregnancy per AI was not affected by treatment at d 32 or 60 (GnRH = 52.5 and 49.8% vs. control = 54.1 and 50.0%), and pregnancy loss averaged 6.0%. Responses to GnRH were not influenced by ovarian status on study d 0. In experiment 2, 1,295 heifers were synchronized for their first insemination and assigned randomly to receive a CIDR on d 0, PGF(2α) and removal of the CIDR on d 5, and either GnRH 56 h after PGF(2α) and AI 16h later (OVS56, n = 644) or GnRH concurrent with AI 72 h after PGF(2α) (COS72 n = 651). Estrus at AI was greater for COS72 than for OVS56 (61.4 vs. 47.5). Treatment did not affect P/AI on d 32 in heifers displaying signs of estrus at AI, but COS72 improved P/AI compared with OVS56 (55.0 vs. 47.6%) in those not in estrus at AI. Similarly, P/AI on d 60 did not differ between treatments for heifers displaying estrus, but CO S72 improved P/AI compared with OVS56 (53.0 vs. 44.7%) in those not in estrus at AI. Administration of GnRH on the first day of the 5-d timed AI program resulted in low ovulation rate and no improvement in P/AI when heifers received a single PGF(2α) injection 5 d later. Moreover, extending the proestrus by delaying the final GnRH from 56 to 72 h concurrent with AI benefited fertility of dairy heifers that did not display signs of estrus at insemination following the 5-d timed AI protocol.
No related grants have been discovered for Pietro Baruselli.