Evaluation of genetic structure across U.S. climate zones using prominent AI sires of Red Angus cattle

Krehbiel, B. C.; Thomas, M. G.; Wilson, C.; Speidel, Scott E; Enns, R. M.; Paiva, Samuel Rezende; Blackburn, Harvey D.

doi:10.1016/j.livsci.2019.04.012

Cited by 3 publications

(6 citation statements)

References 24 publications

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“…Moreover, Surjus et al [24] described no effect on expression of estrus and P/AI of Nelore heifers treated or not with PGF on the first day of a 7d E2/P4-based FTAI protocol. However, in disagreement with our findings, Dadarwal et al [25] reported larger follicles at the time of AI and greater P/AI in beef cattle receiving PGF at the initiation of the synchronization protocol.…”

Section: Discussioncontrasting

confidence: 99%

“…High P4 concentration suppresses LH pulse frequency and negatively impact follicular growth, ovulation efficiency, and fertility in beef cattle [25,26,53,[54][55][56]. Carvalho et al [26] described lower circulating P4 concentrations in cycling beef heifers receiving PGF on of an E2/P4-based FTAI protocol, resulting in greater diameter of the dominant follicle and higher ovulation incidence (78.8 vs. 54.0%).…”

Section: Discussionmentioning

confidence: 99%

“…Bos indicus cattle are widely explored in the world due to their greater adaptability to heat stress, parasites and food shortage than Bos taurus, particularly in tropical climates [3,4,25]. However, zebu cattle (e.g.…”

Section: Discussionmentioning

confidence: 99%

“…The combination of E2 and P4 suppresses the circulating gonadotropins, follicle stimulating hormone (FSH) and luteinizing hormone (LH), leading to atresia of growing follicles and emergence of a new follicular wave [13,14]. At the time of P4 implant removal, prostaglandin F2α (PGF) is administered to induce luteolysis, along with equine chorionic gonadotropin (eCG) that is used to stimulate the final growth of the pre-ovulatory follicle [15,16] Another potential modification is the treatment with PGF prior to P4 device withdrawal, anticipating luteolysis, in order to increase the length of proestrus [24][25][26][27]. For example, studies evaluated administration of PGF on the first day of synchronization protocols in cyclic beef cattle and reported either positive effects [25,26], such as greater diameter of preovulatory follicles, more ovulations and greater pregnancy per AI (P/AI), or no effects on those variables [24,27].…”

Section: Introductionmentioning

confidence: 99%

“…At the time of P4 implant removal, prostaglandin F2α (PGF) is administered to induce luteolysis, along with equine chorionic gonadotropin (eCG) that is used to stimulate the final growth of the pre-ovulatory follicle [15,16] Another potential modification is the treatment with PGF prior to P4 device withdrawal, anticipating luteolysis, in order to increase the length of proestrus [24][25][26][27]. For example, studies evaluated administration of PGF on the first day of synchronization protocols in cyclic beef cattle and reported either positive effects [25,26], such as greater diameter of preovulatory follicles, more ovulations and greater pregnancy per AI (P/AI), or no effects on those variables [24,27]. Another change in E2/P4-based protocols is altering the dose of EC at the time of P4 implant removal (from 0.5 to 1.0 mg), aiming to increase expression of estrus and fertility [28,29].…”

Section: Introductionmentioning

confidence: 99%

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Hormonal combinations for fixed-time artificial insemination aiming to optimize fertility outcomes of Nelore cattle

Alves¹

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Hormonal combinations for fixed-time artificial insemination aiming to optimize fertility outcomes of Nelore cattle Two studies were performed aiming to evaluate reproductive outcomes, including ovarian dynamics and fertility, of Nelore heifers and cows submitted to estradiol (E2)/progesterone (P4)-based fixed-time artificial insemination (FTAI) protocols. The first study was performed using suckled Nelore cows and evaluated some adjustments in protocols with 7 days of P4 implant duration. Cows received an intravaginal P4 implant on Day 0, associated with E2 benzoate (EB) administration, and the implant remained for 7 days. At the time of P4 implant removal, all cows were treated with equine chorionic gonadotropin (eCG), E2 cypionate (EC) and prostaglandin F2α (PGF), and were inseminated 48 hours later. The first adjustment was made at the beginning of the protocol (Day 0) with or without PGF; the second adjustment was made at the time of P4 implant withdrawal (Day 7) and consisted of treating with either 0.5 or 1.0 mg EC. The third adjustment was administration or not of GnRH at the time of FTAI (Day 9). Regarding ovarian dynamics, multiparous had larger follicules than primiparous cows, on both Day 7 and at FTAI, in addition to a greater number of cows with CL at the initiation of the protocol. Overall, pregnancy per AI (P/AI) was high (~58%) and was not affected by PGF treatment on Day 0. Expression of estrus was higher in cows that received 1.0 mg EC, in addition to a tendency of greater P/AI. P/AI was greater when cows received GnRH at FTAI, particularly in cows not expressing estrus. Thus, GnRH improved P/AI especially in cows with lower expression of estrus, such as primiparous, thinner cows (BCS < 3.0), and cows treated with 0.5 mg of EC on Day 7. The second study evaluated the reproductive outcomes of Nelore heifers submitted to 7 or 9 d E2/P4-based FTAI protocols, with PGF administered at different times. An ultrasound evaluation was performed prior to the start of the experiment, to evaluate cyclicity. Heifers with CL were assigned to one of four experimental treatments, one with 7 days of P4 device, and PGF administered on Days 0 and 7, and the other with 9 days of P4 device, and PGF given at different times (Day 0 and 9, Day 7, or Day 9). Prepubertal heifers were submitted to a protocol for induction of cyclicity and, then, were randomly assigned to one of the four treatments, regardless of CL presence. Low number of heifers had CL at the first ultrasound evaluation (~17%), however, protocol for induction of cyclicity resulted in more than 80% of heifers with CL at the initiation of the synchronization protocol. The presence of CL on Day 0, overall, was positively affected by body condition score, although it did not influence expression of estrus and P/AI. There were differences on ovarian dynamics, with lower follicular diameter, at the time of AI, on animals from group 7 d. Expression of estrus was high (~90%) and did not affect P/AI, which also was similar between groups (~53%). Therefore, the st...

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Section: Discussioncontrasting

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Hormonal combinations for fixed-time artificial insemination aiming to optimize fertility outcomes of Nelore cattle

Alves¹

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A review of the role of transcription factors in regulating adipogenesis and lipogenesis in beef cattle

Abebe,

Wang,

et al. 2023

J Animal Breeding Genetics

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In the past few decades, genomic selection and other refined strategies have been used to increase the growth rate and lean meat production of beef cattle. Nevertheless, the fast growth rates of cattle breeds are often accompanied by a reduction in intramuscular fat (IMF) deposition, impairing meat quality. Transcription factors play vital roles in regulating adipogenesis and lipogenesis in beef cattle. Meanwhile, understanding the role of transcription factors in regulating adipogenesis and lipogenesis in beef cattle has gained significant attention to increase IMF deposition and meat quality. Therefore, the aim of this paper was to provide a comprehensive summary and valuable insight into the complex role of transcription factors in adipogenesis and lipogenesis in beef cattle. This review summarizes the contemporary studies in transcription factors in adipogenesis and lipogenesis, genome‐wide analysis of transcription factors, epigenetic regulation of transcription factors, nutritional regulation of transcription factors, metabolic signalling pathways, functional genomics methods, transcriptomic profiling of adipose tissues, transcription factors and meat quality and comparative genomics with other livestock species. In conclusion, transcription factors play a crucial role in promoting adipocyte development and fatty acid biosynthesis in beef cattle. They control adipose tissue formation and metabolism, thereby improving meat quality and maintaining metabolic balance. Understanding the processes by which these transcription factors regulate adipose tissue deposition and lipid metabolism will simplify the development of marbling or IMF composition in beef cattle.

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Bovine landscape genetics in Brazil

Souza

Egito

Peripolli

et al. 2022

Sci. agric. (Piracicaba, Braz.)

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Evaluation of genetic structure across U.S. climate zones using prominent AI sires of Red Angus cattle

Cited by 3 publications

References 24 publications

Hormonal combinations for fixed-time artificial insemination aiming to optimize fertility outcomes of Nelore cattle

Hormonal combinations for fixed-time artificial insemination aiming to optimize fertility outcomes of Nelore cattle

A review of the role of transcription factors in regulating adipogenesis and lipogenesis in beef cattle

Bovine landscape genetics in Brazil

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