Fatores que interferem na manutenção da gestação de bovinos
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Data
2023-11-14
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Universidade Estadual Paulista (Unesp)
Resumo
Falhas reprodutivas estão entre as principais causas de perda econômica em bovinos, sendo que perdas de gestação é uma das principais causas de falhas reprodutivas. Perdas de gestação tem sido o foco de intensas investigações, porém pouco progresso tem sido observado na compreensão dos mecanismos envolvidos, provavelmente devido ao grande número de animais necessários para permitir interpretação correta dos dados. Os objetivos desta pesquisa foram: 1) determinar fatores que contribuem para perdas de gestação em bovinos 2) usar esse conhecimento para tentar desenvolver estratégias para diminuir perdas de gestação. Fêmeas bovinas lactantes da raça holandesa (708 primíparas e 844 multíparas) foram submetidas a protocolo de IATF. A fertilidade foi avaliada no primeiro diagnóstico de gestação aos 31 dias e sua gestação acompanhada até o parto. Perdas de gestação foram mensuradas entre quatro momentos, e as médias por período foram: 31-62d - 13,0% (74/568), 62-120d – 6,48% (32/494), 120d-parto – 12,1% (56/462) e 31d-parto– 28,5% (162/568). Houve efeito de categoria na fertilidade e taxa de parição, de forma que primíparas tiveram maior taxa de parição que multíparas, 32,1% (229/708) vs. 20,7% (177/844), P<0,01 e menor perda de gestação 30d-parto, 21,1% (59/288) vs. 34,9% (103/280), P<0,01, respectivamente. Animais prenhes no d31 e que se mantiveram prenhes até o parto tiveram maior expressão de cio comparado aos animais que não emprenharam e/ou emprenharam e perderam a gestação, P<0,01. Da mesma forma, animais prenhes no d31 e que mantiveram a prenhez até o parto, apresentaram maior concentração média de PAGs no d24 considerando DG31, DG62, DG120 e parto, P<0,01. A haptoglobina no d24 não foi um preditor de sucesso da gestação do 31d parto, P>0,05. Conclui-se que um protocolo de IATF bem definido com alta expressão de cio pode influenciar positivamente a manutenção da gestação, assim como as PAGs no d31 podem ser utilizadas como preditor de sucesso da gestação até o parto, possibilitando associar fatores com estratégias para reduzir as perdas de gestação.
Reproductive failures are among the main causes of economic loss in cattle, with pregnancy loss being one of the main causes of reproductive failures. Pregnancy losses have been the focus of intense investigations, but little progress has been observed in understanding the mechanisms involved, probably due to the large number of animals required to allow correct interpretation of the data. The objectives of this research were: 1) to determine factors that contribute to pregnancy losses in cattle 2) to use this knowledge to try to develop strategies to reduce pregnancy losses. Lactating female Holstein cattle (708 primiparous and 844 multiparous) were subjected to an TAI protocol. Average pregnancy losses per period were: 30-62d - 13.0% (74/568), 62-120d - 6.48% (32/494), 120d-delivery - 12.1% (56/462) and 31d-delivery – 28.5% (162/568). There was a category effect on fertility and calving rate, so that primiparous had a higher calving rate than multiparous, 32.1% (229/708) vs. 20.7% (177/844), P<0.01, and lower 30d-delivery pregnancy loss, 21.1% (59/288) vs. 34.9% (103/280), P<0.01, respectively. Animals pregnant on d31 and that remained pregnant until parturition had greater heat expression compared to animals that did not become pregnant and/or became pregnant and lost the pregnancy, P<0.01. Likewise, animals pregnant on d31 and that maintained pregnancy until parturition had a higher mean concentration of PAGs on d24 considering DG31, DG62, DG120 and parturition, P<0.01. Haptoglobin at d24 was not a predictor of pregnancy success at 31d-partum, P>0.05. It is concluded that a well-defined TAI protocol with high heat expression can positively influence the maintenance of pregnancy, just as PAGs on d31 can be used as a predictor of success from pregnancy to calve, making it possible to associate factors with strategies to reduce pregnancy losses.
Reproductive failures are among the main causes of economic loss in cattle, with pregnancy loss being one of the main causes of reproductive failures. Pregnancy losses have been the focus of intense investigations, but little progress has been observed in understanding the mechanisms involved, probably due to the large number of animals required to allow correct interpretation of the data. The objectives of this research were: 1) to determine factors that contribute to pregnancy losses in cattle 2) to use this knowledge to try to develop strategies to reduce pregnancy losses. Lactating female Holstein cattle (708 primiparous and 844 multiparous) were subjected to an TAI protocol. Average pregnancy losses per period were: 30-62d - 13.0% (74/568), 62-120d - 6.48% (32/494), 120d-delivery - 12.1% (56/462) and 31d-delivery – 28.5% (162/568). There was a category effect on fertility and calving rate, so that primiparous had a higher calving rate than multiparous, 32.1% (229/708) vs. 20.7% (177/844), P<0.01, and lower 30d-delivery pregnancy loss, 21.1% (59/288) vs. 34.9% (103/280), P<0.01, respectively. Animals pregnant on d31 and that remained pregnant until parturition had greater heat expression compared to animals that did not become pregnant and/or became pregnant and lost the pregnancy, P<0.01. Likewise, animals pregnant on d31 and that maintained pregnancy until parturition had a higher mean concentration of PAGs on d24 considering DG31, DG62, DG120 and parturition, P<0.01. Haptoglobin at d24 was not a predictor of pregnancy success at 31d-partum, P>0.05. It is concluded that a well-defined TAI protocol with high heat expression can positively influence the maintenance of pregnancy, just as PAGs on d31 can be used as a predictor of success from pregnancy to calve, making it possible to associate factors with strategies to reduce pregnancy losses.
Descrição
Palavras-chave
Perda de gestação, PAGs, Fertilidade, Haptoglobina, Pregnancy loss, Fertility, Haptoglobin
Como citar
MUNHOZ, A. K. Fatores que interferem na manutenção da gestação de bovinos. 2023. Tese (Doutorado em Zootecnia) – Faculdade de Medicina Veterinária e Zootecnia, Universidade Estadual Paulista, Botucatu, 2023.