Tese
Nível nutricional na gestação de vacas de corte: eficiência reprodutiva e produtiva da prole
Fecha
2023-03-27Autor
Adams, Sander Martinho
Institución
Resumen
Nutritional restriction during fetal development has negative effects on its growth and
development, which can compromise its performance. However, scientific studies that
measured the extent of this compromise are scarce, inconsistent, and non-existent in the case of
long-term evaluations. Therefore, the objective of this study was to evaluate the long-term
impacts of nutritional levels during fetal development of beef cows on their productive and
reproductive performance, as well as the impacts on the animals they generate. The treatments
were formed according to the nutritional level during the final third of fetal development of
cows: Low (cows allocated to native pasture and subjected to mild nutritional restriction),
Medium (cows allocated to native pasture and supplemented to meet 100% of maintenance
requirements), and High (cows allocated to native pasture and supplemented to meet 150% of
maintenance requirements). Forty cows and the 64 calves they produced after being subjected
to three reproductive periods were used. The experimental design used was completely
randomized, with a variable number of repetitions per treatment, and the collected data were
tested for normality and subsequently subjected to variance analysis by the F test, and the means
compared by the Tukey test at a 5% level of probability. There was no difference in birth weight
of beef cows and the birth weight of their calves as a function of the evaluated treatments. Cows
in the High group had a higher average daily gain in live weight during the postnatal period
than those in the Low group. This result impacted the body condition score at the end of the
first reproductive period and consequently, there were higher pregnancy rates and calf
production in the High treatment compared to the Low treatment. In addition, calves from cows
in the High treatment also showed better postnatal development compared to calves from the
Low treatment.