Abstract This study evaluated the effect of crude protein (CP) reduction in four diets (156, 139, 132, and 127 g Kg-1 DM) maintaining constant metabolizable protein (188 g/day) on the follicular fluid and cumulus-oocyte complexes of mid-lactating Girolando cows. Twenty-two Girolando cows with average of 21.55 ±3.19 L daily milk yield, 105.30 ±22.62 days in lactation and 3.22 ±0.03 body condition score were selected. To reduce CP in diets and maintain constant metabolizable protein, urea and soybean meal were gradually replaced by lignosulfonate-treated soybean meal (SoyPass®, Cargill), resulting in an increase in rumen-undegradable protein and a reduction in rumen degradable protein. A linear and quadratic reduction was observed in the plasma and follicular fluid urea nitrogen concentration following CP reduction, with the most intense reduction occurring in the 127 g Kg-1 DM group (p<0.001). As CP reduced, there was a tendency for a linear increase in the follicular growth rate (P=0.0696), on the number and proportion of viable oocytes (P<0.09), and also a linear increase for the number (P=0.0397) and proportion (P<0.09) of grade I viable oocytes. Plus, there was a linear effect for the number of cumulus oophorus cells. Cows fed with the lowest amount of CP had cumulus-oocyte complexes with higher numbers of cumulus oophorus cells (P=0.0238). Also, the reduction of diet crude protein was followed by a decrease in the probability of oocytes’ DNA degradation. In conclusion, the reduction of CP in the diet of mid-lactating Girolando cows, reduces urea nitrogen concentration in both blood plasma and follicular fluid, and, as a consequence, increases the viability of oocytes and the number of cumulus oophorus cells while reducing oocytes’ DNA degradation of follicular included cumulus-oocyte complex. The reduction on dietary CP may improve in vivo oocytes’ embryo development impacting fertility of lactating dairy cows.

Verificou-se a influência do número de ordenhas diárias sobre a produção de leite, a duração da lactação, a incidência de mastite e o desempenho dos bezerros. Foram utilizadas 63 vacas primíparas e multíparas mestiças (Holandês-Zebu) com boa condição corporal ao parto, distribuídas ao acaso, por meio de sorteio, em três grupos experimentais com número igual de repetições, representadas pelo número de ordenhas diárias: vacas ordenhadas uma vez por dia; vacas ordenhadas duas vezes ao dia; vacas ordenhadas alternadamente a cada 14 dias, uma ou duas vezes ao dia. A saúde da glândula mamária não foi influenciada pela diminuição do número de ordenhas diárias. Não houve efeito do número de ordenhas sobre o desempenho dos bezerros, mesmo daqueles submetidos a uma mamada diária. A duração da lactação não foi influenciada pela adoção de duas ordenhas diárias. A adoção da segunda ordenha diária aumentou em 24,54% a produção de leite de vacas com potencial produtivo para 2.500 a 2.800 L por lactação.

This trial was conducted to study the effects of daily milking frequency on milk yield, duration of lactation, incidence of mastitis, and calves body weight gain. Sixty-three crossbred Holstein-Zebu cows were equally and randomly assigned to three experimental groups according to the frequency of daily milkings as follows: once a day milking, twice a day milking, or alternating once or twice a day milking every 14 days. The duration of lactation, mammary gland health, and calf production did not differ among treatments in this study. However, cows milked twice a day yielded 24.54% more milk per lactation (699.9 kg) compared to the other milking regimes.