Desempenho de vacas leiteiras consumindo silagens de dois híbridos de milho convencionais e um BMR-3

Abstract

The objective of this study was to evaluate the effects of feeding conventional or BMR-3 (brown midrib) corn silage hybrids grown in tropical conditions on intake, feeding behavior, performance, and metabolism of dairy cows. Twelve crossbred cows (3/4 and 7/4 Holstein x Gyr) averaging (± SD) 1.8 ± 0.8 lactations, 548.8 ± 73.7 kg of body weight (BW) and 85.9 ± 30.2 days in milk (DIM) were enrolled in a 3 x 3 factorial Latin square design experiment with 4 squares selected according to the above-mentioned variables. Thereafter, cows within the squares were randomly assigned to 1 of the 3 treatments: 1) brown midrib hybrid – BMR-3; 2) conventional hybrid 1 – H1; 3) conventional hybrid 2 – H2. Diets were formulated to be isoenergetic and isonitrogenous according to the NRC (2001). Data were tested for normality by the Lilliefors’ test and statistical significance was considered when P < 0.05. When significant, Fisher’s test was applied to compare means between treatments. Dry matter intake and nutrient intake were not affected by the corn silage hybrids. Also, there was no effect of treatments on DM, OM, CP, and NFC digestibility. The NDF digestibility was similar between BMR-3 and H1, but lower in H2. Milk yield was greater for cows in BMR-3 (32.96 kg/day) and H1 (33.08 kg/day) than for cows in H2 (31.20 kg/day). Feed efficiency was similar between treatments. Cows fed with BMR-3 had lower MUN concentrations than cows in H1 and H2. Feeding behavior did not differ between treatments. Blood glucose and BHBA were not affected by the treatments. On the other hand, cows fed with H2 had greater levels of NEFA than cows in BMR-3 and H1. Blood urea nitrogen was lower in BMR-3 than in H1 and H2. The use of a BMR-3 corn silage hybrid grown in tropical conditions improved milk yield of dairy cows. However, future studies must be addressed to evaluate the effects of this hybrid type in a wider range of systems.