Voluntary intake and milk production in F1 Holstein x zebu cows in confinement

The objective of this study was to evaluate the nutrient intake and milk production in Holstein x zebu (F1) cows in feedlot. Eighteen F1 cows were used, divided into three treatments; six were Holstein x Gir (HGI), six were Holstein x Guzerat (HGU), and another six were Holstein x Nelore (HNE), which had recently calved, distributed into simple, random samples, under the same feeding conditions of corn silage and concentrate with 20% crude protein. The three-marker method was used (LIPEA (R), titanium dioxide, and iADF) to estimate the individual intake and digestibility of the nutrients for the cows in group. The mathematical model used to establish the lactation curves was: Y = at (b) e (-ct) by Wood (Nature 216:164-165, 1967). The statistical analyses for the nutrient intake and digestibility, as well as parameters of metabolic efficiency, were performed using multiple linear regression (alpha = 5%). No effect (P > 0.05) of genetic group was observed for any of the variables studied. The intake and digestibility of the nutrients and the microbial nitrogen presented quadratic curves as a function of the lactation period (P < 0.05). The HGU cows exhibited an accumulated milk production of 4,946.81 kg at 305 days, whereas the HGI cows produced 4,821.78 kg. The HNE cows displayed inferior performance, with a production of 3,674.98 kg. It was concluded that, in confinement, F1 cows from different genetic groups do not exhibit different intake, digestibility, or metabolic efficiency. The HGU and HGI cows have greater cumulative production at 305 days.