Levels of supplementation for grazing pregnant beef cows during the dry season

Abstract

The objective of this study was to evaluate the effect of different levels of multiple supplement supply on the nutritional characteristics and productive performance of pregnant cows grazing on Brachiaria decumbens Stapf. during the dry season. The experimental area was composed of four 3.0 ha paddocks with availability of potentially digestible dry matter of 2,582 kg/ha. Twenty-eight crossbred pregnant cows with predominance of Zebu breed at body weight of 446±12 kg were utilized in a completely randomized experimental design. Treatments consisted of mineral supplement (control treatment) and supply of multiple supplement at 0.5, 1.0 and 1.5 kg/animal/day with 300 g crude protein (CP)/kg of dry matter (DM). There was quadratic effect of multiple supplementation levels on daily weight gain and a linear increase for final body condition score. The intakes of DM, organic matter (OM) and total digestible nutrients presented no effect with levels of multiple supplement. The coefficients of apparent digestibility of DM and OM had cubic effect with multiple supplementation levels. There was no effect of levels of multiple supplementation on the microbial nitrogen flow and efficiency, but the microbial nitrogen flow in relation to nitrogen intake showed decreasing linear profile. The supply of 1.0 kg of multiple supplement optimizes the performance of grazing cows during the dry season.