Suplementação estratégica em bovinos de corte

Abstract

Different objectives were evaluated with different supplementation strategies procedures in beef cattle in two distinct projects. In Experiment 1, Thirty-two multiparous Angus beef cows in moderate body condition score (3 in a 1 to 5 scale) received supplementary feeding during early lactation, for a short period (35d), to determine the effect on milk production and composition and cow and calf performances. Both groups were maintained in grazing native condition during the supplemental period. Milk composition and yield, cow and calf performance were evaluated at 0d (initial); 14d (middle) and 35d (final) of supplementation period. There was no effect (P>0.05) of supplementation on milk production or any milk component, and on calves performance. Milk composition was different between periods, where fat concentration was higher at the middle of supplementation and lactose was higher at the end of this period. Supplemented cows had a higher (P=0.03) average daily gain at the final supplemental period than cows in control group. In conclusion, beef cows in moderate body condition score may gain weight during the lactation period responding to supplementation in a short period, without any influence on milk production, composition in the calf performance. In Experiment 2, Four beef heifers fitted with ruminal and duodenal cannulas were used in a 5 x 4 incomplete Latin square experiment to determine the dietary replacement value of camelina meal for soybean meal in forage-based diets of beef cattle. Heifers were fed bromegrass hay (7.1% CP, 52.2% NDF on an OM basis) and the diet was formulated to meet the RDP requirement for the hay offered with supplemental soybean meal as a protein supplement. In an isonitrogenous basis, the treatments aimed to replace the soybean in five different levels (0, 25, 50, 75 and 100%) using camelina meal as a protein source. There was no difference (P>0.05) of increase levels of camelina meal addition as a replacement of soybean meal on OM, NDF and N digestibility. Consequently, we could not find any difference (P>0.05) on the patterns of ruminal fermentation end-products as well. The lack of differences in site and extent of digestion among dietary treatments is consistent with similar (P>0.05) performance for the heifers. Therefore, camelina meal seems to be a suitable alternative for supplementary soybean meal in forage-based diets consumed by beef cattle.