The Effect of Nutritional Additives and Nitrogen Supplements Used for Nellore Steers During Growth Phase Fed on Deferred Pasture

Dry season reduces the quantity and quality of forage available for cattle. To guarantee the quantity, deferred grazing is a good alternative, however supplementation is necessary to complement the nutritional quality of the diet. Therefore, this work evaluated the inclusion of nutritional additives (virginiamycin and salinomycin) in supplements provide to Nellore steers during growth phase on deferred pasture during the dry season. One hundred and twenty castrated steers with averaging weight 280.40 (±19.59) kg were distributed into groups with 20 animals each in six paddocks with 20 hectares each of Brachiaria brizantha cv. MG4 deferred by 60 days. The total experimental period was 120 days, with rotating groups in paddocks each 15 days. The treatments consisted in a protein-energy-mineral supplement, with 30% crude protein (CP), 40% total digestible nutrient (TDN) containing three different non-protein nitrogen (NPN) sources and with or without nutritional additive. The treatment containing virginiamycin showed better performance (P <0.05) than the treatments with salinomycin and without additive (negative control). The revenue from treatment with virginiamycin (US$ 97.28) was 7.6% and 9.8% higher than of the treatments without additive (US$ 90.41) and with salinomycin (US$ 88.63) respectively. Virginiamycin used in nitrogen supplements during the growing phase of Nellore steers on deferred pasture maintains performance in dry season and increases net margin per animal.