Suplementos protéicos com e sem fontes de enxofre sobre o consumo, a digestibilidade, parâmetros ruminais, sanguíneos e comportamento ingestivo de novilhos alimentados com feno de baixa qualidade

Abstract

This research was realized to study the effects of different sulfur sources, in cattle diets, on voluntary intake, nutrients total apparent digestibility coefficient, ruminal metabolites, blood metabolites and intake behavior. A total of seven Holstein steers weighing 380 kg of live weight and implanted with ruminal cannula, were used. The experimental design was a Latin square 7 x 7, and treatments consisted of supplements use or no with different sulfur sources addition or no: hay + supplement without sulfur (SWS), hay + sulfur 70S (S70), hay + sulfur 98S (S98), hay + calcium sulfate Hemi-hydrated (CSH), hay + calcium sulfate Di-hydrated (CSD), hay + ammonium Sulfate (AS) and hay without supplement (HWS). Independent of sulfur inclusion, supplementation positively affected intake and nutrients digestibility.The inclusion of different sulfur sources did not affect nutrients intake. however, AS presented a higher CP total apparent absorption coefficient. The pH and N-NH3 ruminal concentrations were influenced by supplement use. Considering pos feeding time the elementary sulfur sources showed a cubical effect on pH, while the calcium sulfate sources showed a quadratic effect. AS trended to a quadratic effect. SSE, 70S, 98S, CSH and CSD showed a cubical effect over ruminal N-NH3 concentrations. Independent of sampling time, supplementation showed effect on NUP and P plasmatic concentrations, but did not influence Ca concentrations. The supplementation affected in a positive form the activities of feeding, chewing and resting. Animals that had not been supplemented (HWS) presented a lower total time of feeding, lower total time of chewing, and resting that animals receiving supplement, and made shorter meals, expended more time for rumination chews per ruminal bolus, presented lower feeding efficiency (g DM/hour) and lower rumination efficiency (g of DM/hour and g of NDF/hour). Everything reflected in lower consumption and DM and NDF digestibility. SWS presented higher total time of rumination and lying rumination that supplements with different sulfur sources. Supplements with sulfur produced higher DM and NDF digestibility, and animals had lower number of rumination chews per day and for bolus, but they had not differences in the feeding efficiency and rumination taxes.