Efeito da substituição do farelo de soja por farelo de girassol nos parâmetros ruminais de vacas girolando

Abstract

The objective of this study was to evaluate the effects of soybean meal substitution by sunflower meal on the diet of dairy cows on intake and digestibility of dry matter and nutrients, ruminal parameters (pH, ammoniacal nitrogen, Short chain fatty acids (GCC) and microbial protein synthesis), and nitrogen balance. Four crossbred cows, 7/8 Holstein x Gir, non-lactating cows were used in the rumen, which were distributed in 4x4 latin squares and housed in individual stalls for an experimental period of 68 days, consisting of four periods of 17 days each. The cows were fed diets composed of 50% corn silage and 50% concentrate, based on the dry matter. The treatments consisted of increasing levels of sunflower meal (0%, 33%, 67% and 100%) substitution the soybean meal diet. There were no influence of treatments on dry matter (DM) intake, organic matter (OM), ethereal extract (EE), total carbohydrate (CHOT), and total digestible nutrientes (TDN) (P>0.05).The neutral detergent fiber (NDF) intake increased linearly of substituted soybean meal. non-fibrous carbohydrates (NFC) intake and crude protein (CP) declined linearly. The DM, OM, CP, NDF and CHOT digestibility coefficients were not affected by the treatments (P>0.05). EE digestibility coefficients increased linearly and NFC reduced linearly. The ruminal pH, NAR and concentrations of GCC were not influenced by the treatments. Sampling time significantly affected rumen (pH, NAR and GCC) (P>0.05). the synthesis and the efficiency of microbial protein synthesis increased linearly. The nitrogen balance and urinary nitrogen excretion were not influenced by the treatments. Intake nitrogen and fecal nitrogen excretion increased linearly. Urinary urea nitrogen excretion varied in a quadratic manner with point maximum as a function of the diets (P<0.05). Sunflower meal can partially replace soybean meal from dairy cows' diet without causing harmful changes in the analyzed variables.