Produção e análise marginal em vacas de leite submetidas a níveis de ureia na dieta à base de silagem de sorgo

The objective of this study was to evaluate productive, nutritional and economic traits of dairy cows fed sorghum silage diets with urea levels. Five ¾ Holstein × ¼ Gir lactating dairy cows in the middle third of lactation, at an average age of 60 months and average body weight of 518 kg ± 52 kg, were allocated to five treatments in a 5 × 5 Latin square experimental design. Treatments (U-50, U-75, U-100, U-125 and U-150) consisted of different urea levels in the concentrate (5.7, 8.6, 11.4, 14.3 and 17.1 g urea/kg concentrate, respectively). The significance level of 0.5 was adopted. Urea levels did not influence the feed intake, digestibility, or metabolic parameters of dairy cows. No significant differences were observed for 3.5% fat-corrected milk yield. Milk composition was not significantly affected. Gross revenue from the sale of milk was not significantly affected, averaging BRL 28.65. Marginal rate of return did not differ significantly. The different urea levels did not influence the dairy cows’ milk yield. In conclusion, urea can be included in the concentrate of sorghum silage diets for dairy cows at the levels of 5.7 to 17.1 g/kg of concentrate without compromising production performance.