Concentração plasmática de N ureico e glicose e excreção de ureia em vacas leiteiras alimentadas com farelo de amendoim em substituição ao farelo de soja da dieta

Abstract

The objective of this study was to evaluate the effect of replacing soybean meal with peanut meal in the diet of lactating cows kept in confinement on the blood parameters (glucose and N ureic concentration (NUP)), urinary excretion of urea and N ureic in milk (NUL). Twelve crossbred cows (Dutch x Zebu), multiparous, with an average initial production of 25 kg of milk/day were distributed in three 4x4 Latino squares and confined in individual stalls for a 60 day experimental period. The cows received diets composed of 50% corn silage and 50% concentrate (dry matter basis). The treatments consisted of increasing levels of peanut meal (0%, 33%, 67% and 100%) to replace soybean meal. The levels of peanut meal in the diets did not influence (P>0.05) the plasma glucose concentration, which was higher (P<0.05) at the time 4h after morning feeding (63.89 mg/dL) than the time 0h (47.75 mg/dL). The concentration of NUP varied in a quadratic manner as a function of the diets, reaching the maximum value (18.62 mg/dL) at the 58.8% substitution level. Regarding the collection time, the concentration was higher (P<0.05) in time 4h (17.83 mg/dL) than the time 0h (16.58 mg/dL). Urea urinary excretion increased linearly 1.33 mmol/L for each percentage unit of substituted soybean meal, while the NUL concentration varied in a quadratic form, reaching a maximum concentration (14.43 mg/dL) at the level of 58% of substitution. The use of peanut meal in the diet of confined dairy cows does not influence plasma glucose concentration, however, it increases the urinary excretion of urea and alters NUP and NUL concentrations.