Fresh citrus pulp supplementation effects on weight gain and plasma protein of wintering cows

Abstract

La pulpa fresca de citrus es un suplemento energético (TND > 80%) con escasa concentración proteica (7-8%), por lo que requiere nitrógeno adicional cuando se destina a la alimentación de ganado en crecimiento. El propósito de este trabajo fue verificar el efecto de este subproducto agroindustrial (sin refuerzo nitrogenado) sobre las ganancias de peso y los parámetros plasmáticos nitrogenados de vacas de invernada cruza cebú (n = 80) mantenidas sobre pastura natural. En dos años consecutivos, 20 animales operaron como controles (C) y otros 20 fueron suplementados (S) con pulpa fresca de citrus (15 ± 3 kg/animal, durante 4 meses), efectuándose pesajes y muestreos sanguíneos a los 0, 30, 60, 90 y 120 días. Con relación a C, las estadísticas finales para cada año indicaron que en S se registraron mayores cambios de peso (492 versus 304 y 352 versus -73 g/animal/día), así como más altos niveles de proteínas totales (8.18 versus 7.30 y 7.95 versus 7.18 g/dl), albúminas (3.57 versus 2.92 y 3.20 versus 2.59 g/dl), γ globulinas (2.80 versus 2.64 y 3.23 versus 3.12 g/dl) y urea (0.30 versus 0.24 y 0.30 versus 0.26 g/l), diferencias que en varios casos fueron significativas (p < 0.05). Los valores de α y β globulinas fluctuaron irregularmente, en tanto que la relación albú- minas / globulinas aumentó en S y disminuyó en C. La mejora de los indicadores nutricionales del metabolismo proteico y las ganancias de peso revelan que este económico residuo industrial es útil para el engorde de vacas de invernada, aún sin adición nitrogenada.

Fresh citrus pulp is an energy supplement (TDN > 80%) with low protein concentration (7-8%), that is reason why it requires additional nitrogen when it is feed to growing cattle. In order to verify the effect of a citrus by-product (without nitrogen addition) on live weight gain and nitrogen plasma parameters, 80 wintering half-bred zebu cows grazed on native grassland, were used. During 2 consecutive years, twenty animals were allotted to control (C) and another 20 were supplemented (S) with fresh citrus pulp (15 ± 3 kg/animal, during 4 months). Periodic weighing and blood sampling were carried out at 0, 30, 60, 90 and 120 days. Data were statistically processed using a repeated measures design, with mean comparisons by orthogonal contrasts. In both years, S registered higher live weight change rates (492 versus 304 and 352 versus -73 g/animal/day), total protein (8.18 ± 0.41 versus 7.30 ± 0.33 and 7.95 ± 0.38 versus 7.18 ± 0.39 g/dl), albumin (3.57 ± 0.36 versus 2.92 ± 0.35 and 3.20 ± 0.37 versus 2.59 ± 0.32 g/dl), γ globulin (2.80 ± 0.46 versus 2.64 ± 0.42 and 3.23 ± 0.40 versus 3.12 ± 0.44 g/dl) and urea (0.30 ± 0.08 versus 0.24 ± 0.05 and 0.30 ± 0.05 versus 0.26 ± 0.07 g/l). Differences were significant (p < 0.05) in many cases. The α and β globulins fluctuated irregularly, and the albumin / globulin ratio increased in S and decreased in C. Mean comparison tests showed that in most of the cases the differences between C and S began to be significant at day 60 of the study. Proteic metabolism nutritional indicators improvement and weight gains reveal that this cheap industrial residue is useful for fattening of wintering cows, yet without nitrogen addition.