Inclusión del Nabo forrajero (Brassica rapa) como suplemento estival en dietas ofrecidas a vacas lecheras en predios de la Provincia de Ranco

Abstract

The aim of the study was to analyze the diet composition, utilization of summer turnips and its re- lation with milk production in grazing dairy cows from 35 dairy farms in the Province of Ranco, Los Ríos Region, Chile, during summer 2014. Data regarding agronomical features of summer turnip, dairy herd information, milk production and diet composition were obtained. The diets offered were based on permanent pastures. Summer turnip yielded between 0.47 to 10.13 t DM/ha. This variation was influenced by the crop management and the edapho-climatic con- ditions of each place. The relative proportion of summer turnip in the diet varied from 2.6 to 40.7% and utilization efficiency averaged 76.5%. The intake of summer turnips presented a wide range. A high summer turnip intake resulted in a decrease in concentrate supplementation, suggesting that farmers use summer turnip as an alternative to concentrate supplementation. The total dry matter and metabolizable energy intake were positively correlated with increasing quantities of summer turnip and concentrate in the diet, resulting in greater milk production. Low dry matter intakes were related with low milk production, regardless the level of inclusion of each component and the nutritional composition of the diet.