Influence of calving season and somatic cell score on reproductive and productive performance of Overo Colorado in Los Lagos Region

Abstract

The Overo Colorado breed, is a dual-purpose cattle breed; selection process over time has led it to acquire adaptation traits and rusticity and becoming an alternative to southern Chilean dairy production systems based on grazing. This study was done using milk recording data from the Cooperativa Agrícola y Lechera de Frutillar Ltda. (CAFRA) considering 1,800 lactations, of Overo Colorado cattle at the province of Llanquihue, in Los Lagos Region of Chile. The general objective was to describe productive and reproductive performance of the cows, considering calving season and somatic cell score (RCS). The hypothesis of this study was that calving season and somatic cell score, do not influence dairy production and reproductive performance. Using linear multiple regression models, least square means were obtained for the variables of interest: milk yield and composition, and calving interval (LIP). The descriptive results showed milk yield mean at 4,467 kg cow^-1. Fat and protein percentage mean values were found at 3.63% and 3.4%, respectively. The proposed linear models determined that calving season and RCS, had significant effects on yield and LIP. Regarding milk yield, lactations initiated in winter and autumn were significantly more productive than those commenced in other season; LIPs were lower for winter and autumn calving seasons. For fat percentage, the lactations started in summer obtained higher values, and protein percentage was favorable for lactations starting in spring. Meanwhile, milk production and fat percentage decreases as RCS and LIP increased.