Influence of calving season on milk production and composition in a free stall farm in los Rios Region, Chile

Abstract

The study was conducted on a farm with Holstein Friesian cows kept in complete free stall-housing in the Cudico area of Los Ríos Region of Chile. The data were milk records from the Cooperativa de Inseminación Artificial (COOPRINSEM), which consisted of 955 lactations made from 2011 to 2014.
The general objective was to determine the influence of calving season on yield. Additionally milk quality, somatic cell count and urea across. Data were analyzed using the SAS software by PROC MEANS and PROC GLM modules.
The results show that calving season had a significant influence (p≤0.01) on milk, fat and protein yield, being higher, for milk and fat yield, in cows calving on Fall, 11,932 and 430 kg respectively; while the protein was higher for Summer calving cows at 413 kg. In more than half of the lactations (52.9%), milk yield reached between 11,001 to 12,500 kg of milk. Yields were higher in 2012, 2011 and 2014 for milk, mil fat and milk protein, respectively.
On regard to milk hygienic quality, measured as somatic cell count (RCS), age and calving year were significant. However, age and calving year were not significant for urea.