FIXED EFFECTS ON MILK DAILY PRODUCTION IN A DUAL PURPOSE SYSTEM

Abstract

It was evaluated the records of a herd of Brown Swiss cows (S) xCebu (C), to determine the effect of some fixed factors on the daily production of milk (PDP, n= 6522). This study was conducted in the milk production unit at the Experimental Farm El Ejido since 1996 to 2004. The studied fixed factors were racial group (GR), year of calving (AP), parity number (NP) and calving season (EP). The studied racial groups were ½ S X C and ¾ S X C. The overall average PPD was 8.10 ± 0.03 kg. Significant differences were observed for all studied sources of variation excepting EP. It is concluded that milk production is influenced by the studied fixed effects. In the same way, it reveals a tendency for the eradication of the seasonality of milk production. It is recommended to evaluate the lactation curve through nonlinear models for a better understanding of the behavior of these effects in the Azuero region.