STUDIES OF 305-DAY MILK, DAILY MILK YIELD AND PERSISTENCY OF LACTATION OF FRIESIAN CATTLE IN YEMEN

A total of 188, n and 191 records of 305-day milk,daily milk yield and persistency, respectively, of Friesian cows raised at Krab Dairy Farm (80-85 km south salute- Yemen) through the period 2000-2004 were statistically analyzed. General linear model (GLM) of SAS program was used to investigate the effects of fixed factors. Maximaum lieklihood method was applied to estimate variance components .The overall mean of 305-day milk ,daily milk yield and persistency were 4330, 14.0 and 87.56%, respectively. The 303-day milk and daily milk yield were affected significantly (p<0.05) by calving year,calving season and parity. The effect of parity was found on persistency of milk production lacked significance, whereas persistency was affected (p<0.05) by calving year and calving season(90.74 % in winter and 84.39 % in summer).The heritability of 305-day milk, daily milk yield and persistency were 0.13, 0.17 and 0.11, respectively, while the repeatability of 305-day milk,daily milk yield and persistency were 0.18, 0.21 and 0.23, respectively.