CHANGES OF STAYABILITY, MILK AND CALF PRODUCTION IN FRIESIANS, IN EGYPTIAN ENVIRONMENTS

Data on 1691 lactations of 407 Friesian cows during the period 1978-19 88 were classified into two groups. The first was composed of the dams imported from Holland. The second included their female offsprings lo cally born in Egypt. Records were analysed by general linear models fo r stayability, first lactation milk yield (FMY), total milk yield and calf production up to five years of age (TMY5 & CP5) and total milk yi eld to five years without first lactation milk yield (TMY5-1). The res ults showed that the averages of survival rates up to 48, 60, 72 month s of age were 50, 41 and 22 % for all Friesian cows studied. The staya bility values were lower in locally born than in the imported animals, but the differences were not significant either for 36-48 or 60-72 mo nths of age. The regression coefficients of stayability for 36-48 mont hs on age at first calving and FMY were negative (-016 and -0.0002, re spectively) and significant (P<0.01 and 0.05, respectively). FMY and C P5 were non-significantly and TMY5 and TMY5-1 were significantly (P<0. 01) higher in imported than in locally born cows. Year-season of first calving showed highly significant (P<0.01) effects on FMY, TMY5, CP5 and TMY5-1. The FMY, TMY5, CP5 and TMY5-1 decreased between the years 1981 and 1985. The regression coefficients of FMY of offspring on thos e of dams in Holland, Egypt and both together were not significant. Th e effect of age at first calving on TMY5 was significant (P<0.05) and the effect of FMY on each of TMY5 and TMY5-1 was highly significant (P <0.01).