Some factors affecting the performance of imported Friesian cows in Dujaila project
1985
Taher, K.N.
Least-square method used for analysis 1448 first and second lactation records produced by 1181 pure bred Friesian pregnant heifers over the period 1980-1982, heritabilities estimated by paternal half-sib method for partial (60, 90 and 120 days) and 305-day milk yield, persistancy of lactation, days open and calving interval using 47 sire progeny groups, also the influence of some genetic and nongenetic factors of these characters as well as number of service per conception (S/C) were investigated. Five mathematical models were used and results obtained showed that the sire had no effect on all traits except 305-day milk yield and while age at first calving had effect on persistency of lactation, parity had effect on milk yield and persistency of lactation, calving season affected the latter two parameters as well as calving intervals and (S/C) and while year of calving affected all traits studied, the level of milk production affected calving intervals. Also significant phenotypic correlations were found between partial and 305-day milk yield and between persistancy of lactation and partial and 305-day milk yields
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