A total of 970 normal lactation records of Friesian cows kept at Sakha farm,
Ministry of Agriculture, Egypt during the period from 1968 to 1992 were used to
estimate means, phenotypic, environmental and genetic correlations as well as
heritability for TMY, 305 DMY and LP. The sire effects on milk production traits and
estimates of sire transmitting abilities for TMY and 305 DMY were calculated. The
results obtained could be summarized as follows:- The actual means of TMY, 305 DMY and LP were 4467, 3623 kg and 409 day,
respectively. Year of calving had highly significant effects (P< 0.01) on TMY and 305 DMY and
significant (P< 0.05) on LP. 3. Month of calving had highly significant effect (P< 0.01) on TMY and significant
effect (P< 0.05) on LP, but non Significant on 305 DMY. 4. Sire had highly significant (P< 0.01) effects on TMY and 305 DMY, but non
significant on LP. Heritability (h² ± SE) for TMY, 305 DMY and LP were 0.45±0.11, 0.54±0.12 and
0.09±0.08, respectively. Phenotypic correlations between TMY, 305 DMY and LP were positive and highly
significant (P< 0.01) (0.70 and 0.69) and the corresponding value between 305
DMY and LP (0.15) was positive and highly significant (P< 0.01). Values of the
environmental correlations between traits under study were positive and highly
significant (P< 0.01). All genetic correlations between milk production traits were
positive and highly significant (P< 0.01), and the values of genetic correlations
between TMY with each of 305 DMY and LP were 0.99±0.05 and 0.67±0.24,
respectively, the corresponding value between 305 DMY and LP was 0.62±0.39. Estimates of transmitting ability ranged from -849 to 1220 kg for TMY and -468 to
956 kg for 305 DMY, additionally, the 50 percent of sire showed positive (BLUP) for
the TMY and 305 DMY. Rank correlations among expected values of sires for TMY and 305 DMY was 0.99.