Genetic and phenotypic trends of milk production traits in an Egyptian Friesian herd

الملخص EN

The main objective of this study was to estimate the genetic and phenotypic trends for Total milk yield (TMY), adjusted 305-days milk yield (adj305-MY), daily milk yield (DMY), lactation period (LP), peak yield (PY) and lactation persistency (PER) in Frisian herd.

The final data set included 2,852 records obtained from 741 cows and 76 sires,.

Estimated breeding values (EBVs) of for all traits were obtained by the best linear unbiased prediction (BLUP).

Means for (TMY), (adj305-MY), (DMY), (LP), (PY) and (PER) were 4581 kg, 4646 kg, 14.68 kg, 314.27 d, 22.78 kg and 64.5 % respectively.

Estimates of phenotypic trends for thesetraits were, respectively, +72.65, + 65.71, +0.196, + 0.630, + 0.307 and + 0.002.

The annual genetic changes in the estimated breeding values (EBVs) were positive for all above mentioned traits 11.473 kg/yr, 4.15 kg/yr, 0.0026 kg/yr, 0.58 d/yr, 0.002 kg/yr and 0.0002 %/yr.

The estimates of annual genetic changes for (adj 305 -MY), (DMY), (PY) and (PER) were not significant (p>0.05), the TMY and LP were significant (p < 0.05).

It could be concluded that using top ranking bulls on the basis of their EBVs for TMY in breeding programs will lead to noticeable genetic improvement in productivity of an Egyptian Friesian cows, however, the positive genetic trends for all studied traits which may allow the possibility of improving the current herd.The fluctuated rhythm in the curves maybe due to environmental conditions or use sires with low breeding value.