Phenotypic and Genotypic Trends for Some Economic Traits in Egyptian Buffaloes

A total of 2763 lactation records of Egyptian buffaloes, sired by 147 bulls, were collected from Mahalla Mousa Farm, Kafer El sheihk Government. Traits studied are milk production (MP), lactation length (LL) and age of heifers at calving (AHC). Effects of  period and month of calving, lactation order and  heifers at calving were studied as main effects , beside bull, buffaloes within bulls and errors were studied as random effects.. Also, Animal mode was used to estimate genotypic parameter, transmitting ability, phenotypic and genotypic trends for above traits studied . Least squares analysis of variance  (Table 2) show  a significant effects of   year of calving and month of calving and lactation order on MP, LL and AHC. Linear and quadratic regression coefficients of MP and LL on AHC had also a significant effect.Sires and buffaloes within sires had a significant effect on MP, LL and AHC. Estimates of (h2) were 0.28, 0.20 and 0.10, for MP, LL and AHC respectively. Genotypic correlations between MP and each of LL and AHC were 0.76 and -0.36, respectively. Genotypic correlation between MP and AHC was -0.30. Phenotypic correlation between MP and both of LL and AHC were 0.80 and -0.90, respectively and phenotypic correlation between LL and AHC was -0.40. Predicted transmitting ability from buffaloes ranged from -774 to 933 kg for MP from – 60 to 101 d for LL and from – 4 to 8 mo., for AHC. Predicted sire transmitting ability for MP ranged from – 408 to 535 kg, for LL ranged from -27 to 29 d and for  AHC ranged from -2 to 5 mo., Expected dam transmitting ability  ranged from -388 to 365 kg for MP, from – 30 to 23 d for  LL from - 2 to 2 mo., for AHC. Annual phenotypic and genetic trend for milk production calving was positive and significant. While, annual genotypic change for lactation length and age of heifers at calving were negative and significant.