الفهرس 
SUMMARYOnly 14 pages are availabe for public view
 |  | from | 135 |  |  |
| | | from | 135 | | |
Abstract
A total of 3321 normal lactation records of Egyptian buffaloes, kept at three experimental farms (Mehallet Mousa, El-Nattafe El-Gaded and El-Nattafe El-Kadem), belonging to the Animal Production Research Institute, Ministry of Agriculture, Dokki, Cairo, Egypt, during the period from 2000 to 2007 were used. Each record included cows, sires and dams identification, date of calving (month - year), farm, parity, lactation period (LP), total milk yield (TMY), fat yield (FY), protein yield (PY), lactose yield (LY) and somatic cell counts (SCC). Traits studied of Egyptian buffaloes.
Data were analysis by using Harvey (1987) to study the fixed effects of month and year of calving, parity and farm and random effects of sire on total milk yield (TMY), lactation period (LP) , fat yield (FY), protein yield (PY), lactose yield (LY) and somatic cell count (SCC). In addition, genetic parameters (i.e., heritability, genetic correlation and phenotypic correlation) and breeding values for different traits studied were analysis by using Multi Trait Animal model (MTAM). In addition, phenotypic and genetic trends for different traits studied are estimated.
The results of the present study can be summarized for the following:
1-Means for TMY, LP, FY, PY, LY and SCC were 2070 kg, 223 d, 164.4 kg, 89.5 kg, 128.2 kg and 204.78, respectively.
2-Month of calving had a significant (P < 0.01) effect on TMY, LP, FY and PY while had no significant effect on LY and SCC. Year of calving had a significant effect on TMY, LP, FY, PY, LY, while had no significant effect on SCC. Parity had a significant effect on TMY, LP, FY, PY and LY, while had no significant effect on SCC. Farm had a significant effect on TMY, LP, FY, PY and LY, while had no significant effect on SCC.
3-Sire of the cows had a significant (P < 0.01) effect on all traits studied, expect the effect of sire on SCC.
4-Heritability estimates (+ SE) for TMY, LP, FY, PY, LY and SCC are 0.41 (0.06), 0.31 (0.07), 0.20 (0.09), 0.19 (0.03), 0.22 (0.10) and 0.06 (0.03), respectively.
5-Estimates of genetic correlation rg between milk traits (i.e., TMY, LP, FY, PY and LY) are positive and highly significant and ranged from 0.18 (0.09) to 0.75 (0.07), while the genetic correlation between SCC and all milk traits are negative and ranged from -0.18 (0.10) to -0.66 (0.024).
6-Phenotypic correlation among all traits studied are the same direction of genetic correlations.
7-The range of expected sire breeding values for milk traits were 912 kg, 146 d, 16.1 kg, 5.5 kg, 10.1 kg and 471 kg for TMY, LP, FY, PY, LY and SCC, respectively.