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Paper Information

Journal:   THE SCIENTIFIC JOURNAL OF AGRICULTURE (SJA)   DECEMBER 2006 , Volume 29 , Number 3; Page(s) 11 To 22.
 
Paper: 

ESTIMATION OF GENETIC PARAMETERS OF MILK PRODUCTION TRAITS FOR HOLSTEIN COWS IN KBUZESTAN PROVINCE

 
 
Author(s):  TAHERI DEZFOULI B.*, BEYGI NASIRI M.T.
 
* ANIMAL SCIENCE DEPRTMENT, COLLEGE OF AGRICULTURE, SHAHID CHAMRAN UNIVERSITY, AHWAZ, KHUZESTAN, IRAN
 
Abstract: 

To study milk production traits and estimate genetic related parameters, 3245 records of milk yield, fat yield and fat percentage of Khuzestan Holstein cows were used. The effects of the region, herd, parity, calving year, season and month of calving were evaluated on the traits. Also the effect of Herd-Year-Season (H-Y-S) was investigated on the traits in a mixed model including age of calving as a covariate. The effects of the region, herd and calving year were significant on all traits, but the effects of parity and calving season were not significant on fat percentage. The effect of H-Y-S was significant on all traits, too. The mean and standard deviation of milk yield, fat yield and fat percentage were 3851.57±1073.34 Kg, 136.08±43.51 Kg and 3.57±0.70 percent, respectively. Heritability of milk yield, fat yield and fat percentage were 0.24±0.10, 0.25±0.11 and 0.36±0.10 using univariate model and were 0.19±0.06, 0.30±0.08 and 0.31±0.05 using repeatable model Estimated. Repeatability was 0.32, 0.32 and 0.32 for milk yield, fat yield and fat percentage, respectively. The genetic, residual and phenotypic correlation were 0.70, 0.76 and 0.75 between milk yield - fat yield, -0.30, -0.32 and -0.31 between milk yield – fat percentage and 0.47,0.32 and 0.37 between fat yield - fat percentage. Lactation curves were studied for four calving seasons, using monthly records. The highest peak of milk production and the best persistency of lactation curve were found for winter calving cows and fall calving cows, respectively.

 
Keyword(s): MILK YIELD, FAT YIELD, FAT PERCENTAGE, HOLSTEIN COWS, LACTATION CURVE, KHUZESTAN AND GENETIC PARAMETERS
 
References: 
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