AVEREG MILK YIELD AT SECOND BIRTH AS INDICATOR OF PRODUCTION LIFE IN HOLSTEIN

F.R.Al-Samarai,; N.N.Al-Anbari,

	AVEREG MILK YIELD AT SECOND BIRTH AS INDICATOR OF PRODUCTION LIFE IN HOLSTEIN
The Iraqi Journal of Agricultural Science
Article 1, Volume 38, Issue 2, 2007, Pages 87-93
Authors
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Abstract
At the Nasr Dairy Cattle Station, United Company for Animal Resources Ltd., Al-Soueira ( 50 Km South of Baghdad ) , recoreds over period from 1998 to 2004 belonged to 944 Holstein cows were statistically analyzed. This was to evaluate sires genetically according their daughters average milk yield per day of age at second calving . The General Linear Model (GLM) within the SAS program was used to study the effects of fixed factors (season and year at first calving, age at first calving) on the average milk yield per day of age at second calving. Components of variance for the random effects in the employed mixed model were estimated by the Minimum Variance Quadratic Unbiased Estimation procedure (MIVQE). The Harvey program was also used to estimate Best Linear Unbiased Prediction (BLUP) values for 23 sire. The overall means of average milk yield for the period from birth to seconed calving ".vas 2.79 !;g and the effect of "all fried factors (season , year of first calving and age at first calving ) was significant. Heritability of the studied traits was 0.39. The genetic correlation between the average milk yield per day of age at second calving and each of first total milk yield , first calving interval , productive life and number of lactations were 0.89 ,0.43 , 0.47 and - 0.15 respectively, the corresponding phenotypic correlation were 0.93 , 0.54 , 0.59 and - 0.16 respectively. Best Linear Unbiased Prediction (BLUP) estimate displayed a wide rage among 26 sires included in the current study. Therefore there are of utmost importance for reducing and curtailing the average milk yield per day of age at second calving (ranged from 0.71 to - 0.73 kg respectively). There was a wide range in BLUP values estimated which reflected the importance of genetic additive variance. This could be used latter via selection methods to improve the mentioned characteristics of Holstein cattle in Iraq.

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