The effect of some factors on stillbirth in primiparous and multiparous Holstein cattle in Iraq
A total of 9691 records of calves belonged to 3076 Holstein cows and 58 sires were analyzed from 1995 to 1999 , at Nasr Dairy Cattle Station. The aim of the research is to evaluate sires geneticelly by using best linear unbiased prediction ( BLUP) according to the stillbirths of their daughters after adjusting for fixed effects and to estimate heritability, phenotypic trend for the mentioned trait.Data were analayzed by using General Linear Model within SAS program to investigate the effect of some fixed factors ( season and year of calving, parity sex of calf ) on the stillbirths. Components of variance for the random effects in the employed mixed model were estimated by the Minimum Variance Quadratic Unbiased Estimation (MIVQUE) method. The Harvey program was also used to estimate BLUP values for sires. The overall mean of stillbirths was 11.19% in primiparous, 8.69% in multiparous and 9.49% in both of them.The effect of all fixed factors was significant (P < 0.01 ) . Heritability of direct effect estimated for stillbirth rates in primiparous and multiparous and in both of them were 0.03 , 0.007 , 0.02 respectively ,whereas corresponding estimates of heritability of maternal effects were 0.04 .0.02 ,0.03 respectively. Phenotypic trend of stillbirths in primiparous was positive and non significant ( 0.19% / year) whereas negative and non-significant ( P < 0.05 ) (- 0.11%/year) in multiparous and in both of them (- 0.07%/year). Minimum and maximum BLUP values of sires for stillbirths were 7.33 and 10.33% respectively.
