Genetic and phenotypic studies on milk production traits of friesian cows in Egypt
Abstract: Total of 2860 records from 1st to 6th lactations of Friesian cows were used in the present study. Number of sires and the average number of daughters per sire were 231 and 12.4, respectively. These data were used to estimate genetic and phenotypic parameters for total milk yield (TMY) , 305 day milk yield (305 DMY) and lactation period (LP) . The statistical model included the effect of sire as random effect, month of calving , year of calving and parity as fixed effects and both of cow weight at calving (CW) and age at first calving (AFC) as covariate on milk production traits .
The results obtained could be summarized as follows:
1 – Month of calving had significant effect (P<0.05) on TMY and 305 DMY and non significant effect on LP. 2 – Year of calving had highly significant effect (P<0.01) on TMY and 305 DMY, while non significant on LP. 3–Parity had highly significant effect (P<0.01) on all traits under study . 4 – Estimation of partial linear regression coefficients of TMY on CW was positive and highly significant (P<0.01) , and only significant (P<0.05) for 305 DMY on CW , while , partial quadratic regression coefficients of TMY and 305 DMY on CW were positive and highly significant (P<0.01) , partial quadratic regression coefficients for traits under study of AFC were positive and highly significant (P<0.01) . 5 – The sire had highly significant effect (P<0.01) on TMY and LP , but only significant effect (P<0.05) on 305 DMY . 6 – Heritability estimates ( ± SE) for TMY , 305 DMY and LP were 0.11 ± 0.03 , 0.04 ± 0.02 and 0.07 ± 0.02 , respectively . 7 – Each of genetic and phenotypic correlations between traits the present under study were positive and highly significant.
Publication year 2005
Pages 5849-5856
Availability location معهد بحوث الانتاج الحيوانى- شارع نادى الصيد- الدقى - الجيزة
Availability number
Organization Name
City المنصورة
serial title Journal of Agricultural Science Mansoura University
ISSN 1110-0346
Author(s) from ARC
Agris Categories Animal husbandry
AGROVOC
TERMS		 Cows. Egypt. Genetic parameters. Heritability. Milk production. Phenotypes.
Publication Type Journal
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