Genetic and non-genetic factors affecting total milk yield, days open, number of service per conception and age at first calving of friesian cows in Egypt.
Abstract: Total of 1394 normal records of Friesian cows in first lactation sired by 146 bulls collected from Sakha Farm, Ministry of Agriculture, Egypt during the period from 1970 to 1993 were used in this study. The data were used to estimate: the effects of non-genetic and genetic (sire) factors on total milk yield (TMY) and some reproductive traits namely days open (DO), number of service per conception (NSPC) and age at first calving (AFC), and to estimate genetic and phenotypic parameters for the previous traits. Data were analyzed using linear mixed model of Harvey's (1990). The results obtained could be summarized as follows:-
1. The actual means of TMY, DO, NSPC and AFC were 3391.9 kg, 190.7 days, 2.2 service and 31.8 month, respectively. Coefficients of variation of TMY and some reproductive traits (DO, NSPC and AFC) were 42.8% and (34.7%, 59.3% and 16.8%), respectively.
2. Month of calving had significant (P< 0.05) effect on days open, while, non significant effects on number of service per conception, age at first calving and total milk yield.
3. Year of calving had highly significant (P< 0.01) effect on total milk yield and of reproductive traits under the present investigation.
4. The sire had highly significant (P< 0.01) effects on total milk yield and days open and only significant (P< 0.01) effects on number of service per conception. While, non significant effect on age at first calving. The sire variance component (s2s) were 3.62%, 6.13%, 2.43% and 1.30% for TMY, DO, NSPC and AFC, respectively.
5. The estimates of heritability of total milk yield and reproductive traits of the cows at their first parity (based on parental half-sibs methods) were 0.15, 0.25, 0.10 and 0.05 for TMY, DO, NSPC and AFC, respectively.
6. Genetic correlations between reproductive traits studied were positive and significant (P< 0.01), except NSPC with AFC it was negative and significant (P< 0.01).
7. Phenotypic correlations between some reproductive studied traits were showed positive and significant (P< 0.01) values.
Environmental correlation between reproductive traits studied were positive and highly significant (P< 0.01).
Publication year 2004
Pages 6843-6851
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. Milk yield. Reproductive performance.
Publication Type Journal
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