| Titles |
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English :
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Genetic and phenotypic parameters for milk fat and protein percentage and 305- day milk production in Friesian cows
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Arabic :
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المعايير الوراثية و المظهرية لصفات محصول اللبن و النسبة المئوية لدهن و بروتين اللبن لابقار الفريزيان
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| Abstract |
This sturdy was carried out on 239 lactating Friesian cows belonging to Animal Production Research Institute, Ministry of Agriculture, for three years. Effects of sire, parity season of calving and age at first calving on each of milk yield 305- day (My – 305), milk fat and protein percentages, fat yield 305 – day (CFP- 305) were investigated. Heritabilities as well as genetic and phenotypic correlations for all traits under investigation were evaluated. Sire had highly significant effect on MY- 305, FY- 305, CEP- 305 and fat % and only significant effect on PY-305, as well as non significant effect on protein %. Differences in all studied traits due to cow effect were insignificant. Parity had highly significant effects on My- 305 as well as significant effect on Fy- 305,Py- 305 and CFP- 305, and non- significant effect on protein %. Differences due to season of calving were insignificant for all traits under study. There was no significant regression of all the studied traits on age at first calving. Heritabilities for My- 305, fat %, protein % ,Fy- 305, Py- 305 and CFP- 305were 0.45, 0.33, 0.11, 0.49, 0.31 and 0.44, respectively. Genetic correlation among yield traits were positive, ranged form 0.59 to 0.72 between fat % and yield traits, while they were negative and ranged from-0.41 to-0.41 to –0.57 between protein % and yield traits and – 0.65 between fat % and protein %. Phenotypic correlation among yield traits ranged from 0.85 to 0.97, from 0.31 to 0.62 between fat % and yield traits, from –0.03 to .0.38 between protein % and yield traits and it was 0.05 between fat % and protein %.
Keywords: Dairy cattle, Milk yield, Milk constituents. Sire. Parity. Age at first calving. Genetic parameters.
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| Publication year |
2001
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| Pages |
1923-1931
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| Availability location |
معهد بحوث الانتاج الحيوانى- شارع نادى الصيد- الدقى- الجيزة
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| Availability number |
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| Organization Name |
Animal Production Research Institute (APRI)
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| Country |
Egypt
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| City |
المنصورة
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| serial title |
Journal Agricultural Science
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| Volume |
26
. 4
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| Department |
Cattle Breeding Research Department
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| Author(s) from ARC |
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| Agris Categories |
Animal husbandry
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AGROVOC
TERMS |
Cows.
Genetic distance.
Genetic variation.
Milk fat.
Milk production.
Milk protein.
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| Publication Type |
Journal
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