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A genetic study on the lactation curve in Friesian cattle
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Abstract: Weekly milk production of 3735 records from 1545 Friesian cows belonging to Sakha and El_Karada stations- Ministry of Agriculture were utilized to estimate the shape of the lactation curve using the gamma function of Wood (1967), (Yn= a nb e-cn) where yn is the average daily yield in the nth week, a, b, c are parameters and e is the base of the natural logarithm. Extension factors for extending incomplete records to 308_day milk yield were developed. The parameters of the function (a, b, c) and three generated traits week of peak (b/c), peak yield (a(b/c)b e-b), and persistency (c-b+1)) were estimated for each record. The least squares means + se of a, b, c, week of peak, peak yield, persistency, total milk yield, 305-day milk yield and lactation length were 72.03+3.80, .1964+.03, .0337+.01, 7.03+.36 wk, 79.3+4.41kg, 99.7+5.46, 3537+181 kg, 2673+144 kg and 427+12 d, respectively.
The resulting heritabilities and correlations indicate that selection for high peak yield would be more effective for higher 305-day milk yield than direct selection.
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| Publication year |
1991
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| Pages |
pp.113
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| Availability location |
مكتبة معهد بحوث الانتاج الحيوانى- شارع نادى الصيد- الدقى - الجيزة
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| Availability number |
381
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| Organization Name |
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| Country |
Egypt
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| Author(s) from ARC |
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| Agris Categories |
Animal husbandry
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AGROVOC
TERMS |
Cattle.
Cows.
Genetic correlation.
Heritability.
Lactation.
Milk production.
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| Proposed Agrovoc |
lactation curve;
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| Publication Type |
Master Thesis
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