Ratio and Regression Factors for Predictinc 305 Day Production from Part Lactation Milk Records in a Herd of Holstein Friesian Cattle
Titel:
Ratio and Regression Factors for Predictinc 305 Day Production from Part Lactation Milk Records in a Herd of Holstein Friesian Cattle
Auteur:
H. Atil
Verschenen in:
Pakistan journal of biological sciences
Paginering:
Jaargang 2 (1999) nr. 1 pagina's 31-37
Jaar:
1999
Inhoud:
A normal 3780 lactation records of Holstein Friesian cattle were collected from Dena Farm in Egypt during the period from 1988 to 1996. The means of cumulative milk yield were 535, 1196, 1837, 2419, 2941, 3392, 3777, 4081, 4332 and 4533 kg for 30, 60, 190, 120, 150, 180, 210, 240, 270 AND 305 days milk yield (dMY), respectively. Least squares analysis of variances showed highly significant effects of month and year of calving, parity as a fixed effects, sire and cow within sires as random effects on cumulative monthly milk yield. Heritability estimates were 0.23, 0.25, 0.25, 0.29, 0.32, 0.32, 0.33, 0.34, 0.34 and 0.35 for ten period of cumulative milk yield. All phenotypic and genetic correlations between different traits were significant (P<0.01). The range of ratio factors for different cumulative milk yield were estimated as 1.07 to 8.47. Estimates of partial linear and quadratic regression coefficients of 305 day milk yield on cumulative monthly milk yield were significant. The accuracy of prediction (R2) increased with the increase in the number of cumulative milk yield. Records of the first seven months of lactation are considered sufficient for predicting 305 day milk yield. The predicted 305 day milk yield is more accurate using the regression method from the ratio factors.
Uitgever:
Asian Network for Scientific Information (provided by DOAJ)
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