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Please use this identifier to cite or link to this item: http://hdl.handle.net/123456789/679

Title: Factors affecting lactation curves of friesian cows in Saudi Arabia
Authors: Sharaby, M.A.
Aziz, M.A.
Keywords: Lactation curves
Friesian cows
Saudi arabia
Issue Date: 1994
Publisher: King Saud University
Citation: J. of King Saud University, Agriculture Science: 6(2); 253-259
Abstract: First lactation records of 203 Friesian cows were utilized to estimate parameters of the lactation curve using the incomplete gamma function and to determine the importance of sex, season of calving and the regression of these parameters on coefficients of dam weight, calf weight and age at first calving. Sex of calf had nonsignificant effects on the estimated parameters of the lactation curve. However, aborted cows had lactation curves different from the normally delivered cows. Season of calving had a significant effect on the initial milk yield (Log (a» and rate of increase to peak production (b). Dam weight had a highly significant effect (P<0.01) on log (a) and a significant (P<0.05) effect on the seasonal variation<br>other than season of calving (cosine (v». Its regression coefficients for both parameters were 0.004 :t 0.001 and 0.0005 :t 0.0003, respectively. However, dam age had no effect. Calf weight had a highly significant effect (P<0.01) on all parameters, but the value ofv. The regression coefficients for initial yield (log a), rate of increase to peak production, rate of decrease after peak and seasonal variation (sin u) were-0.091 :t 0.014,0.090 :t 0.011, -0.0055 :t 0.0020 and -0.0097 :t 0.0028, respectively. It could be concluded that seasonality, dam weight and calf weight had an important effect on the shape of the lactation
URI: http://hdl.handle.net/123456789/679
Appears in Collections:Journal of the King Saud University - Agricultural Sciences

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