Journal of Food, Agriculture and Environment

Selection for lactation curve and determination of the lactation curve function in Iranian Holstein cows by empirical mathematical models

Author(s):

Reza Seyed-Sharifi ^1*, Raouf Seyedsharifi ¹, Ali Reza Fallah Kheir ²

Recieved Date: 2009-01-25, Accepted Date: 2009-04-20

Abstract:

In this study, the first lactation daily milk records of Iranian Holstein dairy cattle, which have been collected during 2001-2005 by the Iranian Animal Breeding Center were used. Heritabilities were small for all curve characteristics expect for c and peak yield. The negative correlation between a and b implies that higher initial yield is associated with a lower rate of increase until peak yield. The positive correlations between b and c indicate that cows that peak more rapidly also have a quicker decline after peak. In the present study, five mathematical models were compared based on adjusted R-square, residual standard deviation. The greatest R² values for polynomial regression function proposed by Ali and Schaeffer whereas the Cobby model ranked lowest.

Keywords:

Lactation curve, Holstein cows, mathematical models

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Journal: Journal of Food, Agriculture and Environment
Year: 2009
Volume: 7
Issue: 2
Category: Agriculture
Pages: 453-455

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