Document Type : Research Paper
Authors
1 Department of Animal Science, College of Agricultural Technology, University of Tehran
2 Department of Agricultural Economics, Faculty of Agriculture, University of Tehran
3 Department of Animal and Poultry Science, Faculty of Agricultural Technology, University of Tehran
Abstract
Determining the production function is one of the most effective and best ways to check the continuity of milk production and indicates the relationship between the consumption of food inputs and milk production. The aim of this research was to investigate the effects of the production function in breeding programs and their use in selecting better animals.
To achieve these goals, data on milk production and feed consumption from one of the industrial farms in Tehran province were used. Various methods were examined in this study: 1- using OLS approach in R environment to estimate the milk production function, 2- using the Peykani extended ordinary least square (POLS) method, 3- estimating the breeding value of milk production using POLS function and physical milk production (field data) using Wombat software, 4- comparing OLS production functions obtained in R with POLS production function, 5- Genetic evaluation of animals and ranking dairy cows.
The estimated functions based on the ordinary least squares method were incorrect in terms of signs and coefficients, and did not fit the milk production curve well. Based on the findings of this study, the non-linear regression model of Peykani (POLS) is the best in the curve fitting and economical production of milk. By using the estimated breeding values in this method، one can choose the best animals as the parents of future generations.
The ability to estimate the production function based on the POLS method, to create a standard curve of dairy cows is very high.
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