The aim of this study is to compare the constituent factors of carcass production cost in the pig farms between low and high income per sow. The data are based on the pig farm business survey by Yamagata Livestock Association from April 1991 to March 1992. They were collected from 39 pig operations and classified into two groups, i. e the high class income per sow and the low class income per sow.
The constituent factors of pig production cost were determined by multiple regression analysis. Stepwise forward regression method was used to select the independent variables. The dependent variable is the production cost of pork carcass per kilogram and independent variables are 26 items such as: feed cost per kg gain, yearly numbers of weaned piglets per sow, yearly frequency of farrowing per sow, feed conversion ratio, etc.
The results of this study are as follows:
1) The multiple regression expression in the high income pig farms was as follows.
Y=1.94X
1-46.11X
2-4.08X
3+3.03X
4-50.77X
5+0.09X
6+688.98 (R=0.970)
where, X
1 is the feed cost per kg gain, X
2 is the yearly frequency of farrowing per sow, X
3 is the raising rate per sow, X
4 is the death rate in hog, X
5 is the feed coversion ratio and X
6 is the fixed assets per sow.
2) The multiple regression expression in the low income pig farms was as follows
Y=2.18X
1+0.0014X
2+0.72X
3-7.04X
4+4.06X
5-119.19X
6+504.62 (R=0.893)
where, X
1 is the feed cost per kg gain, X
2 is the cost of depreciation per sow, X
3 is the yearly replacement rate in sow, X
4 is the yearly numbers of nursing piglets per sow, X
5 is the death rate in hog and X
6 is the feed coversion ratio.
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