Data Correction for Seasonal Effect on Daily Gain, Feed Conversion Rate and Testing Period of the Performance Test in Pigs

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  • 豚産肉能力直接検定における季節の影響に関する成績補正法
  • ブタ サンニク ノウリョク チョクセツ ケンテイ ニ オケル キセツ ノ エイ

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Abstract

The data of daily gain (DG), feed conversion rate (FC) and testing period (DAY) in the pig performance test were analysed to evaluate the effect of season on the data and to obtain the seasonal correction factors. The data had been obtained from 138 boars of Large White and Landrace tested from 1981 to 1984 at Fukuoka Agricultural Research Center. The starting day of the performance test in a year was transformed into the clockwise angle around the origin of X, Y-place while the Y-axis for plus value was assigned as the 31st of December. Each performance record was expressed as the length of vector started from the origin and directed by the starting day of the test to describe above the X, Y-plane. In this situation, it was found that the heads of the vectors distributed elliptically. The ellipse was fitted to the distribution of the vector heads and the seasonal correction formulae were derived from the characteristics of the ellipse. The ellipses fitted to the DG, FC and DAY explained 84.4, 65.9 and 89.7% of the original variation, respectively. The seasonal correction equations were derived as;<br>ΔDG(kg/days)=0.759-[1/(2.274-0.5049×sin2θ-0.2692×sinθcosθ)]1/2<br>ΔFC=[1/(0.085+0.0186×sin2θ+0.0194×sinθcosθ)]1/2-3.05<br>ΔDAY(days)={1/[1.48/104+(4.75/105)×sin2θ+(3.21/105)×sinθcosθ]}1/2-70.6<br>where θ was(360°/365days)×(the number of days from the 31st of December to the starting day of the test). The seasonal correction of the data did not change the amount of the error variance and was markedly decreased the variance caused by the difference of the temperature. The basic idea of the seasonal correction can be applied to many different conditions.

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