ホルスタイン種雌牛の線形式体型形質に対する年齢と泌乳ステ-ジの影響

概要

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The objective of this study was to estimate the effects of age and stage of lactation at the time of classification on 15 linear type traits. Linear type data were taken from 55, 213 records of Holstein cows collected between April 1984 and December 1986 and obtained from the Holstein Cattle Association of Japan, Hokkaido Branch. All traits were scored on a scale of 1 to 50, with 25 at the intermediate. The model used to analyze each trait included herd-year within classifier, age and stage of lactation at the time of classification as fixed effects. The means value for linear type traits ranged from 34.10 (stature) to 22.56 (foot angle) with standard deviations of between 6.99 (stature) and 4.07 (rump angle). The effects of herd-year within classifier and age at classification were significant (P<0.01) for all traits. The largest variation in traits for age at classification were observed in rump width, udder depth, rump length, body depth, and strength. The effects of stage of lactation at classification were significant for all traits (P<0.01, only foot angle P<0.05) except stature. Rear udder width, rear udder height, udder depth and angularity showed the largest variation relative to stage of lactation.
社団法人日本畜産学会の論文