00227304

open access

Version of Record

クロゲ ワシュ キョセイギュウ ノ タイジュウ オヨビ タイケイ ソクテイチ ニ カンスル イデンテキ パラメーター ノ ヒイク カテイ ニオケル スイイ

Changes of Estimates of Heritability and Genetic Correlations for Body Weight and Measurements during a Fattening Period in Japanese Black Steers

Japanese (日本語)

神戸大学農学部研究報告

15(2)

427-436

神戸大学農学部

1983-01-30

2006-09-15

本文ファイルは、国立情報学研究所CiNiiより提供されたものです。

Estimates of heritability were calculated for each of body weight and eleven linear measurements at 12 ages during a fattening period, and for those relative growth rates (RGR_s) over 4 subsequent periods. In addition, intra-age genetic and phenotypic correlations between measurements were estimated at a sequence of 3 ages. Data were recorded at 28- or 21-day interval from average 266 days up to average 567 days of age on 732 steers sired by 127 Japanese Black bulls progeny-tested during 1971-1977 at 9 testing stations in Japan. Least squares analysis based on Method 3 of Henderson (1953) was used to estimate the variance and covariance components, taking account of the effect of station-year, sire within station-year, and age of dam as covariate. For all measurements, the heritabilities were estimated in general high, but the age trends were different among measurements. The estimates of body weight and chest girth ranged from 0.79 to 0.70 and from 0.95 to 0.84,respectively, and showed no particular change during the testing period. With respect to withers and hip height the estimates decreased slowly from about 0.75 to 0.55. Similar trends were observed for body length, hip and thurl width. The heritability estimates of chest depth and width, croup length, pin-bone width, and cannon circumference decreased initially and thereafter increased with age. Thus the patterns of changes showed V-shaped curves. The heritabilities of RGR_s over 4 periods changed markedly as compared with those of body size. Generally there was a steady decline from first period to second and/or third period in all measurements except for hip width, croup length, chest girth and width. Thereafter there was a rapidly increase up to fourth period. RGR_s for body width measurements tended to have higher heritability estimates than those of body size at similar age. The patterns of changes in the genetic correlations during the testing period were different by the combination of measurements. The genetic correlations between weight or chest girth and other measurements were stable through the time. However, the correlations involving withers or hip height decreased and those of chest or pin-bone width increased with age. These results suggest that the expression of a genotype can change with age and genetic parameters largely determined by the composition of growth that has taken place during the fattening period.

紀要論文