Random Regression Analysis of Calving Interval of Japanese Black Cows.

Shinichiro Ogawa,Masahiro Satoh

doi:10.3390/ani11010202

Abstract

Simple SummaryGenetic parameters for the calving interval of Japanese Black cows were estimated by using a random regression model and a repeatability model. Legendre polynomials based on age at previous calving, ranging from 18 to 120 months, were used as sub-models for random regression analysis. The estimated heritability for the calving interval was low and was similar between the models. The estimated genetic correlation between ages was always higher than >0.8. Spearman’s rank correlation of the estimated breeding values between the two models was ≥0.97 for cows with their own records and ≥0.94 for sires of these cows. Therefore, this study supports the validity of fitting a repeatability model to the records of the calving interval of Japanese Black cows for breeding value evaluation. Our results could contribute to determining strategies for selection and management of Japanese Black cattle.We estimated genetic parameters for the calving interval of Japanese Black cows using a random regression model and a repeatability model. We analyzed 92,019 calving interval records of 36,178 cows. Pedigree data covered 390,263 individuals. Age of cow at previous calving for each record ranged from 18 to 120 months. We used up to the second-order Legendre polynomials based on age at previous calving as sub-models for random regression analysis, and assumed a constant error variance across ages. Estimated heritability was 0.12 to 0.20 with the random regression model and 0.17 with the repeatability model. With the random regression model, the estimated genetic correlation between ages was ≥0.87, and those between 24 and 36 months, 24 and 84 months, and 36 and 84 months were 0.99, 0.95, and 0.97, respectively. Spearman’s rank correlation between breeding values of 36,178 cows with their own records estimated by the random regression model with those estimated using the repeatability model was ≥0.97, and the rank correlation was ≥0.94 for 314 sires of these cows. These results support the validity of fitting a repeatability model to the records of the calving interval of Japanese Black cows for evaluation of breeding values.

Highlights

Japanese Black beef cattle are well known to excel in meat quality including the degree of marbling [1,2]
In Japan, elite sires are selected for artificial insemination in each region or prefecture; since 1991, when beef importation was liberalized, breeding values for major carcass traits have been routinely evaluated by the Best Linear Unbiased Prediction (BLUP) method [3,4]
36 months, 0.95 between 24 and 84 months, and 0.97 between 36 and 84 months of age at previous calving. These results indicate that the genetic homogeneity of the calving interval (CI) over age is high in Japanese Black cows

Summary

Introduction

Japanese Black beef cattle are well known to excel in meat quality including the degree of marbling [1,2]. In Japan, elite sires are selected for artificial insemination in each region or prefecture; since 1991, when beef importation was liberalized, breeding values for major carcass traits have been routinely evaluated by the Best Linear Unbiased Prediction (BLUP) method [3,4]. To accomplish stable and efficient beef production, it is important to improve female reproductive efficiency in Japanese Black cattle [7,8]. The calving interval (CI) is a female reproductive efficiency trait that can be relatively recorded. A shortened CI is directly associated with an increased number of progenies, so the economic importance of the CI in Japanese

Methods

Results

Discussion

Conclusion