Skip to main content
ARS Home » Plains Area » Clay Center, Nebraska » U.S. Meat Animal Research Center » Genetics and Animal Breeding » Research » Publications at this Location » Publication #99693
Title: HETEROGENEITY OF VARIANCE AND INTERACTION OF GENOTYPE BY ENVIRONMENT FOR MILK PRODUCTION IN HOLSTEIN CATTLE IN MEXICO

Author
item VALENCIA-POSADAS, M. - FMVZ-UNAM, MEXICO
item RUIZ, F. - CENIFMA-INIFAP, MEXICO
item MONTALDO, H. - ICA-UGTO, MEXICO
item TREJO, B. - CIMAT-AGS, MEXICO
item KEOWN, JEFFREY - UNIV. OF NEBRASKA-LINCOLN
item Van Vleck, Lloyd

Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 3/1/1999
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: For the establishment of selection programs for dairy cattle in Mexico it is important to determine if heterogeneity of variance exists for milk production and to investigate genotype x environment interaction (GxE) among regions. The objectives of this study were 1) to estimate variance components (VC) by region and periods of time, 2) to estimate VC after classifying herd-years by standard deviation level (SDL) and 3) to investigate GxE between regions. Records were provided from Mexican Holstein Association. Only mature equivalent 305d milk yields were considered. Records were classified by three regions (North, Central and South), three periods of time (1973-1983, 1984-1990 and 1991-1997) and herd-years divided in three SDL (high, medium and low). Separate analyses were made for first and all lactations. The VC were obtained by REML using an animal model. To study GxE, genetic correlations (rg) were obtained through daughters of sires distributed among regions. The likelihood ratio test was used to test if rg between two regions was different from one. Evidence for heterogeneity of variance, principally additive genetic variance, was found among regions and periods of time with analyses of first and all lactations. Heritability estimates were 0.18 to 0.31 for all lactations and 0.21 to 0.31 for first lactations. Even though genetic and phenotypic variances were different for records classified by SDL, heritabilities were similar (0.23, 0.21 and 0.24, for high, medium and low SDL, respectively). The rg between the North and South regions was statistically different from one (0.38), indicating the presence of GxE. Important differences in ranking of sires by regions were found in all analyses.