Genetic and phenotypic parameters of reproduction and lactation traits of Friesian X Boran crossbred cattle in Kagera region, Tanzania

Abstract

This study was done to estimate genetic and phenotypic parameters for Friesian x Boran crossbred dairy cattle of Kagera region. Parameters estimated were heritability, repeatability and phenotypic correlations of various lactation and reproductive traits. Variance component (VARCOMP) procedure and general linear models (GIM) Procedure of SAS were employed in data analyses. Heritability estimates for 100-day milk yield, 305-day miik yield lactation milk yield (LMY) lactation length (LL). dry period (DP) age at first calving and calving interval (CI), were 0.27, 0.40. 0.40. 0.00. 0.04. 0. 05 and 0.06, respectively. Heritabilities first, second and third CI were 0.02, 0.06 and 0.11 re.spectively. Coefficients soil repeatability for 100-day. 305-day. LMY, LL, DP and CI were 0.34, 0.40, 0.38, 0.15, 0.12 and 0. 16, respectively. Correlation coefficients between mean dairy milk yield (DMY) in a month with 100-day and 305-day milk yield and LMY ranged from 0.11 to 0.90, 0.35 to 0.78 and 0.42 to 0. 63, respectively. Correlation coefficient between -100day miik yield and 305-day milk yield (r_c=0.87) was higher than correlation coefficient between, 100-day and total lactation yield (r_c=0.70). The correlation coefficient between 305-day milk yield and LMY was 0.85. All correlations were highly significant (P < 0.001). Heritability estimates were moderate for milk yields and l0w for LL, DP, AFC, and CI. Selection for genetic improvement in milk yield is possible while low estimates for LL, DP, CI and AFC, suggest that environment plays a major role in affecting these traits.

Keywords: heritability, repeatability, phenotypic correlation, lactation traits, reproductive traits, dairy cattle, Tanzania

Tanzania J. Agric. Sc.(2002) Vol.5 No.1, 65-70