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Estimates of genetic parameters for growth traits in Kermani sheep
Author(s) -
Bahreini Behzadi M. R.,
Shahroudi F. E.,
Van Vleck L. D.
Publication year - 2007
Publication title -
journal of animal breeding and genetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.689
H-Index - 51
eISSN - 1439-0388
pISSN - 0931-2668
DOI - 10.1111/j.1439-0388.2007.00672.x
Subject(s) - heritability , maternal effect , domestic sheep reproduction , zoology , birth weight , biology , covariate , weaning , trait , variance components , animal model , genetic variation , genetic correlation , restricted maximum likelihood , statistics , maximum likelihood , offspring , mathematics , pregnancy , genetics , computer science , gene , programming language , endocrinology
Summary Birth weight (BW), weaning weight (WW), 6‐month weight (W6), 9‐month weight (W9) and yearling weight (YW) of Kermani lambs were used to estimate genetic parameters. The data were collected from Shahrbabak Sheep Breeding Research Station in Iran during the period of 1993–1998. The fixed effects in the model were lambing year, sex, type of birth and age of dam. Number of days between birth date and the date of obtaining measurement of each record was used as a covariate. Estimates of (co)variance components and genetic parameters were obtained by restricted maximum likelihood, using single and two‐trait animal models. Based on the most appropriate fitted model, direct and maternal heritabilities of BW, WW, W6, W9 and YW were estimated to be 0.10 ± 0.06 and 0.27 ± 0.04, 0.22 ± 0.09 and 0.19 ± 0.05, 0.09 ± 0.06 and 0.25 ± 0.04, 0.13 ± 0.08 and 0.18 ± 0.05, and 0.14 ± 0.08 and 0.14 ± 0.06 respectively. Direct and maternal genetic correlations between the lamb weights varied between 0.66 and 0.99, and 0.11 and 0.99. The results showed that the maternal influence on lamb weights decreased with age at measurement. Ignoring maternal effects in the model caused overestimation of direct heritability. Maternal effects are significant sources of variation for growth traits and ignoring maternal effects in the model would cause inaccurate genetic evaluation of lambs.