Estimation of direct and maternal (co)variance components for pre-weaning growth traits in Muzaffarnagari sheep |
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| Institution: | 1. Genetics and Breeding Division, Central Institute for Research on Goats, Makhdoom, Mathura-281 122, Uttar Pradesh, India;2. Department of Animal Wildlife and Grassland Sciences, Faculty of Natural and Agriculture Sciences, Bloemfontein, South Africa;3. Department of Animal and Poultry Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061-0306, USA;1. Pós-Graduação em Zootecnia, Universidade Estadual do Sudoeste da Bahia, Estrada Itapetinga-Itambé, Km 4, CEP 45.700-000, Brazil;2. Departamento de Fitotecnia e Zootecnia, Universidade Estadual do Sudoeste da Bahia, Estrada do Bem Querer, km 4, Vitória da Conquista, Bahia, CEP 45083-900, Brazil;3. Colegiado de Medicina Veterinária, Faculdade de Tecnologia e Ciência, Rua Ubaldino Figueira, 200, CEP 45.020-510, Brazil;4. Departamento de Ciências Biológicas, Universidade Estadual do Sudoeste da Bahia, Rua José Moreira Sobrinho, CEP 45.206-190, Brazil;5. Colegiado de Agronomia, Universidade Estadual do Sudoeste da Bahia, Estrada do Bem Querer, km 4, Vitória da Conquista, Bahia, CEP 45083-900, Brazil;1. Department of Animal Science, Ahar Faculty of Agriculture and Natural Resources, University of Tabriz, Iran;2. Department of Animal Breeding and Genetics, Animal Science Research Institute of Iran (ASRI), Karaj, P.O. Box 1483, Iran;1. Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, China;2. College of Animal Science and Technology, Shanxi Agricultural University, Taigu 030801, China;3. National Center for Molecular Genetics and Breeding of Animal, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing 100913, China;4. Chongqing Academy of Animal Sciences, Chongqing 402460, China;1. Czech University of Life Sciences in Prague, Faculty of Agrobiology, Food and Natural Resources, Kamýcká 129, Prague – 6 Suchdol 165 21, Czech Republic;2. Institute of Animal Science, P?átelství 815, Prague-Uh?íněves 104 01, Czech Republic;1. National Association for Sheep and Goat, Department of Genetics, Res. Maryem, App. B10 Av. Hassan II, Agdal, Rabat, Morocco;2. Department of Animal Production and Biotechnology, Hassan II Institute of Agronomy and Veterinary Medicine, P.O. Box 6202, Rabat 10101, Morocco;3. Department of Animal and Pastoral Productions, National School of Agriculture in Meknes, P.O. Box S/40 50000, Meknes, Morocco;4. Department of Medicine, Surgery and Reproduction, Hassan II Institute of Agronomy and Veterinary Medicine, P.O. Box 6202, Rabat 10101, Morocco |
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| Abstract: | Genetic parameters and (co)variance components were estimated for weight at birth and at 15, 30, 45, 60 and 75 days of age for a flock of Muzaffarnagari sheep maintained at the Central Institute for Research on Goats, Makhdoom, Mathura over a period of 27 years (1976–2002). Records on 5201 lambs descended from 1568 ewes and 170 rams were included in the analysis. Analyses were carried out by REML fitting an animal model and ignoring or including maternal genetic or permanent environmental effects. Six different animal models were fitted for all traits, and the best model was chosen after testing improvements in log-likelihood values. Direct heritability estimates were inflated substantially for all traits when maternal effects were ignored. Direct heritability estimates were 0.08 ± 0.02 for birth weight and 0.02 ± 0.02, 0.02 ± 0.02, 0.27 ± 0.08, 0.09 ± 0.04, and 0.29 ± 0.08 for weights at 15, 30, 45, 60, and 75 days, respectively. Maternal genetic effects contributed only 4 to 8% of the total phenotypic variance from birth to 30 days of age, and this effect diminished further with increasing age. Maternal heritability was low for pre-weaning growth traits and should have only a small effect on selection response. Estimates of the fraction of variance due to maternal permanent environmental effects were 0.09 ± 0.02, 0.15 ± 0.04, 0.12 ± 0.03, 0.11 ± 0.04, 0.14 ± 0.02, and 0.08 ± 0.04 for body weights at birth and at 15, 30, 45, 60, and 75 days, respectively. These results indicate that selecting for improved maternal and/or direct effects in Muzaffarnagari sheep would generate only slow genetic progress in early growth traits. |
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