Estimativas de parâmetros genéticos para características de crescimento de cordeiros mestiços Suffolk

Estimates of genetic parameters for growth traits in Suffolk crossbred lambs

Priscilla Regina Tamioso Laila Talarico Dias Rodrigo de Almeida Teixeira Cláudio José Araújo da Silva Sobre os autores

Resumos

Objetivou-se estimar os coeficientes de herdabilidade e correlação genética entre os pesos ao nascer (PN) e à desmama (PD) de cordeiros mestiços Suffolk, pertencentes a rebanho experimental. Assim, foram testados quatro modelos, os quais consideraram o efeito genético aditivo direto (Modelo 1), os efeitos genético direto e de ambiente permanente materno (Modelo 2), os efeitos aditivo direto, de ambiente permanente e genético materno (cov a,m=0) (Modelo 3), e no Modelo 4, além daqueles contemplados no Modelo 3, foi considerada cov a,m≠0. Após comparar os modelos por meio do teste de razão de verossimilhança (LRT), observou-se que o 3 foi o mais adequado, sendo que as estimativas de herdabilidade foram de baixa magnitude para PN e PD, iguais a 0,08±0,009 e 0,24±0,17, respectivamente, indicando pequena possibilidade de resposta à seleção direta. Da mesma maneira, o coeficiente de correlação genética entre estas características foi 0,43±0,39, resultado que implica pequena possibilidade de resposta correlacionada. A inclusão dos efeitos maternos é necessária para a estimação adequada de parâmetros genéticos para as características avaliadas.

comparação de modelos; correlação genética; herdabilidade; peso corporal


The aim of this study was to estimate the heritability and genetic correlation coefficients between weights at birth (BW) and weaning (WW) in Suffolk crossbred lambs, which belonged to an experimental herd. Thus, four different animal models were fitted, including the direct additive genetic effect (Model 1), the direct additive genetic and maternal permanent environmental effects (Model 2), the direct additive, permanent environmental and maternal genetic effects (cov a,m=0) (Model 3), and in Model 4, in addition to those in Model 3, cov a,m≠0 was considered. After comparing the models through the likelihood ratio test (LRT), Model 3 was chosen as the most appropriate, being the heritability estimates low in magnitude for BW and WW, equal to 0.08±0.009 and 0.24±0.17, respectively, which indicates low possibility of response to direct selection. Likewise, the correlation coefficient between these traits, 0.43±0.39, implies low possibility of correlated response. The inclusion of maternal effects is necessary for the accurate estimation of genetic parameters for the evaluated traits.

body weight; genetic correlation; heritability; model comparison


  • 1
    Bahreini Behzadi MR, Shahroudi FE, Vanvleck LD. Estimates of genetic parameters for growth traits in Kermani sheep. J Anim Breed Genet. 2007; 124:296-301.
  • 2
    Kushwaha BP, Mandal A, Arora AL, Kumar R, Kumar S, Notter DR. Direct and maternal (co)variance components and heritability estimates for body weights in Chokla sheep. J Anim Breed Genet. 2009; 126:278-287.
  • 3
    Prince LLL, Gowane GR, Chopra A, Arora AL. Estimates of (co)variance components and genetic parameters for growth traits of Avikalin sheep. Trop Anim Health Prod. 2010; 42:1093-1101.
  • 4
    Meyer K. WOMBAT -A program for mixed model analyses by restricted maximum likelihood. User notes. Animal Genetics and Breeding Unit, Armidale; 2006. 56p.
  • 5
    Hogg RV, Craig AT. Introduction to Mathematical Statistics. 5 ed. New Jersey: Prentice Hall; 1995. 564p.
  • 6
    Lôbo RNB, Martins Filho R, Penna VM, Lima FAM. Genetic parameters for growth traits of zebu cattle in the semi-arid region of Brazil. Ciênc. Anim. 2000; 10(1):7-12.
  • 7
    Zamani P, Mohammadi H. Comparison of different models for estimation of genetic parameters of early growth traits in the Mehraban sheep. J Anim Breed Genet. 2008; 125:29-34.
  • 8
    Ligda CH, Gabriilidis G, Papadopoulos TH, Georgoudis A. Investigation of direct and maternal genetic effects on birth and weaning weight of Chios lambs. Livest Prod Sci. 2000; 67:75-80.
  • 9
    Mandal A, Neser FWC, Rout PK, Roy R, Notter DR. Estimation of direct and maternal (co)variance components for pre-weaning growth traits in Muzaffarnagari sheep. Livest Sci. 2006a; 99:79-89.
  • 10
    Mandal A, Neser FWC, Rout PK, Roy R, Notter DR. Genetic parameters for direct and maternal effects on body weights of Muzaffarnagri sheep. Anim Sci. 2006b; 82:133-140.
  • 11
    Ghafouri-Kesbi F, Abbasi MA, Afraz F, Babaei M, Baneh H, Arpanahi RA. Genetic analysis of growth rate and Kleiber ratio in Zandi sheep. Trop Anim Health Prod. 2011; 43:1153-1159.
  • 12
    Maxa J, Norberg E, Berg P, Pedersen J. Genetic parameters for growth traits and litter size in Danish Texel, Shropshire, Oxford Down and Suffolk. Small Rumin Res. 2007; 68:312-317.
  • 13
    Rao S, Notter DR. Genetic analysis of litter size in Targhee, Suffolk and Polypay sheep. J Anim Sci. 2000; 78:2113-2120.
  • 14
    Ekiz B, Özcan M, Yilmaz A. Estimates of genetic parameters for direct and maternal effects with six different models on birth and weaning weights of Turkish Merino lambs. J. Vet Anim Sci. 2004; 28:383-389.
  • 15
    Maroof A, Singh SV, Sushil kumar, Arora AL. Comparison of different methods of heritability estimates for body weights and wool yield traits in Avikalin crossbred sheep. Ind J Small Rum. 2005; 11:121-126.
  • 16
    Matika O, Van Wyk JB, Erasmus GJ, Baker RL. Genetic parameter estimates in Sabi sheep. Livest Prod Sci. 2003; 79:17-28.
  • 17
    Safari E, Fogarty NM, Gilmour AR. A review of genetic parameter estimates for wool, growth, meat and reproduction traits in sheep. Livest Prod Sci. 2005; 92:271-289.
  • 18
    Tosh JJ, Kemp RA. Estimation of variance components of lamb weights in three sheep populations. J Anim Sci. 1994; 72:1184-1190.
  • 19
    Snyman MA, Erasmus GJ, Van Wyk JB, Olivier JJ. Direct and maternal (co)variance components and heritability estimates for body weight at different ages and fleece traits in Afrino sheep. Livest Prod Sci. 1995; 44:229-235.
  • 20
    Robison OW. The influence of maternal effects on the efficiency of selection: A review. Livest Prod Sci. 1981; 8:121-137.
  • 21
    Rashidi A, Mokhtari MS, Safi Jahanshahi A, Mohammad Abadi MR. Genetic parameter estimates of pre-weaning growth traits in Kermani sheep. Small Rumin Res. 2008; 74:165-171.
  • 22
    Neser FWC, Erasmus GJ, Van Wyk JB. Genetic parameter estimates for pre-weaning weight traits in Dorper sheep. Small Rumin Res. 2001, 40:197-202.
  • 23
    Gowane GR; Chopra A, Prakash V, Arora AL. Estimates of (co)variance components and genetic parameters for body weights and first greasy fleece weight in Malpura sheep. Livest Sci, 2010; 131:94-101.
  • 24
    Prakash V, Prince LLL, Gowane GR, Arora AL. The estimation of (co)variance components and genetic parameters for growth traits and Kleiber ratios in Malpura sheep of India. Small Rumin Res. 2012; 108:54-58.
  • 25
    Magalhães AFB, Lôbo RNB, Facó O. Estimativas de parâmetros genéticos para características de crescimento em ovinos da raça Somalis Brasileira. Ciênc Rural [Internet]. 2013 [citado 2013 Jun. 05]; 43(5):884-889. Disponível em: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-84782013000500021&lng=pt&nrm=iso
  • 26
    Ghafouri-Kesbi F, Baneh H. Genetic parameters for direct and maternal effects of growth traits of sheep. Archiv Tierzucht. 2012; 55(6):603-611.
  • 27
    Shokrollahi B, Zandieh M. Estimation of genetic parameters for body weights of Kurdish sheep in various ages using multivariate animal models. Afr J Biotechnol. 2012; 11(8):2119-2123.

Datas de Publicação

  • Publicação nesta coleção
    22 Jan 2015
  • Data do Fascículo
    Dez 2014

Histórico

  • Recebido
    10 Jul 2013
  • Aceito
    10 Jul 2014
Universidade Federal de Goiás Universidade Federal de Goiás, Escola de Veterinária e Zootecnia, Campus II, Caixa Postal 131, CEP: 74001-970, Tel.: (55 62) 3521-1568, Fax: (55 62) 3521-1566 - Goiânia - GO - Brazil
E-mail: revistacab@gmail.com