Estimates of Maternal Effects for Pre- and Post- Weaning Daily Gain in Turkish Merino Lambs

The aims of the study were to investigate the importance of maternal effects and to determine the most appropriate model of analyses for pre- and post-weaning daily gain of Turkish Merino lambs. Genetic parameters were estimated by REML procedure using DFREML program. Twelve different animal models were fitted by including or excluding maternal genetic effect, maternal permanent environmental effect, maternal temporary environmental effect and covariance between direct-maternal genetic effects. On the basis of log likelihood ratio test results, Model 2b, which included direct genetic and maternal temporary environmental effects, was determined to be the most appropriate model for both traits. The maternal temporary environmental effect was the most important source of variation for both traits. This effect contributed about 35% and 14% to the phenotypic variance for pre- and post- weaning daily gain, respectively. The maternal genetic and permanent environmental effects were important for only pre-weaning average daily gain. Depending on the model, the estimates of maternal heritability ranged from 0.005 to 0.082 and from 0.010 to 0.027 for pre- and post-weaning daily gain.

Anahtar Kelimeler:

Turkish Merino lambs, maternal effects, variance components, growth

Estimates of Maternal Effects for Pre- and Post- Weaning Daily Gain in Turkish Merino Lambs

Keywords:

Turkish Merino lambs, maternal effects, variance components, growth,

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Mousa, E., van Vleck, L.D., Leymaster, K.A.: Genetic parameters
for growth traits for a composite terminal sire breed of sheep. J.
Anim. Sci., 1999; 77: 1659-1665. 9.
El Fadili, M., Leroy, P.L.: Estimation of additive and non-additive
genetic parameters for reproduction, growth and survival traits in
crosses between the Moroccan D’man and Timahdite sheep
breeds. J. Anim. Breed. Genet., 2001; 118: 341-353.
van Wyk, J.B., Fair, M.D., Cloete, S.W.P.: Revised models and genetic parameter estimates for production and reproduction traits in the Elsenburg Dormer sheep stud. S. Afr. J. Anim. Sci., 2003; 33: 213-222.
Maria, G.A., Boldman, K.G., van Vleck, L.D.: Estimates of variances due to direct and maternal effects for growth traits of Romanov sheep. J. Anim. Sci., 1993; 71: 845-849.
Nasholm, A., Danell, Ö.: Genetic relationships of lamb weight, maternal ability and mature ewe weight in Swedish finewool sheep. J. Anim. Sci., 1996; 74: 329-339.
Matika, O., van Wyk, J.B., Erasmus, G.J., Baker, R.L.: Genetic parameter estimates in Sabi sheep. Livest. Prod. Sci., 2003; 79: 17-28.
Maniatis, N., Pollott, G.E.: Maternal effects on weight and ultrasonically measured traits of lambs in a small closed Suffolk flock. Small Rum. Res., 2002; 45: 235-246.
Notter, D.R.: Genetic parameters for growth traits in Suffolk and Polypay sheep. Livest. Prod. Sci., 1998; 55: 205-213.
Özdamar, K.: Paket Programlar ile İstatistiksel Veri Analizi-1. Kaan Kitabevi, Eskiflehir, 1999.
Meyer, K.: DFREML Programs to Estimate Variance Components by Restricted Maximum Likelihood Using a Derivative - Free Algorithm, User Notes, 1998.
Saatcı, M., Dewi, I.A., Ulutas, Z.: Variance components due to direct and maternal effects and estimation of breeding values for 12-week weight of Welsh Mountain lambs. Anim. Sci., 1999; 69: 345-352.
Willham, R.C.: The role of maternal effects in animal breeding, III. Biometrical aspects of maternal effects in animals. J. Anim. Sci., 1972; 35: 1288-1293.
Ap Dewi, I., Saatcı, M., Ulutas, Z.: Genetic parameters of weights, ultrasonic muscle and fat depths, maternal effects and reproductive traits in Welsh Mountain sheep. Anim. Sci., 2002; 74: 399-408.