Document Type : Original Article

Author

Associate professor, Department of Animal Science, Faculty of Animal Science and Food Industries, Khuzestan Ramin Agricultural and Natural Resources University, Ahwaz, Iran

Abstract

Objective: Estimation of genetic parameters for Kleiber ratio (KR) and genetic trends for pre-weaning weights of Arabi sheep has not been previously conducted.Methods: Data and pedigree information were collected at the Khuzestan Ramin Agricultural and Natural Resources University, Animal Science Research Station, located in southwest Iran, from 2001 to 2008. (Co)variance components and corresponding genetic parameters were estimated using the restricted maximum likelihood procedure by excluding or including maternal genetic or maternal permanent environmental effects. Six animal models were fitted to optimise the model KR from birth to weaning, which is defined as the ratio of growth rate and metabolic rate and can be utilized as an indirect selection for feed conversion. Moreover, three-trait analyses were performed using the most appropriate models obtained in single-trait analyses on the basis of Akaike’s information criterion. Results: Direct heritability (h2d) estimate of 0.11 was obtained and maternal permanent environmental effects (pe2) contributed 10% of the total phenotypic variation for KR. Genetic trends for weight at birth and weaning were obtained by regression of average breeding values, on birth year. Direct genetic trends were positive and significant (p < 0.05) for weight at birth and weaning (6 and 24 g per year, respectively). Genetic correlations among traits ranged from -0.52 to 0.89 and phenotypic correlations from -0.21 to 0. 0.71. Results showed the importance of inclusion of maternal permanent environmental effects in designing appropriate breeding programs to obtain accurate estimates of genetic parameters, and it is sounded that KR is a recommended option in selection program.

Keywords

Main Subjects

Abegaz, S., van Wyk, J. B., Olivier, J. J. (2005). Model comparisons and genetic and environmental parameter estimates of growth and the Kleiber ratio in Horro sheep.
South African Journal of Animal Science, 35: 30-40. Akaike, H. (1974) A new look at the statistical model identification. IEEE Trans. Automat. Contr, 19: 716-723.
Eskandarinasab, M., Ghafouri-Kesbi, F., Abbasi, M. (2010). Different models for evaluation of growth traits and Kleiber ratio in an experimental flock of Iranian fat-tailed Afshari sheep. Journal of Animal Breeding and Genetics,
127: 26-33.
Ghafouri-Kesbi, F., Abbasi, M. A., Afraz, F., Babaei, M., Baneh, H., Abdollahi Arpanahi, R. (2011). Genetic analysis of growth rate and Kleiber ratio in Zandi sheep. Tropical Animal Health and Production, 43: 1153-1159.
Gizaw, S., Lemma, S., Komen, H., Van Arendonk, J. A. M. (2007). Estimates of genetic parameters and genetic trends for live weight and fleece traits in Menz sheep. Small Ruminant Research, 70: 145-153.
Jurado, J. J., Alonso, A., Alenda, R. (1994). Selection response for growth in a Spanish Merino flock. Journal of Animal Science, 72: 1433-1440.
Kamjoo, B., Baneh, H., Yousefi, V., Mandal, A., Rahimi, G. (2014). Genetic parameter estimates for growth traits in Iran Black sheep. Journal of Applied Animal Research, 42: 79-88.
Kleiber, M. 1947. Body size and metabolic rate. Physiology Review, 27: 511-541.
Klerk, H. C., Heydenrych, H. J. (1990). BLUP analysis of genetic trends in Dohne Merino. Proceedings of the Fourth World Congress on Genetics Applied to Livestock production, vol. XV, Edinburgh, UK, 23-27 July 1990. Beef
cattle, sheep and pig genetics and breeding, fibre, fur and meat quality.15:77-80.
Lax, J., Chapman, A. B., Pope, A. L., Baker, R. L., Bradley, B. P. (1979). Comparison of single trait and index selection in sheep. Journal of Animal Science, 48: 776-788.
Lotfi Farokhad, M., Roshanfekr, H., Amiri, S., Mohammadi, K., Mirzadeh, Kh. (2011). Genetic trends estimation for some of the growth traits in Arman sheep. Journal of Animal and Veterinary Advances, 10: 1801-1803.
Maria, G. A., Boldman, K. G., Van Vleck, L. D. (1993).
Estimates of variances due to direct and maternal effects for growth traits of Romanov sheep. Journal of Animal Science, 71: 845-849.
Meyer K (2007). WOMBAT- A program for mixed model analyses by restricted maximum likelihood. User notes, Animal Genetics and Breeding Unit, Armidale, Australia. Mohammadi, H., Moradi Shahrebabak, M., Moradi
Shahrebabak, H., Bahrami, A., Dorostkar, M. (2013). Model comparisons and genetic parameter estimates of growth and the Kleiber ratio in Shal sheep. Archiv Tierzucht, 56: 264-275.
Mohammadi, K., Beigi Nassiri, M. T Fayazi, J., Roshanfekr, H., Aghaei, A. (2010). estimates of phenotypic and genetic parameters for pre-weaning growth traits of Arabi lambs. Journal of Animal and Veterinary Advances 9: 1819-1823.
Mohammadi, K., Rashidi, A., Mokhtari, M. S., Beigi Nassiri, M. T. (2011). The estimation of (co)variance components for growth traits and Kleiber ratios in Zandi sheep. Small Ruminant Research, 99: 116-121.
Mohammadi, Y., Rashidi, A., Mokhtari, M. S., Esmailizadeh, A. K. (2010). Quantitative genetic analysis of growth traits and Kleiber ratios in Sanjabi sheep. Small RuminantResearch, 93: 88-93.
Mokhtari, M. S., Rashidi. A. (2010). Genetic trends estimation for body weights of Kermani sheep at different ages using multivariate animal models. Small Ruminant Research, 88: 23-26.
Savar Sofla, S., Abbasi, M.A., Nejati Javaremi, A., Vaez Torshizi, R., Chamani, M. (2010). Parameters estimation and phenotypic and genetic trend for reproductive traits in Moghani sheep. Animal Science and Research Journal,
6: 75-86.
Scholtz, M. M., Roux, C. Z. (1988). The Kleiber ratio (growth rate/metabolic mass) as possible selection criteria in the selection of beef cattle. In: Proceedings of the 3rd World Congress on Sheep and Beef Cattle
Breeding, Vol. 2, Paris, France, pp. 373–375.
Scholtz, M. M., Roux, C. Z., DE Bruin, D. S., Schoeman, S. J. (1990) Medium term responses and changes in fitness with selection for parameters of the allometric autoregressive model. South African Journal of Animal
Science, 20: 65-70.
Shaat, I., Galal, S., Mansour, H. (2004). Genetic trends for lamb weights in flocks of Egyptian Rahmani and Ossimi sheep. Small Ruminant Research, 51: 23-28.
Shokrollahi, B., Baneh, H. (2012). (Co) variance components and genetic parameters for growth traits inArabi sheep using different animal models. Genetics and Molecular Research, 11: 305- 314.
Vatankhah, M., Moradi-Shahrbabak, M., Nejati-Javaremi, A., Miraei- Ashtiani, S. R., Vaez-Torshizi, R. (2004). A review of sheep breeding in Iran. In: Proceedings of the First Congress on Animal and Aquatic Sciences, vol. 2,
Tehran, Iran, pp. 590- 596.
Ved Prakash, L. L., Prince, L., Gowane, G. R., Arora, A. L. (2012). The estimation of (co)variance components and genetic parameters for growth traits and Kleiber ratios in Malpura sheep of India. Small Ruminant Research, 108:54-58.