Genetic Parameter Estimates for Growth and Reproductive Trait of Sheep for Genetic Improvement and Designing Breeding Program in Ethiopia: A Review

Shigdaf Mekuriaw^1*, Aynalem Haile²

¹Andassa Livestock Research Center, Bahir Dar, Ethiopia.
²International Center for Agricultural Research in the Dry Areas, Addiss Abeba, Ethiopia.

DOI: 10.4236/oalib.1100589                

Abstract

Small ruminants in general and sheep in particular are important investments in the highlands of Ethiopia. Genetic and environmental improvements offer an opportunity to increase production from existing animal resources. Development of effective genetic evaluation and improvement programs requires knowledge of the genetic parameters (genetic variance of each trait and covariance among traits) for economically important production traits. Direct heritability estimates for birth weight of Afar sheep (0.13 to 0.38) and BHS (0.20 to 0.58) using univariate analysis; for Horro sheep (0.18 - 0.32) and Menz sheep (0.46) by fitting a multi-trait individual animal model. The weaning weight direct heritability estimates for sheep in Ethiopia, Afar sheep (0.11 - 0.37) and BHS (0.00 - 0.29), Horro sheep (0.10 - 0.26) and Menz sheep (0.48). Fertility, litter size and lamb survival are the components of the overall ewe reproduction traits. It appears that heritability estimates of these traits are rather low and reflect the generally small genetic variance for most reproductive traits. Moreover, litter size has a higher heritability (0.16 - 0.19) than the other components traits like fertility (0.10) and survival rate (0.07 - 0.09) for Awassi sheep breed. Genetic correlations among most pairs of traits were higher than the corresponding phenotypic correlations. Live weights measured at successive ages were highly correlated, ranging from 0.61 to 0.98 for Menz sheep. Genetic correlations were also high between pre-weaning daily gain and weaning weight for Afar and BHS sheep. Except for Blackhead Somali sheep breed which has high genetic correlation between birth weight and weaning weight, Horro, Menz and Afar sheep have high genetic correlation between post-weaning weight traits. This indicates that selection for one trait improves the other trait in those sheep breeds. In order to develop alternative improvement program for sheep breeds in Ethiopia, estimates of genetic parameters for economical growth and reproduction traits should be done by designing experiments since the information on most sheep breed is nonexistence.

Keywords

Genetic Parameter, Sheep Breed, Heritability, Correlation and Breeding Program

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	Gowane, G.R., Chopra, A., Prince, L.L.L., Paswan, C. and Arora, A.L. (2010) Estimates of (Co)Variance Components and Genetic Parameters for Body Weights and First Greasy Fleece Weight in Bharat Merino Sheep. Animal, 4, 425-431. http://dx.doi.org/10.1017/S1751731109991157
[2]	Nagy, I., Sölkner, J., Komlósi, I. and Sáfár, L. (1999) Genetic Parameters of Production and Fertility Traits in Hungarian Merino Sheep. Journal of Animal Breeding and Genetics, 116, 399-413. http://dx.doi.org/10.1046/j.1439-0388.1999.00204.x
[3]	Abegaz, S. (2002) Genetic Evaluation of Production, Reproduction and Survival in a Flock of Ethiopian Horro Sheep. Ph.D. Dissertation, Faculty of Natural and Agricultural Sciences Department of Animal, Wildlife and Grassland Sciences University of the Free State, Bloemfontein, 118 p.
[4]	Abegaz, S. and Duguma, G. (2000) Genetic and Phenotypic Parameters of Growth, Reproductive and Survival Performance of Horro Sheep at Bako Agricultural Research Center. Research Fellowship Report, International Livestock Research Institute (ILRI), Addis Ababa.
[5]	F.G. Kesbi, Eskandarinasab, M. and Hassanabadi, A. (2008) Estimation of Genetic Parameters for Lamb Weight at Various Ages in Mehraban Sheep (Short Communication). Italian Journal of Animal Science, 7, 95-103.
[6]	Matika, O., Van Wyk, J.B., Erasmus, G.J. and Baker, R.L. (2003) Genetic Parameter Estimates in Sabi Sheep. Livestock Production Science, 79, 17-28.
[7]	Abegaz, S., Negussie, E., Duguma, G. and Rege, J.E.O. (2002) Genetic Parameter Estimates for Growth Traits in Horro Sheep. Journal of Animal Breeding and Genetics, 119, 35-45. http://dx.doi.org/10.1046/j.1439-0388.2002.00309.x
[8]	Juma, K.H. and Alkass, J.E. (2006) Genetic and Phenotypic Parameters of Some Economic Characteristics in Awassi Sheep of IRAQ: A Review. Egyptian Journal of Sheep, Goat and Desert Animals Sciences, 1, 15-29.
[9]	Sang Hyon, O.H. (2003) Estimation of Genetic Parameters for Boar Semen Traits. PhD. Dissertation, Faculty of North Carolina State University, Raleigh.
[10]	Yacob, Y. (2008) Environmental and Genetic Parameters of Growth, Reproductive and Survival Performance of Afar and Blackhead Somali Sheep at Werer Agricultural Research Center. Fellowship Report, International Livestock Research Institute (ILRI) and Ethiopian Institute of Agricultural Research (EIAR), Ethiopia.
[11]	Kanakaraj, P. (2001) A Text Book on Animal Genetics. Army Printing Press, Lucknow.
[12]	Clément, V., Bibé, B., Verrier, é., Elsen, J.M., Manfredi, E., Bouix, J. and Hanocq, é. (2001) Simulation Analysis to Test the Influence of Model Adequacy and Data Structure on the Estimation of Genetic Parameters for Traits with Direct and Maternal Effects. Genetics Selection Evolution, 33, 369-395. http://dx.doi.org/10.1186/1297-9686-33-4-369
[13]	Matos, C.A., Thomas, D.L., Gianola, D., Tempelman, R.J. and Young, L.D. (1997) Genetic Analysis of Discrete Reproductive Traits in Sheep Using Linear and Nonlinear Models: I. Estimation of Genetic Parameters. Journal of Animal Science, 75, 76-87.
[14]	Ozder, M., Sezenler, T., Refik, A. and Ceyhan, A. (2009) Genetic and Non-Genetic Parameter Estimates for Growth Traits in Turkish Merino Lambs. Journal of Animal and Veterinary Advances, 8, 1729-1734.
[15]	Rao, S. (1997) Genetic Analysis of Sheep Discrete Reproductive Traits Using Simulation and Field Data. PhD. Dissertation, Faculty of the Virginia Polytechnic Institute and State University, Department of Animal and Poultry Science, Blacksburg.
[16]	Graser, H.U., Smith, S.P. and Tier, B. (1987) A Derivative-Free Approach for Estimating Variance Components in Animal Models by Restricted Maximum Likelihood. Journal of Animal Science, 64, 1362-1370.
[17]	Reverter, A., Kaiser, C.J. and Mallinckrodt, C.H. (1998) A Bootstrap Approach to Confidence Regions for Genetic Parameters from Method R Estimates. Journal of Animal Science, 76, 2263-2271.
[18]	El-Arian, M.N., Salama, M.A. and Mohamed, H.A. (2008) Estimation of Genetic Parameters and Breeding Value for Growth Traits on Romanov Lambs in Egypt. Mansoura University Journal of Agricultural Sciences, 33, 2569-2576.
[19]	Chrilukovian, W. (2006) Genetic Evaluation of Growth and Reproductive Performance of the Kenya Boran Cattle. M.Sc. Thesis, Production (Animal Breeding Option) of Egerton University, Njoro.
[20]	Haile, A. (2006) Genetic and Economic Analysis of Ethiopian Boran Cattle and Their Crosses with Holstien Friesian in Centeral Ethiopia. Ph.D. Dissertation, National Dairy Research Institute, Deemed University, Karnal.
[21]	Hermiz, H.N., Alkass, J.E., Hobi, A.A. and Asofi, M.K. (2009) Genetic and Phenotypic Parameters of Body Weights in Iraqi Local Goat and Their Crosses with Damascus. Journal of Dohuk University, 12, 189-194.
[22]	Gizaw, S., Lemma, S., Komen, H. and 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. http://dx.doi.org/10.1016/j.smallrumres.2006.02.007
[23]	Hassen, Y., Fuerst-Waltl, B. and Sölkner, J. (2003) Genetic Parameter Estimates for Birth Weight, Weaning Weight and Average Daily Gain in Pure and Crossbred Sheep in Ethiopia. Journal of Animal Breeding and Genetics, 120, 29-38. http://dx.doi.org/10.1186/1297-9686-24-6-487
[24]	Bradford, G.E., Sakul, H., Neira, R., Dally, F.M.R. and Finley, C.M. (1994) Reproduction in Sheep Selected for Weaning Weight or Litter Size in a Range Environment. Proceedings of 5th World Congress on Genetics Applied to Livestock Production, 18, 95.
[25]	Gizaw, S. and Joshi, B.K. (2004) Genetic and Non-Genetic Factors Affecting Survivability of Menz and Awassi × Menz Crossbred Sheep in Ethiopia. Indian Journal of Animal Sciences, 74, 887-889.
[26]	Fogarty, N.M. (1995) Genetic Parameters for Live Weight, Fat and Muscle Measurements, Wool Production and Reproduction in Sheep: A Review. Animal Breeding Abstracts, 63, 101.
[27]	Al-Shorepy, S.A. (1995) Selection to Improvement Spring Fertility in a Crossbred Sheep Population. Ph.D. Dissertation, Virginia Polytechnic Institute & State University, Blacksburg.
[28]	Meyer, K. (1992) Bias and Sampling Covariances of Estimates of Variance Components Due to Maternal Effects. Genetics Selection Evolution, 24, 487-509. http://dx.doi.org/10.1186/1297-9686-24-6-487
[29]	Vatankhah, M., Talebi, M.A. and Edriss, M.A. (2008) Estimation of Genetic Parameters for Reproductive Traits in Lori-Bakhtiari Sheep (Short Communication). Small Ruminant Research, 74, 216-220. http://www.sciencedirect.com/ http://dx.doi.org/10.1016/j.smallrumres.2007.02.008
[30]	Falconer, D.S. (1989) Introduction to Quantitative Genetics. 3rd Edition, Longman, London.
[31]	Atkins, K.D. (1986) A Genetic Analysis of the Components of Lifetime Productivity in Scottish Blackface Sheep. Animal Production, 43, 405-419. http://dx.doi.org/10.1016/S0921-4488(01)00256-5
[32]	Rosati, A., Mousa, E., Van Vleck, L.D. and Young, L.D. (2002) Genetic Parameters of Reproductive Traits in Sheep. Small Ruminant Research, 43, 65-74. http://dx.doi.org/10.1016/S0921-4488(01)00256-5