Estimation of co-variance components, genetic parameters, and genetic trends of reproductive traits in community-based breeding program of Bonga sheep in Ethiopia

다국어 초록 (Multilingual Abstract)

Objective: The objectives of the study were to evaluate reproductive performance and selection response through genetic trend of community-based breeding programs (CBBPs) of Bonga sheep. Methods: Reproduction traits data were collected between 2012 and 2018 from Bonga sheep CBBPs. Phenotypic performance was analyzed using the general linear model procedures of Statistical Analysis System. Genetic parameters were estimated by univariate animal model for age at first lambing (AFL) and repeatability models for lambing interval (LI), litter size (LS), and annual reproductive rate (ARR) traits using restricted maximum likelihood method of WOMBAT. For correlations bivariate animal model was used. Best model was chosen based on likelihood ratio test. The genetic trends were estimated by the weighted regression of the average breeding value of the animals on the year of birth/lambing. Results: The overall least squares mean±standard error of AFL, LI, LS, and ARR were 375±12.5, 284±9.9, 1.45±0.010, and 2.31±0.050, respectively. Direct heritability estimates for AFL, LI, LS, and ARR were 0.07±0.190, 0.06±0.120, 0.18±0.070, and 0.25±0.203, respectively. The low heritability for both AFL and LI showed that these traits respond little to selection programs but rather highly depend on animal management options. The annual genetic gains were -0.0281 days, -0.016 days, -0.0002 lambs and 0.0003 lambs for AFL, LI, LS, and ARR, respectively. Conclusion: Implications of the result to future improvement programs were improving management of animals, conservation of prolific flocks and out scaling the CBBP to get better results.

참고문헌 (Reference)

1 Meyer K, "Wombat: a program for mixed model analyses by restricted maximum likelihood"

2 Willham RC, "The role of maternal effects in animal breeding : III. Biometrical aspects of maternal effects in animals" 35 : 1288-1293, 1972

3 Drouilhet L, "The highly prolific phenotype of Lacaune sheep is associated with an ectopic expression of the B4GALNT2 gene within the ovary" 9 : e1003809-, 2013

4 Edea Z, "Sheep production systems and breeding practices of smallholders in western and south-western Ethiopia : implications for designing community-based breeding strategies" 24 : 117-, 2012

5 SAS Institute Inc, "SAS® 9. 3 Intelligence platform: system administration guide. 2nd ed"

6 Getachew T, "Review of sheep crossbreeding based on exotic sires and among indigenous breeds in the tropics : an Ethiopian perspective" 11 : 901-911, 2016

7 Berhanu B, "Reproductive performance of traditionally managed sheep in the south western part of Ethiopia" 21 : 154-, 2009

8 Berhan A, "Reproductive performance and mortality rate in Menz and Horro sheep following controlled breeding in Ethiopia" 63 : 297-303, 2006

9 Ayele S, "Productive and reproductive performances of indigenous sheep in Ethiopia : a review" 9 : 97-120, 2019

10 Wilson RT, "Pre-weaning mortality and productivity indices for goats and sheep on a Masai group ranch in south-central Kenya" 41 : 201-206, 1985

11 Gizaw S, "Population structure, genetic variation and morphological diversity in indigenous sheep of Ethiopia" 38 : 621-628, 2007

12 Gemeda D, "Participatory definition of breeding objectives and implementation of community based sheep breeding programs in Ethiopia" University of Natural Resource and Life Science 2010

13 Berry DP, "Negative influence of high maternal milk production before and after conception on offspring survival and milk production in dairy cattle" 91 : 329-337, 2008

14 Falconer DS, "Introduction to quantitative genetics" Pearson 1996

15 Getachew T, "How to tailor community based breeding programs for small ruminants to pastoral production systems" 2018

16 Abdoli R, "Genomewide association study of first lambing age and lambing interval in sheep" 178 : 43-45, 2019

17 Negussie E, "Genetic trend and effects of inbreeding on growth performance of tropical fat-tailed sheep" 2002

18 Oliveira Lobo AMB, "Genetic parameters for growth, reproductive and maternal traits in a multibreed meat sheep population" 32 : 761-770, 2009

19 El Fadili M, "Genetic parameters for growth traits of the Moroccan Timahdit breed of sheep" 37 : 203-208, 2000

20 Aguirre EL, "Genetic parameters and genetic trends for reproductive traits of Santa Ines sheep kept in extensive environments in Brazil" 1 : 9-, 2017

21 Amarilho-Silveira F, "Genetic components of birth weight of texel sheep reared in extensive system" 40 : e36481-, 2018

22 Solomon A, "Genetic and phenotypic parameters of growth, reproductive and survival performance of Horro sheep at Bako Agricultural Research Center" International Livestock Research Institute 2000

23 Abegaz S, "Factors affecting reproductive performance and estimates of genetic parameters of litter size in Horro sheep" 139 : 79-85, 2002

24 Lamuno D, "Evaluation framework of community-based livestock breeding programs" 30 : 47-, 2018

25 Bayeriyar M, "Estimation of genetic parameters for economic important traits in Moghani Iranian sheep" 10 : 14678-14683, 2011

26 Mokhtari MS, "Estimates of phenotypic and genetic parameters for reproductive traits in Kermani sheep" 88 : 27-31, 2010

27 Saghi DA, "Estimates of genetic and phenotypic parameters for reproductive traits in Iranian native Kordi sheep" 39 : 323-328, 2017

28 Canché JET, "Environmental effects on productive and reproductive performance of Pelibuey ewes in Southeastern México" 44 : 508-512, 2016

29 Kariuki CM, "Direct and maternal(co)variance components, genetic parameters and annual trends for growth traits of Dorper sheep in semi-arid Kenya" 42 : 473-481, 2010

30 Haile A, "Community-based breeding programmes are a viable solution for Ethiopian small ruminant genetic improvement but require public and private investments" 136 : 319-328, 2019

31 Mirkena T, "Community-based alternative breeding plans for indigenous sheep breeds in four agro-ecological zones of Ethiopia" 129 : 244-253, 2012

32 Wilson AJ, "An ecologist’s guide to the animal model" 79 : 13-26, 2010