ESTIMATION OF GENETIC PARAMETER EVALUATION ON-STATION AND ON-FARM REPRODUCTION AND PRODUCTION PERFORMANCE OF DORPER X MENZ CROSS BREED SHEEP IN AMHARA REGION ETHIOPIA

Abstract

This study was conducted with the overall aim of estimating genetic and non-genetic effects on reproduction and productive traits of Dorper x Menz crossbred sheep at Debre Berhan Sheep Breeding and Multiplication Center (DBSBMC) and on-farm evaluation of performances of crossbreds in North Shoa Zone of Amhara Regional State. Reproduction and production data were obtained from the center record book collected between the year 2015 and 2020. Total of 650 crossbreed performance record of sheep was used. In addition, performance data of crossbred lamb under farmer management and survey data were gathered from Habru, Menjar Shenkora, and Raya Kobo districts where Dorper rams were distributed. A total of 59 households were selected for the survey and on-farm performance evaluation. Statistical Package for Social Science (SPSS) for survey data and Statistical Analysis System (SAS, Version 2008) for sheep performance data were used for data analysis. The overall least squares mean body weight (kg) at birth, weaning, and pre-weaning daily weight gain (gm) of crossbred lambs on station was 3.67±0.03, 15.68±0.16 and 102.62, respectively. Sex, litter size and year were fixed factors affecting birth weight.On the other hand, sex, year, parity and seasons of birth were fixed factors affecting weaning weight. Direct heritability and maternal heritability of birth weight were 0.30±0.05 and 0.026±0.06, respectively whereas corresponding values of weaning weight were 0.25±0.06 versus 0.001±0.003, which indicated the lower influence of maternal at weaning. Direct heritability and repeatability estimated of litter size was observed as 0.083±0.00 and 0.17, respectability. The mean breeding ewe holding (3.85±1.19 heads/households) was significantly different across study districts with higher mean holding in Menjar Shenkora (5.0±1.2). Households in Habru districts owned significantly (p<0.05) lower matured and young breeding ram with the overall mean value of 0.69±0.49 and 0.8±0.5, respectively. Most of the sheep producers (86%) participated in Dorper crossbreeding program witnessed the importance of the breeding program. Mean lambing interval, 7.85±1.5 months observed before crossbreeding program implementation was reduced 6.39±1.0 months. Similarly, mean of 12.39 ±0.9 months of age at first lambing before crossbreeding program was shorten to 11.78±1.2 months after breeding program. The mean age of sheep to achieve market age was reduced by 3.56 months after implementation of crossbreeding program. Generally, feed shortage, poor adaptability, shortage of breeding ram, and disease were observed as major constraints hindering productivity of sheep. Generally, from this study, it can be concluded that different non genetic effects affected productive performance of animals. Genetic analysis showed that consideration of permanent environmental effect as random factor along with direct animal effect is crucial for further genetic improvement. On farm survey result indicated that crossbreeding program had considerable benefit to participants in terms of better sheep growth rate, reduced lambing interval and age at first lambing