CHARACTERIZATION, GENETIC EVALUATION, AND GENETIC TRENDS FOR SOME REPRODUCTIVE TRAITS OF BALADI BLACK RABBITS DOES

Abstract

A total of 792 litters from 210 does of Baladi Black (BB) rabbits were considered to make characterization, and genetic evaluation for some doe traits, including litter traits (litter size at birth; LSB, litter size born alive; LSA, litter size at 21 days; LS21, litter size at weaning; LSW, Litter weight at birth; LWB, Litter weight at weaning; LWW, and the pre-weaning mortality rate; PWM), conception traits (number of services per conception; NSC, and gestation length; GL), and interval traits (kindling interval; KI and days open; DO). Heritability for litter traits was relatively low ranged from 0.08 to 0.14 except this for PWM it was moderate (0.15); h2 for conception and interval traits were low ranged from 0.00 to 0.06. Repeatability (R) for litter traits were low to moderate ranged from 0.11 to 0.34; R estimates for PWM and LWB were higher than other traits (0.16 and 0.34) respectively; and R for conception and interval traits was low ranged from 0.01 to 0.11. Genetic correlations among litter traits were positive, and moderate to strong ranged from 0.23 to 0.92 except for this between LSB and LWW and this between LWB and PWM, it was negative -0.16 and -0.08 respectively. Genetic correlations among conception and interval traits were positive and very strong ranged from 0.68 to 1.00 except this between GL and NSC it was negative and strong (-0.77). The ranges of transmitting abilities (TA) for litter size traits ranged from 1.92 to 2.10 kits. Ranges of TA for litter weight traits ranged from 0.01 to 0.70 grams. The range of TA for PWM was 33.90%. Ranges of TA for conception traits were low, 0.08 days for GL and 0.11 (numbers) for NSC. The ranges of TA were 4.93 and 10.72 days for KI and DO respectively. The percentage of positive transmitting ability ranged from 30.95 to 53.81 for litter traits and from 50.00 to 51.90 for conception, and interval traits. The genetic trends for litter traits at different ages, conception and interval traits were low and had fluctuations by year-season which could be due to variation in climatic conditions. Conclusively, Baladi Black rabbits' does have good potential reproduction. Most of doe reproductive traits of these rabbits were largely affected by environmental conditions which would be improved by improving environmental and management conditions. The moderate estimate of h2 for PWM (0.15) and its range of transmitting ability (33.90%) suggest decreasing pre-weaning mortality by selection. Moderate estimates for PWM and LWB comparing with other traits (0.16 and 0.34) respectively suggests using culling and selection strategies. The negative genetic correlation between LSB and LWW (-0.16) should be taken into consideration when designing a breeding program for these rabbits. The perfect genetic correlation between KI and DO (1.00) reflected that these two traits could be indicators of each other when designing breeding programs.