140 A STUDY ON HINNY PRODUCTION FROM LOCAL JENNIES (EQUUS ASINUS) AND STALLIONS (E. CABALLUS) IN ETHIOPIA: NORMAL OFFSPRING PRODUCED

Abstract

Domestic equids, consisting of 5 million donkeys, 1 million horses and 0.6 million mules, play important roles in Ethiopia’s economy by providing services in transportation and traction sectors. In spite of the large equine population and the common use of mules (jack × mare), the opposite hybrid, hinny (stallion × jenny) is uncommon. Compared to using mules or either parent, hinnies could provide certain economic and environmental advantages. Considering the large female donkey population, it may be easier and more affordable to produce hinnies than mules. Moreover, hinnies are better than donkeys in draft performance. Thus, using hinnies could help in reducing the large donkey population and hence their negative environmental effect. However, there is no recorded attempt of hinny production in Ethiopia. Although data from controlled experiments are limited, interspecies breeding to produce hinnies is less successful than attempts to produce mules mainly because hinnies are thought to be less fertile. In the present study, adult and cycling Abyssinian jennies were divided into two groups (n = 10 each) for natural breeding with three jacks (Jack group) or four stallions (Stallion group). During a period of two years, data on intraspecies and interspecies courtship behavior, mating activities, conception and foaling were recorded. Data were collected mainly by visual observation. Pregnancy was also diagnosed by palpation per rectum at 60 to 90 days after service. Mating was conducted during natural or PGF_2α-induced estrus. Data on the number of services per conception, number of pregnancies and foaling were compared using chi-square or Fisher’s test. Jennies in estrus showed overt sexual interest in jacks, stallions and even female herdmates. Two stallions showed sexual interest in jennies; however, only one mated successfully and hence jennies in heat were exposed to this male. In the Jack group, 9 of the 10 jennies conceived (with 27 cycles bred , or 3 cycles/pregnancy). One pregnant jenny died of unrelated causes. Of the remaining 8 pregnant jennies, 3 aborted and 5 delivered live foals. In the stallion group, 3 of the 10 jennies conceived (with 47 cycles bred, or 15.7 cycles/pregnancy). Two of the three females aborted and one delivered a live female foal. The pregnancy rates between the two treatments (90% v. 30%) were significantly different (P = 0.02); however, treatment did not affect (P > 0.05) foaling rates (63 % v. 33%) or abortion rates (38% v. 67%). Abortion occurred at 192 to 254 days (Jack group) and 147 and 159 days (Stallion group) of gestation. Gestation lengths of 370.2 ± 4.5 v. 330 day and foal body weight of 13.3 ± 1.0 v. 16 kg were recorded in the Jack and Stallion groups, respectively. Foaling did not require assistance in either group. We have demonstrated the possibility of hinny production using local jennies and stallions. The main limitations to hinny production were poor sexual desire of stallions towards jennies and also low conception rates after interspecies mating. The latter also cast doubts on the potential of alternative approaches (e.g. artificial insemination) to circumvent the behavioral barrier to interspecies breeding. We would like to thank RPSUD for funding this project and Dr. Azage Tegegne for overall assistance.