The late A. M. Khalaffalla* and Y. R. Sulieman

Kuku Research Station, P. 0. Box 89, Kuku, Khartoum North.

Introduction

Desert sheep are the most predominant types in the Sudan (Mcleory, 1961). They are raised mainly under extensive harsh environmental conditions for mutton production. Most of the published research work on desert sheep covered the growth performance and carcass characteristics (El Khidir et al., 1988; Mansour et al., 1988 and others), but little information is available on reproductive performance (Sulieman et al., 1978 and Sulieman and Eissawi, 1984).

This note presents information on some reproductive traits of desert ewes in a flock located at Kuku Research Station (Khartoum North).

The flock :

It consisted of 31 ewes and 2 rams of desert sheep (Watish, Shugur and Dubasi) kept at Kuku for the period 1983 – 1987. It originated from the stock of ElHuda Sheep Research Station in Gezira. Mature adult (2 years and more) body weight in the present flock was 54 ± 8 kg.

* Deceased on 28 July 1992.

Management of the flock :

All the animals were ear-tagged, monthly weighed and sprayed with Gamatox against external parasites.

The sheep were fed ad lib. on a concentrate mixture, composed of 25% Wheat bran, 35% Sorghum grains and 15% Groundnut hulls in addition to Berseem fodder (Medicago sativa). Salt licks and water were available all the time. Breeding ewes were penned with the ram (10 – 16 ewes / ram). Late pregnant ewes were group-penned and fed separately till six weeks post-lambing, and then returned to rejoin the main flock.

At lambing, birthweight of Iamb and first parturition weight of the ewe were recorded soon after birth. Lambs when borii were allowed to suckle their dams freely for the first six weeks, then fed the concentrates separately during the day-time, gradually replacing milk till finally weaned at four months of age.

Breeding of female lambs (i.e. Gimmers mated to ram) was allowed; when they attained a good body size condition.

The reproductive traits; lambing interval and age at first parturition (Lambing) were studied in 26 ewes and 15 ewe-lambs respectively, kept under farm conditions.

Results and Discussion

The mean lambing interval was found to be 284 ± 64 days (range 197 – 470 days). This was shorter than 324 days interval that was reported by Sulieman and Eissawi (1984) for desert sheep under irrigated conditions. Lambing interval consists of gestation and service periods. Variations in the gestation length of sheep is negligable. In the present study

the calculated gestation period from ten observed services was 152.8 days (Coefficient of Variation = 1%). Lambing interval is therefore greatly affected by the service period (i.e. period from parturition to conception).

The service period and consequently the lambing interval depends on management of the animals. The mean age at first lambing was to be 420 ± 47 days (range 330 – 507 days). This was found to be shorter than 605 days reported by Sulieman (1982), for the desert sheep at ElHuda Sheep Research Station.

Age at first parturition depends on early occurance of puberty, i.e. when full potential of reproduction is reached. In the farm animals, age at puberty is closely associated with the rate of growth, and consequently age at first parturition depends on weight at puberty, rather than chronological age per se (Ajmer et al., 1968). The information on age and weight of female lambs from birth to first lambing in the study flock, is shown in the following table :-

	Birth	Weaning	Breeding	First parturition
Age (months)	0	4	6 – 8	14
Liveweight (kg)	4.12±0.29	27.4 ± 2.2	34.6 ± 1.6	43.2 ± 3.7
Percent (%) of adult weight	7.6	50.7	64	80

Rapid growing lambs attain heavier weight and reach puberty earlier than slow growing ones. The role of nutrition on body development and sexual maturity was indicated by Allen and Lamming (1961), Younis et al., (1978) and El Khidir et al., (1979). The age at first parturition and lambing interval in this study were less than that obtained by Sulieman (1982) and Sulieman and Eissawi (1984) for the desert flocks under (Gezira) irrigated conditions. This could be attributed to better feeding and management of animals in small groups like in this flock.

Therefore it could be concluded that adequate nutrition and improved management are essential to attain short lambing interval and early first parturition which are traits of economical importance leading to increased productivity in sheep, such as this desert type flock raised under fatm conditions.

References

Allan, D. M. and Lamming, G. E. (1961). Some effects of nutrition on the growth and sexual development of ewe lambs. J. Agric. Sci. Camb., 57: 87 – 95.

Amir, S.; Kali, J. and Volcani, R. (1968). Influence of growth rate on reproduction and lactation in dairy cattle. In “Growth and development of mammals”; (G. A. Lodge and G. E. Lamming; Editors) – Butterworth, London.

El Khidir, 0. A.; Khalifa, N. A. A.; Khalaffalla, A. M. and Gaili, S. E. (1979). A study of some economic traits in a herd of Kenana cattle. (II) – Age at first calving and effect of improved nutrition on body development and

sexual maturity. Z. Tierzuchtg. Zuchtgsbiol., 96: 210 – 220

El Khidir, 0. A.; Khalaffalla, A. M.; Mansour, M. E. and Shadiya, 0. (1988). The effect of feeding diets of variable energy concentration on growth and carcass composition of Sudan desert lambs. Sudan J. Anim. Prod., 1: 81 – 88.

Mansour, M. E.; Sulieman, A. H.; Ahmed, H. E. and Abdalla, S. A. (1988). The effect of feeding complete rations comprising different levels of groundnut hay on performance and carcass characteristics of Sudan desert sheep. Sudan J. Anim. Prod., 1: 89 – 94.

McLeory, G. B. (1961). The sheep of the Sudan. 2 : Ecotypes and tribal breeds. Sudan J. Vet. Sci. Anim. Husb., 2 (2) : 101 – 151.

Sulieman, A. H. (1982). Some reproductive characteristics of female Shugor, Dubasi and Watish sheep reared at El Huda Sheep Research Station. E. Afri. Agric. For. J., 47: 49 – 54. ,

Sulieman, A. H. and Eissawi, M. A. (1984). Reproductive performance of some tribal oreeds of Sudan desert sheep under irrigated condition. Sudan J. Vet. Sci. Anim. Husb., 24 (2) : 87 – 91.

Younis, A. A.; El – Gaboory, I. A.; El – Tawill, E. A. and El – Shobokshy, A. S. (1978). Age at puberty and possibility of early breeding in Awasi ewes. J. Agric. Sci. Camb., 90 : 255 – 260.

Authors:

Abbas Mohamed Khalafalla

Dr. Yousif Rizgalla Sulieman

Central Animal Nutrition reseach Laboratory, Kuku, P.O. Box 89, Kuku.

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