Mohamed E. Mufarrih
Sudan Desert sheep tend to breed at certain periods of the year in such a way that lambs are dropped when range fodder is at its best. A few ewes may miss the traditional breeding season and breed in the rainy season to lamb in winter. Some-ewes occasionally divert from these two seasons and breed in late September or October. If allowed to remain in the flock they would lamb during the period of feed and water shortage which lasts from February to May. The off-season ewes are usually identified in early pregnancy and sold for slaughter. To avoid these occurrences, mating is obstructed with the use of a device called a “kinan”. This is a double-looped string fixed around the neck of the scrotum and the neck of the ram’s sheath to prevent-the penis from emerging. The kinan is released in about mid-December when traditional breeding commences, which lasts for 30 to 45 days.
The flabby base of the ewe’s tail hampers immediate mating unless an assistant quickly intervenes by holding the ewe and shifting the tail with his other hand while the ram stands by to mount. In most cases one mount effects successful mating and conception. On the same day that the ewes show heat, they are distributed among the available rams to avoid exhaustion and a decline in fertility of the rams. Two or more additional assistants are assigned to the flock so that the breeding season reaches a successful conclusion. Kinans are refixed on rams immediately after the conclusion of the breeding season. In the southern part of the semi-desert belt where winter grazing can sustain suckling ewes and lambs, kinans are removed from June to August to cover the few ewes that missed the main breeding season.
About 80 percent of ewes drop lambs in June and July except in the central, eastern and Khartoum regions where the lambing season begins a bit later. There are many twinners, triplers and first lambing ewes, and the lambing period, like the breeding season, is followed with great dedication. The sheep are usually grazed close to the camp whenever grazing conditions permit. An additional assistant is assigned to help in delivery, if needed, and to collect dams and lambs dropped at grazing and to bring them to the camp. All young lambs are retained in the camp and guarded and first lambers are kept with their lambs for two or three days to avoid lamb refusal. Orphan lambs and those refused by dams are nursed on ewes which have lost lambs or nanny goats maintained with the sheep for such a purpose.
Eventually the older lambs are herded to nibble on vegetation around the camp. In the late afternoon the flock is turned from grazing and the lambs are allowed to join the dams and stay with them until next morning. At the age of one month the lambs are usually allowed to run continuously with the dams until they are weaned at three months. Some sheep breeders, especially in semi-residential and residential systems, take some of the daytime milk from ewes with single lambs for marketing as fresh milk, or for butter or sour milk-making.
At weaning age the lambs are sorted out for breeding or market stock. Under the semi-residential and residential systems, where the holdings are comparatively small, sheep are marketed at weaning age as entire male lambs. Under the migratory system the males for market are castrated and retained to the age of one to three years to reach the condition and size required by sheep exporters.
Under tropical environmental conditions, sheep are raised primarily for meat, although milk is also of importance. The value of the breeding ewe is determined by the quantity and quality of lamb or mutton produced and the length of its productive life.
Field-collected data on the lambing rate of Sudan Desert sheep indicate wide differences between localities presumably attributable to climatic, nutritional and management factors. Personally acquired information on migratory groups in the western Kordofan and eastern Darfur areas indicated a 150-170 percent lambing rate. Wilson (1981) reported the lambing rate for a nomadic flock of Sudan Desert sheep in Southern Darfur province to be 146 percent.
Wide differences in lambing rates also exist among individual flocks under a semi-residential system maintained in irrigated areas. Tanmia, an independent consultant group, in their feasibility study (1977) for the El Waha Animal Production Project about 50 km south of Khartoum, reported that ewes under irrigated pasture and in an open breeding system could lamb three times in two years at a rate of 150 percent each time and they could, therefore, achieve a lambing rate of about 225 percent. Under a residential system at El Huda Sheep Research Station, Suleiman and Eisawi (1984) reported an overall lambing rate of 119 percent and a rate of 125 percept for the Shugur variety alone. This subnormal rate can probably be attributed to the low nutritional level experienced by the sheep for a considerable portion of the year.
The performance of ewes of the Sudan Desert type under an improved residential system in an irrigated area is best represented by a small flock of Dubasi and Shugur varieties in Kuku Animal Research Station. The production record of the flock as obtained from the 1986-87 flock book is given in Table 2. The lambing rate of the flock during this period was 143 percent, which would suggest a promising potential productivity and shows that the Sudan Desert ewe can rear twin lambs to an acceptable weaning weight.
Most nomadic, semi-residential and residential families in the Desert sheep raising areas utilize sheep milk and milk products for home consumption and to earn revenue to supplement their incomes. The Animal Resources Economic Administration of the Ministry of Agriculture in their 1980-81 Annual Report estimated total sheep milk production as 553 591 tonnes during this period. Most of this was produced in areas where Desert sheep dominated. Information obtained from the Khartoum suburban area, where sheep are kept mainly for dairying, indicate a daily yield of 2-2.5 litres for the average ewe. This information agrees closely with Tothill (1948) who reported a 2.3-2.5 litre daily yield. Suleiman and El Tahir (1984) investigated the milking capacity of Dubasi and Shugur ewes at El Huda Sheep Research Station in the Gezira irrigated agricultural scheme. They reported 140.2 litres of milk in 186.3 days for Shugur and 134.1 litres in 189.5 days for Dubasi. They mentioned that the ewes were sustained on dry sorghum straw for some days during the rainy season. It is likely that such poor-quality roughage could have caused a substantial decline in milk yield.
Productive life of ewes and rams
Early puberty and a long productive life of breeding stock are very desirable characteristics. In the open range and migratory system, where more than 80 percent of sheep are maintained, dedicated sheep growers do not allow the milking of suckling ewes before their lambs attain the age of two months and are able to maintain their normal rate of growth on range fodder. Consequently all single and most twin ewe lambs attain puberty at the age of seven months and lamb in their 12th month.