- Reproductive performance of hair and wool type Dorper ewes under veld conditions in the Arid Karoo
|Last update: November 25, 2010 09:09:33 AM|
REPRODUCTIVE PERFORMANCE OF HAIR AND WOOL TYPE DORPER EWES
UNDER VELD CONDITIONS IN THE ARID KAROO
M. A. Snyman & J.A.N. Cloete
Grootfontein Agricultural Development Institute, Private Bag X529, Middelburg (EC), 5900
Mutton production is an important component of the agricultural sector in the extensive north-western sheep grazing areas of the Republic of South Africa. Due to the limited natural resources in these areas, it is important to increase the efficiency of mutton production within the limits of these resources. Dorper sheep constitute a large proportion of the small stock numbers in these areas, and it is therefore obvious that the most efficient type within this breed should be identified. Animals within the Dorper breed are classified into different types, mainly according to their coat cover, conformation or fat distribution. Several perceptions as to the productive and reproductive potential of these types exist among breeders and farmers. One of these is that the hair type Dorper is more hardy and adapted and produces better than the more woolly type under extensive conditions. There is, however, no information available on the relative reproductive performance of hair and wool type Dorper sheep under extensive veld conditions. This study was therefore conducted to evaluate reproductive performance in hair and wool type Dorper sheep under extensive conditions at the Klerefontein Experimental Station in the north-western Karoo region of the Republic of South Africa. During July 1993, animals of the existing experimental Dorper flock at the Klerefontein Experimental Station were classed into two groups on the basis of their coat cover, i.e. either hair or wool type. Furthermore, 20 hair and 20 wool type young ewes were bought from the industry during 1994. Flock size was kept at 110 ewes each for the hair and wool types. During the 1993 and 1994 breeding seasons, seven hair and wool type rams from other experimental flocks were used as sires, together with wool and hair type rams from the existing flock at Klerefontein. Since 1995, only rams bred within the hair and wool flocks, were used as sires. Data collected on the ewe flock from 1993 to 2000 included records on body weight before mating, number of ewes mated, number of ewes that lambed, number of lambs born and number of lambs weaned. A total of 872 and 874 reproduction records were available for the hair and wool flocks respectively. Differences between the hair and wool flocks with regard to the percentage of ewes that lambed, percentage of lambs born per ewe mated or lambed, survival rate of lambs from birth till weaning and percentage of lambs weaned per ewe mated, were tested for significance employing the CHI-SQUARE-procedure of SAS. For the analyses of variance for body weight before mating and total weight of lamb produced per ewe per year, fixed effects for flock, year and age of the ewe were included in the models. Leastâ€‘squares means for these traits were obtained with the PROC GLM-procedure of SAS. Body weight at mating was higher for hair ewes than for wool ewes (57.9 " 0.25 kg vs. 56.40 "0.25 kg). No differences were, however, observed for percentage of ewes that lambed (85.9 vs. 82.5), lambs born (128.6 vs. 124.0), lambs weaned (116.2 vs. 111.3), survival rate of lambs (96.9 vs. 95.7) or kg lamb produced per ewe per year (35.3"0.8 kg vs. 33.9"0.8 kg). The same applied for the young ewes, where no differences in reproductive performance were observed between hair and wool type ewes. It is concluded that, in terms of reproductive performance, there are no differences between hair and wool Dorpers.