Crossbred lambs under Eastern Transvaal conditions

Abstract

1. Controlled serving revealed irregularities with regard to fertility in rams and ewes. The fertility of a ram can be assured only by breeding trials or by sperm tests. Old Merino ewes are unsatisfactory and uneconomical for crossbreeding purposes. Large framed, roomy ewes give best results. While controlled or “hand" serving is advocated in order to obtain maximum results, it is considered that free mating in small camps may he practised with advantage when facilities permit. The latter system of mating has been employed during the 1934 mating season in the continuation of these experiments. 2. The lambs of all types did not attain a desirable weight at twenty weeks of age. The Border Leicester-Merino wether lamb weighed 57.6 lb. at twenty weeks of age and 96 per cent. were fit for despatch; they dressed 47.5 per cent. and 11.1 per cent. of the carcasses were graded as "good", 47.2 per cent "medium" and 41.7 per cent. "common". The Ryeland-Merino wether lambs weighed 50.4 lb. at twenty weeks of age and 86 per cent. were fit for despatch; they dressed 46.7 per cent. and none of the carcasses were graded as "good", 36.8 per cent. were "medium" and 63.2 per cent. "common". The Merino flock wether lambs weighed 38.0 lb. at twenty weeks of age and 83 per cent. were fit for despatch; they dressed 46.1 per cent. and none of the carcasses were graded as "good" while 10 per cent. were "medium" and 90 per cent' "common". There was no significant difference between the finish of the Ryeland crosses and the Merino flock lambs, although the former were superior in conformation and shape of hind quarters. 3. Drastic control measures against internal parasites, especially wireworms and tapeworms, are essential if September lambing is to be a success under eastern Transvaal conditions. The use of copper sulphate and tobacco extract as advocated by Monnig (1932) is recommended. This treatment will be given a thorough test during the next season. 4. Due to the poor finish of lambs reared on grass, it appears that a supplementary feeding period will be warranted. Results indicate that supplementary feeding may be commenced when the lambs are twelve weeks old Systems of supplementary feeding will be conducted with the 1934 lamb crop. 5. The experiment reported must be considered as the preliminary work of experiments which will be extended over a number of years. The experiments during the next year will include the use of Corridale rams. When the half-bred ewes, which have been retained, are fit for breeding, they will be included in the further work at this Station.