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Performance of sheep raised in confinement, with special emphasis on their nutritional requirements Bryant, Ronald George

Abstract

Four main experiments were carried out to study the nutrient requirements and management of sheep raised in confinement. Experiment I was designed to study the reproductive performance and protein utilization of ewe lambs bred to lamb at approximately 14 to 16 months of age. Rapeseed meal was compared to soybean meal as a source of supplemental protein during the second half of gestation. Ewe weight gains and lamb birth weights were not affected by either the level or the source of protein. Neither dry matter nor protein digestibility were influenced by the stage of gestation of the ewe. No consistent results were obtained with regard to nitrogen retention of the ewes during the last half of gestation. The results suggest that 11% crude protein (CP) in the dry matter supplying approximately 68 g digestible crude protein (DCP) may be adequate for this class of ewes. The results also indicated that a level of 22% rapeseed meal may be included in the diet of gestating ewes without producing goitrogenic or other adverse effects. Experiment II was conducted to assess the performance of ewe lambs during lactation when fed rapeseed meal or soybean meal together with low quality roughage. Weight changes of the ewes and the average daily gain of the lambs over the eight week lactation period were not affected by the level or the source of protein. The results suggest that 10% CP in the dry matter supplying approximately 92 g DCP may be adequate for the class of ewe studied. A level of 25% rapeseed meal may be included in the diet of lactating ewes. In Experiment III wheat and barley were compared as energy sources in all-concentrate rations for lambs weaned at eight weeks of age. The cereal grains were fed in the whole, rolled, and pelleted forms together with a pelleted protein supplement. Digestiblity trials were also conducted to measure the digestibility of energy and protein as influenced by grain, process and level of intake. There was no difference in growth rate of lambs fed wheat or barley. Whole grains resulted in a faster rate of gain than the pelleted form. Digestibility of energy was not influenced by the method of processing. Protein digestibility was similar for the whole and rolled grains with a tendency for pelleting to depress digestibility of this nutrient. Increasing feed intake from maintenance to appetite resulted in a slight depression in nutrient digestibility. The results of this study suggest that processing of cereal grains for lambs is unnecessary from the standpoint of digestibility and would appear to be detrimental in terms of growth rate and feed conversion efficiency. Experiment IV was designed to study the influence of level of protein supplementation of whole barley based rations for early weaned lambs. A series of digestibility studies were conducted to measure the digestibility of dry matter and protein during three periods of growth. Results of this study demonstrated that 16% CP in the ration of lambs from 20 - 29 kg liveweight was sufficient to produce the most economical gain during this period of growth. In the period from 29 - 36 kg the lambs receiving 14% CP in the ration gained faster and had the best feed conversion efficiency. During the final finishing period the results suggest that one could continue to feed a 14% CP ration. The digestibility of dry matter and crude protein were not influenced by stage of growth of the animal.

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