The effect on nitrogen retention in lambs of feeding protein supplements direct to the abomasum. Comparisonof liquid and dry feeding and of various sources of protein

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Abstract
Three experiments were conducted to investigate the influence on nitrogen retention of feeding protein supplements to early weaned lambs direct to the abomasum via the oesophageal groove. In Exp. 1 the lambs received a basal diet of barley and a protein mixture consisting of soyabean meal, sunflower meal and fish meal which was given either in a liquid suspension from a bottle or as dry feed incorporated with the barley. The results showed that the regression coefficients of nitrogen retention on intake were 0.48 and 0.33 with liquid and dry feeding respectively. The regressions of urinary nitrogen on intake were with liquid and dry feeding respectively 0.26 and 0.44.In Exp. 2, various sources of protein were compared isonitrogenously as substitute for part of a barley concentrate ration. The nitrogen intakes and retentions were 14·28 and 5·09, 20·16 and 9·39, 20·53 and 8·19, 19·00 and 7·80, and 18·87 and 7·86 g/day for the control diet and fish meal, yeast, soyabean meal and sunflower meal supplemented diets respectively.In Exp. 3 the fish meal supplement was compared with a high lysine, bloodmeal and with casein as liquid supplements to a basal diet of barley concentrate. The intake and retention of nitrogen were for bloodmeal, casein and fish meal respectively 23·41 and 7·48, 22·56 and 9·11, and 21·88 and 8·31 g/day. It appeared that the protein sources high in methionine resulted in the highest nitrogen retention. The implications of these findings in relation to the nutrition of young ruminants is discussed together with an evaluation of the experimental method as a technique to study postruminal digestion.