Herbage digestion in the stomach and intestines of weaner lambs at different stages of their maturity

Abstract

Various parameters relating to digestion of a clover diet in the stomach and intestines were measured by marker techniques in the same weaner lambs at 15, 24 and 40 weeks of age when body weights averaged 18, 29 and 44 kg respectively. Significant small changes were observed with increasing age and body size in the values of several of the parameters measured. Thus at 40 weeks relative to 15 weeks values were higher for (i) crude protein digested in the intestines per unit feed intake (+ 10%), (ii) sodium content of rumen liquor and sodium flow from the rumen per unit feed intake (+ 9%, + 14%), (iii) potassium and chloride contents of abomasal liquor (+ 9%, + 7%) and (iv) pH of abomasal digesta (+ 0.3 pH unit). Values were lower for (v) digestibility of organic matter and cell wall constituents in the whole alimentary tract (c. – 1.8%), (vi) ammonia content of rumen liquor and ammonia flow from the rumen and abomasum per unit feed intake (– 15% to – 20%) and (vii) potassium content of rumen liquor (– 9%). No changes attributable to age or body size were observed with several paramefers, including (i) rate of production of volatile fatty acids in the rumen per unit feed intake, (ii) rate of absorption of volatile fatty acids from the rumen, (iii) rate of flow of digesta through the stomach per unit feed intake, and (iv) mean residence time of water-soluble marker in the rumen. The results indicate that care needs to be exercised in applying digestion data obtained with adult sheep to the nutrition of the growing weaner lamb.