Submitted to: Small Ruminant Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/1/1999
Publication Date: N/A
Interpretive Summary: The rumen is a large stomach in sheep which enables the animal to digest grasses and then use the energy of the feed for productive purposes like making milk and meat. In the neonatal lamb, the rumen develops when the lamb begins to eat solid feed. The solid feed is necessary because it has physical bulk as well as energy, which is necessary for the development of a microbial population within the rumen. The microbes that inhabit the rumen digest the feed and produce volatile fatty acids which are chemicals that the ruminant can use for energy. We studied the intestines of lambs to see if we could cause the rumen and the intestines to develop by putting volatile fatty acids into the rumen directly. Lambs were fed milk replacer until they were 56 days old. The lambs were then either fed as much food as they wanted, fed a small amount of food, continued to get milk replacer or milk replacer and volatile fatty acids until they were 84 days old. The lambs were then euthanized and the intestines were studied. The fed animals had rumens which had grown in weight and had changed into a mature rumen. The milk fed animals did not have developed rumens and neither did the animals that were given volatile fatty acids. The volatile fatty acids did cause the intestines to increase in size. The way that we put volatile fatty acids into the rumen was not effective and another method should be used in the future. However, volatile fatty acids do appear to increase cell division in the intestines of lambs.
Technical Abstract: This study was conducted to evaluate the effect of VFA administration and energy intake on sheep gastrointestinal development. Twelve lambs were removed from their dams at birth and trained to nipple buckets. All lambs consumed milk until 49 d and were subsequently assigned to one of four treatments: continued ad libitum intake of milk (M), ad libitum intake of a apelleted lamb starter (F), restricted intake of a pelleted lamb starter (P paired to the energy intake of M lambs), or continued ad libitum intake of milk replacer plus an oral VFA gavage (V;55.2:36.9:7.2 mmol/ 100 mmol acetate:propionate:butyrate)to provide 10% of the predicted NEg of the lambs. At slaughter visceral organs were removed and separated. Ruminal and intestinal tissues were weighed and intestinal tissue length was determined. Subsections of the rumen, duodenum, jejunum, ileum, and the colon were used to determine total, epithelial and musculature DM, protein, ,DNA, and RNA. Data is presented as a percent of empty body weight unless otherwise noted. Both F and P stimulated increases (P<.05) in rumen mass (2.232 +.077 and 2.126 + .238, respectively) while V treatment did not (.761 + .038) in comparison to milk fed animals (.88 + .104). Small intestinal weights were unaffected by P and F, relative to milk fed animals yet increased in V (3.32 + .982 (M), 2.66 + .242(P), 3.122 + .354(F) and 4.061 + .158(V). The ratio of small intestinal length to empty body weight declined (P<.05) with intake of solid feed and VFA treatment. However, weight per unit length of the small intestine was increased by F, P and V above that observed for M. Thus, although VFA treatment at this dose is insufficient to induce normal ruminal development, intestinal development is stimulated by oral VFA infusion in developing lambs.