VARIOUS EFFECTS OF FEEDING HIGH AND LOW TANNIN SORGHUM GRAIN TO LAYING HENS, CHICKS AND RATS
Abstract
Studies were conducted to investigate the effects of feeding high (HTS) and low tannin sorghum (LTS) on various parameters in laying hens, chicks and rats. HTS dramatically reduced growth rate and feed efficiency of both chicks and rats which agreed with previous results from this laboratory. Furthermore, incorporation of HTS into sorghum-soybean meal diets containing 11.5, 13.0 and 14.5% protein depressed egg production and feed efficiency at all protein levels. Supplementation of methionine to the 13% protein diet overcame most of the detrimental effects of tannin. The activity of liver microsomal UDP-glucuronyltransferase (EC 2.4.1.17), an enzyme known to detoxify phenolic compounds, was measured in chicks and rats fed HTS and LTS. Enzyme activity was much greater in chicks fed HTS as compared with those fed LTS. Feeding LTS diets containing varying levels of protein demonstrated that only a small part of the increased enzyme activity could be attributed to a tannin-induced protein deficiency. The same phenomenon of elevated enzyme activity produced by feeding HTS to chicks was not observed in the rat. Investigations were conducted on the dietary effects of HTS on the morphology of isolated sections of the intestinal tract as compared with LTS-fed controls. Villous height, crypt length and wall thickness of the duodenum were reduced in laying hens and chicks fed HTS. Likewise, duodenal crypt length and wall thickness were reduced, but in contrast, villous height was significantly increased in rats fed HTS. Analysis of fecal material of rats indicated mucous secretion was slightly elevated by HTS, but it was not clear whether this response was mediated by a direct effect of tannins per se, or an indirect effect involving reduced digestibility with the resultant increased fecal matter.
Degree
Ph.D.
Subject Area
Livestock
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