CHANGES IN URINARY AND FECAL COMPOSITION AS GOATS ADAPT TO TANNIN SUPPLEMENTATION

Authors: TURNER, KENNETH; WILDEUS, S - VIRGINIA STATE UNIVERSITY; Halvorson, Jonathan

Submitted to: American Forage and Grassland Council Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 4/1/2004
Publication Date: 6/12/2004
Citation: Turner, K.E., Wildeus, S., Halvorson, J.J. 2004. Changes in urinary and fecal composition as goats adapt to tannin supplementation. Proceedings of the American Forage and Grassland Council Conference. 13:484-488.

Interpretive Summary: Ruminants offered high protein hays or grazing well-managed grass and legume pastures can excrete as much as 95% of the ingested nitrogen. Factors that can influence the protein-use efficiency in goats include the dietary energy/protein ratio, protein solubility, and rumen-escape protein levels. Rumen-escape protein levels can be increased by condensed tannins found in plants. We conducted a feeding study to monitor changes in soluble nitrogen and carbon fractions of urine and feces as goats adjusted to hay plus a corn-soybean meal supplement with and without quebracho tannin, a commercially available condensed tannin. Overall, goats offered 5% quebracho tannin excreted less soluble nitrogen and carbohydrate in urine and more soluble nitrogen and carbohydrate in feces compared to goats fed no quebracho. This work is useful to scientists trying to understand the mechanism of condensed tannin influence on protein and carbohydrate dynamics in small ruminants. It will benefit our economy by helping goat producers refine feeding practices to reduce overloads of nitrogen in the environment to help improve overall water quality.

Technical Abstract: A preliminary feeding study was done to monitor changes in soluble nitrogen (N) and carbon (C) fractions of urine and feces as goats adjusted to a supplement with and without added quebracho tannin (QT). Goats were offered orchardgrass (Dactylis glomerata L.) hay plus a corn (Zea mays L.)-soybean [Glycine max (L.) Merr.] meal-based supplement at 1% BW with or without QT. Percent total soluble C in urine was greater on d 2 (P<0.001), d 3 (P=0.05), and d 14 (P<0.05) when animals were offered QT. Percent total soluble N in urine was greater on d 2 (P<0.01) and d 3 (P<0.05) in QT supplemented animals. Total output soluble C from urine (g/d) was greater on d 3 (P<0.01) and d 10 (P<0.05) for animals receiving no QT. Total output of soluble N from urine (g/d) was greater on d 2, d 3 and d 7 for animals receiving no QT. The total soluble C:N ratio in urine was greater on d 1 (P <0.05) and d 3 (P<0.05) and lower on d 2 (P<0.001) and d 14 (P<0.05) for animals receiving no QT. On d 2 through 14, percent soluble total C in feces was higher (P<0.05) when goats were offered supplement with QT compared to the supplement without QT. Percent soluble total N in feces was higher (P<0.05) in QT supplemented animals on d 14 compared to no QT. Total soluble C and N output in feces (g/d) were higher (P<0.01) on d 3. The total soluble C:total soluble N ratio in feces was higher (P<0.001) on d 2 through 14 for animals receiving QT supplement compared to no QT. A longer adaptation period than the 14 d used in our experiment may be needed to more accurately define intake and response parameters when small ruminants are offered diets containing QT. More research is needed to more accurately define condensed tannin-protein-polysaccharide interactions in ruminants.