The effect of condensed tannins in sulla (Hedysarum coronarium) on 4-methylphenol metabolism in the ovine gastrointestinal tract during late lactation
N.C. ROY, K. FRASER, G.A. LANE, B.R. SINCLAIR and W.C. MCNABB
AgResearch Limited, Grasslands Research Centre, Private Bag 11008, Palmerston North, New Zealand
Proceedings of the New Zealand Society of Animal Production 65: 178-181
Twelve lactating ewes were surgically prepared with permanent arterio-venous catheters across the gastrointestinal tract at 1 week post partum. From week 3 to 6 of lactation, all sheep were fed fresh sulla (1500 g dry matter/day; condensed tannins (CT) 4.4 g per 100 g dry matter). Half the ewes were orally drenched (4 times/day) with polyethylene glycol (PEG) (160 g/day in water) to remove the effects of the CT whilst the remaining ewes received a water drench. At week 6, para aminohippurate was infused for 7 h into the cranial mesenteric vein for measuring mesenteric and portal plasma flow and 4-methylphenol concentrations. The mesenteric and portal plasma flows were not affected (P > 0.05) by the treatments. The concentration of 4 methylphenol in the mesenteric artery (Control: 2.8 vs PEG: 9.0 ± 1.2 µg/ml) was lower (P < 0.01) in the control ewes. The net portal appearance of 4 methylphenol was higher (P < 0.01) in the PEG ewes (Control: -663 vs PEG: -1430 ± 159 µg/minute). These results establish that sulla CT reduced the portal flux and peripheral concentration of 4 methylphenol and it is likely that this was a consequence of reduced formation of that metabolite in the rumen due to lowered ruminal protein degradation in the CT-treated ewes.
Keywords: NZSAPAB; plasma net fluxes; gastrointestinal tract; 4-methylphenol; lactation; sheepLast Updated 23/07/2005