Effects of abomasal pectin infusion on milk production, digestion and nitrogen utilization pattern of lactating Saanen dairy goats

To study the effects of graded abomasal infusion of pectin on milk production, nitrogen balance and nutrient digestibilities of goats, four abomasally cannulated lactating Sannen dairy goats were used in a 4×4 latin square design with 14-d periods. Goats were fed the same basal diet and the treatments were the abomasal infusion of 0, 40, 80 or 120 g/d of citrus pectin. Pectin infusion resulted in linear decreases in basal ration intake from 2250 to 1985 g/d. There was insignificant decrease in total tract apparent digestibilities of dry matter and neutral detergent fiber. Decreased basal ration intake and digestibility led to decreased milk production from 1.95 to 1.75 kg/d. Milk fat content increased quadratically with increasing levels of infused pectin (P = 0.04), but milk fat yieldwas unaffected by treatments. Milk total solids and solid-not-fat were also linearly decreased by pectin infusion. There were linear decreases in urinary N and plasma urea N (PUN) with the increase in infusion of pectin. As a proportion of N intake, urinary N excretion decreased from36.31 to 31.92%,whereasNexcretedfromfaeces increasedfrom25.2 to 29.4%, as theamountof pectin infusion increased. Abomasal pectin linearly decreased faecal pH from 7.31 to 6.86 and tended to decrease faecal ammonia from 0.246 to 0.215 mg/g faecal DM. These results suggest that manipulating dairy goats diets to increase postruminal fermentation may reduce urinary N and consequently manure ammonia losses. However, decreased digestibility and milk production at the highest level of pectin infusion is suggesting that pectin may have reduced postruminal nutrient utilization.