Effects of pectin on production and urinary nitrogen excretion in lactating Saanen dairy goats

Extract

Urinary nitrogen (N) is rapidly converted to ammonia (NH₃) during manure collection and storage, whereas faecal N is converted to NH₃ at a much slower rate. Developing nutritional strategies to shift N excretion from urine to faeces may reduce NH₃ from dairy manure which is implicated in reduced air quality. Previous work suggests that increasing post-ruminal fermentation may reduce urinary N and consequently manure NH₃ losses (Gressley and Armentano, 2005). Pectin is a class of neutral detergent-soluble fibre (NDSF) and studies in monogastrics have shown that it is completely degraded by resident intestinal bacteria (Buchanan et al., 1994). Gut bacteria are capable of converting blood urea-N into NH₃ and subsequently microbial protein. Therefore, growth of intestinal microorganisms using energy supplied by pectin can result in a net conversion of blood urea N into faecal microbial N, thereby reducing urinary N. The aim was to determine the effect of increasing carbohydrate fermentation in the large intestine on urinary N in lactating dairy goats.