The nutritive value and chemical composition of energy-rich by-products for ruminants

Abstract

The nutritive value and chemical composition of 29 energy-rich by-products are reported. These comprised two samples of imported dried citrus pulp, one of UK-produced dried citrus pulp, eight of locust bean meal, two of maize gluten feed, one of pearled barley offal, eight of rice bran, two of soya bean hulls, four of molassed sugar beet feed and one of unmolassed sugar beet feed. The crude protein (CP) content of the feedstuffs ranged from 44 to 217 g kg −1 dry matter (DM), the lowest value being for locust bean meal and the highest for maize gluten feed. Total carbohydrates, calculated as the sum of neutral detergent fibre (NDF), water-soluble carbohydrates (WSC) and starch contents, accounted for approximately 510–859 g kg −1 DM for all the feed types studied, and the highest value was found for rice bran, owing to a high starch content (219 g kg −1 DM). The digestible organic matter in the DM (DOMD) contents measured in vivo were all within the range 686–838 g kg −1, with the exception of rice bran and locust bean meal, which had much lower digestibilities (512 g kg −1 and 623 g kg −1, respectively). The metabolisable energy (ME) content of the feedstuffs varied over a relatively wide range (8.2–13.2 MJ kg −1 DM), the lowest value being for rice bran and the highest for UK-produced dried citrus pulp. The ME content of all the feedstuffs studied was predicted from a relationship with neutral detergent amylase-cellulase (NCD, g kg −1 DM) and acid ether extract (AEE, g kg −1 DM) as independent variables: ME = 0.0142NCD + 0.0262 AEE, rsd = 1.19.