The nutritive value of citrus pulp ensiled with wheat straw and poultry litter for sheep

Abstract

In experiment 1, 4 treatments were prepared consisting of a mixture of chopped wheat straw in different proportions, a fixed proportion of poultry litter and 0, 15, 30 and 45% citrus pulp on a dry matter basis. The mixtures were ensiled for 60 days at room temperature in polythene bags. Ensiling (time effect) resulted in an increase (P<0.001) in titrable acidity level and a decrease in pH in the silage. In titrable acidity, there was an interaction effect (P<0.001) between the levels of citrus pulp and the ensiling time, such that there was an increase (P<0.001) in titrable acidity and a decrease (P<0.001) in pH in the 4 treatments both before and after fermentation. However, compared with the premix, there was a large increase in titrable acidity in silage following fermentation. Ensiling resulted in complete elimination of all coliforms in spite of their presence in large numbers in the mixtures before ensiling. Although the total nitrogen content was not affected, ensiling resulted in an increase (P<0.05) in the proportion of soluble nitrogen. The potential degradability of the silage dry matter ranged from 487 to 582 g/kg and increased (P<0.05) with the level of citrus pulp. In experiment 2, the daily intake of dry matter, organic matter, digestible organic matter and the digestibility of organic matter increased significantly with levels of citrus pulp in the basal silage diet, but there was no difference (P>0.05) in dry matter intake between diets containing 0, 76 and 167 g/kg citrus pulp when the intake was expressed on the basis of metabolic body weight. However, there was a decrease (P<0.001) in intake of silage and diet dry matter, organic matter and digestible organic matter when the level of citrus pulp in the basal silage diet increased from 167 to 272 g/kg. Only animals on the basal silage diet containing 167 g/kg citrus pulp had a higher (P<0.05) and positive nitrogen balance of 1.0 g/day. It is concluded that wheat straw and poultry litter can be ensiled successfully with citrus pulp to produce silage that is safe and of high fermentation quality. This silage has a medium to high feeding value in sheep, provided that the level of citrus pulp in the diet is in the range of 150–200 g/kg.