Effect of using cassava products to vary the level of energy and protein in the diet on growth and digestibility in cattle

Abstract

The effects of feeding different levels of energy and protein using cassava products ( Manihot esculenta Crantz) (roots and foliage) in the diet on growth rate and diet digestibility were studied in two experiments with growing cattle. In the growth trial, twenty-eight animals were allocated to a completely randomized 2 × 2 factorial design with seven animals per diet. The four diets consisted of two levels of crude protein (CP) (400 g and 540 g day − 1 ) and two levels of metabolisable energy (ME) (25 MJ and 32 MJ day − 1 ). The diets were formulated based on the nutrient content of cassava foliage, cassava roots, urea and elephant grass. The amount of urea was the same in all diets, 63 g head − 1 day − 1 , on DM basis. The digestibility trial was conducted after two months of the growth experiment. The lowest values of OM and GE digestibility were in the group fed the high CP and low ME level, while the group fed the low CP and high ME level had the lowest CP digestibility. There was a significant linear regression between OM digestibility and HCN intake and tannin intake in the groups fed on the low energy level. There was no significant difference in live weight gain between the groups fed either low ME, or high ME and low CP. The highest nutrient digestibilities were found in the group fed both high CP and ME resulting in a significantly higher daily gain, 558 g day − 1 . In conclusion, an increased level of CP and ME in the diet, achieved using cassava products, improved diet digestibility and growth rate of cattle fed low quality grasses. In order to overcome the negative effect of HCN, cattle fed high amounts of cassava foliage should be supplied with extra energy in the diet.