Coffee hull in the diet of dairy heifers: nitrogen balance and microbial protein synthesis

Abstract

It was evaluated nitrogen compounds and microbial protein synthesis in heifers fed diets containing coffee hulls (0.0; 8.75; 17.25; and 26.25% of dry matter) replacing ground corn concentrate at the following levels of coffee hulls in the total diet dry matter: 0.0, 3.5, 7.0 or 10.5%. It was used 24 crossbreed heifers (7/8, 15/16 and 31/32 Holstein-Zebu), which were distributed in a random block design made up accordingly to the weight of the animals. Spot samples of urine were colleted aproximatelly four hours after morning feeding and were used to estimate microbial protein synthesis by using urine purine derivatives. It was not observed effect of coffee hull levels in the diet on total nitrogen intake (160 g/day) and nitrogen excretion in the urine (87.4 g/day). The inclusion of coffee hull in the diet linearly increased nitrogen excretion in feces, as well as nitrogen balance. There was linear reduction in urinary excretion of allantoin, in total purine derivative and absorbed purine, which reduced 0.715, 0.873, and 0.954 mmol/day to each coffee hull unity added to the concentrate, respectively. Coffee hull altered microbial protein synthesis, which reduced in 0.687 g/day to each coffee hull unity added to the concentrate. Reduction in microbial protein synthesis can reduce weight gain in heifers fed coffee hulls.