Effects of replacing nonfiber carbohydrates with nonforage detergent fiber from cassava residues on performance of dairy cows in the tropics

Abstract

Four HolsteinxIndigenous cows with ruminai canulas were used in a 4x4 Latin square design with 28 d periods to determine the effect of replacing nonforage fiber source (NFFS) from cassava residues for non-fiber carbohydrates (NFC) on ruminai fermentation characteristics and milk production. Dietary treatments contained 17% forage neutral detergent fiber (FNDF) from corn silage and 0, 3, 6 and 9% nonforage NDF from cassava residues and 11% nonforage NDF from other NFFS, so that levels of nonforage NDF were 11, 14, 17 and 20% dry matter (DM). Intakes of DM and net energy for lactation, average daily gain and milk fat percentage were not different (p>0.05). Ruminai pH, ammonia concentrations, acetate to propionate ratios, 24 h in sacco fiber digestibility significantly increased with increasing contents of nonforage NDF from cassava residues. Concentrations of VFA, urinary excretion of purine derivatives, milk protein percentage, production of milk and 4% FCM significantly decreased. These results suggest that NFC in diets is one of the limiting factors affecting productivity of dairy cows in the tropics and thus NFFS is better used as partial replacements for FNDF.