Effect of different levels of mangosteen peel powder supplement on the performance of dairy cows fed concentrate containing yeast fermented cassava chip protein.

This study aimed to investigate the effect of mangosteen (Garcinia mangostana) peel powder (MSP) supplementation on feed intake, nutrient digestibility, ruminal fermentation, and milk production in lactating dairy cows fed a concentrate containing yeast fermented cassava chip protein (YEFECAP). Four crossbred dairy cows (50 % Holstein-Friesian and 50 % Thai native breed) in mid-lactation, 404 ± 50.0 kg of body weight and 90 ± 5 day in milk with daily milk production of 9 ± 2.0 kg/day, were randomly assigned according to a 4 × 4 Latin square design to receive 4 dietary treatments. The treatments were different levels of MSP supplementation at 0, 100, 200, and 300 g/head/day. Rice straw was used as a roughage source and fed ad libitum to all cows, and concentrate containing YEFECAP at 200 g/kg concentrate was offered corresponding to concentrate to milk yield ratio at 1:2. Results revealed that feed intake, apparent nutrient digestibility, ruminal pH and temperature, and total volatile fatty acid were not significantly affected by MSP supplementation (P > 0.05). However, increasing levels of MSP supplementation increased molar proportion of propionate while ammonia-nitrogen, acetate, and acetate to propionate ratio were decreased (P < 0.01). Moreover, milk production and economic return were increased linearly (P < 0.01) with the increasing level of MSP supplementation. The present findings suggested that supplementation of MSP especially at 300 g/head/day with concentrate containing YEFECAP at 200 g/kg could improve rumen fermentation efficiency, milk production and protein content, and economical return of lactating dairy cows fed on rice straw.