Response of Growing Dairy Bulls to Dietary Tannin in Rations with Varying Energy Levels

Abstract

This study was conducted to determine the effect of dietary tannin on growth performance, rumen fluid characteristics, and apparent total-tract digestibility in growing Holstein-Friesian x Sahiwal bulls fed low and high energy rations. Eighteen growing bulls with initial body weight (BW) of 162.8±12.7 kg at 15±0.80 months were used in an unbalanced randomized complete block design set-up in a 2x2 factorial arrangement. The experimental animals were blocked by their respective BW. Animals were fed with concentrates containing metabolizable energy (ME) at 2.47 and 2.72 Mcal/kg without or with 20g/kg tannin in dry matter basis. At the final week of the trial, rumen fluid and fecal samples were collected for the rumen fluid characteristics and apparent total-tract digestibility analyses. No differences (p>0.05) were observed between the growth performance, rumen gas production, volatile fatty acids as well as organic matter, crude protein, and energy digestibility. High energy concentrates had higher (p<0.05) dry matter and neutral detergent fiber digestibility than low energy concentrates. Low energy concentrates without tannin had cheaper (p<0.001) total feed cost but feed cost per kilogram BW gain was similar (p>0.05) across treatments. Feed savings costs of US$ 17.58 per animal were attained in feeding low energy concentrates without tannin. Therefore, feeding concentrates containing 2.47 Mcal/kg ME without additional tannin can still be fed economically to growing cattle without any adverse effect on growth, ruminal fermentation characteristics, and apparent total-tract digestibility.