Effect of Varied Sources of Tannin on Micro-Mineral Bioavailability in Goats Fed Oak Leaves Based Diets

Eighteen crossbred (Chegu×Jamunapari) goats (15.99 kg; 7–9 months) were randomly assigned to three groups. The animals were fed a common concentrate mixture as a supplement to three different forage sources (with a concentrate to roughage ratio of 30: 70) namely, green grass (PC, Pennisetum clandestinum), oak leaves i.e. Quercus semecarpifolia (QS) and Quercus leucotricophora (QL) with the latter two groups serving as tannin-containing diets while the PC group as a control. The condensed and hydrolysable tannin content of the QS and QL diets was CT 1, HT 3.4 vs. CT 1.9, HT 1.6, respectively. A metabolism trial of six days duration was conducted at 90 d post-feeding. Blood samples were collected on 0, 60 and 120 d of experiment for estimation of serum minerals. The digestibility of DM, CP and fibre fractions were lower (P<0.05) in QL than PC and similar with QS. Daily intake and balance of Fe, Mn and Zn was higher (P<0.01) in QS and QL groups than the control group. Serum level of Co, Fe and Zn were higher (P<0.05) in QS than PC, but at par with QL. Average daily gain was higher in QS and QL as compared to PC. Feed gain ratio was better in QS (22.9±0.08) than PC (39.5±0.06), but at par with QL (29.9±0.04). Overall, the study revealed that goats fed tannin-from QS-based diet showed comparatively better performance than that of QL-based diet. Further, feeding of oak leaves was beneficial in augmenting feed intake, micro-mineral balance and growth performance of goats as compared to animals fed grass based diet.