Effect of supplemented chestnut hydrolysable tannin on feed intake and ewes' performance during late pregnancy and early lactation.

Late pregnancy and early lactation are periods of high nutritional demand in ewes, and improving protein utilisation during these stages may enhance animal performance. Hydrolysable tannins have the potential to reduce ruminal protein degradation and increase the supply of metabolisable protein, although their effects when supplemented with lucerne silage have not been fully established. Therefore, this study was designed to investigate the effects of supplemental chestnut tannin offered with lucerne silage to ewes on their performance in late pregnancy and early lactation. Twenty tonnes of second-cut lucerne were used for silage making. Chopped lucerne was wilted for 48 h before ensiling. The clamp was filled rapidly, rolled and covered with three layers of plastic sheet and ensiled for 115 days. Forty single-bearing ewes were used in the experiment and, from 6 to 4 weeks prepartum, were acclimatised to lucerne silage as a group. At 4 weeks prepartum, ewes were blocked according to parity, liveweight and condition score and housed individually. Ewes were divided into four feeding groups (10 ewes per group). Each group was offered a 380 g/day concentrate diet and lucerne silage ad libitum, supplemented with hydrolysable tannin (HT) at 0, 25, 50 or 75 g/kg DM, with free access to clean water. The observations were taken between 4 weeks prepartum and 6 weeks postpartum. Forage DM intake was measured, and ewe liveweight (LW) and body condition scoring (BCS) were recorded weekly. At 2 weeks prepartum and 4 weeks postpartum, DM and CP digestibility were measured using the acid-insoluble ash method. Experimental data were analysed by ANOVA as a randomised complete block design using GenStat 15. Supplemental tannin did not significantly affect forage DM intake or ewe LW and BCS change pre- or postpartum. However, a high level of supplemental tannin (75 g/kg DM) significantly reduced CP digestibility, both prepartum and postpartum, when compared with the other tannin levels (25 and 50 g/kg DM). Dietary supplementation of HT significantly increased milk yield, with the 25 and 50 g/kg DM treatments producing 2.7 and 2.6 l/d, respectively, compared with 2.4 l/d in both the control and 75 g/kg DM groups. These findings indicate that moderate supplementation with chestnut HT (25-50 g/kg DM) improved milk yield without adversely affecting feed intake or ewe performance, whereas the highest supplementation level (75 g/kg DM) reduced CP digestibility.