Effect of feeding tree leaves as supplements on the nutrient digestion and rumen fermentation pattern in sheep grazing on semi-arid range of India - I

A study was carried out to determine the effect of feeding different tree leaves as supplements on nutrient digestion, rumen fermentation and blood parameters of sheep grazing on a semi-arid rangeland. Thirty adult Malpura rams of uniform body weight (39.0 ± 0.75) were divided into five groups of six each. They were grazed as a single flock from 08.00 to 17.00 h on a semi-arid rangeland. After the end of the grazing period, the first group (G1), which was not provided with any supplementation, served as the control. The second group (G2) was supplemented with 200 g of a concentrate mixture per head per day, whereas the third, fourth and fifth groups (G3-G5) were provided with approximately 200 g DM d−1 of freshly cut foliage from Prosopis cineraria, Acacia nilotica and Albezia lebbek. The foliage from P. cineraria contained 133.4 g kg−1 DM condensed tannin (CT) with protein precipitating capacity (PPC) of 66 g kg−1 DM, whereas A. nilotica contained 18.9 g kg−1 DM hydrolysable tannin (HT) with PPC of 11.5 g kg−1 DM. However, A. lebbek did not contain any tannin. The protein contents were 119, 139 and 194 g kg−1 DM, respectively. The DMI (g d−1) was 688, 916, 1024, 1003, 999 in G1, G2, G3, G4 and G5, respectively. Digestible crude protein (DCP) and metabolizable energy (ME) intakes in supplemented groups G2-G5 were higher (P < 0.05) than in the control (G1). Supplementation improved the DM digestibility in all groups, whereas CP digestibility was lower (P < 0.05) in G3 compared to G2, G4 and G5. Rumen fermentation study conducted 6 h after supplementation revealed that total N, ammonia N, and total VFA levels were lower (P < 0.05) in G3 compared to the other supplemented groups. Although the haemoglobin (Hb) levels were similar among groups, blood urea N (BUN) was lowest in G3 compared to the other groups. The initial body weights were similar among groups (mean 39 kg). After 60 days of experimental feeding, all groups maintained their body weight, except the control group (G1), which lost body weight. It was observed, that supplementation with tree leaves containing CT like P. cineraria helps in better rumen fermentation pattern by preventing excessive loss of nitrogen. It was concluded that maximum nutritional benefits of tree leaves could be harvested, if used as supplement rather than as a sole feed.