Tannins
The banj oak is one of the most tannin-rich forage tree of the Himalayas (Vir Singh et al., 1988). Its foliage contains high levels of tannins with a high protein-binding capacity (Singh et al., 2005). In ruminants, these tannins decrease diet palatability, feed intake and nutrient utilization (in particular protein utilization), resulting in lower performance (Makkar, 2003). Processing banj oak leaves by drying (sun-drying or oven-drying) or steaming was shown to be ineffectual for decreasing tannin content and alleviating their adverse effects (Makkar et al., 1991). In India, a case of cattle poisoning by nephrotoxicity and hepatotoxicity consecutive to the feeding of immature banj oak leaves containing 9.7% tannins and 5.8% condensed tannins was reported. Mortality was 70% after the animals had exhibited anorexia, constipation and brisket oedema (Garg et al., 1992).