Can green tea leaf supplementation of ensiled grass-consuming lambs impact their growth and nutrient digestibility

Green tea leaves (GTL) is a potential natural feed supplement to replace undesirable growth-promoting antibiotics for ruminants. This 3 × 2 factorial study involved 3 experimental diets based on a concentrate (CON) containing GTL at either 0% or 10% (12 g DM/day) or 20% (24 g DM/day). These CON were then offered daily per lamb at two levels of either high (HiCON) or low (LoCON) alongside ad libitum ensiled grass (SIL) to evaluate the effects of GTL on feed intake, growth performance, and nutrient digestibility in growing lambs. The GTL inclusion had no adverse effects on total dry matter intake (DMI) or average daily gain (ADG). Instead, it increased ash, Ca, Mn, and Zn digestibility and tended to improve the digestibility of Fe, Mg, and P, but not K digestibility, whereas Na digestibility tended to decrease by GTL inclusions. The lambs fed LoCON appeared to equate tDMI to those fed HiCON by consuming more SIL but the higher CON intake increased DM digestibility and it tended to result in greater ADG. In conclusion, up to 20% GTL can be safely incorporated in a concentrate DM, as a sustainable strategy to enhance mineral utilization in lambs without compromising their growth.