EN
A 60-day feeding experiment was conducted to study the effects of including 0, 20, 40, or 60 g · kg–1 leaf meal of tetraploid Robinia pseudoacacia (TRLM) in diets on performance, egg quality, and apparent nutrient and amino acid digestibility of hens. Egg mass and egg weight were both higher when feeding 40 g · kg–1 TRLM than the other three diets, the egg shape index linearly increased (P < 0.05). No significant effects of diet were seen on the other hen performance or egg quality parameters. Apparent nutrient and amino acid digestibilities increased at first and subsequently decreased with increasing inclusion of the foliage, but no significant differences were observed in dry matter or glycine. Digestibility of crude protein, ether extract, gross energy and acid detergent fibre increased up to 20 g · kg–1 TRLM and subsequently decreased, and similar trends were observed for 13 amino acids, but the digestibility of neutral detergent fibre decreased up to 40 g · kg–1 TRLM and subsequently increased. A significant linear decrease (P < 0.05) in the digestibility of proline was observed with increasing inclusion of TRLM into the diets. Tetraploid Robinia pseudoacacia leaf meal could be a potential supplementary protein source in laying hen diets at inclusion levels not exceeding 60 g · kg–1.