The nutritive value for rats and chicks of unextracted and defatted leaf protein concentrates from red clover and Italian ryegrass

Leaf protein concentrates (LPCs) from red clover and Italian ryegrass were produced in a pilot production plant using a standard method. Half of each preparation was defatted using petroleum ether. Unextracted preparations contained a high amount of fat (21.2% and 16.3% of DM, respectively). LPC from red clover was also rich in carotenoids (1209 mg per kg). True digestibility (TD) and biological value (BV) of protein of unextracted and defatted preparations were estimated on rats using the Thomas-Mitchell balance method. All preparations were compared with a control diet based on soya bean meal protein (SBM) using leaf protein in chick diets mixed with SBM in a protein ratio 1:1. Both TD and BV of protein of LPC from red clover were lower than those of LPC from Italian ryegrass (62 and 79, and 31 and 58, respectively, significant at P < 0.01). Ether extraction significantly improved the biological value of red clover protein (from 31 to 60, significantly different at P < 0.01), but had no effect on the Italian ryegrass LPC (58 and 60). Chicks fed diets containing LPCs in the second period of the experiment grew slightly better than those fed on SBM alone though these differences were not statistically significant. Defatting did not improve the nutritive value of LPCs for chicks. Concentrate from red clover induced an important storage of carotenoid in the liver and proved to be a good source of carotene: vitamin A content of chick livers in that group was significantly (P < 0.05) higher than in the control group (248.7 μg g−1 and 117.6 μg g−1, respectively).