Effect of different levels of raw and heated grass pea seed (Lathyrus sativus) on nutrient digestibility, intestinal villus morphology and growth performance of broiler chicks.

Abstract

This study aimed to investigate chemical composition and effect of different levels (0%, 10% and 20%) of raw grass pea (RGP) and heat-treated (120 °C for 30 min) grass pea seed (HGP) on nutrient digestibility, dressing percentage, relative internal organ weights, intestinal villous morphology and broiler chicks' performance. A total number of 200 day-old male chicks were raised under similar condition for 10 days. On day 11, chicks were randomly assigned to five dietary treatments and four replicates of 10 birds each. The result of chemical analysis indicated that Iranian grass pea seed has low levels of total and condensed tannin, and it may be considered as a good source of protein (36.1%) and energy (17.09 kJ GE/g). Heat treatment reduced (p < 0.05) the total and condensed tannin to 21% and 78% respectively. Grass peas seed had higher levels of nitrogen-free extract, P, Na, Mg and Zn than soya bean meal. The apparent digestibility of gross energy and lipid was affected (p < 0.01) by the treatment diets, and it was the lowest after feeding 20% of HGP (p < 0.05). The relative weight of breast and pancreas (p < 0.05) was affected by treatments. Percentage weight of breast and pancreas increased (p < 0.05) after feeding high levels (20%) of RGP and HGP. Substitution of 20% of RGP and HGP increased the duodenal crypt depth (p < 0.05); however, it had no suppressive effect on villus height as the absorptive surface of intestine. The feed conversion ratio was not affected by the treatments in the total experimental period. This study showed that, although the high level of grass pea seed caused a remarkable increase in the relative weight of pancreas and decreased the apparent digestibility of gross energy and lipid, it had beneficial effect on breast relative weight. It seems that heat processing is not effective method for improving quality of Iranian grass pea seed.