Substitution effects of soybean meal by Lathyrus sativus L. (grass pea) on nutrient digestibility, growth performances, carcass traits and meat quality of lambs grazing on saline area

Abstract

Considering the substitution of soybean meal by locally legumes in Mediterranean saline areas, the present work aimed to determine the effect of Lathyrus sativus L. (grass pea) seeds incorporation on digestibility, growth performances, carcass and meat qualities of lambs grazing natural saline rangeland. Forty-five weaned female Queue Fine de l′Ouest lambs (IBW 21.5 ± 2.17 kg) were randomly divided into three groups (n = 15). Each group received 300 g per animal of one of three concentrates containing 0 (Control), 12% (G12) and 30% (G30) of grass pea seeds. All groups were reared on pasture rich on spontaneous halophytic shrubs and herbs for two months. At the end of the experiment, eight lambs per group were slaughtered. Replacing soybean meal by grass pea seeds with the reduction in amount of maize, barley and alfalfa pellet had no effect on nutrient digestibility and feed intake. Digestible crude protein (DCP)/ metabolizable energy (ME) ratio and average daily gain (ADG) were similar among groups (11.15; 183 g/day, respectively). The incorporation of grass pea did not affect (P > 0.05) cold carcass weight and commercial dressing percentage and averaged 13.17 kg and 44.84%, respectively. Red offal percentage was not modified. Moreover, it was found that grass pea seeds did not have any significant effect on carcass fatness (P > 0.05). The average percentage of high-priced joints was 60.87% and was not affected by grass pea seeds incorporation. All lambs had the same shoulder tissue composition. Meat pH, drip and cooking losses were not influenced by diet treatments, as well as the meat chemical composition. Indeed, lamb meat had the same proportions of protein and intramuscular fat. From these findings, it can be concluded that a supply up to 90 g/head/d of grass pea seeds had no effect on digestibility, growth rate, carcass traits and quality of the resultant meat and reduced the use of imported feed ingredients (soybean meal, maize, alfalfa pellet). These results may present significant opportunities for fattening lambs on saline lands.