Effect of alfalfa hay on growth performance, carcass characteristics, and meat quality of growing lambs with ad libitum access to total mixed rations

ABSTRACT Forty male Naemi lambs were used to evaluate the effect of total mixed rations (TMR) alone or in combination with supplementation of alfalfa hay offered at different schedules on growth, carcass characteristics, and meat quality. Lambs at the age of three months, with an average weight of 28.85±1.09 kg, were randomly selected and distributed into four different feeding systems, 10 lambs each, as follows: TMR diet (control); TMR plus 100 g alfalfa hay; TMR plus 200 g alfalfa hay every two days; and TMR plus 300 g alfalfa hay every three days. The TMR and fresh drinking water were offered ad libitum. Lambs in the treated groups (with alfalfa hay) had significantly higher body weight, body weight change, dry matter intake, and feed conversion ratio compared with the control. Similarly, slaughter weight, carcass weight (hot and cold), and internal organs weight significantly increased in the treated groups, except for dressing weight percentage, which improved only in the treatment with TMR plus 300 g alfalfa hay. By contrast, mesentery fat, back fat, and body wall fat decreased in treated groups. Meat quality characteristics indicated that cooking loss and pH values did not differ between the control and treated groups; however, meat colour (lightness, yellowness, and redness) and pH (1 and 24 h) improved in post-slaughter treated groups. Furthermore, no difference was found in texture profile analysis (hardness, springiness, cohesiveness, and chewiness), although the shear force decreased significantly in treated groups. Addition of alfalfa hay offered at the present plan may not only improve the growth and carcass characteristics, but also enhance the meat quality of Naemi lambs. From the labour and economic point of view, TMR plus 300 g alfalfa hay every three days may be adopted while taking into account the management decision.