Effect of Weight at Slaughter in Muscle Tissue Distribution in Carcasses of The Awassi and Karadi Lambs

Abstract

This study was conducted at the farm of the Filed of Animal Production Department College of Agriculture - University of Tikrit, From 17/2 /2014 to 5/6/2014 . Using Thirty lambs ( 15 Awassi and 15 Karadi ) with average age 4 month + 15 days and averaged 22.9±0.27 and 23.83±0.29 kg live body weight were used and reared at the farm of Agriculture collage –University of Tikrit for the period from 17/2 to 5/6/2014. Randomly the lambs divided to six groups by three groups for each breed . Eeach group consists of five lambs . Concentrate diets was providing to animals by 4% of live body weight for whole period of rearing (107 days), wheat straw was provided adlibitum as a roughage diet. Thirty animals were slaughtered at three weights are 30, 37.5 and 45 kg (five animals for each weight) . Karadi lambs record high (P≤0.01) proportion of muscle groups MG1, MG2 and EMG and low (P≤0.05) proportion of muscle groups MG4 , MG8 and MG9 compared with Awassi lambs .The slaughter weight have significant effect on proportion of muscle groups MG1 and EMG that decreased (P≤0.01) in lambs that slaughtered at 45 Kg compared with lambs slaughtered at 30 and 37.5 Kg , muscle group MG2 decreased (P≤0.05) on lambs slaughtered at 45 Kg compared with that 30 Kg , while MG8 and MG9 increased (P≤0.01) with increased slaughter weight from in 30 Kg to 37.5 and 45 Kg . The Rectus Femoris , Vastus Lateralis and Biceps Femoris (P≤0.01) and (P≤0.05) increased proportions in Karadi lambs compared with Awassi , while Semimembranosus record highest (P≤0.01) proportion in Awassi lambs compared with Karadi , proportion of Biceps Femoris and Vastus Lateralis decreased (P≤0.01) in lambs slaughtered at 45 Kg compared with that slaughtered at 30 and 37.5 Kg , the proportion of Infraspinatus ,Supraspinatus and Vastus medialis decreased (P≤0.01) in lambs slaughtered at 37.5 and 45 Kg compared with that slaughtered at 30 Kg , while Biceps Femoris and Gracilis proportion decreased (P≤0.01) increased with slaughter weight.