اثر مدت پروار بر رشد و خصوصيات لاشه بره هاي نر تركي ـ قشقايي

Effect of fattening period on growth and carcass characteristics of male Turkey-Ghashghaii lambs

This trial was conducted in order to investigation effects of fattening periods on growth and carcass characteristics of male Turkey-Ghashghaii lambs. Eigthy lambs with age of 90 7 days and with an average of 23.1 2.5 kg body weight were used. At the end of each periods (60, 90, 120 and 150 days) 16 lambs were slaughtered for evaluating the carcass characteristics. Results indicated fattening period showed a highly significant effect (p<0.01) on body weight and feed conversion ratio,whereas, hadnot significant effect on daily gain, carcass efficiency and meat percentage (p>0.05). There was a significant effect on fat and bone percentage (p<0.05) while by increasing of fattening period,fat percentage increased but bone percentage decreased. The most of carcass meat (49.8%), fat (17.9%) and bone (19.2%) have been seen after 120, 150 and 60 days respectively and the least of them (47.1, 13.7 and 13.9%) have been seen after 150, 60 and 150 days respectively. By increasing of fattening period fat-tail percentage increased.The highest (20.1%) and the lowest (17.4%) fat-tail have been after 150 and 60 days respectively. The eye muscle length in different fattening period were 11.07, 14.23, 15.50 and 15.73 cm2 respectively and was highly significant (p<0.01) on 60 days fattening and other periods. Fattening period had significant effect on carcass composition. With increasing fattening period, percentage of moisture, protein and ash decreased but fat percentage increased (p<0.05).The 90 – day period has the best performance due to the lowest feed conversion , highest daily weight gain and the best carcass characteristics.