اثر مدت پروار بر رشد و خصوصيات لاشه بره هاي نر لري بختياري

Effect of the length of fattening period on growth and carcass characteristics of Lori-Bakhtiari male lambs

The data of 1 18 male lambs with average age of 135 days and 58 carcass Lori-Bakhtiari male lambs were used to determine effect of the length of fattening period on growth and carcass characteristics. Lambs were weaned at 90±5 days of age. They were fed ad libitum for 60, 80 orlOO days. At the end of fattening period of each level of treatment l8. 20 and 20 lambs were randomly selected and slaughtered. respectively. Due to the unequal number of observation in the subclasses, data were analyzed by the least-squares procedure. The length of fattening period had highly significant effect on final weight, but did not influence on daily weight gain. Age of dam and type of birth had not any significant effect on final weight and daily weight gain. Initial weight of single lambs was significantly higher than twin lambs. The effect of dam age on initial weight was significant. Lambs, which were slaughtered after fattening period 60 days, had significantly lighter carcass, meat and bone weight as compared to those that were fattening for 80 or 1 00 days. The means for cuts weights of shoulder, back, leg and flank+brisket were significantly higher among the lambs which slaughtered after 80 days in fattening period compared with those which were feedlot for 60 days, but between Iambs which were slaughtered after 80 and 100 days had not significant different, In conclusion, due to final weight, meat weight, carcass cuts weights and not any significant increase for fat-tail, 80 days length of fattening period for Lori-Bakhtiari are recommending.