Study On Fattening Method And Effect Of High-quality Mutton Lambs

Seventy male, wether and female crossbred lambs of Borderdale(♂) × Mongolia sheep (♀), Poll Dorset(♂) × Mongolia sheep (♀) were selected to evaluate the fattening method and effect of high-quality mutton lambs. Local lambs(Mongolia lamb,♂) were selected as control group. Single factor design was adopted. (ⅰ) One feeding experiment was conducted using 10 of each crossbred lambs which were 5-month and 3-month old to compare the growing performance under barn feeding condition and grazing plus supplement feeding condition. Finally the economic benefits of each group were computed. The feeding period of two feeding model were 60 days and 30 days. (ⅱ) At the end of feeding experiment 5 crossbred lambs were selected to be slaughtered and carcass trait and mutton quality were measured, which included Amino Acid level, mineral element level, Pb level and As level. The main results were as follows:Ⅰ.Fattening experiment. (ⅰ) In barn feeding, average daily gain (ADG) in 5-minth old crossbred lambs group was 240 g/d and feed conversion ratio (FCR) was 2.7～3.8︰1, which were significant higher than those of local lambs(P﹤0.01), especially ADG of male Borderdale crossbred lambs and male Dorset crossbred lambs were 288 g/d and 285 g/d. 3-month old male Borderdale crossbred lambs and Dorset crossbred lambs` ADG were 317 g/d and 235 g/d, which were significant higher than those of other lambs(P﹤0.01), FCR averaged between 1.9～3.3︰1; In grazing plus supplement feeding, the ADG of 5-month old crossbred lambs (265 g/d) were significant higher than that of local ones(P﹤0.01), ADG of male Borderdale crossbred lambs were the highest l(300 g/d), and FCR was between 3.7～4.4︰1. ADG of 3-month old male crossbred lambs (Dorset male crossbred lambs are the highest, which were 317 g/d) were significant higher than that of local ones(P﹤0.01), FCR was between 2.7～3.9︰1. The results of this experiment showed that the growing performance of crossbredized combination such as B×M and D×M were excellent, crossbred lambs were better than local lambs, male crossbred lambs were better than female and wether ones. (ⅱ) Economic benefits : The average economic benefits of 5-month and 3-month old crossbred lamb in barn feeding and 60 d wer 74.30 Yuan per head and 85.30 Yuan per head, which were 276% and 133% higher than those of local lambs, which were 19.90 Yuan per head and 36.50 Yuan per head in the same rearing condition; In grazing plus supplement condition, the average economic benefits of crossbred lambs were 44.70 Yuan per head and 52.00 Yuan per head, which were 174% and 107% higher than that of local lambs . The ratio income to outcome in grazing plus supplement feeding group (1︰2.28 and 1︰2.93) was higher than barn feeding group (1︰2.08 and 1︰2.71). So we could draw the conclusion that crossbred lambs had better economic efficiency than local lambs group. As far as beginning fattening as was concerned, the economic benefits of fattening from 3-month old was higher than that from 5-minth old. As to fattening period, 60 days was better than 30 days.Ⅱ.Slaughter test. The carcass of crossbred lamb was plump, two rear legs looked like "U" when hung and the carcass grade was No.1 grade. Slaughter weight and carcass weight of Borderdale male crossbred lamb was the highest of all, which were 35.40 kg and 17.8 kg. The dressing percentage of crossbred lambs, net meat percentage, carcass net meat percentage, ratio of muscle to bone, area of longissimus doris and GR value of crossbred lambs were 50.12%, 39.27%, 79.19%, 1︰3.63, 11.18 cm2, and 9.15 mm respectively, which were all significant higher than that of local lamb in the same rearing condition(P﹤0.01).Ⅲ. Mutton quality. (ⅰ) Mutton color of crossbred was between 3～4 and that of local lambs was 4.5. Marbled strait of crossbred lamb was between 2～3, which showed the fat level between muscle fiber was more moderate than that of local lamb. The pH of mutton was in the normal range. And as to shear-force value, local lamb was higher than that of crossbred...