Slaughter characteristics, carcass quality and fatty acid composition of lambs under four different production systems

Forty five Kivircik lambs were used to investigate the effects of production system on lamb performance, carcass quality characteristics and on fatty acid composition of longissimus dorsi muscle. W-C lambs (n = 12) were weaned between 45 and 60 days of age and then were finished with concentrates in the sheepfold until slaughter. During the finishing period, W-C lambs had free access to alfalfa hay and concentrate feed. W-G-S lambs (n = 10) were weaned between 45 and 60 days of age and then grazed on pasture for 96 days and then wheat stubble until slaughter. UW-C lambs (n = 11) were finished with ad libitum alfalfa hay and concentrate feed in the sheepfold and these lambs suckled their mothers until slaughter. Lambs of UW-G system (n = 12) were kept together with the main-flock and were grazed on pasture in the day-time. During the night, UW-G lambs suckled their mothers in sheepfold. Target slaughter weight was assumed as 30 kg. Mean finishing duration was 62 days, 147 days, 66 days and 98 days in lambs from W-C, W-G-S, UW-C and UW-G systems, respectively. Average daily gain during experiment was higher in W-C (207 g) and UW-C (197 g) lambs than W-G-S (87g) and UW-G lambs (131 g). Cold carcass weight was 13.18, 12.10, 14.03 and 13.49 kg, and cold dressing based on empty body weight was 53.45, 50.04, 56.45 and 53.82% in lambs from W-C, W-G-S, UW-C and UW-G systems, respectively. Carcass fatness parameters (omental and mesenteric fat percentage, back fat thickness, kidney knob and channel fat percentage and fat proportion in pelvic limb joint) in lambs of W-G-S system were lower than lambs in other production systems. W-G-S lambs also had higher lean proportion and lean/fat ratio in pelvic limb joint. UW-G lambs had lower carcass fatness and higher lean proportion in pelvic limb than lambs finished with concentrate feed (W-C and UW-C systems). Proportions of pelvic and thoracic limb joints were higher in grazed lambs than lambs of concentrate based systems. The proportion of fatty acids in intramuscular fat was similar across animals on all four feeding systems except for C14:0 and C18:0. The percentage of C14:0 was the highest in UW-C lambs while higher proportions of C18:0 were found in intramuscular fat of W-G-S lambs than those of weaned lambs fed concentrate and unweaned lambs. As a conclusion, weaning at 45-60 days of age for lambs fed concentrate in sheepfold should be considered by farmers, who aim to get ewe milk as an additional product without any disadvantages in lamb growth performance and carcass quality. Indigent farmers, who prefer the use of natural grasslands to produce high quality lamb carcasses, might consider pasture feeding with mother's milk without concentrate feed cost. (c) 2013 Elsevier B.V. All rights reserved