Effect of different weaning ages on growth performance, carcass components and long bone characteristics in dorper lambs

This trial was conducted at MARDI Research Station, Muadzam Shah, Pahang for 10 months from March 2015 to February 2016. The objectives of this experiment were (i) to investigate the dietary intake and growth performance of lamb before and after weaning at different durations, (ii) to investigate the nutrient digestibility of lamb before and after weaning and (iii) to investigate the effects of weaning age on carcass components and long bone characteristics. A total of 27 newborn male Dorper sheeps (average body weight, 3.06±0.74kg) were selected randomly and divided into three groups. Animals in group 1 (n=9) were weaned at day 30, while animals in group 2 (n=9) and 3 (n=9) were weaned at day 60 and 90, respectively. Group 3 was acted as a control group. Creep feeds were given to the respective groups of lambs before weaning at the above dates while growing feeds were given after weaning. The amount of feed given was based on 3.5% of the animal mean body weight. During the pre-weaning stage, the highest average daily gain (ADG) was 0.205kg/day in group 3 as compared to other groups. Higher feed conversion ratio (FCR) was also recorded for group 1 as compared to other groups. Group 3 showed the highest level of DMI while the highest percentage of dry matter, crude protein (CP), crude fibre (CF), ash and phosphorus (P) digestibility were 94.9±2.7%, 77.9±12.3%, 95.0±4.2%, 92.3±1.9% and 91.1±3.2%, respectively in group 1. The highest percentage of ether extract (EE) digestibility was 39.4±3.6% in group 2 while group 3 recorded the highest percentage of calcium (Ca) and nitrogen-free extract (NFE) digestibility with the values of 62.7±8.1% and 80.7±3.1%, respectively. However, no significant differences (P<0.05) were observed in growth performance and nutrient digestibility between the treatment groups during the pre-weaning stage. During the post-weaning stage, group 3 showed better performance in ADG (0.139kg/day) and DMI (0.898kg/day). Meanwhile, better FCR (4.762kg feed/kg weight gain) recorded in group 1 as compared to other groups. Group 3 also recorded the heaviest weight at 9 month of age as compared to other groups. In term of apparent nutrient digestibility, the highest percentage of dry matter, CP, P and NFE were obtained in group 3 as compared to other groups but no significant differences were observed in these parameters between the treatment groups. The dressing percentage was the highest in group 2 even though the heaviest live weight was observed in group 3. However, the meat to bone ratio was higher in group 3. The weight of carcass also indicated the smallest differences between the groups. No significant difference was observed between the groups in the carcass evaluation. There were no significant differences (P<0.05) between treatments in length, breadth of mineralized bone (BOMB), area of mineralized bone (AOMB) and volume of mineralized bone (VOMB) of tibia, femur and humerus, however a significant difference in cortical bone index (CBI) of tibia was found between group 2 and group 3. From this experiment, it can be concluded that Dorper lambs can be weaned as early as 2 month of age to maximise the farm production.