Weight Grouping as an Animal Welfare Issue on Performance, Immunity and Meat Composition in Pigs

Animal welfare is an important issue for animal production which can affect the performance and meat composition as well. In our previous study, we observed that, weight grouping was effective for obtaining uniform carcass group with better carcass characteristics and animal welfare. For further detail research, present study was undertaken with an aim to investigate the impact of weight grouping on meat composition as a focus point and in general the growth performance and immunity of pigs. The treatment groups were 1) MW = a heterogeneous group of high and low weight pigs, 2) HW = a homogeneous group of high weight pigs and 3) LW = a homogeneous group of low weight pigs. Overall higher average daily gain was investigated in HW and LW (P <0.05), while tendency of feed intake was found higher in HW than MW (P <0.10). However, gain: feed ratio among the weight groups did not differ significantly (P >0.05). Behavioral aggression was found higher in MW compared to HW and LW (P <0.05). In addition, meat composition was not significantly affected by the weight grouping; however, crude fat content of HW and LW was lower than that of MW (P <0.05). There were observed no significant differences in serum immunoglobulin status among weight groups (P >0.05). Time required for marketing the pigs was lower for HW and LW in comparison to MW (P <0.05). Overall, uniform weight grouping of pigs might be applicable for obtaining uniform carcass groups with better productivity and animal welfare without having a long term negative impact on meat composition and immunity.