饲养密度和玩具对育肥猪生产性能、行为和生理指标的影响

Effects of stocking density and toy provision on production performance,behavior and physiological indexes of finishing pigs

为研究饲养密度和玩具对育肥猪生产性能、行为和生理指标的影响及其交互作用,确定育肥阶段适宜饲养密度范围。该研究基于中国相关标准和生产实际,采用3×2双因素设计(3个饲养密度水平×有/无玩具),分别设置0.75、1.05和1.35 m^(2)/头密度水平,在各饲养密度水平下设置玩具组和空白组。结果表明,1.35 m^(2)/头饲养密度下,猪的日均质量增长量显著高于其他密度水平,料重比显著低于0.75 m^(2)/头组(P<0.05);随着密度升高,猪只在群体稳定期的躺卧和饮水时长减少,采食和其他行为时长增加(P<0.05),猪只体表温度、血清皮质醇和炎性细胞因子浓度均明显升高(P<0.05)。设置玩具能够增加猪只在圈栏内行为多样性,有效减少饮水消耗和异常行为(P<0.01),显著降低血清IgG和炎性细胞因子浓度(P<0.05),有利于增加采食量和质量增长。饲养密度和玩具在影响育肥猪耗水量、躺卧和采食行为上具有显著的交互作用(P<0.05)。基于试验结果和国内外研究分析,认为在提供福利设施条件下,1.05~1.35 m^(2)/头的密度范围在发挥育肥猪生产性能、提升福利水平和质量效益方面效果更优。

Stocking density and toy provision are the major measures widely-used to improve environmental enrichment for pig welfare farming.However,the specific interaction of stocking density and toy provision is still lacking.In this study,a 3×2 arrangement(three stocking density levels×with/without toys)was designed to explore the interaction of stocking density and toys on the production performance,behavior,and physiology indexes of finishing pigs,thereby determining a proper stocking density for the production with/without toy provision in China.A field experiment was conducted in a growing-finishing pig house in Chongqing City from September to November 2018.Stocking density was set at three levels of 0.75,1.05,and 1.35 m^(2)/pig.A total of 144 finishing pigs with an initial average body weight of 57.0±4.4kg were also randomly assigned into 12 pens with 12 pigs in each pen.Four chewing toys were suspended in each pen for the toy provision group.The results showed that the average daily gain(ADG)of finishing pigs with a 1.35 m^(2)/pig stocking density was 10.0%and 7.7%higher than that of 0.75 m^(2)/pig and 1.05 m^(2)/pig(P<0.05)in the groups without toy settings,whereas,the F/G(feed/gain)was 7.3%and 2.0%lower,respectively(P<0.05).Meanwhile,the average daily feed intake(ADFI)of pigs housed in 1.05 m^(2)/pig was lower than that of two stocking densities(P<0.05).Pigs spent less time on lying and drinking with the increase of stocking density,while more time on feeding and other behaviors when the groups stabilized(P<0.05).There was a significant increase in the surface temperature of the pig body,serum cortisol,and inflammatory cytokines concentrations(P<0.05).Toy provision inside pens enhanced the behavior diversity,while effectively decreased the water consumption and abnormal behaviors(P<0.01),where there was a significant decrease in the serum IgG and inflammatory cytokines concentration(P<0.05).The IL-1β,IL-6 and TNF-αconcentrations of pigs housed in 1.05 m^(2)/pig with toy provision at the 53rd day were 20.2%(P<0.01),23.2%(P<0.05)and 15.7%(P<0.05)higher than those without toys,respectively.Moreover,pigs with toy provision gained more weight and feed intake,especially at lower space allowance environment(0.75 m^(2)/pig).Consequently,a significant correlation was observed in the stocking density and toy provision on water consumption,lying,and feeding behaviors(P<0.05),indicating that the space occupation of toys inside the pen played an essential role to improve the welfare of finishing pigs.A relatively lower stocking density was beneficial to the weight gain,feed conversion,welfare,and health level of finishing pigs.Consequently,toy provision can meet the behavior expression needs of pigs,while greatly reduce the abnormal behaviors and stress levels in barren and crowded environments.In addition,it is relatively limited for better welfare finishing pig via enriching the pen environment and the space allowance in the commercial farming level.Therefore,stocking densities between 1.05 and 1.35 m^(2)/pig with toy provision can achieve better performance on the production,welfare,and efficiency under the various conditions for finishing pigs.