维生素水平和不同饲养密度对生长猪生长性能、营养物质消化率和血液特性的影响

本研究旨在评估日粮中维生素水平和饲养密度对生长猪生长性能、营养物质消化率和血液特性的影响。试验采用2×3因子设计(2个维生素水平,3个饲养密度:0.38、0.48和0.65m^2/头)的方法,对720头平均体重为(23.16±0.92)kg的生长猪进行为期36d的饲养试验。基础日粮组维生素水平为正常水平,高水平维生素组维生素水平是正常日粮的2倍。结果 :1~18d随着饲养密度的增加,日增重和平均日采食量表现为显著线性降低(P <0.05),而饲养密度对饲料报酬的影响呈显著二次效应(P <0.05)。从第19~36天,随着饲养密度的增加,平均日采食量和饲料报酬也表现为显著线性降低(P <0.05)。在整个试验过程中(1~36d),随着饲养密度的增加,猪的日增重和平均日采食量呈线性下降(P <0.05)。在整个试验期,与对照组相比,高维生素组猪的饲料报酬显著降低了5%(P <0.05)。高维生素水平处理组显著降低干物质和氮表观消化率(P <0.05),且随着饲养密度的升高,氮表观消化率表现为显著线性降低(P <0.05)。在第18和36天,随着饲养密度的增加,皮质醇浓度表现为显著线性增加(P <0.05),同时高维生素日粮组皮质醇浓度显著降低(P <0.05)。随着饲养密度的升高,36d生长猪血液尿素氮含量和白细胞数量表现为显著线性降低(P <0.05)。此外,高维生素水平日粮较对照组显著降低了18和36d血液皮质醇浓度(P <0.05)。结论 :饲养密度过高会降低生长猪的日增重和采食量,额外补充维生素并没有改善高饲养密度对日增重的负面效应。

Effects of vitamin levels and different feeding densities on growth performance,nutrient digestibility and blood characteristics in growing pigs

The purpose of this study was to assess the effects of dietary vitamin levels and stocking density on growth performance,nutrient digestibility,and blood characteristics in growing pigs.Using a 2×3 factor design(2 vitamin levels,3 stocking densities:0.38,0.48,and 0.65 m2/head),720 growing pigs with an average body weight of(23.16±0.92)kg were fed for 36 days.Vitamin levels in the basal diet group were normal,while vitamin levels in the high vitamin group were twice as high.Results:daily weight gain and average daily feed intake decreased linearly with the increase of feeding density(P<0.05),while feeding density had a significant secondary effect on feed return(P<0.05).From the 19th to the 36th day,with the increase of feeding density,the average daily feed intake and feed remuneration also decreased linearly(P<0.05).During the whole experiment(1~36 days),daily weight gain and average daily feeding range of pigs decreased linearly with the increase of feeding density(P<0.05).During the whole trial period,the feed rewards of the high-vitamin group were significantly reduced by 5%compared with the control group(P<0.05).The apparent digestibility of dry matter and nitrogen decreased significantly in the high-vitamin group(P<0.05),and the apparent digestibility of nitrogen decreased linearly with the increase of feeding density(P<0.05).At the 18th and 36th day,with the increase of feeding density,cortisol concentration increased linearly significantly(P<0.05),while cortisol concentration in the high-vitamin diet group decreased significantly(P<0.05).With the increase of the feeding density,the blood urea nitrogen content and white blood cell count of the 36 d growth pigs decreased linearly significantly(P<0.05).In addition,the high-vitamin diet significantly reduced blood cortisol concentrations on days 18 and 36 compared with the control group(P<0.05).Conclusion:high feeding density can reduce the daily weight gain and feed intake of growing pigs,and additional vitamin supplementation does not improve the negative effect of high feeding density on daily weight gain.