Effects Of Stocking Density On Growth Performance And Pancreas Function In Pigs

The intensive pig production model focuses on reducing costs and increasing profits,and often uses higher stocking densities.Pigs at higher stocking densities are often in a sub-health state and do not perform their best performance.The aim of this study was to investigate the effects of stocking density on growth performance,serum free amino acids,and pancreatic function in piglets and growing pigs.Experiment?:Effect of Stocking Density on Growth Performance and Serum Free Amino Acid of PigletsIn order to research the effect of stocking density on growth performance and serum free amino acids of the piglets,720(7.72±0.29 kg)crossbred barrows(Large White×Landrace)aged 28 days were randomly divided into 3 groups with 6 replicates in each group.The stocking densities of the 3 groups were 0.91 m~2/a pig in the control group,0.68 m~2/a pig in the high density group,and 0.55 m~2/a pig in the extremely high density group.The experiment period was 28 days.The results showed that the increasing in stocking density significantly reduced the ADG(P<0.05)and ADFI(P<0.05),increased F/G(P<0.05),and diarrhea rate has an increasing trend(0.05<P<0.1);With the increasing of stocking density,serum Ser,Arg and Met levels in piglets decreased significantly(P<0.05),serum Phe and Tyr had a decreasing trend(0.05<P<0.1).The results of the study showed that increasing the stocking density reduced the performance of piglets and reduced the free amino acids in the serum of piglets which are associated with metabolic processes and immune function.Experiment?:Effect of Stocking Density on Pancreatic Function of Growing PigsIn order to research the effects of stocking density on insulin secretion and pancreatic stress response,inflammatory response and secretion-related mRNA expression in growing pigs,288 heads of(Duroc×Landrace×Large)pigs with similar genetic background and similar body weight were selected.44.35±0.50 kg),randomly divided into three groups with different stocking densities:the experiment adopts the circle feeding mode,the housing area is 19.67m~2(length 5.2m*width 3.8m),each treatment is 6 repetitions,the test period is 30 d.The results showed that the stocking density significantly increased the insulin level in the serum of growing pigs(P<0.05).The expression of TRX,HSP90,Cas8,NF-?B and IL-1?in the growing pig pancreas increased with the increase of stocking density.The amount of PDX-1 mRNA,which regulates the secretion of insulin,decreased(P<0.05).The expression of NF-?B and IL-1?in the pancreas of the medium density group was significantly higher than the low density group(P<0.05).The results showed that the stocking density affected the insulin secretion level of growing pigs and affected the expression of stress,inflammation and secretory function-related mRNA and partial protein expression in growing pig pancreas.Experiment?:Effect of Stocking Density and Group Size on Growth Performance and Pancreatic Function of PigletIn order to reaserch the effects of stocking density and group size on growth performance,insulin secretion level,pancreatic stress response,inflammatory response and secretion function-related mRNA expression in piglets,198(Landrace×Large)piglets with similar genetic background and similar body weight were selected.(10.32±0.18kg),divided into 6 groups:A(4m~2,12 pigs,0.33m~2/a pig),B(4m~2,6 pigs,0.67m~2/a pig),C(4m~2,4 pigs,1m~2/a pig),D(2m~2,6 pigs,0.33m~2/a pig),E(2m~2,3 pigs,0.67m~2/a pig),F(2m~2,2 pigs,1m~2/a pig)test adopts the circle feeding mode,and there are two kinds of housing specifications.,2m~2 and 4m~2,6 replicates per treatment,the experiment period is 30 days.The results showed that the increase of stocking density significantly decreased the ADG,ADFI and insulin content of piglets(P<0.05),and the ADG and ADFI of piglets in the large group were significantly lower(P<0.05).The increase of stocking density significantly increased the insulin level in the serum of growing pigs(P<0.05).The expression of HSP90,Cas8,IL-1?and JNK-1 in the pancreas mRNA of piglets was significantly increased(P<0.05).The expression of PDX-1 mRNA,which regulates insulin secretion,was significantly decreased(P<0.05).The expression of NF-?B in piglet pancreas mRNA was significantly increased(P<0.05).The results showed that the stocking density affected the insulin secretion level of piglets and affected the expression of mRNA which related stress response,inflammation and secretory in the piglet pancreas.The effect of group size on the expression of these genes was not obvious.