The Effects Of Dietary Energy Density On Fatty Deposition-related Indices In Adipose Tissues Of Finishing Swine

This study was conducted to investigate the effects of dietary energy density ongrowth performance, carcass quality, plasma lipid profile, morphofunctional aspects,NADPH-generating enzyme activity and the expression of peroxisomeproliferator-activated receptorγ(PPARγ) in adipose tissue of finishing pigs. Thirtyfinishingfemalepigs(Duroc×LargeWhite×Landrace,averageinitialBWof42.6±1.7kg)were givenfreeaccess tolow-energydensity(LD)diet,medium-energydensity(MD)diet,or high-energydensity(HD) diet. The digestible energy (DE) of the three diets was 12.82,14.24 and 15.66 MJ/kg, respectively. On 61 d, blood samples were collected, and then 15pigs were sacrificed to collect the dorsal subcutaneous (ST), abdominal (AT), mesenteric(MT) adipose tissues. The results showed that: 1) Average daily feed intake was increasedsignificantlyin LD as compared with MD, and average daily gain was decreased in LD ascompared with in HD (P<0.05), respectively. Feed/gain ratio was decreased with theincrease of dietary energy density (P<0.05). There was no significant effect of dietaryenergy density on total digestible energy intake and some carcass characteristics. 2) TheLD pigs had a lower plasma glucose and a higher triglyceride (TG) than MD and HD pigs(P<0.05). There was no significant effect of dietary energy density on plasma totalcholesterol (TC), low densitylipoprotein cholesterol (LDL-C) and high densitylipoproteincholesterol (HDL-C). However, the LD pigs had a higher LDL/HDL than HD pigs(P<0.05). 3) Compared to MD group, malate dehydrogenase activity was significantlyincreasedinSTandMTofHDgroup(P<0.05),whilewassignificantlydecreasedinMTofLD group (P<0.05). Compared to the MD pigs, glucose-6-phosphate dehydrogenaseactivity was increased in all three depots of HD pigs (P<0.05). 4) Compared to LD, pigsfed HD had a greater adipocyte size in ST (area and volume, P<0.05). However, Both HDand LDdiets increasedtheadipocytesize(adipocytediameter,areaandvolume)inATandMT (P<0.05). 5 Pigs fed HD had greater cell proliferation index in ST compared to theother two feeding groups (P<0.05). Compared to MD pigs, a decreased apoptosis indexwas seen in ST of HD pigs, and in AT of LD pigs (P<0.05), and both HD and LD dietsreducedapoptosisindexinMT(P<0.05).6)PPARγ-positivepercentagewaselevatedinSTandMTofHDpigs comparedtoMDpigs and LDpigs (P<0.05),whiledecreasedinSTofLDpigscomparedtoMDpigs(P<0.05).These results suggest that dietary energy density could regulate fat deposition infinishing pigs. It is possible that high energy diet may induce fat deposition viaup-regulatingPPARγexpression.