Effects Of Cross-fostering On Growth Performance, Digestive Enzyme Activities,Serum Parameters And Fat Metabolism Of Meishan And Large White Piglets

The prevalence of obesity in children and adults has increased dramatically over the past decade. Obesity is a chronic disease, which is result in cardiovascular disorder,type2diabetes and the occurrence of cancer. Interaction between genotype and environmental factors contributes to the appearance of obesity. Genetic plays a central role in the occurrence of obesity, it is reported that the heritability of obesity is estimated at40%to70%. Environmental factors like food intake and diet component also have influence on obesity. Most of the recent developments want to manipulate fat metabolism, to reduce body fat synthesis and storage and to increase fat oxidation, to reduce food intake, and to increase energy expenditure. Fat metabolism is a dynamic process between lipid synthesis and degradation, which is affected by genetic and environmental factors. Porcine is widely used in experiment as an important model for human nutrition. Large white is a high muscled, low fat breed, while Meishan is low muscle rate,high fat breed. Cross-fostering can be very useful technique for the life of rejected by parents or orphan infants, mainly in the case of species with low reproduction rate in capacity or those threatened by extinction, as well for investigating the environmental effects on the typical behavior of species. Under cross-fostering, the genotype of itself and maternal factors influence animal phenotype. This paper was conducted to compare the fat digestive enzyme activities,hormone levels,serum parameters, fat metabolism related enzyme activities and the relative expression of genes in Meishan and Large white piglets, furthermore to evaluate the effects of genetic and environmental factors on fat metabolism, to provide theory basis for regulation mechanism of fat metabolism.1Effects of cross-fostering on growth performance, digestive enzyme activities and serum parameters of Meishan and Large White pigletsIn order to investigate the effects of genotype and cross-fostering on the growth performance, nutrient digestibility and serum parameters of piglets, the average daily gain (ADG), digestive enzyme activities in jejunum and pancreas of Meishan and Large White piglets were determined. The results showed that genotype had a significantly influence on ADG of piglets (P<0.01), Large White piglets had a higher ADG than Meishan piglets from0to28d; Genotype, cross-fostering and their interaction significantly affected the digestive enzyme activities in jejunum and pancreas of piglets, they had influence on the pancreatic enzyme activities at the28d of age. The pancreatic amylase and protese activities of Meishan piglets were greater than Large White piglets; Genotype had a significantly influence on the digestive enzyme activities of piglets at the age of49days, the pancreatic lipase activities of Meishan piglets was higher than Large White, it is useful for fat digestion. Genotype and cross-fostering had no influence on the concentration of serum lipid. However, the effects of genotype were significant for the concentration of serum HDL (P<0.01), the HDL level of Large White was higher than Meishan piglets. Both genotype and cross-fostering had significant influence on serum urea levels of piglets (P<0.05) at the age of28days, non cross-fostered Meishan piglets had higher serum levels than fostered Meishan piglets (P<0.05), fostered Large White piglets also had higher urea levels than non cross-fostered Large White piglets (P<0.01). The effect of genotype and cross-fostering on the total protein concentration was significant (P<0.05), fostered Large White piglets had greater TP concentration than non cross-fostered Large White piglets(P<0.05). Meishan sows are of particular significance on the protein metabolism of piglets.2Effects of cross-fostering on fat metabolism related hormone levels and key enzyme activities of Meishan and Large White pigletsTo investigate the effects of genotype and cross-fostering on fat metabolism of piglets, the hormone levels and fat metabolism related enzyme activities were determined. The results showed that cross-fostering had a significantly influence on serum leptin level (P<0.01), fostered large white piglets had the highest leptin concentration. Interaction between genotype and cross-fostering significantly affected the insulin level of piglets at the28d of age (P<0.05). Both genotype and cross-fostering significantly affected the growth hormone level (P<0.05), the GH concentration of Large white piglets nursed by Large white sows was higher than fostered large white piglets and Meishan piglets. Genotype had a significantly influence on liver MDH activities at28d (P<0.05), while cross-fostering had a significantly influence on liver MDH activities at49d (P<0.05). Cross-fostering had a significantly influence on liver LPL activities at the age of28and49days. The LPL activities of Large white piglets reared by Large white sows was greater than fostered Large white piglets, fostered Meishan piglets was higher than Meishan piglets reared by Meishan sows at28d of age. There was no significant difference on liver HL activity at28and49d of age. The liver TL activities of Large white piglets was higher than fostered Large white piglets at28d (P<0.05). At49d, There was no difference on liver TL activity among the four groups, but the effects of interaction between genotype and cross-fostering was significant (P<0.05). Cross-fostering had a significantly influence on the activity of LPL in adipose tissue at28d of age (P<0.05), fostered Meishan piglets was higher than Meishan piglets nursed by Large white sows. Cross-fostering had a significantly influence on the activity of LPL in adipose tissue at49d of age (P<0.05), Large white piglets reared by Large white sows was higher than fostered Large white piglets. There was no difference among groups on HSL activities in adipose tissue. The results suggest that fostered Large white piglets had a higher lipid synthesis ability in liver under cross-fostering. The liver triglyceride utilization of Large white piglets nursed by Large white sows was enhanced; interaction between genotype and cross-fostering was contribute to a higher growth rate of Large white piglets.3Effects of cross-fostering on fat metabolism related genes expression of Meishan and Large White pigletsEffects of genotype on porcine fat deposition had been widely reported, while fat deposition was attributed to the interaction between genotype and environmental factors, combination genotype with environmental factors was a good approach to research fat deposition. We cross fostered piglets form sows of different breed at birth, through which we found out the effects of cross-fostering on the relative expression of lipid anabolism genes(Sterol regulatory element binding protein-1c, SREBP-1c; Fatty acid synthase, FAS; Acetyl-CoA carboxylase, ACC; Peroxisome proliferator-activated receptors gamma, PPARy) and catabolism genes (Peroxisome proliferator-activated receptors a, PPARa; Carnitine palmitoyltransferase-lb, CPT-1b; Hormone-sensitive lipase, HSL; Acyl-CoA oxidase, ACOX). The result showed that genotype and cross-fostering had no significantly influence on the relative expression of SREBP-1c, PPARa, PPARy, HSL, ApoB and CPT-lb in adipose tissue, and SREBP-1c,ACC,PPARy, ACOX, HSL, ApoB in liver. Cross-fostering had a significantly influence on the FAS expression (P<0.05), but there was no difference between group. Genotype had a significantly influence on the expression of ACC in adipose tissue (P<0.05), Meishan sows reared Meishan piglets was greater than Large white piglets. Interaction between genotype and cross-fostering had significantly influence on the expression of ACOX (P<0.05) in adipose tissue,Large white piglets nursed by Large white sows was higher in ACOX expression than fostered Meishan piglets. Interaction between genotype and cross-fostering was significant for the expression of FAS in liver (P<0.05), Meishan sows reared Meishan piglets was greater in liver FAS expression than fostered Large white piglets. Genotype had a significantly influence on PPARa expression (P<0.01), Meishan piglets was higher Large white piglets reared by the same Meishan sows. The expression of CPT-1b in liver was significantly influenced by genotype, but there was no difference between group. Genotype had a significantly influence on the expression of SREBP-lc and ApoB in longissimus dorsi muscle (P<0.05). Genotype and cross-fostering were important for fat metabolism. The results suggested that In transcriptional level, the expression of lipid synthesis and oxidation related genes in Meishan piglets was higher than Large white piglets, which was controlled by genotype; To be affected by interaction between genotype and cross-fostering, the expression of lipid oxidation genes in adipose tissue from Large white piglets was greater than Meishan piglets, while the expression of genes-related to lipid synthesis in liver from Meishan piglets was higher than Large white piglets.