Birth weight alters the response to postnatal high-fat diet-induced changes in meat quality traits and skeletal muscle proteome of pigs

Muscle Fiber, Connective Tissue and Meat Quality Characteristics of Pork from Low Birth Weight Pigs as Affected by Diet-Induced Increased Fat Absorption and Preferential Muscle Marbling

This study investigated how birth weight differences in piglets affected carcass and muscle fiber properties as well as meat quality at slaughter. Within litters, piglets were grouped according to their birth weight as either normal (NBW; 1.62-1.73 kg) or low (LBW; 1.18-1.29 kg). At 5 weeks of age, NBW piglets were randomly transitioned to control (C) or isocaloric high fat diets derived from non-dairy (HF), while LBW piglets were randomly transitioned to high fat diets derived from non-dairy (HF) or dairy sources (HFHD). Piglets were reared in individual pens under standardized housing and feeding conditions. Live weight was recorded weekly, and pigs were slaughtered at 12 weeks of age. Hot carcass weights, dressing percentages, lean meat yield, and primal cut proportions were determined. The m. longissimus thoracis was collected from the right side of the carcass for measurement of physical and chemical properties of meat and muscle fiber characteristics. Results indicated that LBW pigs compensated for their live weight compared to NBW pigs at 6 weeks of age. The mean muscle fiber diameter of LBW-HFHD group is significantly higher than NBW-C and NBW-HF group, and the type I muscle fiber diameter is significantly higher than NBW-C group. Dairy fat inclusion in LBW pig diet reduced carcass back fat thickness. This increased the calculated lean meat yield to be comparable to that of NBW pigs fed a commercial diet. Incorporating dairy-sourced high-fat into LBW pigs' diets appears to be an effective strategy for producing carcasses equivalent to NBW pigs.

Reduced Meal Frequency Decreases Fat Deposition and Improves Feed Efficiency of Growing-Finishing Pigs

An experiment was conducted to examine the effect of meal frequency on growth performance, nutrient digestibility, carcass quality, and lipid metabolism in growing−finishing pigs. Sixty-four Duroc × Landrace × Yorkshire barrows and gilts (26.40 ± 2.10 kg initial body weight) were used in a 112-d experiment in a randomized complete blocked design. The two treatments were the free-access feed group (FA) and the three meals per day group (M3), respectively. The result showed that the average daily feed intake (ADFI) and F: G of the FA group were significantly higher than that in the M3 group during the whole experiment (p < 0.05). Reducing meal frequency also decreased the concentration of triglycerides and urea nitrogen but increased the concentration of insulin and free fatty acids in the blood (p < 0.05). Reducing meal frequency decreased compositions of backfat, belly, and fatty pieces but increased compositions of ham, longissimus muscle, and lean pieces in the carcass (p < 0.05). Greater enzyme activities of ME and FAS and higher mRNA expression of FAS and PPARγ were found in the LM of FA pigs compared with M3 pigs (p < 0.05). In summary, a lower meal frequency improves feed efficiency by regulating lipid metabolism and reducing fat deposition.

Comparative study of weaning pigs' muscle proteins using two-dimensional electrophoresis

The proteostasis system of animals, including various types of protein modification during the growth stage, leads to an almost incomprehensible number of possible forms of protein, and each can regulate numerous functions. In the presented work, the composition of muscle tissue protein from different portions of piglets was studied to understand the main muscle protein formation. Comparative analysis of weaned piglets' main muscle protein from l. dorsi, biceps femoris, and brachiocephalicus were analyzed using two-dimensional electrophoresis. Changes in the staining intensity of protein fractions inherent in different muscles were revealed. As part of this work, candidate groups of pig muscle proteins have been selected. Eleven protein spots were revealed for the longest muscle of the back, and seven for the biceps; the muscles of the neck are characterized by indicators of low protein fraction volume. Among the proteins found, myosin light chains, phosphoglycerate mutase, troponins, and adenylate kinase is most likely present. The obtained results of protein identification in muscle tissues, obtained during the intensive growth period, will allow a more detailed understanding of protein regulation, function, and interactions in complex biological systems, which will subsequently be significantly important for biomonitoring health and predicting farm animals productivity.

Resveratrol improves meat quality, muscular antioxidant capacity, lipid metabolism and fiber type composition of intrauterine growth retarded pigs

This study investigated whether resveratrol could improve meat quality, muscular antioxidant capacity, lipid metabolism and fiber type composition of intrauterine growth retarded pigs. Thirty-six pairs of male normal birth weight and intrauterine growth retardation (IUGR) piglets were orally fed with 80 mg resveratrol/kg body weight/d or vehicle during the sucking period (7-21 d). Then the offspring were fed with a basal diet containing 300 mg resveratrol/kg or a basal diet from weaning to slaughter (150 d). The IUGR-impaired meat quality (luminance and yellowness) was associated with muscular oxidative stress via increased Keap1 protein level, fat accumulation, and higher MyHC IIb gene expression. Expectedly, resveratrol increased glutathione peroxidase activity and MyHC I gene expression, reduced protein carbonyl and malondialdehyde contents, enhanced fatty acid oxidation via upregulated PPARα and targeted genes expression, and thereby improving drip loss and yellowness. Results indicate that resveratrol improved meat quality of IUGR pigs through enhancing antioxidant capacity, increasing oxidative fiber composition, and suppressing lipid accumulation.

Effects of Birth Weight and Postnatal Nutritional Restriction on Skeletal Muscle Development, Myofiber Maturation, and Metabolic Status of Early-Weaned Piglets

Piglets with light weaning weight commonly have a slow post-weaning growth rate due to impaired skeletal muscle development. Therefore, the present study aimed to investigate the impact of birth weight and nutrient intake on skeletal muscle development, myofiber maturation, and metabolic status of early-weaned piglets. Twelve pairs of normal birth weight and intrauterine growth-retarded (IUGR) piglets (seven days old) were randomly assigned to receive adequate nutrient intake or restricted nutrient intake for 21 days. Serum and muscle samples were collected for further analysis. The results indicated that muscle weight, cross-sectional areas, and muscular glycogen were lower (p < 0.05) in both IUGR and restricted fed piglets. Nutrient restriction decreased the contents of RNA, the RNA to DNA ratio, and the percentages of myosin heavy chain (MyHC) IIx (p < 0.05), whereas increased the activity of β-hydroxy-acyl-CoA-dehydrogenase (HAD), the ratio of HAD to citrate synthase, as well as the percentages of MyHC I (p < 0.05). In addition, nutrient restriction significantly decreased muscular glycogen, mRNA levels of fatty acid transport protein 1, cationic amino acid transporter 1, and glucose transporter 4 in IUGR piglets compared with the other groups (p < 0.05). The results of the present study showed that IUGR impaired skeletal muscle growth and disturbed the hormone and mRNA expression of genes related to energy metabolism, which led to a more severe energy deficit when receiving postnatal nutritional restriction. Postnatal nutritional restriction resulted in delayed myofiber maturation of the piglets, which may be associated with the transformation of MyHC isoform and the change of metabolic status.

Establishing a model for childhood obesity in adolescent pigs

OBJECTIVE

Rising worldwide prevalence of obesity and metabolic diseases in children has accentuated the importance of developing prevention and management strategies. The objective of this study was to establish a model for childhood obesity using high-fat feeding of adolescent pigs, as pigs have a longer developmental period and are physiologically more similar to humans than rodents.

METHODS

Crossbred pigs were fed a high-fat diet (HFD) or low-fat diet (n = 6/treatment) from postnatal day 49 to 84. On postnatal day 84, an oral glucose tolerance test was performed, jugular blood sampled to determine lipopolysaccharide levels and plasma lipids, intestinal digesta collected to characterize microbial and metabolite composition and back fat and intestinal tissue assayed for gene expression.

RESULTS

Five-week HFD increased weight gain and back fat thickness, caused dyslipidaemia and impaired glucose tolerance and increased expression of genes in back fat suggesting inflammation. HFD pigs had distinct proximal colon microbiota with 48% reduction (P < 0.05) in Bacteroidetes and increased expression of pro-inflammatory genes interleukin-18 and tumour necrosis factor in ileum (P < 0.05).

CONCLUSIONS

These findings indicate that adolescent pigs should be considered a suitable model for childhood obesity, because short-term HFD feeding is sufficient to induce obesity and glucose intolerance, recapitulating disease characteristics in adolescent pigs.

Off to the right start: how pregnancy and early life can determine future animal health and production

Animal producers are well aware that a low-birthweight animal is more likely to die in the first few days of life, and, if it survives, it is likely to perform poorly. We are now coming to appreciate that early life events can permanently change an animal’s developmental trajectory, also often referred to as developmental programming. This is an area of current interest in biomedicine, where the concept is known as the ‘developmental origins of health and disease’ (DOHaD). Current gaps in understanding include many of the underlying mechanisms, and whether and how we might intervene and restore the potential for healthy and productive development. This review introduces the biomedical perspective of developmental programming, reviews some of the evidence for long-term effects of early life exposures on welfare and productivity in animal production, with a focus on prenatal growth and maternal stress in pig production, and discusses options for intervening to improve long-term outcomes.

Effects of feeding frequency on meat quality traits and Longissimus muscle proteome in finishing pigs

Sixty-four barrows with an initial body weight of 59.8 ± 2.1 kg were allocated to one of the two feeding frequency regimes (had free access to diet and fed two meals per day). Pigs had free access (FA) to feed were fed on an ad libitum basis during the 8-week experimental period. Pigs fed twice daily (M2) were allowed to consume their meals in 2 h. Pigs fed twice daily had lower average daily feed intake (p < 0.01) and average daily gain (p < 0.1), but a greater G:F (p < 0.05) than FA pigs. Lower perirenal fat deposition, hot carcass weight, intramuscular fat content (p < 0.05) and dressing percentage (p < 0.1) were found in M2 pigs compared with FA pigs. Activities of citrate synthase, β-hydroxylacyl-CoA dehydrogenase and lactate dehydrogenase were greater in the Longissimus muscle (LM) of M2 pigs compared with FA pigs (p < 0.05). Proteomic analysis revealed that expression abundances of proteins involved in glucose metabolism, energy production and lipid utilization were upregulated, but expression levels of proteins participating in protein and amino acid metabolism, stress response and redox homeostasis were downregulated in the LM of M2 pigs than those in FA pigs (p < 0.05). In conclusion, the less meal frequency impairs growth rate, has marginal effects on carcass and meat quality traits and affects expression abundances of proteins in the LM of finishing pigs.

Nutrient-intake-level-dependent regulation of intestinal development in newborn intrauterine growth-restricted piglets via glucagon-like peptide-2

The objective of the present study was to investigate the intestinal development of newborn intrauterine growth-restricted (IUGR) piglets subjected to normal nutrient intake (NNI) or restricted nutrient intake (RNI). Newborn normal birth weight (NBW) and IUGR piglets were allotted to NNI or RNI levels for 4 weeks from day 8 postnatal. IUGR piglets receiving NNI had similar growth performance compared with that of NBW piglets. Small intestine length and villous height were greater in IUGR piglets fed the NNI than that of piglets fed the RNI. Lactase activity was increased in piglets fed the NNI compared with piglets fed the RNI. Absorptive function, represented by active glucose transport by the Ussing chamber method and messenger RNA (mRNA) expressions of two main intestinal glucose transporters, Na+-dependent glucose transporter 1 (SGLT1) and glucose transporter 2 (GLUT2), were greater in IUGR piglets fed the NNI compared with piglets fed the RNI regimen. The apoptotic process, characterized by caspase-3 activity (a sign of activated apoptotic cells) and mRNA expressions of p53 (pro-apoptotic), bcl-2-like protein 4 (Bax) (pro-apoptotic) and B-cell lymphoma-2 (Bcl-2) (anti-apoptotic), were improved in IUGR piglets fed the NNI regimen. To test the hypothesis that improvements in intestinal development of IUGR piglets fed NNI might be mediated through circulating glucagon-like peptide-2 (GLP-2), GLP-2 was injected subcutaneously to IUGR piglets fed the RNI from day 8 to day 15 postnatal. Although the intestinal development of IUGR piglets fed the RNI regimen was suppressed compared with those fed the NNI regimen, an exogenous injection of GLP-2 was able to bring intestinal development to similar levels as NNI-fed IUGR piglets. Collectively, our results demonstrate that IUGR neonates that have NNI levels could improve intestinal function via the regulation of GLP-2.

Proteomics in food: Quality, safety, microbes, and allergens

Food safety and quality and their associated risks pose a major concern worldwide regarding not only the relative economical losses but also the potential danger to consumer's health. Customer's confidence in the integrity of the food supply could be hampered by inappropriate food safety measures. A lack of measures and reliable assays to evaluate and maintain a good control of food characteristics may affect the food industry economy and shatter consumer confidence. It is imperative to create and to establish fast and reliable analytical methods that allow a good and rapid analysis of food products during the whole food chain. Proteomics can represent a powerful tool to address this issue, due to its proven excellent quantitative and qualitative drawbacks in protein analysis. This review illustrates the applications of proteomics in the past few years in food science focusing on food of animal origin with some brief hints on other types. Aim of this review is to highlight the importance of this science as a valuable tool to assess food quality and safety. Emphasis is also posed in food processing, allergies, and possible contaminants like bacteria, fungi, and other pathogens.

iTRAQ-based proteomic analysis reveals alterations in the liver induced by restricted meal frequency in a pig model

OBJECTIVE

The present study was conducted to investigate the effects of meal frequency on metabolite levels in pig plasma and hepatic proteome by isobaric tags for relative and absolute quantitation (iTRAQ) analysis.

METHODS

Twenty-four pigs (60.7 ± 1.0 kg) consumed the same amount of feed either in 2 (M2, n = 12) or 12 (M12, n = 12) meals per day. After an 8-wk feeding period, plasma concentrations of metabolites and hormones, hepatic biochemical traits, and proteome (n = 4 per group) were measured.

RESULTS

Pigs on the M12 regimen had lower average daily gain and gain-to-feed ratio than pigs fed the M2 regimen. The M2 regimen resulted in lower total lipid, glycogen, and triacylglycerol content in the liver and circulating triacylglycerol concentration than that in the M12 pigs. The metabolic hormone concentrations were not affected by meal frequency, with the exception of elevated fibroblast growth factor 21 concentrations in the M2 regimen compared with the M12 regimen. The iTRAQ-based proteomic analysis revealed 35 differentially expressed proteins in the liver between pigs fed two and 12 meals per day, and these differentially expressed proteins were involved in the regulation of general biological process such as glucose and energy metabolism, lipid metabolism, protein and amino acid metabolism, stress response, and cell redox homeostasis.

CONCLUSION

Altogether, the proteomic results provide insights into the mechanism mediating the beneficial effects of restricted meal frequency on the metabolic fitness.

Postnatal high-fat diet enhances ectopic fat deposition in pigs with intrauterine growth retardation

OBJECTIVES

Intrauterine growth retardation (IUGR) and postnatal nutrition are risk factors for adult metabolic syndrome. However, the influences of long-term high-fat diet (HFD) intake on ectopic fat deposition in non-adipose tissues in IUGR pigs remain unclear. The present study was to determine whether HFD consumption would enhance ectopic fat deposition in IUGR pigs.

METHODS

At day 28, IUGR and control pigs were fed ad libitum to either a regular diet or a HFD. Lipid store, enzymatic activities and mRNA expression of lipid metabolism-related factors in liver and semitendinosus muscle (SM) were quantified at postnatal day 178.

RESULTS

Feeding a HFD to IUGR pigs but not to control pigs significantly increased daily weight gain, carcass fat mass, plasma leptin level and lipid content and lipoprotein lipase (LPL) activity and mRNA abundances of LPL and peroxisome proliferator-activated receptor gamma (PPARγ) in liver and SM, but decreased daily feed intake and mRNA expression of hormone-sensitive lipase (LIPE) and carnitine palmitoyl transferase-1 (CPT-1) in liver and SM (P < 0.05). Compared with control pigs, IUGR pigs had a lower body weight but higher plasma levels of total cholesterol (TC) and insulin (P < 0.05). HFD-fed pigs exhibited greater body weight, plasma concentrations of triglyceride (TG), high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C), regardless of birth weight (P < 0.05).

CONCLUSION

Our results suggested that IUGR increased the vulnerability of HFD-fed pigs to ectopic fat deposition via enhanced fatty acid flux toward ectopic sites and reduced lipolysis and fatty acid oxidation.

iTRAQ-based quantitative proteomic analysis of longissimus muscle from growing pigs with dietary supplementation of non-starch polysaccharide enzymes

Non-starch polysaccharide enzymes (NSPEs) have long been used in the feed production of monogastric animals to degrade non-starch polysaccharide to oligosaccharides and promote growth performance. However, few studies have been conducted on the effect of such enzymes on skeletal muscle in monogastric animals. To elucidate the mechanism of the effect of NSPEs on skeletal muscle, an isobaric tag for relative and absolute quantification (iTRAQ) for differential proteomic quantitation was applied to investigate alterations in the proteome in the longissimus muscle (LM) of growing pigs after a 50-d period of supplementation with 0.6% NSPEs in the diet. A total of 51 proteins were found to be differentially expressed in the LM between a control group and the NSPE group. Functional analysis of the differentially expressed protein species showed an increased abundance of proteins related to energy production, protein synthesis, muscular differentiation, immunity, oxidation resistance and detoxification, and a decreased abundance of proteins related to inflammation in the LM of the pigs fed NSPEs. These findings have important implications for understanding the mechanisms whereby dietary supplementation with NSPEs enzymes can promote growth performance and improve muscular metabolism in growing pigs.