Differential expression of lipid metabolism-related genes and myosin heavy chain isoform genes in pig muscle tissue leading to different meat quality

The aim of this study was to investigate the variations in meat quality, lipid metabolism-related genes, myosin heavy chain (MyHC) isoform genes and peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α) gene mRNA expressions in longissimus dorsi muscle (LM) of two different pig breeds. Six Rongchang and six Landrace barrows were slaughtered at 161 days of age. Subsequently, meat quality traits and gene expression levels in LM were observed. Results showed that Rongchang pigs not only exhibited greater pH, CIE a*_{24 h} and intramuscular fat content but also exhibited lower body weight, carcass weight, dressing percentage, LM area and CIE b*_{24 h} compared with Landrace pigs (P<0.05). Meanwhile, the mRNA expression levels of the lipogenesis (peroxisome proliferator-activated receptor gamma, acetyl-CoA carboxylase and fatty acid synthase) and fatty acid uptake (lipoprotein lipase)-related genes were greater in the Rongchang (P<0.05), whereas the lipolysis (adipose triglyceride lipase and hormone sensitive lipase) and fatty acid oxidation (carnitine palmitoyltransferase-1B)-related genes were better expressed in the Landrace. Moreover, compared with the Landrace, the mRNA expression levels of MyHCI, MyHCIIa and MyHCIIx were greater, whereas the mRNA expression levels of MyHCIIb were lower in the Rongchang pigs (P<0.05). In addition, the mRNA expression levels of PGC-1α were greater in Rongchang pigs than in the Landrace (P<0.05), which can partly explain the differences in MyHC isoform gene expressions between Rongchang and Landrace pigs. Although the small number of samples does not allow to obtain a definitive conclusion, we can suggest that Rongchang pigs possess better meat quality, and the underlying molecular mechanisms responsible for the better meat quality in fatty pigs may be partly due to the higher mRNA expression levels of lipogenesis and fatty acid uptake-related genes, as well as the oxidative and intermediate muscle fibers, and due to the lower mRNA expression levels of lipolysis and fatty acid oxidation-related genes, as well as the glycolytic muscle fibers.     

Protein retention,growth performance and carcass traits of individually housed immunocastrated male- and female- and surgically castrated male Iberian pigs fed diets of increasing amino acid concentration

Immunocastration (IC, vaccination against gonadotropin releasing hormone (GnRH)) is one alternative to surgical castration (SC) for preventing sexual development and boar taint in male pigs. A temporal increase in performance has been described for IC pigs before the second vaccination against GnRH. The objective of this work was to assess the effects of IC on Iberian male and female pigs (fed diets of increasing CP content) on performance, nitrogen retention (NR) and digestibility, and carcass traits. Fifty-four pure Iberian pigs individually housed were allocated to a 3 × 3 factorial arrangement with three sex groups (IC males, IC females and SC males), three diets (153, 137 and 119 g CP/kg DM; 14 MJ metabolisable energy/kg DM) and six pigs per treatment combination. Pigs were vaccinated at 18 weeks of age (40 kg BW) and seven weeks later (70–80 kg BW) and fed at 0.9 × ad libitum on BW basis. Two digestibility and nitrogen balance assays were performed before and after the second vaccination, respectively. Pigs were slaughtered at 105 kg BW. Before the second vaccination, Iberian IC males showed higher growth rate (g/day), feed efficiency, NR (g/day) and efficiency of NR than the other groups (P < 0.001). The NR and efficiency of NR was 40% greater in IC v. SC males (P < 0.001). After the second vaccination, no differences in performance between sex groups were detected (P > 0.05). Growth rate and feed efficiency were higher in IC males than in the other groups for the whole experimental period (from the first vaccination to slaughter; P < 0.001). After the second vaccination, differences among sex groups in NR and the efficiency of NR disappeared (P > 0.05). NR efficiency was 0.177 on average. No significant effects of dietary CP were detected on performance. The NR was greater in pigs fed the 153 CP diet (17 to 37%; P > 0.05). Lean components of carcass (sirloin, loin and butt lean) were greater in IC males than in the other groups (0.001 < P < 0.05). There were no significant sex group × dietary CP interactions. Iberian IC males grew at higher rate, deposited more protein, and more efficiently, than Iberian SC males before the second vaccination against GnRH. Iberian IC females showed similar growth performance to SC males and intermediate protein deposition efficiency between IC and SC males. Despite the higher growth performance, protein deposition rate, and efficiency of protein deposition of IC males v. SC males, no significant differences in amino acid requirements were detected between them.     

Conjugated linoleic acid and betaine affect lipolysis in pig adipose tissue explants

Consumers’ demand of leaner meat products is a challenge. Although betaine and conjugated linoleic acid (CLA) have the potential to decrease porcine adipose tissue, their mode of action is poorly understood. The aim of the study was to determine the lipolytic effect of betaine and CLA in the adipose tissue of Iberian pigs. Adipose tissue explants from five pigs (38 kg BW) were prepared from dorsal subcutaneous adipose tissue samples and cultivated for 2 h (acute experiments) or 72 h (chronic experiments). Treatments included 100 µM linoleic acid (control), 100 µM trans-10, cis-12 CLA, 100 µM linoleic acid + 1 mM betaine and 100 µM trans-10, cis-12 CLA + 1 mM betaine (CLABET). To examine the ability of betaine or CLA to inhibit insulin’s suppression of isoproterenol-stimulated lipolysis, test medium was amended with 1 µM isoproterenol ±10 nM insulin. Media glycerol was measured at the end of the incubations. Acute lipolysis (2 h) was increased by CLA and CLABET (85% to 121%; P < 0.05) under basal conditions. When lipolysis was stimulated with isoproterenol (1090%), acute exposure to betaine tended to increase (13%; P = 0.071), while CLA and CLABET increased (14% to 18%; P < 0.05) isoproterenol-stimulated lipolysis compared with control. When insulin was added to isoproterenol-stimulated explants, lipolytic rate was decreased by 50% (P < 0.001). However, supplementation of betaine to the insulin + isoproterenol-containing medium tended to increase (P = 0.07), while CLABET increased (45%; P < 0.05) lipolysis, partly counteracting insulin inhibition. When culture was extended for 72 h, CLA decreased lipolysis under basal conditions (18%; P < 0.05) with no effect of betaine and CLABET (P > 0.10). When lipolysis was stimulated by isoproterenol (125% increase in rate compared with basal), CLA and CLABET decreased glycerol release (27%; P < 0.001) compared with control (isoproterenol alone). When insulin was added to isoproterenol-stimulated explants, isoproterenol stimulation of lipolysis was completely blunted and neither betaine nor CLA altered the inhibitory effect of insulin on lipolysis. Isoproterenol, and especially isoproterenol + insulin, stimulated leptin secretion compared with basal conditions (68% and 464%, respectively; P < 0.001), with no effect of CLA or betaine (P > 0.10). CLA decreased leptin release (25%; P < 0.001) when insulin was present in the media, partially inhibiting insulin stimulation of leptin release. In conclusion, betaine and CLA produced a biphasic response regarding lipolysis so that glycerol release was increased in acute conditions, while CLA decreased glycerol release and betaine had no effect in chronic conditions. Furthermore, CLA and CLABET indirectly increased lipolysis by reducing insulin-mediated inhibition of lipolysis during acute conditions.     

Evolution of the fatty acid profile of subcutaneous back-fat adipose tissue in growing Iberian and Landrace × Large White pigs

The lipid content and fatty acid (FA) profile in pig tissues are strongly influenced by genotype and nutrient supply, with implications in meat quality. The de novo lipid synthesis and pattern of FA unsaturation could be an important cause of variation in the overall efficiency of energy utilization among breeds. To test the effects of pig genotype and CP supply on the evolution of back-fat tissue FA profile throughout the growing and finishing stages, 32 Iberian (IB) and Landrace × Large White (LR × LW) barrows were offered one of two diets differing in CP content (13% or 17% as fed). A pair-fed procedure (0.8 × ad libitum intake of IB pigs) was used. Subcutaneous fat samples were taken at the dorso-lumbar region at ∼38, 50, 65, 90 and 115 kg BW. Higher proportions of total monounsaturated FA (MUFA; P < 0.01) and lower proportions of total saturated FA (SFA; P < 0.01 to 0.05) were found in the outer back-fat layer of pigs both at 50 and 115 kg BW. Pig genotype affected the FA composition of both subcutaneous back-fat layers. The proportions of C18:0 and SFA in fat tissue were higher in IB than in LR × LW pigs from 38 to 65 kg BW, especially in the outer layer. In addition, MUFA contents were higher in IB pigs at 115 kg BW in both layers (+5% on average; P < 0.01). Increased proportions of C18:2 n-6 and polyunsaturated FA (PUFA) were found in LR × LW pigs, irrespective of the stage of growth and back-fat layer (P⩽0.02). At 50 kg BW, pigs receiving the high-protein diet presented the highest C18:2 n-6, C18:3 n-3, C20:5 n-3 and PUFA contents. A significant genotype × CP content interaction was observed for C18:3 n-3 because of the increased concentration of this FA in LR × LW pigs when offered the 17% CP diet (P < 0.05). Higher C16:0 and SFA contents (+5%; P = 0.03) were found in pigs offered the 13% CP diet and slaughtered at 115 kg BW. There was a genotype × CP interaction for MUFA concentration because of the higher MUFA content observed in IB pigs offered the highest protein content diet (P = 0.03). Our results suggest that genetic variation in de novo lipid synthesis and pattern of FA unsaturation might contribute to explain differences in back-fat FA profile of IB and LR × LW pigs under identical nutritional management. They could be also relevant to explain the low efficiency of nutrient and energy utilization in the IB pig.     

Effectiveness of Maifanite in Reducing the Detrimental Effects of Cadmium on Growth Performance, Cadmium Residue, Hematological Parameters, Serum Biochemistry, and the Activities of Antioxidant Enzymes in Pigs

This study was conducted to investigate the toxicity of cadmium and to evaluate the effectiveness of maifanite in preventing cadmium-induced adverse effects. Thirty-two crossbred pigs (Duroc × Landrace × Large white, sex balanced, 17.25?±?0.07 kg average body weight) were randomly allotted to one of four dietary treatments in a 2?×?2 factorial arrangement, with eight replicates per treatment and one pig per replicate. The dietary treatments included two cadmium (as CdCl₂) doses (0.32 and 30.49 mg/kg) and two maifanite doses (0 and 1 %). The results showed that pigs treated with cadmium decreased their average daily feed intake (P?<?0.05) and increased (P?<?0.05) the feed/gain ratio. Cadmium was found in the tissues of pigs that were fed with cadmium-contaminated diets, but the level of cadmium was much lower when maifanite was added to the cadmium-contaminated diets. Ingestion of diets that were artificially contaminated with cadmium (30.49 mg/kg of cadmium) reduced (P?<?0.05) the number of lymphocytes, the total erythrocyte count, the hemoglobin level, and the hematocrit. However, the activities of serum aspartate aminotransferase and gamma glutamyltransferase were increased (P?<?0.05). The total protein level was lower (P?<?0.05) in pigs fed with cadmium-contaminated diets. The contents of malondialdehyde increased (P?<?0.05), while the total antioxidant capacity and the activities of total superoxide dismutase, glutathione peroxidase, glutathione S-transferase, and catalase decreased (P?<?0.05) in pigs fed with cadmium-contaminated diets. Dietary addition of maifanite can, to some extent, prevent the negative effects associated with feeding cadmium diets (30.49 mg/kg of cadmium) to pigs.     

The novel gene pFAM134B positively regulates fat deposition in the subcutaneous fat of Sus scrofa

In this study, we analyzed the global gene expression profiles in the subcutaneous fat (SAT) of Jinhua pigs and Landrace pigs at 90 d. Several genes were significantly highly expressed in Jinhua pigs, including genes encoding the rate limiting enzymes in the TCA cycle, fatty acid activation, fatty acid synthesis and triglyceride synthesis. We identified a novel gene tagged by the EST sequences as public No. BF702245.1, which was named porcine FAM134B (pFAM134B) and the pFAM134B mRNA levels of SAT was significantly higher in Jinhua pigs than that in Landrace pigs at 90 d (P < 0.01). Then the effects of pFAM134B on lipid accumulation were investigated by using RNAi and gene overexpression in the subcutaneous adipocytes. The results showed that pFAM134B played a significant positive role in regulating lipid deposition by increasing the mRNA levels of PPARγ, lipogenic genes fatty acid synthetase (FAS) and acetyl-CoA carboxylase (ACC) (P < 0.01) and reducing the mRNA levels of adipose triglyceride lipase (ATGL) and lipase, hormone-sensitive (HSL) (P < 0.01). This study implied that pFAM134B might be a positive factor in lipid deposition, providing insight into the control of fat accumulation and lipid-related disorders.     

Effects of composition and density of the group on the performance,behaviour and age at puberty in swine

Two hundred and eighteen cross-bred pigs (Duroc × Hampshire × Landrace × Yorkshire) were assigned to a 3 × 2 factorial experiment; the factors being composition of the group and density. The composition of the group factor consisted of pigs not reaggregated (NR), re-aggregated below the median body weight (RBMW), and re-aggregated above the median body weight (RAMW) at the time of transfer to the finishing pens. The density factor consisted of groups of 6 or 12 pigs/pen. Two trials with 2 replications of each trial were conducted. Twenty-six gilts from Trial I were used to determine their age and ovulation rate at the pubertal oestrus. During the nursery phase, composition of the group had no effect (P>0.05) on average daily feed intake (ADFI) or feed efficiency (F/G). Pigs in the NR and RAMW groups had a similar (P>0.05) average daily gain (ADG), whereas, those pigs in the RBMW group gained (P<0.05) at a slower rate. Pigs housed in groups of 6 had a higher (P<0.05) ADFI, had similar (P>0.05) ADG and poorer (P<0.05) F/G than those housed in groups of 12. During the finishing phase, composition of the group had no effect (P>0.05) on ADFI, ADG or F/G. Pigs housed in groups of 6 had a greater (P<0.05) ADFI and ADG, but similar (P<0.05) F/G compared to those housed in groups of 12. Correlation coefficients between the various behaviours and the performance variables suggested that the more active pens of pigs gained less per day and were less efficient. Gilts housed in the NR groups of 6 were younger (P<0.05) at puberty than gilts in the other groups of 6 or 12. Also, gilts housed in the RBMW groups of 6 were younger (P<0.05) at puberty than those housed in the RAMW groups of 6, whereas those housed in the RBMW groups of 12 were older (P<0.05) at puberty than those housed in the RAMW groups of 12. Ovulation rate was not affected (P>0.05) by composition of the group, density or their interaction. In summary, composition and density of the group affected the performance of pigs and was correlated to some of the behavioural measurements. The most noticeable effect was that these same factors caused a delay in the onset of puberty in gilts.     

Evolution of viscera and muscle fractional protein synthesis rate in lean meat selected hybrids and castrated Duroc pigs fed under moderate crude protein restriction

Differences in producing performance and organoleptic meat characteristics among pig genotypes and/or producing types are widely known. These parameters are also subjected to the animal’s development, feeding and management. Detailed knowledge of the effects of production phase (PP), pig producing type (PT), dietary protein availability and their interactions on nutrient digestibility, nitrogen balance and protein metabolism is essential information to improve precision feeding techniques. The experiment was a 2 (PP) × 2 (PT) × 2 (diet) factorial design conducted with 32 male pigs, 16 entire F2 pigs progeny of Pietrain sires and Duroc × Landrace dams, and 16 castrated purebred Durocs belonging to two production phases (growing: 29.5 ± 3.19 v. fattening: 88.6 ± 6.26 kg BW), and assigned to one of two dietary CP levels, either standard (SP: 17% in growing and 15% in fattening) or low (LP: 15% in growing and 13% in fattening). Viscera and muscle fractional protein synthesis rates (FSRs; %/day) were conducted through a single infusion of 15% L-[ring-²H₅]-phenylalanine, with subsequent blood sampling from 12 to 40 min, and sample collection of liver, duodenum, biceps femoris and longissimus dorsi skeletal muscles after sacrifice. Fattening animals acquired a greater feed ingestion capacity, average daily gain (P < 0.01) and apparent ileal digestibility, whereas growing pigs showed higher FSRs in both viscera (duodenum and liver) and in longissimus dorsi. F2 pigs showed higher average daily gain, nitrogen retention rates and FSR in liver and longissimus dorsi (P < 0.01). Nevertheless, apparent ileal digestibility in all essential amino acids was lower in F2 compared with Duroc pigs (P < 0.05). Protein metabolism was barely influenced by dietary CP content, although animals fed LP registered the lowest apparent ileal digestibility for CP and also for most of the essential amino acids compared with SP-fed pigs. This information may reveal differences in amino acid requirements between both PTs, with Duroc pigs receiving excess of dietary amino acids.     

Involvement of Zn Depletion in Cd-Induced Toxicity on Prenatal Bone Formation in Rat

This experiment was conducted to evaluate the effects of chromium methionine with/without zinc sulfate or zinc amino acid complex on the growth performance, carcass traits, meat quality, serum parameters, endocrine parameters, and antioxidant status of growing-finishing pigs. A total of 180 (32.0 ± 1.7 kg body weight, BW) crossbred pigs (Duroc × Landrace × Yorkshire) were used in a completely randomized design with three dietary treatments and 10 replicates per treatment (five pens of barrows and five pens of gilts with six pigs per replicate). Three treatments were corn-soybean meal-based diets supplemented with 100 mg Zn/kg from zinc sulfate (ZnSO₄), 100 mg Zn/kg from ZnSO₄ + 0.2 mg Cr/kg from chromium methionine complex (CrMet), or 50 mg Zn/kg from ZnSO₄ + 50 mg Zn/kg from zinc amino acid complex (ZnAA) + 0.2 mg Cr/kg from CrMet, respectively. The experiment lasted 105 days, of which was divided into three stages including phase 1 (30 to 50 kg BW), phase 2 (50 to 80 kg BW), and phase 3 (80 to 110 kg BW). Results showed that supplementation with CrMet and ZnAA improved (P < 0.05) the feed conversion of the pigs in phase 2, phase 3, and the overall experiment. Hot carcass weight, dressing percentage, and a longissimus dorsi muscle area were increased (P < 0.05) in pigs fed with diets supplemented with both CrMet and ZnAA compared with pigs fed with diets containing only ZnSO₄ (P < 0.05). There was also an increase (P < 0.01) pH_24 h in the longissimus dorsi muscle in pigs fed with diets supplemented with CrMet and ZnAA. The concentration of serum glucose in pigs fed with diets containing CrMet and ZnAA was decreased (P < 0.05) compared with that in pigs fed with the diet containing ZnSO₄. Supplementation with CrMet and ZnAA increased (P < 0.05) the circulating levels of insulin and decreased (P < 0.05) cortisol. There was an increase (P < 0.05) in total serum antioxidant capacity and Cu/Zn superoxide dismutase activity as well as a decrease (P < 0.05) in serum malondialdehyde concentrations in pigs fed with diets supplemented with CrMet and ZnAA compared with pigs fed with the diet supplemented only with ZnSO₄. In conclusion, supplementation of CrMet only or CrMet together with ZnAA improved feed conversion, carcass traits, and meat quality in the growing-finishing pigs.     

Pigs that are divergent in feed efficiency,differ in intestinal enzyme and nutrient transporter gene expression,nutrient digestibility and microbial activity

Feed efficiency is an important trait in the future sustainability of pig production, however, the mechanisms involved are not fully elucidated. The objective of this study was to examine nutrient digestibility, organ weights, select bacterial populations, volatile fatty acids (VFA’s), enzyme and intestinal nutrient transporter gene expression in a pig population divergent in feed efficiency. Male pigs (n=75; initial BW 22.4 kg SEM 2.03 kg) were fed a standard finishing diet for 43 days before slaughter to evaluate feed intake and growth for the purpose of calculating residual feed intake (RFI). Phenotypic RFI was calculated as the residuals from a regression model regressing average daily feed intake (ADFI) on average daily gain (ADG) and midtest BW^0.60 (MBW). On day 115, 16 pigs (85 kg SEM 2.8 kg), designated as high RFI (HRFI) and low RFI (LRFI) were slaughtered and digesta was collected to calculate the coefficient of apparent ileal digestibility (CAID), total tract nutrient digestibility (CATTD), microbial populations and VFA’s. Intestinal tissue was collected to examine intestinal nutrient transporter and enzyme gene expression. The LRFI pigs had lower ADFI (P<0.001), improved feed conversion ratio (P<0.001) and an improved RFI value relative to HRFI pigs (0.19 v. −0.14 SEM 0.08; P<0.001). The LRFI pigs had an increased CAID of gross energy (GE), and an improved CATTD of GE, nitrogen and dry matter compared to HRFI pigs (P<0.05). The LRFI pigs had higher relative gene expression levels of fatty acid binding transporter 2 (FABP2) (P<0.01), the sodium/glucose co-transporter 1 (SGLT1) (P<0.05), the glucose transporter GLUT2 (P<0.10), and the enzyme sucrase–isomaltase (SI) (P<0.05) in the jejunum. The LRFI pigs had increased populations of lactobacillus spp. in the caecum compared with HRFI pigs. In colonic digesta HRFI pigs had increased acetic acid concentrations (P<0.05). Differences in nutrient digestibility, intestinal microbial populations and gene expression levels of intestinal nutrient transporters could contribute to the biological processes responsible for feed efficiency in pigs.     

Meishan neonatal piglets tend to have higher intestinal barrier function than crossbred neonatal piglets

Meishan pigs tend to have higher disease resistance than commercial breeds, although more studies are needed to confirm this difference. This study compared intestinal barrier function between Meishan and crossbred neonatal piglets to provide guidance for both the breeding and nutritional regulation of pigs. Six Meishan piglets and 6 Duroc × (Landrace × Yorkshire) crossbred neonatal piglets (all with normal birth weights) were obtained and allocated into the MEIS and CROSS groups, respectively. Intestinal morphology, goblet cell numbers, antioxidant enzyme activity, and cytokine gene and tight junction protein expression were assessed. The results showed that BW was lower in the MEIS group than in the CROSS group (P < 0.01). The relative lengths of the duodenum (P < 0.05), jejunum (P < 0.01) and ileum (P < 0.01) in the MEIS group were higher than those in the CROSS group. Compared with the CROSS group, the MEIS group exhibited shorter villus lengths in the duodenum and jejunum (P < 0.01), a shallower crypt depth in the ileum (P < 0.001) and denser and longer microvilli in the intestine. The numbers of GCs in the duodenum (P < 0.01) and jejunum (P < 0.001) and the activity levels of glutathione peroxidase (P < 0.05) in the jejunum and of catalase (P < 0.01) and superoxide dismutase (P < 0.01) in the ileum were higher in the MEIS group than in the CROSS group. Compared with the CROSS group, the MEIS group exhibited higher gene expression levels of interleukin (IL) 4 and interferon γ (IFNγ) in the jejunum (P < 0.05); IL2 (P < 0.05), IL4 (P < 0.01) and IFNγ (P < 0.001) in the ileum; and mucin 2 (P < 0.01) and occludin (P < 0.05) in the duodenum. In conclusion, Meishan neonatal piglets showed lower birth weights but higher intestinal barrier function than crossbred piglets.     

Effects of soybean isoflavones on the growth performance,intestinal morphology and antioxidative properties in pigs

Soybean meal is rich in soybean isoflavones, which exhibit antioxidant, anti-inflammatory, antiviral and anticancer functions in humans and animals. This study was conducted to investigate the effects of soybean isoflavones on the growth performance, intestinal morphology and antioxidative properties in pigs. A total of 72 weaned piglets (7.45 ± 0.13 kg; 36 males and 36 females) were allocated into three treatments and fed corn-soybean meal (C-SBM), corn-soy protein concentrate (C-SPC) or C-SPC supplemented with equal levels of the isoflavones found in the C-SBM diet (C-SPC + ISF) for a 72-day trial. Each treatment had six replicates and four piglets per replicate, half male and half female. On day 42, one male pig from each replicate was selected and euthanized to collect intestinal samples. The results showed that compared to pigs fed the C-SPC diet, pigs fed the C-SBM and C-SPC + ISF diets had higher BW on day 72 (P < 0.05); pigs fed the C-SBM diet had significantly higher average daily gain (ADG) during days 14 to 28 (P < 0.05), with C-SPC + ISF being intermediate; pigs fed the C-SBM diet tended to have higher ADG during days 42 to 72 (P = 0.063), while pigs fed the C-SPC + ISF diet had significantly higher ADG during days 42 to 72 (P < 0.05). Moreover, compared to pigs fed the C-SPC diet, pigs fed the C-SBM diet tended to have greater villus height (P = 0.092), while pigs fed the C-SPC + ISF diet had significantly greater villus height (P < 0.05); pigs fed the C-SBM and C-SPC + ISF diets had significantly increased villus height-to-crypt depth ratio (P < 0.05). Compared with the C-SPC diet, dietary C-SPC + ISF tended to increase plasma superoxide dismutase activity on days 28 (P = 0.085) and 42 (P = 0.075) and reduce plasma malondialdehyde (MDA) content on day 42 (P = 0.089), as well as significantly decreased jejunal mucosa MDA content on day 42 (P < 0.05). However, no significant difference in the expression of tight junction genes among the three groups was found (P > 0.05). In conclusion, our results suggest that a long-term exposure to soybean isoflavones enhances the growth performance, protects the intestinal morphology and improves the antioxidative properties in pigs.     

Body composition and organ development of intra-uterine growth restricted pigs at weaning

Sow litter sizes have increased, subjecting more small piglets to intra-uterine growth restriction (IUGR). Research on the development and growth of IUGR pigs is limited. The objective of this study was to compare the body composition and organ development of IUGR pigs at weaning, and to estimate their growth performance from birth to 30 kg. A total of 142 IUGR and 142 normal piglets were classified at birth based on their head morphology. At weaning, 20 IUGR and 20 normal piglets were collected, a whole-body dual-energy x-ray absorption scan was performed, and the piglets were euthanized for organ measurements. Body weight (BW) was measured weekly from birth to 30 kg, rectal temperature and whole-blood glucose levels were measured weekly from birth to weaning, and blood samples were collected at days 7, 14 and 21 for IGF-1 analysis. Results showed that IUGR pigs have a similar percentage of adipose tissue (P > 0.05) compared to normal pigs at 24 days of age. Organs were smaller (P < 0.001) in IUGR pigs than in normal pigs, whereas brain, liver, lungs and adrenal glands were relatively larger (P < 0.05) in relation to the BW of IUGR pigs. Average birth weight (BiW) of normal pigs was greater (P < 0.001) compared with IUGR pigs (1.38 v. 0.75 kg), and the average daily gain (ADG) of IUGR pigs was reduced from day 0 to 14, day 0 to 28 (weaning) and from weaning to 30 kg compared to normal pigs. From birth to weaning at day 28, IUGR piglets had a 72.9 g/day greater fractional ADG (FADG) in relation to their BiW (P < 0.05), but FADG did not differ (P > 0.05) from weaning to 30 kg. Rectal temperature of IUGR piglets was greater (P < 0.05) on day 7 compared with normal piglets, and, even though blood glucose levels were decreased (P < 0.001) in IUGR piglets at day 0, neither glucose nor IGF-1 concentrations differed (P > 0.05) between IUGR and normal piglets. In conclusion, IUGR piglets exhibited some relatively larger organs at weaning compared to normal pigs, but body composition was similar between IUGR and normal pigs. In addition, IUGR pigs had a reduced ADG from birth to 30 kg, and, although they exhibited a greater FADG during nursing, IUGR pigs still require six additional days to reach a BW of 30 kg in comparison to normal pigs.     

Betaine increases net portal absorption of volatile fatty acids in Iberian pigs

Betaine is an osmolyte with the potential to increase volatile fatty acids (VFAs) production and hence improve intestinal health.The present study investigated how betaine affects portal and arterial concentrations and net portal absorption (NPA) of VFA in growing Iberian pigs. Eight 30 kg BW Iberian growing barrows with indwelling catheters in portal vein, ileal vein and carotid artery were randomly assigned to a control diet or a diet supplemented with 0.5% betaine. Para-aminohippuric acid was infused into the ileal vein as a marker to determine portal blood flow using the dilution method. Blood samples were simultaneously taken from the carotid artery and portal vein at −60, 60, 120, 180, 240, 300 and 360 min after feeding 1 200 g of the diet. The NPA of VFA (acetate, propionate, butyrate, valerate, isobutyrate and caproate) was determined by multiplying the porto-arterial plasma concentration differences by portal plasma flow. Betaine increased NPA of acetate (1.44 fold; P < 0.001) and total VFA (0.55 fold; P < 0.001) while decreased NPA of propionate (−0.38 fold; P < 0.05) and valerate (−1.46 fold; P < 0.05) compared with control pigs. Estimated heat production potentially derived from NPA of VFA accounted for 0.20–0.27 of metabolizable energy for maintenance. Acetate and propionate accounted for most of the total VFA estimated heat production (0.83–0.89). Regarding bacterial communities, betaine apparently did not change the DNA abundance of fecal total bacteria, Lactobacillus, Bifidobacterium, Enterobacteriaceae, Bacteroides and the Clostridium clusters I, IV and XIV. In conclusion, betaine increased portal appearance and NPA of VFA, contributing to cover maintenance energy requirements.     

Effects of Copper-Loaded Chitosan Nanoparticles on Intestinal Microflora and Morphology in Weaned Piglets

The objective of the present study was to investigate the effects of dietary supplementation with copper-loaded chitosan nanoparticles (CNP-Cu) on growth performance, intestinal microflora, and morphology in weaned piglets. A number of 90 weaned piglets (Duroc × Landrace × Yorkshire), weaned at 21?days with body weight of 7.2?±?0.81?kg, were randomly divided into three groups by weight and sex, each treatment including three replicates of ten pigs. The piglets were fed the same basal diet supplemented with 0 (the control group), 100?mg/kg CNP-Cu, and 100?mg/kg chlortetracycline (the positive group). The results showed that 100?mg/kg CNP-Cu significantly increased average daily gain and feed intake and decreased feed/gain ratio and diarrhea rate (P?<?0.05). Compared with the control group, the amount of Escherichia coli in duodenum, jejunal, and caecum were significantly decreased by 100?mg/kg CNP-Cu; the number of lactobacillus in jejunal and caecum were increased (P?<?0.05), and the amount of bifidobacterium in duodenum and caecum were also increased (P?<?0.05). Moreover, the villous height of duodenum, jejunum, and ileum mucosa was significantly increased (P?<?0.05), and the crypt depth was significantly decreased (P?<?0.05). The results indicated that CNP-Cu is beneficial to growth and intestinal microflora and morphology and could be a potential substitution of chlortetracycline in diets of weaned piglets.     

Effects of resistant starch on behaviour,satiety-related hormones and metabolites in growing pigs

Resistant starch (RS) has been suggested to prolong satiety in adult pigs. The present study investigated RS-induced changes in behaviour, satiety-related hormones and metabolites in catheterized growing pigs to explore possible underlying mechanisms for RS-induced satiety. In a cross-over design with two 14-day periods, 10 pigs (initial BW: 58 kg) were assigned to two treatments comprising diets containing either 35% pregelatinized starch (PS) or 34% retrograded starch (RS). Diets were isoenergetic on gross energy. Pigs were fed at 2.8× maintenance. Postprandial plasma response of satiety-related hormones and metabolites was measured at the end of each period using frequent blood sampling. Faecal and urinary energy losses were measured at the end of each period. Behaviour was scored 24 h from video recordings using scan sampling. Energy digestibility and metabolizability were ~6% lower in RS compared with PS diet (P<0.001), and metabolizable energy (ME) intake was ~3% lower in RS-fed than in PS-fed pigs (P<0.001). RS-fed pigs showed less feeder-directed (P=0.001) and drinking (P=0.10) behaviours than PS-fed pigs throughout the day. Postprandial peripheral short-chain fatty acid (SCFA) levels were higher in RS-fed than in PS-fed pigs (P<0.001). Postprandial glucose and insulin responses were lower in RS-fed than in PS-fed pigs (P<0.001). Triglyceride levels were higher in RS-fed than in PS-fed pigs (P<0.01), and non-esterified fatty acid levels did not differ between diets (P=0.90). Glucagon-like peptide-1 (GLP-1) levels were lower in RS-fed than in PS-fed pigs (P<0.001), and peptide tyrosine tyrosine (PYY) levels did not differ between diets (P=0.90). Blood serotonin levels were lower (P<0.001), whereas monoamine oxidase activity (P<0.05) and tryptophan (P<0.01) levels were higher in RS-fed than in PS-fed pigs. Despite a lower ME intake, RS seemed to prolong satiety, based on behavioural observations. Possible underlying mechanisms for RS-induced satiety include increased 24 h plasma SCFA levels, and decreased postprandial glucose and insulin responses. GLP-1 and PYY seemed not to play a role in RS-induced satiety. Low blood serotonin levels in RS-fed pigs suggested a difference in intestinal serotonin release between treatments. Increased postprandial plasma triglyceride levels corresponded with increased SCFA levels, but it is unclear whether triglycerides may have signalled satiety in RS-fed pigs.     

Low protein diets without medicinal zinc oxide for weaned pigs reduced diarrhea treatments and average daily gain

The use of medicinal zinc oxide (ZnO) in post-weaning diets must be phased out in the European Union by 2022, resulting in urgent needs for alternative strategies to prevent diarrhea in pigs. The objective of this study was to test the effect of four different dietary protein strategies with different amino acid profiles on diarrhea frequency and pig performance as alternative diet plans when medicinal ZnO was will be excluded from the diet. A total of 6 800 Duroc x (Danish Landrace x Yorkshire) pigs, weaned around 28 days of age, were randomly assigned by sex and size to six dietary treatments. The treatments were; standard CP levels (191, 184, 184 g/kg CP) and allocated 2 500 ppm ZnO in phase 1 (PC = positive control), standard CP levels (191, 184, 184 g/kg CP) and no added ZnO in phase 1 (NC = negative control), CP levels of 166, 184, 184 g/kg (LSS = low-standard-standard), CP levels of 166, 162, 192 g/kg (LLH = low-low-high), CP levels of 140, 193, 192 g/kg (VHH = very low-high-high), and lastly 140, 174, 192 g/kg CP levels (VMH = very low-medium-high). The pigs entered the trial at ~ 7 kg BW and exited at ~ 30 kg BW. As expected, the PC treatment resulted in 42% fewer diarrhea pen treatments in the total trial period compared to the NC group (P < 0.05), whereas both PC and LLH had fewer diarrhea treatment days per pig compared to NC pigs (P < 0.05). Additionally, at the point of treatment, the NC pens had 33% fecal floor samples positive for pathogens, compared to 80% samples positive for pathogens in the PC pens. This suggests that ZnO has a particular positive effect on non-infectious diarrhea without bacterial involvement. A reduction in dietary CP levels in phase 1 led to a reduced average daily gain (ADG) in LLH and VMH pigs and a poorer feed conversion ratio (FCR) in VHH pigs during the overall study period compared to the NC pigs (P < 0.05). Conclusively, a diet with low CP levels from weaning to about 15 kg BW had a reducing effect on diarrhea, but decreased ADG without affecting the FCR.     

Estimating fermentative amino acid catabolism in the small intestine of growing pigs

Fermentative catabolism (FAAC) of dietary and endogenous amino acids (AA) in the small intestine contributes to loss of AA available for protein synthesis and body maintenance functions in pigs. A continuous isotope infusion study was performed to determine whole body urea flux, urea recycling and FAAC in the small intestine of ileal-cannulated growing pigs fed a control diet (CON, 18.6% CP; n=6), a high fibre diet with 12% added pectin (HF, 17.7% CP; n=4) or a low-protein diet (LP, 13.4% CP; n=6). ¹⁵N-ammonium chloride and ¹³C-urea were infused intragastrically and intravenously, respectively, for 4 days. Recovery of ammonia at the distal ileum was increased by feeding additional fibre when compared with the CON (P<0.05) but was not affected by dietary protein (0.24, 0.39 and 0.14 mmol nitrogen/kg BW/day for CON, HF and LP, respectively; P<0.05). Lowering protein intake reduced urea flux (25.3, 25.7 and 10.3 mmol nitrogen/kg BW/day; P<0.01), urinary urea excretion (14.4, 15.0 and 6.2 mmol N/kg BW/day; P<0.001) and urea recycling (12.1, 11.3 and 3.23 mmol nitrogen/kg BW/day; P<0.01) compared with CON. There was a rapid reduction in ¹⁵N-ammonia enrichment in digesta along the small intestine suggesting rapid absorption of ammonia before the distal ileum and lack of uniformity of enrichment in the digesta ammonia pool. A two-pool model was developed to determine possible value ranges for nitrogen flux in the small intestine assuming rapid absorption of ammonia. Maximum estimated FAAC based on this model was significantly lower when dietary protein content was decreased (32.9, 33.4 and 17.4 mmol nitrogen/kg BW/day; P<0.001). There was no impact of dietary fibre on estimates of small intestine nitrogen flux (P>0.05) compared with CON. The two-pool model developed in the present study allows for estimation of FAAC but still has limitations. Quantifying FAAC in the small intestine of pigs, as well as other non-ruminants and humans, offers a number of challenges but warrants further investigation.     

Signaling Pathways Related to Protein Synthesis and Amino Acid Concentration in Pig Skeletal Muscles Depend on the Dietary Protein Level,Genotype and Developmental Stages

Muscle growth is regulated by the homeostatic balance of the biosynthesis and degradation of muscle proteins. To elucidate the molecular interactions among diet, pig genotype, and physiological stage, we examined the effect of dietary protein concentration, pig genotype, and physiological stages on amino acid (AA) pools, protein deposition, and related signaling pathways in different types of skeletal muscles. The study used 48 Landrace pigs and 48 pure-bred Bama mini-pigs assigned to each of 2 dietary treatments: lower/GB (Chinese conventional diet)- or higher/NRC (National Research Council)-protein diet. Diets were fed from 5 weeks of age to respective market weights of each genotype. Samples of biceps femoris muscle (BFM, type I) and longissimus dorsi muscle (LDM, type II) were collected at nursery, growing, and finishing phases according to the physiological stage of each genotype, to determine the AA concentrations, mRNA levels for growth-related genes in muscles, and protein abundances of mechanistic target of rapamycin (mTOR) signaling pathway. Our data showed that the concentrations of most AAs in LDM and BFM of pigs increased (P<0.05) gradually with increasing age. Bama mini-pigs had generally higher (P<0.05) muscle concentrations of flavor-related AA, including Met, Phe, Tyr, Pro, and Ser, compared with Landrace pigs. The mRNA levels for myogenic determining factor, myogenin, myocyte-specific enhancer binding factor 2 A, and myostatin of Bama mini-pigs were higher (P<0.05) than those of Landrace pigs, while total and phosphorylated protein levels for protein kinase B, mTOR, and p70 ribosomal protein S6 kinases (p70S6K), and ratios of p-mTOR/mTOR, p-AKT/AKT, and p-p70S6K/p70S6K were lower (P<0.05). There was a significant pig genotype-dependent effect of dietary protein on the levels for mTOR and p70S6K. When compared with the higher protein-NRC diet, the lower protein-GB diet increased (P<0.05) the levels for mTOR and p70S6K in Bama mini-pigs, but repressed (P<0.05) the level for p70S6K in Landrace pigs. The higher protein-NRC diet increased ratio of p-mTOR/mTOR in Landrace pigs. These findings indicated that the dynamic consequences of AA profile and protein deposition in muscle tissues are the concerted effort of distinctive genotype, nutrient status, age, and muscle type. Our results provide valuable information for animal feeding strategy.