Association of an SNP marker in exon 24 of a class 3 phosphoinositide‐3‐kinase (PIK3C3) gene with production traits in Duroc pigs

A C?T single nucleotide polymorphism (SNP) on exon 24 of the porcine class 3 phosphoinositide‐3‐kinase (PIK3C3) gene is considered a possible genetic marker for selecting backfat (BF) thickness and carcass fat, although only one study has published results on its effects by performing experiments on a single resource family. We analyzed the association of this PIK3C3 polymorphism with production traits in 739 Duroc pigs. The C allele frequency was 67.9% in our study population. PIK3C3 polymorphism showed significant effects on average daily weight gain (ADG), BF thickness, intermuscular fat content (IMF), and the size of the loin eye muscle area (EMA). The C alleles increased ADG, BF and IMF, and decreased EMA. The predicted differences in traits between the homozygous pigs of the C and T alleles were 40 g/day for DG, 1.2 mm for BF, 0.44% for IMF, and 1.6 cm² for EMA. Furthermore, the statistical models for estimating the breeding values of each trait had lower Akaike's information criterion values when adding PIK3C3 genotype information. We therefore confirmed that the polymorphism in PIK3C3 (C2604T) has the potential to be a genetic marker for production traits in Duroc pigs.     

Effects of breed, sex and halothane genotype on fatty acid composition of triacylglycerols and phospholipids in pork longissimus muscle

The objective of this study was to estimate the effects of breed, sex, and halothane (HAL‐1843^TM) genotype on fatty acid composition of triacylglycerols (TAG) and phospholipids (PL) extracted from porcine longissimus muscle (LM). Purebred Yorkshire (n = 131), Duroc (n = 136), Hampshire (n = 49), Spotted (n = 35), Chester White (n = 74), Poland China (n = 51), Berkshire (n = 169) and Landrace (n = 82) pigs (n = 727; 427 barrows and 300 gilts) from the 1994 and 2001 National Barrow Show Sire Progeny Tests were used. For statistical analyses, a mixed model was used that included fixed effects of breed, sex, HAL‐1843^TM genotype, year, slaughter date within each year, interaction of breed × sex and random effects of sire and dam within breed. Breeds and sex were significantly associated with the percentages of the majority fatty acids in TAG. Duroc pigs had greater total saturated fatty acids (SFA) and lower total monounsaturated fatty acids (MUFA) (p < 0.05) contents than did pigs of all other breeds except Berkshire (p > 0.05). The concentration of total polyunsaturated fatty acids (PUFA) was the greatest in Hampshire pigs (p < 0.05). The content of total SFA was greater (p < 0.01), whereas the concentrations of total MUFA and PUFA were lower (p < 0.01) in barrows than those in gilts. The contents of major SFA in PL did not differ significantly among pigs from different breeds and sex groups. However, breed and sex significantly affected the concentrations of major MUFA and PUFA in PL and strong negative correlation between the total contents of MUFA and PUFA in PL was observed in the current study. Chester White pigs had greater total MUFA and lower total PUFA contents (p < 0.05) in PL than did pigs of all other breeds except Spotted (p > 0.05). In contrast to breed and sex effects, the concentrations of fatty acids in PL were more affected by HAL‐1843^TM genotype than those in TAG. The content of C16:0, a major SFA in PL, differed significantly in pigs with different HAL‐1843^TM genotypes. In conclusion, these results suggest that breed and sex are important sources of the variations for fatty acid composition of TAG and PL in LM.     

Nucleotide sequence polymorphisms of beta1‐, beta2‐, and beta3‐adrenergic receptor genes on Jinhua,Meishan, Duroc and Landrace pigs

The full amino acid coding sequences of adrenergic receptor genes beta1, beta2, and beta3 (ADRB1, ADRB2, and ADRB3)were determined for Jinhua, Meishan, Duroc and Landrace pigs. Non‐synonymous substitution of Arg458Pro was found in the porcine ADRB1 gene, resulting in a 469 amino acid sequence. Continuous substitutions of Asn29Asp and Glu30Gln were found in the porcine ADRB2 gene, resulting in a 418 amino acid sequence. Additionally, a Lys30 polymorphism of the ADRB2 gene was found in the Jinhua pigs. There were three non‐synonymous substitutions of Asn24Thr, Arg264Gln and Asn398Asp on the porcine ADRB3 gene. A thymine insertion in the ADRB3 gene, resulting in a protein with two fewer amino acids, was found in the Jinhua and Meishan pigs. To assess the effect of ADRB polymorphisms on porcine subcutaneous fat layer thickness, we calculated the genetic frequency of the variants in fatty and lean groups, each consisting of 24 pigs that were crossbreds of Duroc and Jinhua pigs. The effect of the ADRB3 gene polymorphism was not evaluated, because there was insufficient variation on the ADRB3 gene in the examined groups. Although Fisher's exact test showed no significant difference in the frequency of ADRB1 and ADBR2 variants between the two groups, the Arg458 variant of ADRB1 was higher (P = 0.11) in the lean group, and pigs in that group had a thinner fat layer than did those with the Pro458 variant. These results imply a possibility of ADRB1 polymorphism as a minor factor in porcine fat layer thickness. The Asp29 variant of ADRB2 was higher in the lean group (P = 0.11), and the Glu30 variant was higher in the fatty group (P = 0.15), but the Asp29 variant was found only in the Chinese pigs. Thus, the effect of ADRB2 polymorphisms was not clear in this study.     

Effects of porcine leptin receptor gene polymorphisms on backfat thickness,fat area ratios by image analysis,and serum leptin concentrations in a Duroc purebred population

The leptin receptor (LEPR) gene is considered a candidate gene for fatness traits. It is located on SSC 6 in a region in which quantitative trait loci (QTLs) for backfat thickness (BF), fat area ratios, and serum leptin concentration (LEPC) have previously been detected in a Duroc purebred population. The objectives of the present study were to identify porcine LEPR polymorphisms and examine the effects of LEPR polymorphisms on fatness traits in this same population. The Duroc pigs (226 to 953 pigs) were evaluated for BF, fat area ratios using image analysis, and LEPC. A total of seven single nucleotide polymorphisms (SNPs) in the full‐length LEPR coding region were identified in pigs from the base population. Four non‐synonymous SNPs of the LEPR gene and 15 microsatellite markers on SSC 6 were then genotyped in all pigs. During candidate gene analysis, we detected significant effects of the non‐synonymous SNP c.2002C>T in exon 14 on all traits. In fine mapping analysis, significant QTLs for BF, fat area ratios, and LEPC were detected near the LEPR gene in the same region. These results indicated that the c.2002C>T SNP of LEPR has a strong effect on BF, fat area ratios and LEPC.     

An assessment of reproductive and lifetime performances of Kagoshima Berkshire gilts and sows

We investigated the reproductive and lifetime performances of Kagoshima Berkshire gilts and sows. We examined 20 605 parity records of 4419 pigs for 2008 to 2012 on a farrow‐to‐finish commercial farm. The mean parity (± SD) of all animals was 3.0 ± 2.1. For farrowing performance, the highest numbers of total pigs born and pigs born alive were found in sows with parities 5 and 6 and with parity 3–6, respectively (P < 0.05). Regarding weaning and mating performance, sows with parity 2 had the lowest preweaning mortality (P < 0.05). The longest weaning‐to‐first‐mating interval was found in parity 1 pigs, and the interval decreased as parity increased (P < 0.05). Parities 0 and 1 pigs had the lowest farrowing rate and those with parity 4 had the highest farrowing rate (P < 0.05). The mean parity at culling, total number of pigs born alive in a lifetime, and nonproductive days in a lifetime were 5.5 ± 2.93, 49.2 ± 24.72 pigs, and 132.1 ± 83.34 days, respectively. These animals had a lower litter size and fertility that the F₁ crossbred sows mainly used in Japan, but a similar tendency for performance by parity.     

Allelic frequencies of PRKAG3 in several pig breeds and its technological consequences on a Duroc × Landrace‐Large White cross

The allelic frequencies of PRKAG3 gene (the RN gene) have been investigated in several pig breeds. R200Q mutation appear only in Hampshire pigs, whereas V199I mutation is most abundant in Iberian, Porco Celta or Bizaro, and less in breeds selected for muscularity as Duroc, Landrace and Pietrain. A thorough study of phenotypic effects of V1991 has been performed in a Duroc × Landrace‐Large White cross. 199I homozygous pigs show increased pH₂₄ values in ham homogenates and loin (0.14 and 0.16 pH units, respectively) compared to 199V homozygous ones. Meat of 199I homozygous pigs exudates 42.6% less fluid and is darker (2.46 ‘L’‐value units). 199I homozygous pigs are fatter (4.2 mm more backfat thickness) and contain less muscle mass in ham (1.0 percentage points) and shoulder (2.7 percentage points), than 199V homozygous ones. 199I homozygous pigs contain 7.3% less protein in the belly and 8.5% more fat in shoulder muscle mass than 199V homozygous pigs. 199I homozygous pigs have also superior functional properties: better gelling (22.8% larger G′ value) and emulsion capacities (14 percentage points less of total exuded fluid), and higher curing yield in the belly (6 percentage points more). These data support the adipogenic character of the V199I mutation. The advantages and disadvantages of selecting any of the two PRKAG3 alleles for position 199 are discussed.     

Evaluation of effects of multiple candidate genes (LEP,LEPR, MC4R,PIK3C3, and VRTN) on production traits in Duroc pigs

We evaluated multiple effects of genetic variations of five candidate loci (LEP, LEPR, MC4R, PIK3C3 and VRTN) on four production traits (average daily weight gain (ADG); backfat thickness (BFT); loin eye muscle area (EMA); and intramuscular fat content (IMF)) in a closed nucleus herd of pure Duroc pigs. Polymorphisms in LEPR, MC4R and PIK3C3 had significant single gene effects on ADG and BFT. The additive genetic variance in ADG and BFT (16.99% and 22.51%, respectively) was explained by genetic effects of these three loci. No correlations were observed between the LEP genotype and production traits in this study. Although we detected marginally epistatic interactions between LEPR and PIK3C3 on the eye muscle area, there were no significant epistatic effects on any traits among all loci pairs. These results suggest that LEPR, MC4R, PIK3C3 and VRTN may independently influence growth rate and fat deposition. Furthermore, the statistical models for predicting the breeding values of each trait had the lowest Akaike's information criterion values when considering the effect of the MC4R, LEPR, PIK3C3 and VRTN genotype simultaneously. These results suggest that LEPR, MC4R, PIK3C3 and VRTN are useful markers for accurately predicting breeding values in Duroc pigs.     

An imputation‐based genome‐wide association study on traits related to male reproduction in a White Duroc × Erhualian F2 population

Boar reproductive traits are economically important for the pig industry. Here we conducted a genome‐wide association study (GWAS) for 13 reproductive traits measured on 205 F₂ boars at day 300 using 60 K single nucleotide polymorphism (SNP) data imputed from a reference panel of 1200 pigs in a White Duroc × Erhualian F₂ intercross population. We identified 10 significant loci for seven traits on eight pig chromosomes (SSC). Two loci surpassed the genome‐wide significance level, including one for epididymal weight around 60.25 Mb on SSC7 and one for semen temperature around 43.69 Mb on SSC4. Four of the 10 significant loci that we identified were consistent with previously reported quantitative trait loci for boar reproduction traits. We highlighted several interesting candidate genes at these loci, including APN, TEP1, PARP2, SPINK1 and PDE1C. To evaluate the imputation accuracy, we further genotyped nine GWAS top SNPs using PCR restriction fragment length polymorphism or Sanger sequencing. We found an average of 91.44% of genotype concordance, 95.36% of allelic concordance and 0.85 of r² correlation between imputed and real genotype data. This indicates that our GWAS mapping results based on imputed SNP data are reliable, providing insights into the genetic basis of boar reproductive traits.     

Influence of Bacillus subtilis GCB‐13‐001 on growth performance,nutrient digestibility,blood characteristics,faecal microbiota and faecal score in weanling pigs

The present study investigated the influence of Bacillus subtilis GCB‐13‐001 on growth performance, nutrient digestibility, blood characteristics, faecal microbiota and faecal score in weanling pigs. A total of 120 weaning pigs [(Landrace × Yorkshire) × Duroc; 7.73 ± 0.75 kg (28 days of age)] were randomly allotted into three treatments according to their initial body weight (BW) and gender in a 6‐week experiment. There were 8 replication pens in each treatment, with five pigs/pen. Dietary treatment groups were as follows: (a) basal diet (CON), (b) CON + 0.1% Bacillus subtilis GCB‐13‐001 1 × 10⁸ CFU/kg (T1) and (c) CON + 0.1% Bacillus subtilis GCB‐13‐001 1 × 10⁹ CFU/kg (T2). Days 1 to 7, the BW and ADG with T2 treatment were higher (p < .05) than CON treatment, as well as F:G showed trends in linear reduction (p < .1). Days 8 to 21, the BW and ADG were improved (p < .05) in pigs offered T1 and T2 diets compared with CON diet. Days 22 to 42, BW and ADG were higher (p < .05) in pigs fed T2 diet than CON and T1 diets, and the pigs fed T1 diet had higher BW than CON treatment. Overall, the ADG with the T2 treatment was higher (p < .05) than that with the T1 and CON treatments, and pigs offered T1 treatment had higher (p < .05) ADG than CON treatment. Moreover, F:G ratio were significantly decreased (p < .05) by T2 treatment compared with CON treatment. The faecal Lactobacillus counts were improved, and E. coli counts were reduced (p < .05) in pigs fed T2 diet compared with CON at the end of the experiment. In conclusion, supplementation of 0.1% Bacillus subtilis GCB‐13‐001 1 × 10⁹ CFU/kg has shown a beneficial effect in improving BW, increase ADG, decrease F:G ratio.     

Association of swine vertnin (VRTN) gene with production traits in Duroc pigs improved using a closed nucleus breeding system

Vertnin (VRTN) is involved in the variation of vertebral number in pigs and it is located on Sus scrofa chromosome 7. Vertebral number is related to body size in pigs, and many reports have suggested presence of an association between body length (BL) and meat production traits. Therefore, we analyzed the relationship between the VRTN genotype and the production and body composition traits in purebred Duroc pigs. Intramuscular fat content (IMF) in the Longissimus muscle was significantly associated with the VRTN genotype. The mean IMF of individuals with the wild‐type genotype (Wt/Wt) (5.22%) was greater than that of individuals with the Wt/Q (4.99%) and Q/Q genotypes (4.79%). In addition, a best linear unbiased predictor of multiple traits animal model showed that the Wt allele had a positive effect on the IMF breeding value. No associations were observed between the VRTN genotype and other production traits. The VRTN genotype was related to BL. The Q/Q genotype individuals (100.0 cm) were longer than individuals with the Wt/Q (99.5 cm) and Wt/Wt genotypes (98.9 cm). These results suggest that in addition to the maintenance of an appropriate backfat thickness value, VRTN has the potential to act as a genetic marker of IMF.     

The effect of Eucommia ulmoides leaf supplementation on the growth performance, blood and meat quality parameters in growing and finishing pigs

The aim of the present study was to investigate the effect of Eucommia ulmoides leaf (EUL) supplementation on the growth performance, blood and meat quality parameters in growing and finishing pigs. Ninety gilts (L × LW × D, 20 kg initialBW) were housed 10 per pen in a front‐open building with three replicate pens per treatment. Experimental treatment was started from the beginning of the growing stage (20 ± 3 kg) by supplementing EUL at 0(C), 3(T1) and 5% (T2) to the growing and finishing diet. Pigs were slaughtered by electrical stunning at 105 ± 3 kg live weight. Average daily feed intake (ADFI, kg/day) decreased (P < 0.05) by addition of EUL in growth performance, average daily gain (ADG, kg/day) was lower (P < 0.05) in T1 and T2 than in C. In hematology, leukocytes (WBC, 10³/mm³) decreased (P < 0.05) in T1 and T2 than in C. Erythrocytes (RBC, 10⁶/mm³), hemoglobin (HGB, g/dL) and hematocrit (HCT, %) increased (P < 0.05) in T1 and T2 than in C. Platelet (PLT, 10³/mm³) was lower (P < 0.05) in T2 than in C and T1. In biochemical composition of serum, total protein (g/dL), r‐GTP (μ/L), total cholesterol (mg/dL) and triglycerides (mg/dL) were lower (P < 0.05) in T1 and T2 than in C. On longissimus dorsi muscle, crude protein was higher (P < 0.05) in T1 than in C. Crude ash was higher (P < 0.05) in T1 and T2 than in C. Yellow to blue color scale (CIE b*) in meat color was higher (P < 0.05) in T2 than in C. CIE b* in back fat color was higher (P < 0.05) in T2 than in the other treatments. In sensory evaluation scores for fresh meat, the values of meat color, fat color, drip loss and marbling were not significantly affected by addition of EUL. In cooked meat, the values of chewiness and overall acceptability were higher (P < 0.05) in T1 and T2 than in C. The results indicate that the addition of EUL affected growth performance, blood parameters and meat quality parameters in growing and finishing pigs.     

Litter Size and Vagina–cervix Catheter Penetration Length in Gilts

As in other species, the reproductive tract in pigs increases in size with age and body weight, and the development of the reproductive tract depends on a balance between development of the pituitary–ovarian axis and the influence of metabolic hormones. Two experiments were conducted in prepubertal Duroc gilts, 150–180 days of age, to determine whether litter size is related to vaginal–cervix catheter penetration length during insemination. In experiment 1, oestrus was induced in 452 gilts with a combined dose of 400 IU Pregnant Mare Serum Gonadotrophine (PMSG) + 200 IU human chorionic gonadotropin (hCG). The gilts were classified into three catheter penetration length groups: Ih, ≤ 21 cm; IIh, > 21 and < 28 cm; IIIh, > 28 cm. The litter size was lowest in group Ih (7.35 ± 0.15) compared with groups IIh (7.81 ± 0.12; p < 0.05) and IIIh (10.0 ± 0.36; p < 0.001). In experiment 2, first oestrus was induced in 162 gilts by boar exposure. The gilts were classified into three catheter penetration length groups at insemination during their second oestrus: In, ≤ 24 cm; IIn, > 24 and < 26 cm; IIIn, > 26 cm. As in experiment 1, the litter size was lowest in the group with the shortest catheter penetration length (8.32 ± 0.19). The litter size was not different among gilts of groups IIn and IIIn (8.84 ± 0.35 and 9.56 ± 0.46, respectively), but litter size was lower (p < 0.05) in group In than in group IIn. Based on the combined data from both experiments, the correlation between the catheter penetration length and total number of piglets born was expressed as: y=5.346 ± 0.104x; r=0.361 (p < 0.05). Fertility rate was not different among the groups of gilts induced into oestrus by hormone treatment or inseminated in the second oestrus; however, the total fertility rate of boar‐exposed gilts was higher (p < 0.0001) than PMSG/hCG treated animals. Thus, it is possible to conclude that litter size at first farrowing is associated with vaginal–cervix catheter penetration length during insemination of the gilt.     

Effect of VRTN gene polymorphisms on Duroc pig production and carcass traits,and their genetic relationships

The thoracic vertebral number is associated with body length and carcass traits, and represents one of the most important traits in the pig industry. Recent studies have shown that vertnin (VRTN) gene is associated with variations in the vertebral number in commercial European pigs. However, the genetic relationships and effect of this VRTN gene in pig production and carcass traits remain uncertain. Therefore, we investigated the genetic relationships among traits such as vertebral numbers, carcass weight and length‐related traits, and meat production traits, and the effect of VRTN gene polymorphisms on these traits in a Duroc purebred population selected for its meat production traits. Highly positive genetic correlations were obtained between the thoracic vertebral numbers and length‐related traits (0.56 to 0.84), whereas low correlations were obtained with production traits and carcass weight (?0.16 to 0.05). VRTN gene polymorphisms indicated that the number of thoracic vertebrae and length‐related traits were significantly associated with the VRTN genotype, but had no significant effect on production traits and carcass weight. The results indicate that VRTN gene may be used as an effective selection marker to obtain pigs with high thoracic vertebral numbers and length‐related traits, without adversely affecting meat production traits.     

Effects of Chinese traditional herbal medicine complex supplementation on the growth performance,immunity and serum traits of pigs

The purpose of this study was to investigate the effects of a traditional Chinese herbal medicine complex supplementation on the growth performance, immunity and serological traits of pigs, and the feasibility of its use as a substitute for antibiotics. Thirty‐six weaned pigs LYD with average initial body weight of 10 ± 0.55 kg were randomly divided into three treatments with three replicates. These constituted the control, the antibiotics group (chlortetracycline 100 µg/kg, oxytetracycline 100 µg/kg), and 0.3% Chinese herbal medicine complex group (CHM). Experiment results indicated that the CHM group exhibited significantly increased average feed intake and peripheral blood CD3⁺CD8⁺ T cell percentage as compared with those of the antibiotics group (P < 0.05). High‐density lipoprotein (HDL) level was greater while low‐density lipoprotein + very low‐density lipoprotein (LDL + VLDL) level was lower in the CHM group than the control group (P < 0.05). The in vitro results indicated that peripheral blood mononuclear cells (PBMC) stimulated by Con‐A produced a greater interleukin (IL)‐6 level in the CHM group and IL‐6 level stimulated by lipopolysaccharide was greater than the antibiotics groups (P < 0.05). Above all, this study has indicated that the addition of Chinese traditional herbal complex to pigs' diets has beneficial results.     

Effects of amino acids supplementation in low crude protein diets on growth performance,carcass traits and serum parameters in finishing gilts

This study investigated the effects of amino acids (AA) supplementation in low crude protein (CP) diets on growth performance and carcass characteristics in finishing gilts. One hundred and eighty gilts (59.1 ± 5.1 kg) were randomly allotted to one of five diets which consisted of a high CP (15.6%) diet or four low CP (11.6%) diets for 50 days. The low CP diets were supplemented with lysine + threonine + methionine (LCM), LCM + tryptophan (LCT), LCT + valine (LCV) or LCV + isoleucine (LCI), respectively. Gilts were housed at six pigs per pen with six pens per treatment. At the end of the 50‐day experiment, 30 gilts (one pig per pen) with average body weight (BW) of 98 kg were killed to evaluate carcass traits. The pigs fed the diet supplemented with LCV obtained the highest average daily gain (ADG), which was higher than those of pigs fed the diet supplemented with LCM (P < 0.05). Dietary supplementation with tryptophan, valine and isoleucine in low CP diets increased ADG (linear and quadratic effect, P < 0.05), serum levels of valine (quadratic effect, P < 0.05) and isoleucine (linear and quadratic effect, P < 0.05) and immunoglobulin G (IgG) and IgA (linear and quadratic effect, P < 0.05) in finishing gilts. © 2016 Japanese Society of Animal Science     

Association of a single nucleotide polymorphism in the 5' upstream region of the porcine myosin heavy chain 4 gene with meat quality traits in pigs

We identified a potential molecular marker associated with meat quality traits in the myosin heavy chain 4, MYH4 gene of Landrace pigs. Sequencing revealed a single nucleotide polymorphism (SNP; g.‐1398G>T) in the 5' upstream region of MYH4. It was significantly associated with the number of type IIa muscle fibers and water‐holding capacity based on filter‐paper fluid uptake. The GG genotype groups had a greater number of type IIa fibers and a larger area composed of type IIa fibers than the other genotype group (P = 0.004 and P = 0.061, respectively). Expression level of MYH4 gene in the genotype TT or GT was higher than in genotype of GG (P < 0.0001). The T allele may enhance expression level of MYH4 gene and then the portion of IIb type fiber in the muscle be increased by the T allelle. Therefore, we suggest that the g.‐1398G>T in the 5' upstream region of the porcine MYH4 may be used as a molecular marker for meat quality traits, although its functional effect is not defined yet.     

Hepatic Ethoxy‐, Methoxy‐ and Pentoxyresorufin O‐Dealkylase Activities in Landrace and Duroc Pigs Stimulated with hCG

The effect of human chorionic gonadotropin (hCG) stimulation on the activities of ethoxyresorufin O‐deethylase (EROD), methoxyresorufin O‐demethylase (MROD) and pentoxyresorufin O‐depentylase (PROD) was studied in intact male pigs of purebred Landrace and Duroc breeds. Pigs were divided into four groups: two control groups of each breed, without hCG stimulation (n = 20 for each breed), and two experimental groups (n = 18 for each breed), with hCG stimulation (Pregnyl^®; N.V. Organon, Oss, The Netherlands, 30 IU/kg live weight). Pigs were slaughtered 3 days after hCG stimulation and enzyme activities were measured in hepatic microsomes using two approaches. First, only one substrate concentration was used for the analysis of each enzyme activity. We found that EROD activity was suppressed by hCG‐stimulation in Landrace (p = 0.004), but not Duroc pigs (p > 0.05). Generally, EROD activity was higher in Duroc pigs compared with Landrace (p = 0.017). Methoxyresorufin O‐demethylase and PROD activities did not differ between groups (p > 0.05). To further characterize EROD, MROD and PROD, enzyme kinetic studies were performed. V_max values for EROD and MROD in both breeds were lower after hCG stimuation (p < 0.001 for Landrace and p < 0.05 for Duroc). Additionally, V_max values for EROD significantly differed between Landrace and Duroc pigs being higher in Duroc pigs (p < 0.05). We concluded that both hCG stimulation and breed differences may be important in the regulation of EROD and MROD activities. This study provides the first data on the effect of hCG stimulation and thus high testicular steroids, on EROD, MROD and PROD activities. Further studies are needed to investigate individual CYP450 enzymes and their regulation in porcine tissues.     

No major effect of the leptin gene polymorphism on porcine production traits

Porcine leptin gene (LEP) and its association with production traits was analysed in the Polish Large White (PLW, n = 135), Polish Landrace (PL, n = 120) and synthetic line 990 (L990, n = 184). Two fragments of exon 3 of LEP were studied with the use of RFLP and SSCP techniques. The frequencies of C allele for the T3469C polymorphic site were 0.11, 0.10 and 0.11 in PLW, PL and L990, respectively. Phenotypic data were collected for the average daily weight gain, the feed conversion ratio, the weight of abdominal fat, backfat thickness (five measurements), intramuscular fat, meat content, loin weight, loin muscle area, ham weight and ham cut weight. The contrasts between TT and TC genotypes at the T3469C polymorphic site were estimated in the unitrait Animal Model with genotype at the RYR1 locus included. The lowest p values occurred for association test between T3469C polymorphism and intramuscular fat content in PLW (0.26 ± 0.14%, p = 0.05) and loin weight in L990 (?0.32 ± 0.13 kg, p = 0.01). We conclude that the detected associations are population‐specific and the analysed polymorphism of the LEP gene does not contribute directly to genetic variability of growth and carcass traits in pigs.     

Effects of an immune stimulant,inactivated Mycobacterium phlei,on the growth performance as well as meat quality of fattening pigs

Inactivated mycobacterium phlei (M. phlei) is well known for its immune‐stimulatory functions in humans and livestock, but less information is available about the influence on meat quality of pigs when used as a feed additive. This study was designed to evaluate the effects of inactivated M. phlei on growth performance as well as meat quality of fattening pigs. A total of 240 cross‐bred pigs ([Landrace × Yorkshire] × Duroc) with initial body weight of 80.14 ± 0.29 kg were randomly allocated to five treatments, each of which consisted of eight replicates with 6six pigs per replicate. The basal diet supplemented with five levels of inactivated M. phlei preparations (0, 3.5 × 10⁹ [0.1% w/w], 7 × 10⁹ [0.2%], 1.4 × 10¹⁰ [0.4%] or 2.1 × 10¹⁰ [0.6%] colony‐forming units/kg) was respectively fed to the control group and four treatment groups for 30 days. Adding 0.4% of inactivated M. phlei to diet increased the average daily feed intake and average daily gain of pigs. Importantly, intramuscular fat percentage in the Longissimus dorsi (LD) was increased by feeding diet containing 0.2%, 0.4% and 0.6% of inactivated M. phlei, despite the pH value, drip loss, cooking loss and filter paper fluid uptake not being influenced. Analysis of the fatty acid components showed that some saturated fatty acids were decreased in LD after feeding inactivated M. phlei, but some monounsaturated fat acids (MUFAs) and polyunsaturated fatty acids were increased (PUFAs), which induced the total contents of MUFAs and PUFAs were improved. RT‐PCR assay revealed that feeding inactivated M. phlei up‐regulated genes implicated in fat metabolism in muscle, including ELOVL6, FASN, SCD1 and H‐FABP. This study revealed that feeding inactivated M. phlei not only increased growth performance of fattening pigs, but also improved the meat quality by increasing intramuscular fat content, thus inactivated M. phlei probably has high utilization value in modern pig production.