Effect of dietary fiber on methane production in Chinese Lantang gilts

The objective of this study was to determine the effect of dietary fiber on methane (CH₄) production in pigs using the Chinese native Lantang gilts as study model. The study consisted of two experiments. In the first, 12 Lantang gilts (58.7±0.37 kg), individually housed in open-circuit respiration chambers were randomly divided into two groups (six replicates per dietary group) and fed either with low fiber diet [LFD; neutral detergent fiber (NDF)=201.5 g/kg] or high fiber diet (HFD; NDF=329.7 g/kg). Wheat bran was the main source of fiber for the LFD while ground rice hull (mixture of rice bran and rice hull) was used in the HFD. Results of the study showed that gilts fed LFD recorded higher (P<0.05) digestibility coefficients for dry matter (DM), total organic carbon (TOC), acid detergent fiber (ADF) and cellulose than those in the HFD. However, digestibility coefficient for NDF did not differ between treatments but that for hemicellulose was higher for HDF than for LDF. Because of the higher NDF and hemicellulose contents in the diet, pigs in the HFD recorded higher (P<0.05) amount of digested NDF (126.1 vs. 83.6 g/d) and hemicellulose (38.7 vs. 11.9 g/d) than those fed LFD. The higher amount of digested NDF and hemicellulose recorded for the HFD treatment was inconsistent with the lower (P<0.01) daily CH₄ production from gilts fed the HFD compared to that fed LFD (2.46 vs. 3.90 L/pig). To better explain for the unexpected higher CH₄ production from pigs fed LFD, an in vitro fermentation study was conducted using a factorial design comprised of two inocula (collected from low fiber and high fiber diets) and eight substrates (LFD, HFD, wheat bran, ground rice hull and their respective NDF residues). Results of the in vitro trial seems to suggest that the low CH₄ production from the HFD animals was primarily the results of low fermentation rates of HFD and the ground rice hull. However, the calculated CH₄ productions based on the molar percentage of volatile fatty acids (VFA) in both, in vivo and in vitro experiments reaffirmed the in vivo result, that is, CH₄ production from pigs fed HFD was lower than that fed LFD. Although there is a lack of scientific data from this study to fully explain for the unexpected lower CH₄ production from pigs fed the HFD, our results seems to suggest that quantity of digested fiber (including NDF) was not the sole factor affecting enteric CH₄ production in pigs.     

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.     

Metabolic and microbial responses in western crossbred and Meishan growing pigs fed a high-fiber diet

Four Duroc x White composite crossbred (21.8 +/- 1.0 kg BW) and four 12-wk-old Meishan purebred (20.7 +/- 1.6 kg BW) growing barrows were used to determine the relative breed differences in metabolic and microbial responses to a high-fiber diet. The pigs were trained to consume 700 g of a diet containing 35% (as-fed basis) dehydrated alfalfa meal once daily. The pigs' daily intakes of DM, N, GE, NDF, and ADF were 610 g, 16.6 g, 2.64 Mcal, 150 g, and 88 g, respectively. On d 12 after surgical catheterization of the portal vein, ileal vein, and carotid artery, a 3-d total urine and feces collection was conducted. On d 24 after surgery, each pig was placed in an open-circuit calorimeter, and its catheters were connected to a system for simultaneous measurements of oxygen consumption by portal-drained viscera and by whole body, and the net portal absorption of VFA after a 24-h fasting and during a 5-h postprandial period. The VFA measured included acetic, propionic, isobutyric, butyric, isovaleric, and valeric acids. A second 3-d total urine and feces collection was conducted on d 30 after surgery. There were no differences (P = 0.13) between the first and second collections in apparent total-tract digestibility coefficients for nutrients and N retention of pigs. Compared with Duroc x White composite crossbred pigs, Meishan pigs had lower (P = 0.05) apparent digestibility coefficients for DM, N, NDF, hemicellulose, and N retention, but their portal-drained viscera used a greater (P = 0.05) fraction of whole-body oxygen consumption. No differences (P = 0.12) were found between Duroc x White composite crossbred and Meishan pigs in total viable bacteria and cellulolytic bacteria from fecal samples, in vitro digestibility of alfalfa NDF fractions by fecal inocula, whole-body oxygen consumption, net portal absorption of VFA, total energy of absorbed VFA, and the potential of absorbed VFA for meeting the energy needs for whole-body heat production. These results indicate that, in contrast to previous beliefs, the ability of Meishan growing pigs to utilize a high-fiber diet is not superior to that of Duroc x White composite crossbred growing pigs.     

品种、体重和营养对猪背最长肌肌纤维组织学特性的影响

选用荣昌(RC)猪和杜×长×大(DLY)杂交猪为试验对象,研究猪背最长肌肌纤维直径和密度的发育性变化及品种与营养影响特点。结果表明:2个品种猪的背最长肌肌纤维直径和密度的发育规律较为类似,肌纤维直径随体重增加呈线性增长,而肌纤维密度则随体重增加呈乘幂方程式降低。相关分析表明,肌纤维密度与直径均存在极显著负相关(P≤0.003)。背最长肌肌纤维直径和密度在20～50kg阶段品种间差异不显著(P≥0.099),但在80kg,RC猪的肌纤维直径显著低于DLY猪(P=0.0043),而RC猪的肌纤维密度则显著高于DLY猪(P=0.0049)。饲粮营养水平对2个品种猪背最长肌的肌纤维直径和密度均无显著影响。以上结果提示,2个品种猪的背最长肌肌纤维的生长规律较为类似,但不同品种的肌纤维直径存在差异,主要表现在80kg,RC猪显著低于DLY猪,可能与其优良肉质有关。     

Nutrient digestibility, blood profiles and fecal microbiota are influenced by chitooligosaccharide supplementation of growing pigs

This study was conducted to evaluate the effects of dietary chitooligosaccharide (COS) supplementation on growth performance, nutrient digestibility, blood profiles and fecal microbiota in growing pigs. A total of 144 [(Landrace × Yorkshire) × Duroc] pigs with an initial body weight of 23.6 ± 1.1 kg were allotted to one of the following dietary treatments: 1) basal diet; 2) basal diet with 44 mg/kg of tylosin (100 mg/kg tylosin); 3) basal diet with 5 g/kg of COS and 4) basal diet with 5 g/kg COS and 44 mg/kg tylosin. There were nine replications per treatment with four pigs per pen. Throughout the experiment, pigs that were treated with a combination of COS and tylosin had a lower ADFI (P = 0.02) and higher gain/feed ratio (P < 0.05) than the other treatments. In addition, administration of either COS or tylosin alone significantly increased the digestibility of dry matter, nitrogen and gross energy (P < 0.05). The red blood cell (RBC) and white blood cell (WBC) counts, as well as the serum albumin concentrations were not affected by COS or tylosin supplementation. However, the lymphocyte proportion and serum total protein concentration were increased in pigs fed tylosin supplemented diets compared with those pigs fed diets not supplemented with tylosin (P < 0.05). Administration of tylosin significantly increased serum IgG concentration (P = 0.02); however, treatment with COS or tylosin supplementation had no effect on the total cholesterol or triglyceride concentrations. The serum HDL cholesterol concentration was significantly increased in pigs treated with COS (P = 0.02) compared to the pigs fed diets without COS. The COS administration also decreased the number of fecal Escherichia coli (P < 0.01), whereas the number of fecal Lactobacilli was not influenced by either COS or tylosin administration. Results of the current study indicate that dietary supplementation of COS can improve nutrient digestibility and haematological profiles, as well as decrease of fecal E. coli populations in growing pigs.     

Effects of hCG Stimulation on Hepatic Activities of Cytochromes P4502E1 and P4502A in Pubertal Male Pigs

The effects of human chorionic gonadotropin (hCG) stimulation on fat skatole concentrations and hepatic activities of cytochromes P4502E1 (CYP2E1) and P4502A (CYP2A) were studied in Landrace and Duroc breeds of entire male pigs. Pigs were divided into four groups: two control groups of each breed, without hCG stimulation (n = 20 for each breed), and two experimental groups of each breed, with hCG stimulation (n = 18 for each breed). Pigs were slaughtered 3 days after hCG stimulation and activities of CYP2E1 and CYP2A were measured in liver homogenate. Activities of both CYP2E1 and CYP2A were lower in hCG‐stimulated pigs than control pigs for both Landrace (p = 0.005 for CYP2E1, p = 0.016 for CYP2A) and Duroc breeds (p = 0.003 for CYP2E1, p = 0.001 for CYP2A), and skatole concentrations in fat were higher in the hCG‐stimulated pigs of both breeds (p < 0.01). For both control and hCG‐stimulated groups, Duroc pigs had lower skatole concentrations than Landrace pigs (p = 0.001 for both groups). The activity of CYP2E1 did not differ significantly between breeds in either the control group or the experimental group (p = 0.233 for control pigs and p = 0.210 for experimental pigs). However, whereas CYP2A activity did not differ significantly between breeds in the control groups (p = 0.181 for CYP2A), in the hCG‐stimulated groups, CYP2A activity was lower in Duroc pigs than in Landrace (p = 0.011). Based on these findings, we conclude that hCG stimulation can suppress hepatic CYP2E1 and CYP2A activities, probably through an increase in the levels of testicular steroids. Between‐breed variations in skatole levels in fat were not related to the activities of CYP2E1 and CYP2A.     

Differential electrocardiographic study on Iberica and Duroc breeds of pig during physical maturation

Sequential electrocardiograms were taken of 50 pigs (25 Iberica and 25 Duroc), from the ages of 5 days to 205 days. The records were analysed to establish the normal values of the different electrocardiographic intervals (RR, QRS, QT, TQ and ST intervals), the diastole/systole quotient and heart score in the first 7 months of life, as well as age-related electrocardiographic variations. In addition, it was intended to determine which of these two breeds showed the greater heart recovery capacity. Finally, positive or negative correlations between the RR interval and the electrocardiographic incidents studied were analysed. The mean values obtained for the electrocardiographic parameters were similar in the two breeds and increased with their physical maturity. Analysis of the correlation between the duration of the heart cycle and the different electrocardiographic incidents showed a positive and significant correlation, the r-values being higher for the RR interval-TQ interval correlation. There was very little correlation between RR interval and heart score in Duroc pigs and practically no correlation between the RR interval and the QRS interval in either breed.     

Effects of Duroc, Meishan, Fengjing, and Minzhu boars on carcass traits of first-cross barrows.

Duroc, Meishan, Fengjing, and Minzhu boars were mated to crossbred gilts during two breeding seasons. From each sire breed group each season, six pens of approximately eight barrows each were slaughtered. A pen of pigs from each sire breed group was slaughtered at 7-d intervals from 168 to 203 d of age each season. Breed of sire effects were significant for all age-adjusted carcass traits except carcass length, fat thickness at the last rib, color score, and firmness score. At 184 d of age, Duroc crosses had the heaviest (P less than .05) slaughter and carcass weights; Minzhu crosses were lighter (P less than .05) than Meishan crosses but not lighter than Fengjing crosses. Differences among age-constant traits reflect differences in BW. After adjustment to a constant carcass weight of 78 kg, the three Chinese breeds had very similar carcass characteristics. Carcasses sired by Durocs had significantly less backfat and larger longissimus muscle area than carcasses sired by the Chinese breeds. Weight of each trimmed wholesale lean cut and their total weight were significantly higher for Duroc crosses than for Chinese crosses. Breed of sire means did not differ significantly for belly weight, but Duroc crosses had less (P less than .05) weight of leaf fat. Relative to Chinese crosses, longissimus muscles from Duroc crosses had more marbling (P less than .05). Sire breed groups did not differ significantly for color or firmness score. Pigs sired by Meishan, Fengjing, and Minzhu produced carcasses with significantly less lean content at a carcass weight of 78 kg than did pigs sired by Duroc.     

In vitro fermentation of various fiber and starch sources by pig fecal inocula

Freeze-dried ileal effluent (1% wt/vol) from cannulated pigs fed rice-based diets with the inclusion of either animal protein (CON), animal protein plus potato starch (PS), animal protein plus sugar beet pulp (SBP), or animal protein plus wheat bran (WB) was incubated anaerobically at pH 6.0 in fermenters containing 5% (wt/vol) fecal slurry comprising mineral salts medium and 50 g/L of fresh feces from pigs fed the same diets as the cannulated pigs. Samples were collected from the fermenters at 0, 2, 4, 12, 24, and 48 h during in vitro fermentation for measuring nonstarch polysaccharides (NSP), starch, and short-chain fatty acids (SCFA). Results showed that the major SCFA produced were acetate, propionate, and butyrate. The inclusion of soluble dietary fiber (diet SBP) caused the highest concentrations of acetate, propionate, butyrate, and total SCFA, whereas the increase in the production of propionate resulting from the addition of insoluble dietary fiber (diet WB) only occurred at the initial stages during 48 h in vitro fermentation. At all sampling occasions (except for 4 h), the levels of butyrate were increased (P < 0.01) by resistant starch compared with fiber sources, showing that a higher level of butyrate can be achieved through microbial fermentation by potato starch. Lowered (P < 0.05) butyrate concentrations were observed with diet WB during in vitro fermentation. With the inclusion of fiber sources, the energy originating from SCFA was similar to that from NSP disappearance, whereas the values were lower (P < 0.05) from NSP disappearance than for SCFA generated without fiber sources supplemented. We conclude that more substrate is available in ileal effluent with the addition of soluble dietary fiber, and an increased level of butyrate could be achieved through microbial fermentation by resistant starch.     

Use of refined potato (Solanum tuberosum L. cv. Gogu valley) protein as an alternative to antibiotics in weanling pigs

This study investigates the use of refined potato protein (RPP) obtained from the potato (Solanum tuberosum) tubers of “Gogu valley” for their antimicrobial properties and its effects on growth performance, apparent nutrient digestibility and microbial populations in feces and large intestine of weanling pigs. Pigs (n = 280; Landrace × Yorkshire × Duroc; average initial body weight of 5.96 ± 0.66 kg; 23 ± 3 d of age) were allotted on the basis of their body weight and sex to five dietary treatments (each treatment comprised of 4 replicate pens with 14 pigs in each) in a randomized complete block design. The dietary treatments were: PC (positive control; basal diet + 150 ppm apramycin sulfate and 10 ppm colistin sulfate), and RPP (basal diet added with 0, 200, 400 and 600 ppm RPP). The RPP showed in vitro antimicrobial activity and at the concentration of 150 ppm inhibited the growth of tested microbes (Staphylococcus aureus, Salmonella choleraesuis, Salmonella gallinarum and Escherichia coli). Pigs fed with antibiotic diet showed better growth performance and had lower populations of total bacteria, coliforms and Staphylococcus spp. in the feces and large intestine when compared with pigs fed RPP diets. Increasing the levels of RPP in diets linearly improved performance and reduced the populations of total bacteria, coliforms and Staphylococcus spp. in feces and contents of colon and rectum. The apparent fecal digestibility of DM, CP and apparent ileal digestibility of amino acids did not differ among pigs fed antibiotic and RPP diets. These results suggest that antibiotics were more effective in improving the performance of pigs, while feeding of RPP also improved the performance and reduced the harmful microbes being more effective at higher levels. Thus at higher levels RPP obtained from the potato tubers of Gogu valley can be a potential replacement of antibiotics in the feed of weanling pigs.     

Comparison of growth performances,carcass characteristics,and meat qualities of Okinawan indigenous Agu pigs and crossbred pigs sired by Agu or Duroc boar

Indigenous Okinawa Agu pigs are crossed with Large White × Landrace (WL) pigs to improve their meat production, but there is little information regarding the crossbreeding effects. The study aims to compare growth, carcass characteristics, and meat qualities of Agu pigs with those of WL crossbreeds with Agu sires (WLA) or Duroc sires (WLD). WLA pigs showed better growth performance and carcass characteristics and less intramuscular fat (IMF) contents than Agu ones, but they had higher fat deposition, smaller longissimus dorsi muscle area, and higher IMF contents than WLD pigs. Agu pigs showed higher water holding capacity than the other two breeds. The inner layer of Agu backfat contains higher and lower proportions of monounsaturated fatty acids (MUFA) and polyunsaturated fatty acid (PUFA), respectively, than that in WLD animals. WLA animals had intermediate values for the fatty acid content in the inner backfat, although MUFA contents were equal to those of Agu pigs. Fatty acid profiles in IMF were similar to those in the backfat. These results indicate that crossbreeding of Agu with WL pigs improves growth performance and carcass quality. Particularly, WLA pigs have higher IMF contents and MUFA concentrations and lower PUFA concentrations than WLD pigs.     

Silage preparation and fermentation quality of kudzu,sugarcane top and their mixture treated with lactic acid bacteria,molasses and cellulase

We studied silage fermentation of kudzu (KZ), sugarcane top (ST) and their mixtures treated with additives to be able to effectively use available local feed resources. The silages were prepared using KZ, ST, KZ 90% + ST 10%, KZ 80% + ST 20%, KZ 70% + ST 30% and KZ 60% + ST 40%, based on fresh matter (FM). These silages were treated with 10⁸ colony‐forming units/g epiphytic lactic acid bacteria (LAB), 5% molasses and 0.02% cellulase of FM. The KZ contained higher crude protein (CP; 14.52%) content and lower levels of neutral detergent fiber (NDF; 62.15%) than those of ST (6.84% CP and 64.93% NDF) based on dry matter (DM). The KZ 60% + ST 40% silage fermented well with a higher (P < 0.05) lactic acid content and lower (P < 0.05) pH than those of the other mixed silages. Silages treated with molasses had lower (P < 0.05) ammonia‐N, NDF, acid detergent fiber, and hemi‐cellulose contents as well as pH, but higher (P < 0.05) DM, water‐soluble carbohydrate, and lactic acid contents, than those of the control, LAB and cellulase treatments. The results confirmed that KZ 60% + ST 40% was the best mixing ratio to prepare silage, and molasses improved silage fermentation and fiber degradation.     

Effects of different levels of dietary protein with or without plant extract YGF251 on growth performance,nutrient digestibility,blood profiles,fecal microbial shedding,and fecal gas emission in growing pigs

This experiment was conducted to evaluate the effects of plant extract YGF251 supplementation in different protein level diets on growth performance, nutrient digestibility, blood profiles, fecal microbial shedding, and fecal gas emission in growing pigs. A total of 144 pigs (24.72 ± 1.54 kg) were randomly assigned to the treatments in a 2 × 3 factorial arrangement of dietary protein levels (15.50%, 14.00% or 12.50%) and plant extract YGF251 levels (0 or 0.05%) with 6 replications per treatment and 4 pigs per pen. Pigs fed low protein diets had reduced average daily gain (p < 0.05) and increased feed conversion ratio (p < 0.01) compared with pigs fed high protein diets. The apparent total tract digestibility of nitrogen was decreased (p < 0.05) when reducing dietary protein level. Fecal ammonia and hydrogen sulfide emissions were reduced (p < 0.05) when reducing dietary protein level. In conclusion, the results of the current study indicated that reducing dietary protein level impaired growth performance and nitrogen digestibility but reduced ammonia and hydrogen sulfide emissions in growing pigs. Dietary supplementation with 0.05% herbal extract YGF251 was not effective in improving growth performance, nutrient digestibility, or in decreasing gas emission in different protein diets.     

不同品种猪肌肉组织miR-1和miR-133基因的表达分析

本研究旨在探讨猪miR-1和miR-133基因在不同品种猪肌肉组织中的表达情况。试验以180日龄的蓝塘猪、长白猪以及大花白猪的背最长肌为材料,采用Stem-loop实时定量RT-PCR法检测miR-1和miR-133在长白猪、大花白猪及蓝塘猪背最长肌组织中的表达情况。结果表明,在蓝塘猪中,miR-1的表达量分别为长白猪和大花白猪的4.7和6.4倍,前者与后两者之间表达水平有显著的差异(P<0.05),而后两者之间表达量差异不显著(P>0.05);同样,miR-133在蓝塘猪中的表达量最高,其次为长白猪,两者分别是大花白猪的7.2和5.7倍,且差异显著(P<0.05),但蓝塘猪与长白猪之间差异不显著(P>0.05)。miR-1和miR-133在不同品种猪中存在特异性表达,提示可能与肌肉发育性状相关。     

Genetic differences in serum-neutralization titers of pigs after vaccination with pseudorabies modified live-virus vaccine

Four-week-old pigs of the Chester White, Duroc, Hampshire, Landrace, and Yorkshire breeds (n = 518) were vaccinated with a pseudorabies modified live-virus vaccine to determine whether genetic differences existed for immune response after vaccination. All pigs and their dams (sows) were tested before vaccination to determine preimmunization antibody titers, using a microtitration serum-neutralization (SN) test. The SN test results of sows were negative, as were preimmunization tests of the pigs. At 4 weeks after pigs were vaccinated, additional blood samples were collected from the pigs, and end-point SN titers were determined, using a 2-fold dilution scheme. Small, but statistically significant, breed differences existed for antibody response, with Yorkshire and Chester White pigs having the highest response, and Duroc and Landrace pigs, the lowest. Differences among sire progeny groups were small, but there were significant differences among dams. Genetic differences as seen by differences among breeds indicates that the efficacy of vaccines may vary from breed to breed and that vaccine trials should not neglect this potential source of variation.     

In vitro and In vivo Association of Porcine Hepatic Cytochrome P450 3A and 2C Activities with Testicular Steroids

The aim of this study was to screen the inhibitory potential of several testicular steroids on cytochrome P450 3A (CYP3A) and 2C (CYP2C) activities in porcine liver microsomes. The microsomes used in this study were obtained from pubertal male pigs of two breeds, Landrace and Duroc. For the in vitro inhibition study, porcine microsomes were incubated in the presence of 17β‐estradiol, 17α‐estradiol, androstenone, dehydroepiandrosterone and dihydrotestosterone. Both reversible and mechanism‐based inhibitions were examined. 7‐benzyloxyresorufin (BR) and 7‐benzyloxy‐4‐trifluoromethylcoumarin (BFC) were used as substrates for CYP3A, and diclofenac and tolbutamide (TB) as substrates for CYP2C. 7‐benzyloxyresorufin O‐dealkylase (BROD) activity was inhibited by all tested steroids in the microsomes from Landrace pigs via mechanism‐based mode, but in the microsomes from Duroc pigs, BROD activities were inhibited only in the presence of 17β‐oestradiol. Mechanism‐based inhibition of BFC metabolism by the tested steroids was observed in the microsomes from both breeds, but this inhibition was weak and did not exceed 20%. TB hydroxylase (TBOH) activity in the microsomes from Duroc pigs was inhibited by 17α‐oestradiol through the mechanism‐based mode of inhibition. None of the investigated steroids inhibited TBOH activity in Landrace pigs. For the in vivo study, male pigs were injected with a single dose of human chorionic gonadotropin (hCG) to stimulate testicular steroid production by the Leydig cells. In vivo stimulation with hGC did not alter BROD activity either in Landrace or in Duroc pigs. BFC metabolism was significantly induced by hCG stimulation in both breeds and TBOH activity only in Duroc pigs. Activity of diclofenac hydroxylase was not detected in either Landrace or Duroc pigs. Breed significantly affected BROD and TBOH activity with BROD being higher in Landrace and TBOH in Duroc pigs. This study improved our understanding of the role of testicular steroids in the regulation of porcine CYP450 activity.     

猪骨骼肌发育过程中免疫相关基因的表达分析

为探究猪骨骼肌发育过程中免疫相关基因的表达模式以及相关生物学功能,本研究根据蓝塘猪和长白猪骨骼肌10个发育时期的转录组数据,对各时期免疫相关基因的表达数目和表达量进行分析,鉴定了相邻发育时期之间以及同一时期品种间差异表达的免疫相关基因,并对后者进行功能注释分析。结果表明:在蓝塘猪与长白猪骨骼肌发育过程中存在1 129个表达的免疫相关基因;胚胎期35 d和49 d、胚胎期91 d和生后期2d这2组相邻时期之间的差异表达免疫相关基因数目最多;品种间差异表达免疫相关基因数目则在胚胎期49d以及生后期180d最多,且趋向于在蓝塘猪上调表达,并富集在NIK/NF-κB信号传导、细胞凋亡的负调控等生物学过程中。本研究表明免疫相关基因在猪骨骼肌发育过程中存在表达,长白猪与蓝塘猪骨骼肌生长发育差异可能与NF-κB介导的细胞凋亡有关。     

Adjustment of pig or litter weights to a 21-day basis in Duroc, Landrace, and crossbred swine

A total of 457 Duroc, 137 Landrace, 131 Duroc x Landrace, and 110 three-and four-breed crossbred pigs were used to estimate multiplicative adjustment factors. Sixty-one Duroc, 24 Landrace, 18 Duroc x Landrace, and 16 three- and four-breed crossbred litters were weighed every 3 or 4 d from 13 to 30 d of age. Prediction equations for estimating pig weights from birth to 30 d and from 13 to 30 d of age are presented. Multiplicative adjustment factors for adjusting pig or litter weights to a 21-d basis for pigs or litters that are weighed between 13 and 30 d of age for different breeds and crossbred combinations are listed. Breed, litters within breed, and pigs within litter x breed effects adjusted for age at weighing were different (P less than .01). Quadratic regression coefficients of weight on age of pig from 13 to 30 d of age did not differ (P greater than .10) from zero for Landrace and three- and four-breed crossbred pigs but were significant for Duroc and Duroc x Landrace pigs.     

猪SLA-DRA基因外显子2多态性及其与仔猪腹泻的关联分析

为探索SLA-DRA基因作为猪抗病育种分子标记的可能性,本研究采用PCR-SSCP和克隆测序方法对大白、长白和杜洛克共216头猪的SLA-DRA基因外显子2进行了多态性研究,分析了该基因与仔猪腹泻的关联性。结果,在SLA-DRA外显子2上检出了3个等位基因和6种基因型;6种基因型(AA、AB、BB、AC、BC和CC)在大白猪和长白猪中都存在,而在杜洛克猪中只检出4种基因型(AA、BB、AB和BC)。杜洛克猪与大白猪和长白猪间基因型分布均差异极显著(P<0.01);3个品种的基因型分布均处于Hardy-Weinberg平衡状态(P>0.05)。最小二乘法分析表明,品种和性别对仔猪腹泻影响不显著(P>0.05),基因型与仔猪腹泻显著相关(P<0.05);AA和BB基因型个体腹泻评分的最小二乘均值均显著高于AC和CC基因型个体(P<0.05)。本研究表明,SLA-DRA基因不同基因型对仔猪腹泻有着重要的影响,可作为猪抗病育种应用中的一个潜在遗传标记。