Multilocus sequence typing performed on Campylobacter coli isolates from humans, broilers, pigs and cattle originating in Denmark

AIMS: To assess whether Campylobacter coli isolated from different sources in Denmark constitute separate populations. METHODS AND RESULTS: Multilocus sequence typing (MLST) was applied to 160 C. coli isolates from animal origin, food products and human cases of gastroenteritis. The isolates were collected in Denmark over a 2-year period. In total, 84 sequence types (STs) were obtained and 57 of these STs were novel to this study. Ten per cent of the isolates possessed STs that were found in both human, poultry and pig isolates. Only 10% of the isolates from pigs shared ST with isolates from humans, and these shared STs were found in poultry isolates as well. CONCLUSIONS: Great genetic diversity was seen within the Danish C. coli population. Furthermore, we found that the C. coli types isolated from Danish pigs constitute a small fraction of the C. coli causing human disease. SIGNIFICANCE AND IMPACT OF THE STUDY: C. coli isolates from pigs is presumably not a significant source of human campylobacteriosis in Denmark. The Danish C. coli isolates include 68% STs novel to this study, showing a great diversity compared with studies from other countries.     

Breeding replacement gilts for organic pig herds

In this study, breeding structures and commercial sow lines were evaluated by economic and genetic simulation studies for their suitability to provide the Dutch organic pig sector with replacement gilts. Sow and litter performance from over 2000 crossbred sows from 2006 to 2007 were collected on 11 to 14 Dutch organic pig herds, respectively, and compared with conventional herds. Results showed that organic herds had lower farrowing rates (3.6% to 7.5%), more live born piglets per litter (0.4% to 1.2%) and higher preweaning mortality rates (7% to 13%) compared to conventional herds. These results were used to simulate economic performance of various combinations of breeding structures and sow lines under organic conditions, under the assumption of absence of genotype-environment interactions. Sow and litter performance data under organic conditions (total piglets born/litter, stillborn piglets/litter, mortality until weaning, lactation length, interval weaning-oestrus and sow culling rate) and the costprice calculation for the Dutch organic pig sector were used as input for the economic simulation studies. The expected genetic progress was simulated for three potential breeding structures of the organic sector: organic breeding herds producing F1 gilts (OrgBS), a flower breeding system (FlowerBS) and a two-line rotation breeding system (RotBS). In FlowerBS, an organic purebred sow line is bred, using on-farm gilt replacement. The OrgBS with a Yorkshire × Landrace cross had the highest margin per sow place (€779), followed by RotBS with Yorkshire × Landrace cross (€706) and FlowerBS with Yorkshire sow line (€677). In case that an organic purebred sow population of 5000 sows would be available, FlowerBS gave the highest genetic progress in terms of cost price reduction (€3.72/slaughter pig per generation), followed by RotBS and OrgBS (€3.60/slaughter pig per generation). For FlowerBS, additional costs will be involved for maintaining a dedicated breeding programme. In conclusion, OrgBS using conventional genetics is economically the most viable option for the organic pig sector. However, this structure has clear disadvantages in terms of risks with regard to disease transmission and market demand. FlowerBS using a dedicated purebred organic line will only be cost-effective if sow population size is sufficiently large. RotBS might be a viable alternative, especially in combination with artificial insemination (AI) boars that are ranked according to an organic selection index. Regardless of breeding structure, the Yorkshire sow line gave the highest prolificacy and the highest economic returns on organic herds.     

Integrated models of livestock systems for climate change studies. 2. Intensive systems

The potential impact of climate change by the year 2050 on intensive livestock systems in Britain is assessed through the use of simulation models of farming systems. The submodels comprise livestock feeding, livestock thermal balance and the thermal balance of controlled environment buildings and a stochastic weather generator. These are integrated to form system models for growing pigs and broiler chickens. They are applied to scenarios typical of SE England, which is the warmest region of the country and represents the worst case. For both species the frequency of severe heat stress is substantially increased, with a consequent risk of mortality. To offset this, it would be necessary to reduce stocking densities considerably, or to invest in improved ventilation or cooling equipment. Other effects on production are likely to be small.     

Detection of quantitative trait loci for androstenone, skatole and boar taint in a cross between Large White and Meishan pigs

'Boar taint' is a strong perspiration-like, urine-like unpleasant odour given off upon heating or cooking of meat from some intact (uncastrated) male pigs. Data from the F(2) generation of a Large White (LW) x Meishan (MS) crossbred population were analysed to detect quantitative trait loci (QTL) for traits associated with boar taint. Fat samples from 178 intact male pigs slaughtered at 85 +/- 5 kg were analysed for the major contributors to boar taint (androstenone, indole and skatole). Fat and lean samples from cooked meat were scored for boar, abnormal and pork flavour and odour by a trained sensory panel (SP). A scan with 117 markers covering the whole genome was performed in the F(2) individuals, together with their F(1) parents and purebred grandparents. At the 5% chromosomal significance threshold (approximately equal to the genome-wide suggestive significance threshold), QTL were detected for the laboratory estimate of androstenone on chromosomes 2, 4, 6, 7 and 9. However, only on chromosome 6 were there QTL for boar flavour (BF) traits in the same or adjacent marker intervals as a QTL for the laboratory estimate of androstenone. On chromosome 14, QTL were detected for the laboratory estimates of indole and skatole, the SP score for skatole and the scores for BF in lean and BF in fat. In all five cases, the MS allele generally increased the estimate or score, compared with the LW allele, but it appeared that desirable and undesirable alleles were present in both breeds. This locus on chromosome 14 has considerable potential for use to reduce the incidence of boar taint, especially if further research can identify the causative polymorphism or strongly associated markers.     

Effects of the MyoG Gene on the Partial Growth Traits in Pigs

Single-nucleotide polymorphisms of the MyoG gene were tested using PCR-SSCP in different pig breeds including Landrace, Large White, Duroc, Shanxi Black, and Mashen pigs, and the effects of the MyoG gene on the birth weight, the weaning weight, the 6-month body weight, and the backfat thickness were also analyzed. On the basis of the published sequence of the porcine MyoG gene, ten pairs of primers were designed, and one polymorphism was found in the PCR product amplified with In2-3 primers. The results showed that: (1) the Landrace, the Large White, and the Duroc breeds differ significantly (P < 0.05) in genotype distribution from the Shanxi Black and the Mashen breeds; (2) On the basis of the fixed effect model, significant differences were found in the birth weight and the backfat thickness among the different MyoG genotypes, whereas no significant differences existed in the weaning weight and the 6-month body weight; (3) Using least square analysis, it was seen that individuals of the BB genotype had significantly less (P < 0.01) birth weight than those of the AA and AB genotypes, with the order being AA>AB>BB; the pigs of the AA genotype had significantly lower (P < 0.01) backfat thickness than those of the AB and BB genotypes, with the order being AA<AB<BB. These results suggest that the genotype has significant effects on the individual birth weight and the backfat thickness, and that the selection of the A allele is favored with regard to the birth weight and the backfat thickness.     

Effect of rearing system and mixing at loading on transport and lairage behaviour and meat quality: comparison of outdoor and conventionally raised pigs

The effect of raising pigs outdoors or conventionally in a barren environment was investigated with respect to behaviour during a 3 to 4 h journey and a 2 h lairage, blood chemistry at slaughter and meat quality characteristics. Pigs were either kept in farm pen groups or were mixed at loading and kept in the groups, so formed, until slaughter. Non-mixed outdoor pigs settled more quickly during transport and lay down to a greater extent at the end of the journey and lairage period compared with conventionally raised pigs. Mixing led to fewer pigs sitting and lying during transport for conventionally raised pigs, where nearly 80% were still standing at the end of the journey. Mixing had no effect on pig posture in the lairage. Outdoor pigs were less aggressive than conventionally raised pigs especially during lairage and had a lower frequency of unacceptable skin damage in the rear and shoulder area. Aggressive interactions were almost exclusively confined to mixed groups and occurred mainly between pigs from different farm pens, i.e. between unfamiliar animals. Mixing at loading led therefore to higher levels of unacceptable skin damage. Cortisol concentrations in slaughter blood were not affected by rearing system or mixing, but mixed, conventionally raised pigs had higher plasma creatine kinase (CK) activities than non-mixed ones (1132 v. 761 U/l, respectively, P < 0.05). Outdoor pigs had similar CK activities, irrespective of mixing (682 and 771 U/l for mixed and non-mixed, respectively). Muscle pH early post mortem was highest in outdoor pigs and muscle temperature lower, but no pig showed pH values below 6.0. Ultimate pH values were both higher (Semimembranosus (S)) and lower (Semispinalis capitis (SC)) than in conventionally raised pigs, and outdoor pigs tended to have a lower frequency of higher than normal pH values. Internal reflectance (MQM) values in Biceps femoris (BF) were highest in outdoor pigs but the incidence of pale, soft and exudative (PSE) meat was low, varying between 0% and 1% for experimental groups. In general, the effects of rearing system and mixing on meat quality measurements taken early post mortem or the day after slaughter were slight, but the trends seen support the CK results, and show that conventionally raised pigs may have found mixing pre-slaughter to be more physically stressful than outdoor pigs did.     

Effect of dietary supplementation of different oils during the first or second half of pregnancy on the glucose tolerance of the sow

Poor glucose tolerance may be an under-researched contributory factor in the high (10% to 20%) pre-weaning mortality rate observed in pigs. Insulin resistance commences at around week 12 of gestation in the sow, although there are conflicting reports in the literature about the extent to which insulin resistance is modulated by maternal diet. The aim of the study was to determine the effects of supplementing the maternal diet with different dietary oils during either the first half or the second half of gestation on the glucose tolerance of the sow. Sows were offered the control (C: n = 5) diet as pellets or the C diet plus 10% extra energy (n = 16 per group) derived from either: (i) extra pellets; (ii) palm oil; (iii) olive oil; (iv) sunflower oil; or (v) fish oil. Experimental diets were fed during either the first (G1) or second (G2) half of gestation. A glucose tolerance test (GTT) was conducted on day 108 of gestation by administering 0.5 g/kg glucose i.v. Blood samples were taken every 5 to 10 min for 90 min post administration. The change in body weight and backfat thickness during gestation was similar but both type and timing of dietary supplementation influenced litter size and weight. With the exception of the sunflower oil group, supplementing the maternal diet in G1 resulted in larger and heavier litters, particularly in mothers offered palm oil. Basal blood glucose concentrations tended to be more elevated in G1 than G2 groups, whilst plasma insulin concentrations were similar. Following a GTT, the adjusted area under the curve was greater in G1 compared to G2 sows, despite no differences in glucose clearance. Maternal diet appeared to influence the relationship between glucose curve characteristics following a GTT and litter outcome. In conclusion, the degree of insulin sensitivity can be altered by both the period during which maternal nutritional supplementation is offered and the fatty acid profile of the diet.     

Genotype by environment interaction for litter size in pigs as quantified by reaction norms analysis

A Bayesian procedure was used to estimate linear reaction norms (i.e. individual G × E plots) on 297 518 litter size records of 121 104 sows, daughters of 2040 sires, recorded on 144 farms in North and Latin America, Europe, Asia and Australia. The method allowed for simultaneous estimation of all parameters involved. The analysis was carried out on three subsets, comprising (i) parity 1 records of 33 641 sows of line B, (ii) all parity records of 52 120 sows of line B and (iii) all parity records of 121 104 sows of lines A, B and A × B. Estimated heritabilities ranged from 0.09 to 0.10 (smallest to largest subset) for the intercept of the reaction norms, and were 0.15, 0.08 and 0.02 (ditto) for the slope. Estimated genetic correlations between intercept and slope were -0.09, +0.26 and +0.69 (ditto). The three subsets therefore showed a progressively lower genetic component to environmental sensitivity, and progressively less re-ranking of genotypes across the environmental (herd-year-season) range. In a genetic evaluation that does not include reaction norms in the statistical model, part of the G × E effect remains confounded with the additive genetic effect, which may lead to errors in the estimates of the additive genetic effect; the reaction norms model removes this confounding. The intercept estimates from the largest data subset show correlations with litter size estimated breeding values (EBV) from routine genetic evaluation (without reaction norms included) of 0.78 to 0.85 for sows with one to seven litter records, and 0.75 for sires. Hence, including reaction norms in genetic evaluation would increase the reliability of the EBV of young selection candidates without own performance or progeny data by considerably more than 100 × (1/0.75-1) = 33%. Reaction norm slope estimates turn out to be very demanding statistics; environmental sensitivity must therefore be classified as a 'hard-to-measure' trait.     

Developmental patterns of serum leptin levels, leptin gene expression in adipose tissue and Ob-Rb gene expression in hypothalamus of Erhualian and Large White pigs

~~Developmental patterns of serum leptin levels, leptin gene expression in adipose tissue and Ob-Rb gene expression in hypothalamus of Erhualian and Large White pigs~~     

雌性藏猪不同生长发育阶段肌肉生长和脂肪沉积相关基因的表达模式

本研究利用包含140个与猪肌肉生长和脂肪沉积密切相关基因的Oligo功能分类基因芯片检测了藏猪在2、4、6和8月龄间背最长肌中这些基因的表达量变化,并在2月龄时与脂肪型的太湖猪和瘦肉型的长白猪进行比较.ANOVA分析结果表明:2-8月龄间藏猪分别有10和 7个基因的表达差异达极显著(P<0.01)和显著水平(P<0.05);2月龄时藏猪体重极显著低于长白猪(P<0.01)和显著低于太湖猪(P<0.05),而藏猪肌纤维面积却为最大,但品种间差异未达显著水平(P>0.05);2月龄时3个品种间分别有15和13个基因的表达差异达极显著 (P<0.01)和显著水平(P<0.05).STEM聚类分析结果表明:直线下降和上升是藏猪在2 -8月龄间最具代表性的基因表达模式(P<0.01).另外,5个差异表达基因的荧光定量RT -PC R验证结果与基因芯片结果的Person相关系数平均高达0.856±0.109.提示:藏猪在2-8月龄间骨骼肌生长发育强度较肌内脂肪合成沉积占优势,2月龄时藏猪脂肪酸合成相关基因的表达水平较其他两品种低,而脂肪酸β氧化和肌纤维生长相关基因的表达水平较高,与其在高原独特的自然生态环境和全放牧散养的饲喂方式下长期形成的品种特性相符 [动物学报 54(3):442-452,2008].