Effect of oral administration of 3,3',4,4',5-pentachlorobiphyenl on the intestinal microbiota of Sprague–Dawley rats

The effect of the endocrine-disrupting chemical 3,3',4,4',5-pentachlorobiphyenl (PCB 126) on intestinal microbiota after oral administration, and the improvement of intestinal microbiota and feces quantity by the subsequent administration of Lactobacillus acidophilus or Lactobacillus reuteri was investigated. All the rats were given 100 μg/kg bodyweight of PCB 126. The changes in bacterial counts were confirmed using a culture method. The administration of PCB 126 tended to decrease the bacterial counts of lactobacilli (10^9.6−10^10.2 to 10^8.8−10^9.2) and bifidobacteria (10^5.3−10^6.1 to 10^3.6−10^4.2), and to increase those of Enterobacteriaceae (10^8.2−10^9.1 to 10^9.4−10^10.3) and staphylococci (10^6.6−10^7.4 to 10^7.2−10^8.4) compared to no PCB 126 administration. After administration of PCB 126, L. acidophilus or L. reuteri orally administered to rats caused Enterobacteriaceae and staphylococci counts to decrease, suggesting that the intestinal microbiota was improved by the lactobacilli. The administration of L. acidophilus and L. reuteri improved the balance of intestinal microbiota, and defecation volume returned to its normal level. L. acidophilus and L. reuteri have a remedial effect on intestinal microbiota affected by PCB 126 and can function to lessen accumulated PCB 126 volume.     

Genetic parameters for production traits and measures of residual feed intake in Duroc and Landrace pigs

Data on 380 Duroc boars from seven generations, and 1026 Landrace pigs (341 boars and 685 gilts) from six generations were used to estimate genetic parameters for daily gain (DG), backfat thickness (BF), metabolic weight (MWT), daily feed intake (FI), feed conversion ratio (FCR) and residual feed intake (RFI). Two measures of RFI were estimated as the difference between actual feed intake and that predicted from models that included initial test age and weight and DG (RFI1); and initial test age and weight, DG and BF (RFI2). Heritability estimates for DG, MWT and FI were moderate for both breeds. BF estimates were high for both the breeds. The measures of feed efficiency (FCR and RFI) were moderately heritable. Genetic correlations of BF with measures of RFI were stronger when BF was not included in the estimation of RFI (0.40 and 0.46 for Duroc and Landrace, respectively (for RFI1), compared with 0.05 and 0.06 for Duroc and Landrace, respectively (for RFI2)). Genetic correlations of MWT with measures of RFI were all negative and low. Genetic and phenotypic correlations between DG and measures of RFI were close to zero, which indicated that selection for reduced RFI could be made without adversely affecting DG. BF should also decrease, and MWT should increase under selection for reduced RFI. The reduction in BF would depend on the measure of RFI used.     

Changes in circulating adiponectin and metabolic hormone concentrations during periparturient and lactation periods in Holstein dairy cows

Although our previous report demonstrated that adiponectin and AdipoR1 gene expressions changed among different lactation stages in the bovine mammary gland, its in vivo kinetics remain unclear in ruminant animals. In this study, we investigated the changes in circulating concentrations of adiponectin, as well as other metabolic hormones and metabolites, (i) during the periparturient period and (ii) among different lactation stages, in Holstein dairy cows. In experiment 1, serum adiponectin concentrations increased after parturition. Serum insulin concentrations were lower in the postpartum than prepartum period, whereas serum growth hormone (GH) concentrations increased in the postpartum period. Serum nonesterified fatty acids (NEFA) levels were increased during the postpartum period and were dependent on the parity. In experiment 2, there was no significant difference in plasma adiponectin concentrations among lactational stages. Plasma insulin concentrations tended to be lower in early lactation while plasma GH levels tended to be higher. Plasma NEFA concentrations were significantly lower in mid‐ and late‐lactation stages than non‐lactation stages. These findings indicate that elevation of serum adiponectin might be involved in energy metabolism just around parturition, and might exert its action through regulation of receptor expression levels in target tissues in each lactational stage in Holstein dairy cows.     

Reproductive characteristics of the feral raccoon (Procyon lotor) in Hokkaido,Japan

Reproduction of feral raccoons (Procyon lotor) in Hokkaido, Japan, was examined during a 2-year period by analysis of placental scars or fetuses in the uterus. Of 242 collected females, 69 (29%) were juveniles, 71 (29%) yearlings, and 102 (42%) adults. The pregnancy rate averaged 66% in yearlings and was significantly lower than the 96% average observed in adults (p<0.01). Litter size ranged from 1 to 7 offspring per female, and averaged 3.6 in yearlings and 3.9 in adults. There was no significant difference in mean litter size between yearlings and adults. In Hokkaido, the raccoon mating season peaked in February and the majority of litters were born between March and May, similar to patterns described in North America, but some females mated in summer. The reproductive potential of feral raccoons in Hokkaido was similar to that reported in North America. The recent increase in raccoon numbers can be explained by their high productivity. Harvest data suggest that hunting pressure on juveniles is lower than that for older age classes when using box traps in summer. In order to reduce the feral raccoon population, alternative hunting methods that increase juvenile mortality rates are needed.     

Inhibition of growth hormone secretagogue receptor antagonist, [D-Lys-3]-GHRP-6, in adipogenesis of ovine and rat adipocytes

Ghrelin and growth hormone secretagogues receptor (GHS‐R or ghrelin receptor) have been reported as being one of the factors of adipogenesis in adipocytes. To investigate the involvement of ghrelin and GHS‐R in adipocytes, the effect of the GHS‐R antagonist, [D‐Lys‐3]‐GHRP‐6 (His‐D‐Trp‐D‐Lys‐Trp‐D‐Phe‐Lys‐NH₂), on the process of adipogenesis in ovine and rat adipocytes was evaluated. [D‐Lys‐3]‐GHRP‐6 (10^?7 mol/L) significantly inhibited adipogenic differentiation of ovine and rat preadipocytes prepared from adipose tissues. The level of peroxisome proliferator activated receptor (PPAR)‐γ2 mRNA, an adipogenic marker, was decreased during the differentiation of adipocytes treated with [D‐Lys‐3]‐GHRP‐6 for 10 days. Ghrelin stimulated adipogenesis, also causing an increment of glycerol‐3‐phosphate dehydrogenase and upregulation of PPAR‐γ2. Furthermore, the antilipolytic effect of ghrelin was attenuated by treatment with [D‐Lys‐3]‐GHRP‐6 in both types of isolated adipocytes. Overall, the results of the present study highlight that GHS‐R in adipogenesis can be blocked by treatment with [D‐Lys‐3]‐GHRP‐6.     

Heritability estimates of liabilities to digestive diseases in heavy racehorses

Data on 1410 heavy racehorses were taken from the Hokkaido Banei Horse Racing Result Book published during 1997–2000. Heritabilities were estimated using the restricted maximum likelihood method with a full data set of the accumulated prize winnings and the frequency of medical treatment against digestive diseases. Heritability estimates for the same traits were also obtained using a partial data set from affected animals only. In addition, a ‘two classes, one threshold’ model was applied to the full data set for the heritability estimation of liability to the diseases. Heritabilities estimated by restricted maximum likelihood with the full data set were quite low: 0.09 ± 0.02 for the prize winnings and 0.08 ± 0.03 for all three digestive diseases – colic resulting from flatulence, constipation and overfeeding. Low heritabilities were also estimated for each of the three kinds of colic. Medium heritabilities were estimated for colic resulting from constipation (0.30 ± 0.19) and overfeeding (0.46 ± 0.22) using the partial data set taken from the affected animals. Using the threshold model, higher heritabilities from 0.42 ± 0.04 to 0.57 ± 0.03 were estimated for the liabilities to all three digestive diseases and to the individual digestive diseases. These results suggest that liability evaluation of the frequency of medical treatment is insufficient because all non‐affected animals are scored as 0. The high heritabilities estimated by the threshold model with half‐sib relationships should be verified in future studies by comparing them with estimates from other genetic relationships and with realized heritabilities from a small‐scale practical selection program.