Effects of dietary phytoestrogens on plasma testosterone and triiodothyronine (T3) levels in male goat kids

Background

Exposure to xenoestrogens in humans and animals has gained increasing attention due to the effects of these compounds on reproduction. The present study was undertaken to investigate the influence of low-dose dietary phytoestrogen exposure, i.e. a mixture of genistein, daidzein, biochanin A and formononetin, on the establishment of testosterone production during puberty in male goat kids.

Methods

Goat kids at the age of 3 months received either a standard diet or a diet supplemented with phytoestrogens (3 - 4 mg/kg/day) for ~3 months. Plasma testosterone and total and free triiodothyronine (T₃) concentrations were determined weekly. Testicular levels of testosterone and cAMP were measured at the end of the experiment. Repeated measurement analysis of variance using the MIXED procedure on the generated averages, according to the Statistical Analysis System program package (Release 6.12, 1996, SAS Institute Inc., Cary, NC, USA) was carried out.

Results

No significant difference in plasma testosterone concentration between the groups was detected during the first 7 weeks. However, at the age of 5 months (i.e. October 1, week 8) phytoestrogen-treated animals showed significantly higher testosterone concentrations than control animals (37.5 nmol/l vs 19.1 nmol/l). This elevation was preceded by a rise in plasma total T₃ that occurred on September 17 (week 6). A slightly higher concentration of free T₃ was detected in the phytoestrogen group at the same time point, but it was not until October 8 and 15 (week 9 and 10) that a significant difference was found between the groups. At the termination of the experiment, testicular cAMP levels were significantly lower in goats fed a phytoestrogen-supplemented diet. Phytoestrogen-fed animals also had lower plasma and testicular testosterone concentrations, but these differences were not statistically significant.

Conclusion

Our findings suggest that phytoestrogens can stimulate testosterone synthesis during puberty in male goats by increasing the secretion of T₃; a hormone known to stimulate Leydig cell steroidogenesis. It is possible that feedback signalling underlies the tendency towards decreased steroid production at the end of the experiment.     

Comparison of grass haylage digestibility and metabolic plasma profile in Icelandic and Standardbred horses

The aim of the present study was to compare digestibility and metabolic response in Icelandic and Standardbred horses fed two grass haylages harvested at different stages of maturity. Six horses of each breed were used in a 24‐day change‐over design. A total collection of faeces was made on days 15–17 and 22–24. Blood samples were collected on day 24 of each period and analysed for total plasma protein (TPP), plasma urea, non‐esterified fatty acids, cortisol and insulin concentration. There were no differences in digestibility coefficients of crude protein, neutral detergent fibre or energy between breeds but organic matter digestibility was higher in the Standardbred horses. On both haylages, the Icelandic horses gained weight whereas the Standardbred horses lost weight. The Icelandic horses had higher TPP, plasma insulin and lower plasma urea concentrations. Our results indicate that the Icelandic horse may be more prone to maintain positive energy balance in relation to the Standardbred horse, but there were no indication of a better digestive capacity in the Icelandic horses.     

Detection of Renibacterium salmoninarum in tissue samples by sequence capture and fluorescent PCR based on the 16S rRNA gene

The 16S rRNA genes from eight isolates of Renibacterium salmoninarum with different origins and dates of isolation were sequenced to evaluate the possibility to construct a diagnostic PCR system with target sites within this gene. The sequences were found to be identical but for one single position in one of the isolates, and two regions with an adequate number of nucleotide differences as compared to closely related species were identified. Species-specific fluorescent PCR primers complementary to these regions were constructed as well as oligonucleotides for DNA preparation by sequence capture. A mimic molecule was constructed to be used as an internal control. The PCR was specific and allowed the detection of DNA equivalent to 1-10 R. salmoninarum genomes per reaction. The DNA preparation with sequence capture and analysis by PCR with a mimic was found to be a reliable method for analysis of kidneys from fish with BKD. The amount of PCR inhibiting substances present in the tissue was reduced, and the relevant DNA was concentrated in the capture step. Furthermore, the use of the mimic molecule in the system assured that false negative results could be identified.     

Phenotypic and molecular characterization of Brachyspira spp. isolated from laying hens in different housing systems

Several species of intestinal spirochaetes, Brachyspira (B.) alvinipulli, B. intermedia and B. pilosicoli, may cause reduced egg production and faecal staining of eggshells in chickens. The aim of this study was to characterize potentially pathogenic and presumably non-pathogenic Brachyspira spp. from commercial laying hens. Selective culture, phenotyping, PCR and 16S rRNA gene sequencing were used and clinical data were collected. Phenotypic profiles were obtained for 489 isolates and 351 isolates obtained after subculture, and 30 isolates were selected for molecular characterization. Seven isolates were positive by a B. intermedia-specific PCR based on the nox gene, and two were positive in a B. hyodysenteriae-specific 23S rRNA gene based PCR. By comparative phylogenetic analysis in combination with PCR and phenotyping, seven isolates were identified as B. intermedia, eight isolates as B. innocens, five as B. murdochii, and three isolates each as B. alvinipulli and "B. pulli". The remaining four isolates could not be assigned to any presently recognized species. Co-infection with several species or genetic variants of Brachyspira spp. were detected in some flocks and samples, suggesting a high level of diversity. Organic flocks with access to outdoor areas were at higher risk (RR=2.3; 95% CI 1.5-3.6) for being colonized than chickens in other housing systems. No significant differences between colonized and non-colonized flocks were found regarding clinical parameters, i.e. mortality, egg production, faecally contaminated eggshells, and wet litter. Our results show that a combination of traditional laboratory diagnostics, molecular tests and phylogeny is needed for identification of Brachyspira sp. from chickens.     

Diagnosis of bacterial kidney disease by detection of Renibacterium salmoninarum by real-time PCR

Bacterial kidney disease (BKD), caused by Renibacterium salmoninarum (Rs), is a serious threat to salmon in aquaculture as well as to wild populations. We have developed a real-time polymerase chain reaction (PCR) for detection of Rs in kidney samples. The PCR is based on detection of unique parts of the 16S rRNA gene of Rs and DNA equivalent to 1-10 Rs genomes was detected per reaction. No cross-reactivity with other fish pathogenic or related bacteria could be demonstrated. Analysis of individual kidney samples collected from BKD classified populations identified 39.9% of the fish as positive by real-time PCR compared with 28.0% by polyclonal enzyme-linked immunosorbent assay (ELISA). The real-time PCR assay was found to be well suited for complementary use with ELISA for diagnosis of BKD, with the ability to detect clinical as well as covert Rs infections. The infection level determined by the polyclonal ELISA and by real-time PCR was significantly correlated.     

欧洲山杨叶片衰老与光周期候选基因SNPs的关联分析

利用自然更新的欧洲山杨群体,以光周期途径基因为候选基因,通过连锁不平衡作图,对候选基因中能够引起氨基酸改变的单核苷酸多态性(SNP)与欧洲山杨秋季叶片衰老相关指标进行关联分析.结果表明:光敏色素A中第291个核苷酸A和G的转换,导致了3个基因型叶片衰老指数有显著差异(P=0.018,经Bonferroni修正后,P=0.04);光周期候选基因中的SNP、叶片衰老持续时间基因型值间无显著差异,SNP与叶片衰老持续时间之间不存在线性相关;同样是光敏色素A中位于第291个核苷酸位点的3种基因型,其叶片衰老起始时间的基因型值差异显著,但是经Bonferroni修正后的显著水平P>0.05,差异又不显著,反映了欧洲山杨秋季叶片衰老起始时间的复杂性.     

Nutrient Concentrations of Catfish Feces and Practical Diets After Immersion in Water

A study was conducted to quantify changes in the proximate components of fish feces and feeds when immersed in water for varying time periods. Catfish feces, a floating catfish diet, and a sinking trout diet were immersed for 5, 10, 20, 40, or 80 minutes. Dry matter losses were noted for all samples after immersion in water. There was a disproportionate loss of crude protein, ash, and nitrogen free extract (NFE) from the catfish fecal samples, ash and ether extract from the floating catfish feed, and NFE from the sinking trout feed. The losses noted would change crude protein, ether extract, NFE, and energy digestion coefficients by less than 7%, but ash and crude fiber digestion coefficients could change by as much as 23 and 35%, respectively. The ash concentration of unimmersed catfish feces indicated that this component may be a reliable indicator of nutrient digestibility in catfish.     

Copper,Zinc and Molybdenum in Livers of Norwegian Cattle At Slaughter

The concentrations of copper, zinc and molybdenum were measured in samples of cattle liver from 10 slaughter-houses in Norway. A total of 335 samples were analysed. A clear accumulation of copper with age was found, the average copper level in the younger animals (≦ 3 years, n = 194) being 30 µg Cu/g liver wet weight, and in the older ones (> 3 years, n = 141) 59 µg Gu/g. The range in the copper values found was considerable, though significant differences between some of the districts were recorded. Copper concentrations were classified as low (≦10 µg Gu/g) in 9.6 % of the samples. Zinc showed no accumulation with age, nor were there any differences in zinc levels found in animals from different districts, the average level being 32 µg Zn/g liver wet weight. The picture was the same for molybdenum, no differences between age groups or districts being found. The average level was 1.0 µg Mo/g liver. There was no significant correlation between levels of copper, zinc or molybdenum.The supply of copper and zinc to cattle in Norway seems close to sufficient, but copper- and zinc-fortified mineral supplementation of cattle feed is still to be recommended. There seems to be no need for molybdenum supplementation in cattle.     

The Concentrations of Copper,Zinc and Molyrdenum in Swine Liver and the Relationship to the Distrirution of Solurle Copper- and Zinc-Rinding Proteins

The concentrations of copper, zinc and molybdenum were measured in liver samples from 21 normal slaughter pigs (average age about 6 months) and in 36 sows (average age about 2 years). The following mean values were found: Slaughter pigs: 15 ± 8 µg Cu/g, 45 ± 7 μg Zm/g and 1.0 ± 0.2 μg Mo/g wet weight; sows: 46 ± 70 μg Cu/g, 70 ± 26 μg Zn/g and 1.3 ± 0.3 μg Mo/g wet weight. The concentrations of all 3 elements were significantly higher in the sows than in the young pigs. There was no correlation between the concentrations of copper, zinc or molybdenum. The recorded copper levels in the slaughter pigs were in accordance with the levels of non-supplemented pigs given in the literature. The soluble hepatic copper- and zinc-binding proteins were separated into 3 different fractions by gel filtration. With increasing copper and zinc levels in the liver, a higher relative amount of these elements were found in the low molecular weight fraction.