Transfer of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and polychlorinated biphenyls (PCBs) from oral exposure into cow's milk - part II: toxicokinetic predictive models for risk assessment.

Understanding the transfer of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) as well as polychlorinated biphenyls (PCBs) from oral exposure into cow's milk is not purely an experimental endeavour, as it has produced a large corpus of theoretical work. This work consists of a variety of predictive toxicokinetic models in the realms of health and environmental risk assessment and risk management. Their purpose is to provide mathematical predictive tools to organise and integrate knowledge on the absorption, distribution, metabolism and excretion processes. Toxicokinetic models are based on more than 50 years of transfer studies summarised in part I of this review series. Here in part II, several of these models are described and systematically classified with a focus on their applicability to risk analysis as well as their limitations. This part of the review highlights the opportunities and challenges along the way towards accurate, congener-specific predictive models applicable to changing animal breeds and husbandry conditions.

[Chronic oversupply with copper as a potential herd health problem on a German dairy farm - Diagnostic value of different sample types for assessment of copper supply in dairy cows]. / Chronische Kupferüberversorgung als mögliches Bestandsproblem in einer deutschen Milchviehherde.

In contrast to sheep, chronic copper oversupply or toxicity represent infrequent events in cattle. This case report describes a chronically elevated exposure to copper arising from excessive supplementation of mineral feedstuff leading to a herd health problem in a German Holstein dairy herd. For diagnosis on herd level, 10 cows of both the close-up (VB) and high-yielding (HL) groups were selected and blood as well as urine samples were collected. Clinical chemistry investigation of these samples only revealed slightly raised activities of liver enzymes in cows of the HL group. Analysis of the total mixed ration (TMR) of both groups revealed a significant oversupply with copper, zinc, cobalt, and selenium. On the basis of these findings, the copper content of urine, feces, pigmented hair as well as plasma ceruloplasmin activity were measured additionally. Liver biopsies were performed in cows of the HL group and in heifers, the latter of which had received a mineral feed for young cattle according to the manufacturer's instructions. Results indicated increased fecal copper in both HL and VB groups as well as above normal or high-normal values of hepatic copper and cobalt resp. selenium, zinc, and manganese in the HL cows. In contrast, heifers had physiological amounts of trace elements in their liver tissues. This report demonstrates the suitability of fecal analysis and TMR for a reliable assessment of copper supply, while blood, urine, and hair failed to represent appropriate sample types. In order to attain a dependable diagnosis of potential copper oversupply, a liver biopsy - which may also be performed in buiatric practice - is deemed necessary.

Fermentable fiber ameliorates fermentable protein-induced changes in microbial ecology, but not the mucosal response, in the colon of piglets.

Dietary inclusion of fermentable carbohydrates (fCHO) is reported to reduce large intestinal formation of putatively toxic metabolites derived from fermentable proteins (fCP). However, the influence of diets high in fCP concentration on epithelial response and interaction with fCHO is still unclear. Thirty-two weaned piglets were fed 4 diets in a 2 × 2 factorial design with low fCP/low fCHO [14.5% crude protein (CP)/14.5% total dietary fiber (TDF)]; low fCP/high fCHO (14.8% CP/16.6% TDF); high fCP low fCHO (19.8% CP/14.5% TDF); and high fCP/high fCHO (20.1% CP/18.0% TDF) as dietary treatments. After 21-23 d, pigs were killed and colon digesta and tissue samples analyzed for indices of microbial ecology, tissue expression of genes for cell turnover, cytokines, mucus genes (MUC), and oxidative stress indices. Pig performance was unaffected by diet. fCP increased (P < 0.05) cell counts of clostridia in the Clostridium leptum group and total short and branched chain fatty acids, ammonia, putrescine, histamine, and spermidine concentrations, whereas high fCHO increased (P < 0.05) cell counts of clostridia in the C. leptum and C. coccoides groups, shifted the acetate to propionate ratio toward acetate (P < 0.05), and reduced ammonia and putrescine (P < 0.05). High dietary fCP increased (P < 0.05) expression of PCNA, IL1ß, IL10, TGFß, MUC1, MUC2, and MUC20, irrespective of fCHO concentration. The ratio of glutathione:glutathione disulfide was reduced (P < 0.05) by fCP and the expression of glutathione transferase was reduced by fCHO (P < 0.05). In conclusion, fermentable fiber ameliorates fermentable protein-induced changes in most measures of luminal microbial ecology but not the mucosal response in the large intestine of pigs.