BackgroundClostridium (C.) perfringens is the causative agent of several diseases in animals and humans, including histotoxic and enteric infections. To gain more insight into the occurrence of its different toxin-genotypes in dairy herds, including those toxin genes previously associated with diseases in cattle or humans, 662 isolates cultivated from feces, rumen content and feed collected from 139 dairy farms were characterized by PCR (detecting cpa, cpb, iap, etx, cpe, and both allelic variants of cpb2).ResultsIsolates from feces were assigned to type A (cpa positive, n = 442) and D (cpa and etx positive, n = 2). Those from rumen content (n = 207) and feed (n = 13) were all assigned to type A. The consensus and atypical variants of the cpb2 gene were detected in 64 (14.5 %) and 138 (31.22 %) of all isolates from feces, and 30 (14.5 %) and 54 (26.1 %) of all isolates from rumen content, respectively.ConclusionBoth allelic variants of cpb2 occurred frequently in animals without signs of acute enteric disease, whereby the atypical variant dominated. Five (0.8 %) of all type A isolates were positive for the cpe gene. Therefore, the present study indicates that dairy cows are no primary source for potentially human pathogenic enterotoxin gene positive strains.

BackgroundBovine erythrocytes undergo important changes in their morphology and chemical composition during the first weeks of age, which must be understood to accurately interpret hematology results in calves. The objectives of this prospective cohort study were to describe physiological changes of calf erythrocytes and to investigate mechanisms potentially causing these changes.MethodsBlood samples from 30 clinically healthy dairy calves were obtained from birth to the tenth week of age in weekly intervals. Hematological and plasma biochemical parameters as well as the mineral electrolyte content of erythrocytes were determined and followed over time. The changes of parameters characterizing the erythrocyte phenotype over time were compared to the changes of plasma and erythrocyte biochemical parameters and possible associations were investigated using correlation and stepwise regression analyses.ResultsAlthough the erythrocyte mean corpuscular volume (MCV) declined from 43.6 ± 3.7 fL to 35.6 ± 3.2 fL between the first and seventh week, the red blood cell count (RBC) increased from 7.2 ± 1.1 × 1012/L to 9.3 ± 1.0 × 1012/L until the fifth week of age. The blood hemoglobin (Hb) concentration increased from 0.96 ± 0.16 g/L to 1.16 ± 0.11 g/L in the first three weeks of age and remained at this level until the end of the study. Changes in MCV were accompanied by a decline of the erythrocyte potassium content (KERY) from 91.9 ± 13.5 to 24.6 ± 7.2 mmol/L and a concomitant increase of the erythrocyte sodium content from 45.0 ± 32.0 to 102.7 ± 26.5 mmol/L. MCV was found to be associated with KERY, the primary determinant of the intra-erythrocyte osmotic pressure from the sixth week of age and with blood hemoglobin, the primary determinant of the intra-erythrocyte oncotic pressure from the eighth week of age, when KERY, blood Hb and MCV already had reached or approached normal levels of adult cattle. The plasma iron concentration was not found to be associated to any of the studied hematological parameters.ConclusionA volume reduction of 20% in bovine neonatal erythrocytes is a physiological change occurring during the first weeks of age and is neither associated with sideropenia nor with anemia in healthy calves. The mechanism driving the observed erythrocyte volume change could not be identified. Results of the correlation and regression analyses indicate that changes in intra-erythrocyte osmotic or oncotic pressure are improbable underlying causes. Results reported here show that KERYis an unreliable indicator for the K homeostasis of the intracellular space in neonatal calves and that a decrease in MCV in early life per-se is an unreliable indicator for the development of microcytic anemia.

Sphingolipids are bioactive lipids that can modulate insulin sensitivity, cellular differentiation, and apoptosis in a tissue-specific manner. However, their comparative profiles in bovine retroperitoneal (RPAT) and subcutaneous adipose tissue (SCAT) are currently unknown. We aimed to characterize the sphingolipid profiles using a targeted lipidomics approach and to assess whether potentially related sphingolipid pathways are different between SCAT and RPAT. Holstein bulls (n = 6) were slaughtered, and SCAT and RPAT samples were collected for sphingolipid profiling. A total of 70 sphingolipid species were detected and quantified by UPLC-MS/MS in multiple reaction monitoring (MRM) mode, including ceramide (Cer), dihydroceramide (DHCer), sphingomyelin (SM), dihydrosphingomyelin (DHSM), ceramide-1-phosphate (C1P), sphingosine-1-phosphate (S1P), galactosylceramide (GalCer), glucosylceramide (GluCer), lactosylceramide (LacCer), sphinganine (DHSph), and sphingosine (Sph). Our results showed that sphingolipids of the de novo synthesis pathway, such as DHSph, DHCer, and Cer, were more concentrated in RPAT than in SCAT. Sphingolipids of the salvage pathway and the sphingomyelinase pathway, such as Sph, S1P, C1P, glycosphingolipid, and SM, were more concentrated in SCAT. Our results indicate that RPAT had a greater extent of ceramide accumulation, thereby increasing the concentration of further sphingolipid intermediates in the de novo synthesis pathway. This distinctive sphingolipid distribution pattern in RPAT and SCAT can potentially explain the tissue-specific activity in insulin sensitivity, proinflammation, and oxidative stress in RPAT and SCAT.

Metabolic consequences of an energy and protein rich diet can compromise metabolic health of cattle by promoting a pro-inflammatory phenotype. Laminitis is a common clinical sign, but affected metabolic pathways, underlying pathophysiology and causative relationships of a systemic pro-inflammatory phenotype are unclear. Therefore, the aim of this study was to elucidate changes in metabolome profiles of 20 months old Holstein bulls fed a high energy and protein diet and to identify novel metabolites and affected pathways, associated with diet-related laminitis. In a randomized controlled feeding trial using bulls fed a high energy and protein diet (HEP; metabolizable energy [ME] intake 169.0 ± 1.4 MJ/day; crude protein [CP] intake 2.3 ± 0.02 kg/day; calculated means ± SEM; n = 15) versus a low energy and protein diet (LEP; ME intake 92.9 ± 1.3 MJ/day; CP intake 1.0 ± 0.01 kg/day; n = 15), wide ranging effects of HEP diet on metabolism were demonstrated with a targeted metabolomics approach using the AbsoluteIDQ p180 kit (Biocrates Life Sciences). Multivariate statistics revealed that lower concentrations of phosphatidylcholines and sphingomyelins and higher concentrations of lyso-phosphatidylcholines, branched chain amino acids and aromatic amino acids were associated with an inflammatory state of diet-related laminitis in Holstein bulls fed a HEP diet. The latter two metabolites share similarities with changes in metabolism of obese humans, indicating a conserved pathophysiological role. The observed alterations in the metabolome provide further explanation on the underlying metabolic consequences of excessive dietary nutrient intake.

Botulism caused by neurotoxins of Clostridium (C.) botulinum is a rare, but serious life-threatening disease in humans and animals. Botulism in livestock is usually caused by the oral uptake of C. botulinum neurotoxins (BoNT) via contaminated feed and is characterized by flaccid paralysis. In the recent past a new syndrome caused by BoNT in dairy cattle was postulated. It was supposed that C. botulinum is able to colonize the lower intestine and may subsequently produce neurotoxin. The continuous resorption of small amounts of these BoNT may then provoke the so called syndrome of "chronic" or "visceral" botulism involving unspecific clinical symptoms, reduced performance of dairy cows and massive animal losses in the affected herd. To test this hypothesis a case-control study was conducted involving 92 affected farms and 47 control farms located in Northern Germany. Fecal samples of 1388 animals were investigated for the presence of BoNT to verify the key requirement of the hypothesis of chronic botulism. BoNT was not detected in any of the fecal samples using the most sensitive standard method for BoNT detection, the mouse bioassay. Therefore, the existence of "chronic" or "visceral" botulism could not be proven.