Risk Factors for the Development of Hypokalemia in Neonatal Diarrheic Calves

Background

Neonatal diarrheic calves have a clear negative potassium balance because of intestinal losses and decreased milk intake but in the presence of acidemia, they usually show normokalemic or hyperkalemic plasma concentrations.

Objectives

To assess whether marked hypokalemia occurs in response to the correction of acidemia and dehydration and to identify factors that are associated with this condition.

Animals

Eighty‐three calves with a clinical diagnosis of neonatal diarrhea.

Methods

Prospective cohort study. Calves were treated according to a clinical protocol using an oral electrolyte solution and commercially available packages of 8.4% sodium bicarbonate, 0.9% saline and 40% dextrose infusion solutions.

Results

The proportion of hypokalemic calves after 24 hours of treatment (19.3%) was twice as great as it was on admission to the hospital. Plasma K⁺ after 24 hours of treatment was not significantly correlated to venous blood pH values at the same time but positively correlated to venous blood pH values on admission (r = 0.51, P < .001). Base excess on admission (Odds ratio [OR] = 0.81, 95% confidence interval [CI] = 0.70–0.94), duration of diarrhea (OR = 1.37, 95% CI = 1.05–1.80), milk intake during hospitalization (OR = 0.54, 95% CI = 0.37–0.79) and plasma sodium concentrations after 24 hours (OR = 1.12, 95% CI = 1.01–1.25) were identified to be independently associated (P < .05) with a hypokalemic state after 24 hours of treatment.

Conclusions and Clinical Importance

Findings of this study suggest that marked depletion of body potassium stores is evident in diarrheic calves that suffered from marked metabolic acidosis, have a low milk intake and a long history of diarrhea.     

Pythium yorkensis sp. nov., a potential soybean pathogen from southeastern Pennsylvania,USA

Biodiversity surveys of natural as well as agricultural ecosystems commonly reveal novel isolates. A new species, Pythium yorkensis sp. nov., is reported here, isolated from field soil during a survey of oomycete diversity in symptomless soybean across southeastern Pennsylvania. Molecular data from both mitochondrial and nuclear loci support a unique phylogenetic position for the isolates collected, and morphological features distinguish this new species from close relatives in Pythium clade J. Pathogenicity assays suggest that this new species may be a potential agricultural pathogen, as isolates were mildly aggressive on soybean. This study highlights the continued need for culture‐based surveys in collaboration with high‐throughput sequence‐based approaches for environmental sampling.     

The α2A‐adrenoceptor subtype plays a key role in the analgesic and sedative effects of xylazine

Xylazine, the classical α₂‐adrenoceptor (α₂‐AR) agonist, is still used as an analgesic and sedative in veterinary medicine, despite its low potency and affinity for α₂‐ARs. Previous pharmacological studies suggested that the α_2A‐AR subtype plays a role in mediating the clinical effects of xylazine; however, these studies were hampered by the poor subtype‐selectivity of the antagonists used and a lack of knowledge of their bioavailability in vivo. Here, we attempted to elucidate the role of the α_2A‐AR subtype in mediating the clinical effects of xylazine by comparing the analgesic and sedative effects of this drug in wild‐type mice with those in α_2A‐AR functional knockout mice using the hot‐plate and open field tests, respectively. Hippocampal noradrenaline turnover in both mice was also measured to evaluate the contribution of α_2A‐AR subtype to the inhibitory effect of xylazine on presynaptic noradrenaline release. In wild‐type mice, xylazine (10 or 30 mg/kg) increased the hot‐plate latency. Furthermore, xylazine (3 or 10 mg/kg) inhibited the open field locomotor activity and decreased hippocampal noradrenaline turnover. By contrast, all of these effects were abolished in α_2A‐AR functional knockout mice. These results indicate that the α_2A‐AR subtype is mainly responsible for the clinical effects of xylazine.     

Lack of haplotype structuring for two candidate genes for trypanotolerance in cattle

Bovine trypanotolerance is a heritable trait associated to the ability of the individuals to control parasitaemia and anaemia. The INHBA (BTA4) and TICAM1 (BTA7) genes are strong candidates for trypanotolerance‐related traits. The coding sequence of both genes (3951 bp in total) were analysed in a panel including 79 Asian, African and European cattle (Bos taurus and B. indicus) to identify naturally occurring polymorphisms on both genes. In general, the genetic diversity was low. Nineteen of the 33 mutations identified were found just one time. Seventeen different haplotypes were defined for the TICAM1 gene, and 9 and 12 were defined for the exon 1 and the exon 2 of the INHBA gene, respectively. There was no clear separation between cattle groups. The most frequent haplotypes identified in West African taurine samples were also identified in other cattle groups including Asian zebu and European cattle. Phylogenetic trees and principal component analysis confirmed that divergence among the cattle groups analysed was poor, particularly for the INHBA sequences. The European cattle subset had the lowest values of haplotype diversity for both the exon1 (monomorphic) and the exon2 (0.077 ± 0.066) of the INHBA gene. Neutrality tests, in general, did not suggest that the analysed genes were under positive selection. The assessed scenario would be consistent with the identification of recent mutations in evolutionary terms.     

Analysis of genomic mutation and immunohistochemistry of platelet‐derived growth factor receptors in canine vascular tumours

We examined whether mutation of the platelet‐derived growth factor receptor protein tyrosine kinase (PDGFR)‐α and PDGFR‐β genes contributes to their overexpression in canine vascular tumours. Genomic sequences of trans‐ or juxtamembrane regions of PDGFR‐α and PDGFR‐β were analysed with immunohistochemical staining and polymerase chain reaction‐direct sequencing using DNA from paraffin‐embedded neoplastic tissues of 27 hemangiosarcomas (HSAs) and 20 hemangiomas (HAs). Immunohistochemically, 75% of the HA cases were positive for PDGFR‐α and almost most of the HA cases were negative for PDGFR‐β. Of the HSA cases, 55.6% were negative for PDGFR‐α and 63% were strongly positive for PDGFR‐β. Among the HA cases, 1 missense mutation was detected in PDGFR‐α exon 18 and 1 in PDGFR‐β exon 17. Two HSA cases had missense mutations in exon 14 and 1 in exon 17 of PDGFR‐β. Thus, genomic mutation of trans‐ or juxtamembrane regions of PDGFRs was not the main mechanism driving the activation of receptors in HSA and HA.     

Effects of dietary Lactobacillus acidophilus and Bacillus subtilis on laying performance,egg quality,blood biochemistry and immune response of organic laying hens

The objective of this study was to evaluate the effects of two different probiotic micro‐organisms on the performance, egg quality and blood parameters of organically reared hens. A total of 900 16‐week‐old Hy‐Line layer hybrids were randomly assigned to three groups of 300 birds each. The control (CTR) group was fed a corn–soya bean cake‐based diet; the L group was fed the same diet supplemented with 0.1% Lactobacillus acidophilus, while the B group was fed the same diet supplemented with 0.05% Bacillus subtilis. Data were recorded at the beginning (weeks 5 and 6: T1) and at the end (weeks 19 and 20: T2) of the experiment, and no differences in hen performance were recorded between dietary groups or sampling times. All of the investigated clinical chemistry parameters, except GGT, were affected by diet (p < 0.05), with the best results recorded for the probiotic‐treated groups. The immune‐response values showed higher blood bactericidal activity in the B and L groups at T2 (p < 0.05) and a lower lysozime concentration in the B group at T1. Higher antibody production against Newcastle disease virus was observed in the L group compared to the CTR (p = 0.013). No differences in oxidative status were recorded, and no effects of diet on egg quality were observed. Among the physical egg characteristics, only the Roche scale colour was affected by diet (p < 0.05): the egg yolk was paler in the L group. The age of the hen was the most relevant factor affecting physical egg characteristics. The chemical parameters of the egg were almost unaffected by supplementation with probiotics except for the lipid content, which decreased with the L diet (p < 0.05). Both probiotic inclusions had beneficial effects on hen metabolism and welfare, and L. acidophilus induced the best immune response.     

Effects of pistachio by‐products on digestibility,milk production,milk fatty acid profile and blood metabolites in Saanen dairy goats

The objective of this study was to investigate the effects of pistachio by‐products (PBP) on nutrient digestibility, blood metabolites and milk fatty acid (FA) profile in Saanen dairy goats. Nine multiparous lactating Saanen goats (on day 90 post‐partum, 45 ± 2/kg BW) were randomly assigned to a 3 × 3 Latin square design with three treatment diets: 1) control diet (alfalfa hay based), 2) 32% PBP and 3) 32% PBP + polyethylene glycol (PEG‐4000; 1 g/kg dry matter). Each period lasted 21 days, including 14 day for treatment adaptation and 7 day for data collection. Pistachio by‐products significantly decreased (p < 0.01) crude protein (CP) digestibility compared with the control diet (64.4% vs. 58.7%), but PEG addition did not differ for CP digestibility of goats fed 32% PBP + PEG and those fed the two other diets. The digestibility of NDF tended (p = 0.06) to decrease for goats fed PBP compared with those fed the control diet. Yields of milk and 4% fat‐corrected milk were not affected by dietary treatments. Compared with the control diet, PBP supplementation appreciably changed the proportions of almost all the milk FA measured; the main effects were decreases (p < 0.01) in FA from 8:0 to 16:0 and increases (p < 0.01) proportions of cis‐9, trans‐11 18:2 and trans‐11 18:1, monounsaturated FA, polyunsaturated FA and long‐chain FA. The saturated FA, short‐chain FA and medium‐chain FA proportions were lower (p < 0.01) in goats fed the two PBP supplemented diet than in those fed the control diet and PEG addition led to intermediate proportions of saturated FA, unsaturated and monounsaturated FA. Inclusion of PBP in the diet decreased (p < 0.01) plasma concentrations of glucose and urea nitrogen compared with the control diet. It was concluded that PBP can be used as forage in the diet of dairy goats without interfering with milk yield. Inclusion of 32% PBP in the diet of dairy goats had beneficial effects on milk FA profile but PEG addition to PBP did not contribute to enhance further milk FA profile.