Response to hormonal treatment and conception rates of Sahiwal cows subjected to fixed time artificial insemination in pastoral dairy systems.

This study aimed at determining factors influencing response of Sahiwal cows/heifers to fixed time artificial insemination protocol in pastoral systems in Kenya. Available cows/heifers were inspected for conformity to Sahiwal breed characteristics, parity, body condition score, and subsequently rectal palpation to determine pregnancy status, ovarian structures, and estimated ovarian diameter. Consequently, these animals were injected with 100 µg of gonadotrophin-releasing hormone. On days 7 and 9, only responsive cows/heifers were injected with 500 µg of cloprostenol and 100 µg of gonadorelin Acetate, respectively. On day 10, animals were inseminated and separated from bulls for 45 days and pregnancy diagnosis done after 90 days. Analysis of variance was performed to determine the effects of production system, parity, and ovarian structures on ovary diameters pre- and post-hormonal treatment. Logistic regression was used fitting a logit function to account for the binomial distribution of conception. Overall, 56.2%, 23.1%, and 20.7% of the animals had follicles (F), corpus luteum (CL), and corpus albicans (CA), respectively, at day 0, and 16.6%, 68.6%, and 14.8%, respectively, at day 7. Human and environmental factors had no influence on conception. Among the animal factors, only the ovarian structures at day 7 had a significant effect on conception. Ovaries with CL at this time were about 6 times significantly more likely to conceive than those with F. For higher conception rates, animals with ovaries with CL should be recruited into the FTAI program as they are significantly more likely to conceive than those with other ovarian structures.

Reflections on IDEAL: What we have learnt from a unique calf cohort study.

The year 2020 marks a decade since the final visit was made in the 'Infectious Diseases of East African Livestock' (IDEAL) project. However, data generation from samples obtained during this ambitious longitudinal study still continues. As the project launches its extensive open-access database and biobank to the scientific community, we reflect on the challenges overcome, the knowledge gained, and the advantages of such a project. We discuss the legacy of the IDEAL project and how it continues to generate evidence since being adopted by the Centre for Tropical Livestock Genetics and Health (CTLGH). We also examine the impact of the IDEAL project, from the authors perspective, for each of the stakeholders (the animal, the farmer, the consumer, the policy maker, the funding body, and the researcher and their institution) involved in the project and provide recommendations for future researchers who are interested in running longitudinal field studies.

Characterization of Clostridium perfringens recovered from broiler chicken affected by necrotic enteritis.

Necrotic enteritis (NE) caused by Clostridium perfringens has emerged as an important disease associated with major economic losses in the poultry industry worldwide. The ban and voluntary withdraw of antimicrobial growth promoters used to control NE have resulted in resurgence of NE. Moreover, consumer demand for antibiotic free poultry product has continued to grow. The presence of the netB gene encoding for pore forming toxin in C. perfringens has been shown to be essential for pathogenesis of NE. The aim of this study was to characterize C. perfringens isolates recovered from broiler chickens affected by NE. A total of 230 isolates obtained from commercially raised broilers between 3 and 4 wk of age affected by NE were characterized using multiplex PCR (mPCR) and antibiotic susceptibility test. A subset of isolates (n = 75) were analyzed using pulsed-field gel electrophoresis (PFGE). Toxin typing using mPCR revealed that all C. perfringens isolates were toxinotype A. However, 68% (59 of 85) of the isolates from apparently healthy birds and 81% (119 of 145) from dead birds were positive for netB gene. Antimicrobial susceptibility testing using a disk diffusion method indicated that 53% of the isolates had a multidrug resistant profile that comprised of streptomycin, gentamicin, erythromycin, tetracycline, and bacitracin. PFGE analysis of 53 typeable isolates indicated a wide genetic relatedness even among isolate from the same state with the same antibiotic resistance profile. The results obtained from this study suggest that the presence of C. perfringens with netB gene in broiler chicken does not automatically result in death but other factors such as health of the bird before proliferation of virulent C. perfringens may be critical for development of NE.

Effect of manganese preconditioning and replacing inorganic manganese with organic manganese on performance of male broiler chicks.

The effects of manganese (Mn) preconditioning, 96 h post-hatch followed by the replacement of inorganic Mn with different levels of organic Mn (5 to 21 D), on growth, tissue excreta Mn content, gene expression, and enzyme activity were evaluated. A total of 420 day-old male Cobb 500 broilers were divided into 2 groups. One group was fed a corn-soybean meal basal diet containing 17 mg of Mn/kg (preconditioning diet, MnPD); the second group was fed the non-preconditioning diet (NPCD), which was the MnPD supplemented with 60 mg of Mn/kg from manganese sulfate (MnSO4). On day 5, each group was divided into 5 subgroups and were randomly assigned to dietary treatments consisting of MnPD alone or MnPD supplemented with 12 or 60 mg Mn/kg Mn as MnSO4 or Mn proteinate (6 replicate cages of 6 birds). Broiler chicks that were fed the MnPD had lower (P ≤ 0.05) body weight gain (BWG) and G:F ratio when compared to those that were fed the NPCD for 4 D. Birds that were fed MnPD (1 to 4 D) and switched to MnPD supplemented with 60 mg/kg Mn (5 to 21 D) had lower (P ≤ 0.05) BWG compared to those that were fed NPCD (1 to 4 D) and switched to MnPD supplemented with 60 mg/kg Mn for 21 D. Excreta, tibia ash, liver, and heart Mn levels were increased (P ≤ 0.05) by supplemental Mn. The expression of jejunum divalent metal transporter-1 mRNA levels, as well as activities of plasma total super oxide dismutase and liver alanine transaminase, was not affected by MnPD or Mn source and levels. These results confirmed that feeding marginally deficient Mn diets to broiler chicks post-hatch does affect growth rate and tissue Mn concentration.

Effect of zinc imprinting and replacing inorganic zinc with organic zinc on early performance of broiler chicks.

The goal of this study was to determine the effects of feeding a zinc (Zn) deficient diet to broiler chicks for 96 h post-hatch followed by feeding diets with different Zn sources and supplemental levels (5 to 21 d) on the growth performance, tissue, and excreta Zn content. At the start of the study, four hundred 20-day-old male broiler chicks were divided into two groups. One group was fed a corn soybean meal based diet containing 25 mg of Zn/kg (imprinting diet, ID). The second group was fed the basal diet supplemented with 40 mg of Zn/kg from Zn oxide (ZnO) (non-imprinting diet, NID). Both groups were fed these diets for 96 h. At d 5, chicks from each group were randomly assigned to the dietary treatments consisting of the basal diet alone or the basal diet supplemented with 8 or 40 mg/kg Zn as ZnO or Zn proteinate. Main effects of post-hatch Zn ID were observed on feed intake and G:F. ID decreased (P < 0.05) feed intake and improved (P < 0.05) the gain to feed ratio (G:F) of 14 and 21 d old chicks compared to G:F of chicks fed NID. Additionally, G:F for 14 and 21 d was improved (P < 0.05) by interaction of Zn source × level. Furthermore, at d 21 chicks fed the ID had a lower (P < 0.05) Zn content in the tibia ash and excreta, and a higher (P < 0.05) Zn content in the pancreas tissue compared to chicks fed NID. These results suggest that Zn imprinting can affect body Zn stores and early performance.

A longitudinal assessment of the serological response to Theileria parva and other tick-borne parasites from birth to one year in a cohort of indigenous calves in western Kenya.

Tick-borne diseases are a major impediment to improved productivity of livestock in sub-Saharan Africa. Improved control of these diseases would be assisted by detailed epidemiological data. Here we used longitudinal, serological data to determine the patterns of exposure to Theileria parva, Theileria mutans, Babesia bigemina and Anaplasma marginale from 548 indigenous calves in western Kenya. The percentage of calves seropositive for the first three parasites declined from initial high levels due to maternal antibody until week 16, after which the percentage increased until the end of the study. In contrast, the percentage of calves seropositive for T. mutans increased from week 6 and reached a maximal level at week 16. Overall 423 (77%) calves seroconverted to T. parva, 451 (82%) to T. mutans, 195 (36%) to B. bigemina and 275 (50%) to A. marginale. Theileria parva antibody levels were sustained following infection, in contrast to those of the other three haemoparasites. Three times as many calves seroconverted to T. mutans before seroconverting to T. parva. No T. parva antibody response was detected in 25 calves that died of T. parva infection, suggesting that most deaths due to T. parva are the result of acute disease from primary exposure.

Colonic motor dysfunction in human diabetes is associated with enteric neuronal loss and increased oxidative stress.

BACKGROUND: Gastrointestinal dysfunction is very common in diabetic patients. We assessed the changes in the colonic enteric nervous system using colectomy specimens and intestinal biopsies from diabetic subjects and age-matched controls. METHODS: In control and diabetic colons, we determined the total ganglion area (hematoxylin-eosin staining), changes in neuronal markers-protein gene product 9.5, peripherin, neuronal nitric oxide synthase (nNOS), neuropeptide Y (NPY), choline acetyl transferase (ChAT) and vasoactive intestinal peptide (by immunostaining), apoptosis (cleaved caspase-3 staining) and reduced glutathione levels. Superoxide dismutase mRNA was determined in enteric ganglia isolated by laser capture micro dissection. Isometric muscle recording was used to assess contraction and relaxation responses of colonic circular muscle strips. Apoptosis in enteric neurons under hyperglycemia in vitro was determined by cleaved caspase-3 Western blotting and protective effects of lipoic acid were evaluated. KEY RESULTS: Diabetic subjects had higher incidence of lower gastrointestinal symptoms like constipation and diarrhea at baseline prior to surgery. Diabetic ganglia displayed significant decrease in ganglion size due to enhanced apoptosis and loss of peripherin, nNOS, NPY, and ChAT neurons. Reduced glutathione levels in the diabetic colon (HbA1C > 7%) were significantly less than the control, indicating increased oxidative stress. Colonic circular muscle strips from diabetic subjects showed impaired contraction and relaxation responses compared with the healthy controls. Hyperglycemia-induced cleaved caspase-3 in enteric neurons was reversed by lipoic acid. CONCLUSIONS & INFERENCES: Our data demonstrate loss of enteric neurons in the colon due to increased oxidative stress and apoptosis which may cause the motility disturbances seen in human diabetes. Antioxidants may be of therapeutic value for preventing motility disorders in diabetes.

Blockade of adenosine A2B receptors ameliorates murine colitis.

BACKGROUND AND PURPOSE: The adenosine 2B (A2B) receptor is the predominant adenosine receptor expressed in the colon. Acting through the A2B receptor, adenosine mediates chloride secretion, as well as fibronectin and interleukin (IL)-6 synthesis and secretion in intestinal epithelial cells. A2B receptor mRNA and protein expression are increased during human and murine colitis. However, the effect of the A2B receptor in the activation of the intestinal inflammatory response is not known. In this study, we examined the effect of A2B receptor antagonism on murine colitis. EXPERIMENTAL APPROACH: Dextran sodium sulphate (DSS)-treated mice and piroxicam-treated IL-10-/- mice were used as animal models of colitis. The A2B receptor-selective antagonist, ATL-801, was given in the diet. KEY RESULTS: Mice fed ATL-801 along with DSS showed a significantly lower extent and severity of colitis than mice treated with DSS alone, as shown by reduced clinical symptoms, histological scores, IL-6 levels and proliferation indices. The administration of ATL-801 prevented weight loss, suppressed the inflammatory infiltrate into colonic mucosa and decreased epithelial hyperplasia in piroxicam-treated IL-10-/- mice. IL-6 and keratinocyte-derived chemokine (KC) concentrations in the supernatants of colonic organ cultures from colitic mice were significantly reduced by ATL-801 administration. CONCLUSIONS AND IMPLICATIONS: Taken together, these data demonstrate that the intestinal epithelial A2B receptor is an important mediator of pro-inflammatory responses in the intestine and that A2B receptor blockade may be an effective therapeutic strategy to treat inflammatory bowel disease.

Glial cell line-derived neurotrophic factor-mediated enteric neuronal survival involves glycogen synthase kinase-3beta phosphorylation and coupling with 14-3-3.

Glial cell line-derived neurotrophic factor (GDNF) promotes the growth and survival of enteric neurons, but the mechanisms involved are poorly understood. GDNF is known to promote the survival of enteric neurons through activation of the PI3-Kinase/Akt signaling pathway. We investigated the role of glycogen synthase kinase-3beta (GSK-3beta) in enteric neuronal survival, and the ability of GDNF to regulate the activity of GSK-3beta using primary rat embryonic enteric neurons. GDNF, through activation of the PI3-kinase pathway enhanced the phosphorylation of GSK-3beta at its N-terminal serine-9 residue, and promoted the association of GSK-3beta with 14-3-3. Transfection of a constitutively active S9A-GSK-3beta mutant prevented the survival effects of GDNF, whereas a dominant negative GSK-3beta construct prevented GDNF withdrawal-induced cell death. Increased GSK-3beta activity was associated with an increase in tau phosphorylation. Thus, GDNF promotes enteric neuronal survival by modulating GSK-3beta and its downstream target tau. Inhibitors of GSK-3beta activity may have therapeutic potential in improving enteric neuronal survival.

Expression and characterization of a recombinant soluble form of bovine tumor necrosis factor receptor type I.

A recombinant soluble bovine tumor necrosis factor receptor type I (sboTNF-RI) was expressed in the methylotrophic yeast Pichia pastoris and evaluated for its ability to inhibit bovine tumor necrosis factor alpha (TNF-alpha) cytotoxicity. A cDNA encoding the extracellular domain of bovine TNF-RI was placed under the control of the powerful and tightly regulated alcohol oxidase1 (AOX1) gene promoter of the pPICZa A vector and the resulting construct integrated into the 5' region of the alcohol oxidase genes of GS115 and KM71 strains of Pichia. Soluble bovine TNF-RI was secreted into the medium following induction of the AOX1 gene promoter with methanol, and purified to greater than 95% purity by ion-exchange chromatography. In in vitro assays, the purified recombinant sboTNF-RI will block the cytolytic activity of bovine TNF-alpha on WEHI 164 cells clone 13 by 50% when used at a concentration of 170 microg/ml, and by nearly 90% when used at a concentration of 310 microg/ml. Results of this study suggest that recombinant sboTNF-RI may have therapeutic value as a TNF inhibitor in cattle with coliform mastitis.

Bovine stem cell factor: production of a biologically active protein and mRNA analysis in cattle infected with Trypanosoma congolense.

The cDNA coding for the soluble form of bovine stem cell factor (boSCFAla165) was cloned and recombinant protein was produced in bacteria as a histidine tagged-protein. The protein was purified from the inclusion bodies in one step by metal chelation chromatography under denaturing conditions. Recombinant bovine SCF was shown to act synergistically with interleukin 3 (IL-3) and erythropoietin (EPO) in stimulating the growth of bone marrow progenitor cells such as colony forming units-granulocyte macrophage (CFU-GM) and burst forming units-erythroid (BFU-E). Analysis of SCF mRNA expression by reverse transcription-polymerase chain reaction (RT-PCR) revealed that the transcripts were detectable in bone marrow, lymph nodes and spleen of cattle, and that the level of transcription was upregulated in lymph nodes of cattle infected with Trypanosoma congolense. Two isoforms of SCF mRNA were amplified by RT-PCR. The availability of recombinant bovine SCF provides a valuable tool for studying the role of SCF in the development, growth and differentiation of bovine hematopoietic cells.

Cloning of the bovine interleukin-3-encoding cDNA.

Interleukin-3 (IL-3) is one of the cytokines that act during the early and late stages of blood cell formation. To enable the study of the role of IL-3 in bovine haemopoietic stem cell differentiation, the polymerase chain reaction was used to amplify an IL-3 cDNA from first-strand cDNAs prepared from RNA isolated from 4- and 5-hour concanavalin-A-stimulated peripheral blood lymphocytes (PBL) from N'Dama cattle. An analysis of the cDNA sequence reveals that it contains a 432-nucleotide (nt) open reading frame which codes for 144 amino acids (aa). Cleavage of the putative signal peptide consisting of the first 17 aa yields the mature form of the protein (14.5 kDa). Comparisons of the bovine IL-3 sequence with the sheep, human and mouse IL-3 sequences show that the bovine sequence shares 90.7, 55.8 and 51.9% nt identity, respectively, in the coding region, and 85.4, 35 and 27.7% aa identity, respectively.

The effect of Trypanosoma brucei brucei infection on rabbit plasma iron and zinc concentrations.

Changes in plasma iron and zinc concentration were studied in rabbits following a needle challenge with Trypanosoma brucei brucei clone ILTat 2.1. The infection resulted in a decrease of the concentration of both trace elements. Plasma iron concentrations decreased gradually and were decreased maximally to 52.3% of pre-infection levels on day 18 post-inoculation. Plasma zinc concentrations, on the other hand, decreased more rapidly and were decreased maximally to 27.4% of pre-infection levels on day 3 post-inoculation. The onset of these decreases coincided with the appearance of parasites in the peripheral blood. Furthermore, the magnitude of their decrease correlated closely with the level and duration of the parasitaemia. Other abnormal findings, namely, anaemia and periods of leucocytosis and leukopenia, were also observed. This study therefore demonstrates that depression in plasma iron and zinc concentrations is part of the acute phase response in rabbits infected with this clone of T. b. brucei.