Gastrointestinal health and function in weaned pigs: a review of feeding strategies to control post‐weaning diarrhoea without using in‐feed antimicrobial compounds

For the last several decades, antimicrobial compounds have been used to promote piglet growth at weaning through the prevention of subclinical and clinical disease. There are, however, increasing concerns in relation to the development of antibiotic‐resistant bacterial strains and the potential of these and associated resistance genes to impact on human health. As a consequence, European Union (EU) banned the use of antibiotics as growth promoters in swine and livestock production on 1 January 2006. Furthermore, minerals such as zinc (Zn) and copper (Cu) are not feasible alternatives/replacements to antibiotics because their excretion is a possible threat to the environment. Consequently, there is a need to develop feeding programs to serve as a means for controlling problems associated with the weaning transition without using antimicrobial compounds. This review, therefore, is focused on some of nutritional strategies that are known to improve structure and function of gastrointestinal tract and (or) promote post‐weaning growth with special emphasis on probiotics, prebiotics, organic acids, trace minerals and dietary protein source and level.     

半套式RT-PCR法检测腹泻延边黄牛血液伤寒沙门氏菌试验

为建立一种快速、特异性和实用性强、灵敏度高的沙门氏菌检测方法,参考GeneBank中登录号为U25631的沙门氏菌基因序列.设计并合成引物,组成半套式RT-PCR,扩增片段为581bp.应用该半套式RT-PCR对标准菌株伤寒沙门氏菌、大肠杆菌、链球菌、巴氏杆菌和结核杆菌及临床伤寒分离出的沙门氏菌H1、H2株进行检测.并对延边地区牧场的产生-临床腹泻的延边黄牛血液中分离培养的不同菌株进行检测.结果表明,仪伤寒沙门氏菌标准株和临床一株样品在581bp处扩增出了特异的片段;该方法检测灵敏度为1 fg 核酸,且重复性好.说明此半套式RT-PCR法可以准确、灵敏、快速地检测出腹泻延边黄牛血液中的伤寒沙门氏菌.     

Enteral fluid therapy in large animals

Enteral fluids administered alone, or in conjunction with intravenous fluids, are reported to be useful for the treatment of dehydration and electrolyte loss associated with diarrhoea in a number of species, following exercise in horses and for feed impaction of the large intestine of horses. Enteral fluids are suitable for treatment of mild to moderately dehydrated patients with some intact intestinal epithelium and motile small intestine. In patients that will drink voluntarily or tolerate nasal intubation the use of enteral fluids may avoid the complications associated with intravenous fluid administration. However the labour costs associated with repeated nasal intubation in intensively managed patients requiring large volumes of fluids may make the use of enteral fluids less economical than intravenous fluid administration. Enteral fluid use alone is contraindicated in patients that are severely dehydrated and/or in hypovolaemic shock, however, if used in conjunction with intravenous fluids, the effects of villous atrophy and malnutrition may be ameliorated and the duration of hospitalisation shortened. There is a variety of commercially available enteral fluids available to veterinary practitioners. While the key components of these fluids are sodium, chloride and carbohydrates, the amounts of ions and other ingredients such as potassium, alkalising agents, amino acids and shortchain fatty acids may vary. The species of the animal, the underlying condition, and the constituents of the fluid, should influence the choice of an enteral fluid.     

Supplemental lipoic acid relieves post‐weaning diarrhoea by decreasing intestinal permeability in rats

Lipoic acid (LA) is a naturally existing substance which widely distributed in the cellular membranes and cytosol of animal cells. Its intracellular functions include quenching of free radicals and repairing oxidized proteins. The purpose of this study was to evaluate the effects of LA on post‐weaning diarrhoea using a rat model. Sixty weaned rats were fed either a basal diet or a LA‐supplemented diet, or a zinc oxide (ZnO)‐supplemented diet as a positive control. Rats in the LA and ZnO groups had better performance and reduced incidence of diarrhoea (p < 0.05). Both LA and ZnO treatments enhanced intestinal homeostatic and architecture, significantly decreased urinary lactulose to mannitol ratios (p < 0.05) and increased the expression of the intestinal mucosal tight junction proteins occludin (OCLN) and zonula occludens protein‐1 (ZO‐1) (p < 0.05). LA significantly increased the activities of antioxidant enzymes, and reduced glutathione while decreasing the levels of oxidative glutathione and malondialdehyde in the intestinal mucosa (p < 0.05). Furthermore, an in vitro study indicated that supplementation with LA in IEC‐6 intestinal epithelial cells significantly enhanced the expression of OCLN and ZO‐1 under hydrogen peroxide‐induced oxidative stress. Collectively, these results suggest that LA relieves post‐weaning diarrhoea by reducing intestinal permeability and improving antioxidant indices.     

ORIGINAL ARTICLE: Increased colostral somatic cell counts reduce pre‐weaning calf immunity,health and growth

Our objective was to study the relationships between colostral somatic cell counts (SCC, a criterion for mastitis severity at parturition) and early calf growth, blood indicators of immunity, and pre‐weaning faecal and health states. Sixty‐nine Holstein cows were assigned to three groups of greater (n = 21, 5051 × 10³), medium (n = 38, 2138 × 10³) and lower (n = 10, 960 × 10³) colostral SCC (per ml) in a completely randomized design. Calves received 2 l of colostrum on day 1, and jugular blood was sampled at birth, at 3 h after the first colostrum feeding and at 42 days of age for immunoglobulin G (IgG) measurements. Calves were fed transition milk from their dams until 3 days of age and whole milk from 4 to 60 days of age twice daily at 10% of body weight. Health status and faecal physical scores were recorded daily for 42 days. Increased colostral SCC was associated with increased serum IgG at parturition. Colostral pH increased and fat percentage decreased linearly with the rising SCC. Feeding colostrum with greater SCC was associated with reduced serum IgG concentrations at 3 h after first colostrum feeding, greater incidences of diarrhoea and compromised health status during the first 42 days of age, and reduced weaning weight gain, but had no effects on calf body length and withers height. Colostral volume and percentages of protein, lactose, solids‐non‐fat, total solids and IgG were comparable among groups. Results suggest a role for SCC, as an indicator of mastitis and colostral health quality, in affecting calf health. As a result of the novelty of calf health dependence on colostral SCC found, future studies to further characterize such relationships and to uncover or rule out possible mediators are required before colostral SCC could be recommended for routine on‐farm use in managing dry cow and calf production.     

一株猪流行性腹泻病毒S、M、N基因的遗传变异分析

为研究猪流行性腹泻病毒(PEDV)CV777疫苗毒株与流行毒株的遗传变异和抗原位点的差异性,以RT-PCR进行PEDV CV777疫苗株和JS2016流行株S、M、N 3个基因的克隆测序,进行PEDV S、M、N 3个基因的核酸序列同源性分析,并通过软件比对CV777与JS2016毒株在这3个基因上的抗原差异。S、M、N基因的同源性分析表明流行毒株与CV777存在变异,但同源性在93%以上;免疫原性预测结果显示2个毒株在S、M、N 3个基因上的抗原区域存在较小的差异。     

猪流行性腹泻病毒实时荧光RPA等温检测方法的建立

为建立一种简单、快速的猪流行性腹泻病毒（PEDV）分子检测方法,本研究基于PEDV病毒M基因保守序列,设计一系列扩增引物及其荧光探针,以包含PEDV病毒M基因片段的pUC57质粒为模板,同时以包含猪传染性胃肠炎病毒（TGEV）、猪繁殖与呼吸综合征病毒（PRRSV）、猪圆环病毒2型（PCV2）及古典猪瘟病毒（CSFV）等病毒膜蛋白或核衣壳蛋白基因序列的质粒作为对照,建立了一种PEDV实时荧光重组酶聚合酶扩增（RPA）等温检测方法,测定了方法的特异性与敏感性。结果表明,该实时荧光RPA方法可在39℃恒温反应20 min特异性扩增PEDV病毒M基因,与TGEV、PRRSV等对照病毒基因无交叉反应,其检测限为10拷贝/μL。应用该实时荧光RPA方法可有效检测出血浆及血浆蛋白粉中的PEDV核酸。本研究建立的实时荧光RPA检测方法简单、快速、灵敏度高,可为PEDV的检测防控提供一种新的、可靠的技术支持。     

Herd-level risk factors for infectious diseases in Swedish dairy calves aged 0-90 days

The effect of environmental factors and management routines on the risk of diarrhoea, respiratory disease and other infectious diseases was investigated in 3081 heifer calves 0–90 days old in 122 Swedish dairy herds. The farmers kept records on cases of diseases in their heifer calves and in addition, project veterinarians clinically examined all calves every 2–3 months. At each visit, the veterinarians also measured the ammonia concentration and relative air humidity in the housing facilities for the calves. The cleanliness of the animals and their environment was recorded as a measure of the hygienic status of the farm. The presence or absence of draught (i.e. wind velocity > 0.5 m/s) was recorded twice during the study period. The effect of these factors, as well as the placing of the calf pens, the nature of the pen walls, air volume per animal, management factors (such as the status of the caretaker and feeding routines) and presence or absence of a bovine viral diarrhoea virus (BVDV) infection in the herd, was evaluated by means of a two-level variance component logistic model. The placing of calf pens along an outer wall was significantly associated with the risk of diarrhoea (odds ratio (OR): 1.92, P < 0.01). The risk for respiratory disease was significantly associated with an ammonia concentration below 6 ppm (OR: 0.42, P < 0.05) while the odds ratio for moderately to severely increased respiratory sounds was significantly associated with a BVDV infection in the herd (OR: 2.39, P < 0.05) and draught (OR: 3.7, P < 0.02). Absence of draught was significantly associated with the risk for infectious diseases other than diarrhoea and respiratory disease (OR: 0.42, P < 0.01).     

A scoring system for risk assessment of the introduction and spread of bovine viral diarrhoea virus in dairy herds in Northern Italy

To support a voluntary disease control program, this study aimed to develop an integrated scoring system for the risk assessment of bovine viral diarrhoea virus (BVDV) infection in dairy herds in Northern Italy. Sixty-two dairy herds were classified according to their BVDV serological status. Farmers were interviewed using a questionnaire on potential BVDV risk factors. Scores were used to define risk levels for factors related to (1) BVDV introduction (through livestock trade, attendance of animals at shows/exhibitions and grazing common pasture), (2) within-herd spread of BVDV and (3) the results of initial serological testing. The calculated odds ratios were significant for all categories, except for livestock trade. The application of the screening test, the questionnaire and the related risk assessment showed this to be a practical approach to predicting BVDV herd status.     

Effects of epidermal growth factor on atrophic enteritis in piglets induced by experimental porcine epidemic diarrhoea virus

Epidermal growth factor (EGF) promotes gastrointestinal mucosal recovery by stimulating the mitogenic activity of intestinal crypt epithelial cells. The aim of this study was to determine the effects of EGF on atrophic enteritis induced in piglets by experimental infection with porcine epidemic diarrhoea virus (PEDV) strain Dr13. Two groups of 12 conventional, colostrum-deprived, 1-day-old, large White-Duroc cross breed piglets were inoculated orally with PEDV (3 x 10(5) 50% tissue culture infective doses), with or without EGF (10 microg/kg/day, intraperitoneally once daily for 4 days after infection) and compared to 12 uninfected, untreated control piglets. PEDV+EGF piglets had less severe clinical signs than PEDV only piglets at 48 and 60 h post-infection (hpi). Histologically, the ratio of villous height:crypt depth of PEDV+EGF piglets was significantly higher than PEDV only piglets at 36 and 48 hpi. Immunohistochemistry for Ki67 demonstrated increased proliferation in intestinal crypt epithelial cells of PEDV+EGF piglets compared to PEDV only piglets at 36, 48 and 60 hpi. EGF stimulates proliferation of intestinal crypt epithelial cells and promotes recovery from atrophic enteritis in PEDV-infected piglets.