The costs and benefits of pregnancy diagnosis in dairy cows: A simulation model     

Joyce Boneschanscher  A.D. James  A.J. Stephens  R.J. Esslemont 《Agricultural Systems》1982,9(1):29-34

An evaluation of the effect of pregnancy diagnosis on calving intervall is made using a computerised simulation model. Three different methods of pregnancy diagnosis are assessed (milk progesterone test at 24 days after service, rectal palpation test at 44 days and a rectal palpation test at 65 days post-service in combination with a treatment of cows diagnosed as not pregnant with prostaglandin or a heat-mount-detector).When the interval between insemination and pregnancy diagnosis is short, when the accuracy of a pregnancy test is relatively low, the use of a heat-mount-detector is preferred to the treatment with prostaglandin on cows diagnosed as not pregnant while, at later stages of pregnancy, it is better to use prostaglandin.  相似文献   

Identification of galegine, an isoprenyl guanidine, as the toxic principle of Schoenus asperocarpus (poison sedge)     

CR HUXTABLE  PR DORLING  SM COLEGATE 《Australian veterinary journal》1993,70(5):169-171

SUMMARY An Isoprenyl guanldine, galegine, was isolated from the Western Australian sedge Schoenus asperocarpus (Cyperaceae). Synthetic galegine was shown to reproduce the clinical and pathological features of poisoning by this plant. Preliminary results suggest that the massive thoracic effusion observed in sedge poisoning is the result of a direct effect on pulmonary vascular permeability.  相似文献   

NEUTRALISING ANTIBODIES FOR AVIAN INFECTIOUS BRONCHITIS VIRUS IN QUEENSLAND POULTRY FLOCKS     

Penelope  Stephens B.Sc.  G. C. Simmons  B.Sc. 《Australian veterinary journal》1968,44(1):29-30

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Prevalence of chlamydia, toxoplasma, toxocara and ringworm in farm cats in south-west England     

P M Gethings  G L Stephens  J M Wills  P Howard  A H Balfour  A I Wright  K L Morgan 《The Veterinary record》1987,121(10):213-216

The prevalence of infection with Chlamydia psittaci, Toxoplasma gondii, Toxocara cati and Microsporum canis was examined in 51 cats on 22 sheep farms in the Bristol area. Serum antibody to C psittaci and T gondii was present in 45 per cent and 47 per cent of cats, respectively. At the time of sampling C psittaci was isolated from 6 per cent of the cats, T cati was identified in 63 per cent of faecal samples but neither T gondii nor M canis was isolated. When examined according to the farm of origin, 22.7 per cent of farms had cat populations with no evidence of infection with C psittaci or T gondii. Of the remainder, 45.5 per cent supported cat populations with evidence of both infections and 31.8 per cent had evidence of T gondii infection alone. None of the farms had cat populations with evidence of C psittaci infection alone. Two of the cats infected with C psittaci were excreting viable organisms in the faeces. The possible significance of this to the epidemiology of ovine enzootic abortion is discussed.  相似文献   

Nutrition of orphan marsupials.     

T Stephens 《Australian veterinary journal》1975,51(10):453-458

Marsupial milk has been found to be high in fats, protein and ash compared to eutherian milk. The generally low lactose content of marsupial milk and the corresponding low intestinal lactase activity of pouch young marsupials, when considered with the incidence of diarrhoea and the occasional formation of cataracts in orphan kangaroos fed on cow's milk (which has a high lactose content), suggests that a lactose-free milk be fed to orphan marsupials. Of the lactose-free milk substitutes for children now available, it is recommended that Pregestimil, Glucose Nutramigen and particularly CFI be used for very young orphan marsupial herbivores (especially kangaroos), as these are both lactose- and sucrose-free. Isomil, Prosobee and Triglyde, containing sucrose, may be suitable for older kangaroos which are also ingesting solids and brush-tailed possums of all ages. The appropriate natural diet of the orphan marsupial should be available at the time when initial solid food ingestion would occur in the natural state. It is suggested that milk substitute continue to be given until the orphan animal reaches the age where, in the natural state, it would be full independent.  相似文献   

The role of dendritic cells in shaping the immune response     

Howard CJ  Charleston B  Stephens SA  Sopp P  Hope JC 《Animal health research reviews / Conference of Research Workers in Animal Diseases》2004,5(2):191-195

Dendritic cells are central to the initiation of primary immune responses. They are the only antigen-presenting cell capable of stimulating naive T cells, and hence they are pivotal in the generation of adaptive immunity. Dendritic cells also interact with and influence the response of cells of the innate immune system. The manner in which dendritic cells influence the responses in cells of both the innate and adaptive immune systems has consequences for the bias of the adaptive response that mediates immunity to infection after vaccination or infection. It also provides an opportunity to intervene and to influence the response, allowing ways of developing appropriate vaccination strategies. Mouse and human studies have identified myeloid, lymphoid and plasmacytoid dendritic cells. Studies in domesticated animals with agents of specific infectious diseases have confirmed the applicability of certain of the generic models developed from mice or from in vitro studies on human cells. In vivo and ex vivo studies in cattle have demonstrated the existence of a number of subpopulations of myeloid dendritic cells. These cells differ in their ability to stimulate T cells and in the cytokines that they produce, observations clearly having important implications for the bias of the T-cell response. Dendritic cells also interact with the innate immune system, inducing responses that potentially bias the subsequent adaptive response.  相似文献   

Mineral balance in juvenile horses in race training     

Tonya L. Stephens MS  Gary D. Potter PhD  Pete G. Gibbs PhD  David M. Hood DVM  PhD 《Journal of Equine Veterinary Science》2004,24(10):438-450

Twenty-four long yearlings were fed rations containing differing amounts of calcium, phosphorus, and magnesium to further elucidate the requirements for these minerals during exercise-induced skeletal modeling and remodeling in juvenile racehorses. The animals were assigned randomly within gender subgroups to 1 of 4 diets. Total collections of feces and urine were performed on days 0, 64, and 128 of the trial for determination of mineral absorption and retention. Horses were maintained in a typical race-training protocol to mimic the nutritional stresses placed on long yearlings during strenuous exercise. Calcium absorption and retention were lower (P < .05) at day 64 than at day 0 and day 128. Also, the efficiency of retaining absorbed calcium was lower at day 64 than at day 0 or day 128. Thus, lower calcium retention at day 64 was due to both reduced absorption and reduced systemic demand. At day 64, calcium absorption and retention were not maximized at calcium intake of 160 mg/kg per day. At day 128, calcium absorption was maximal at a daily intake of 124 mg/kg per day, and retention was maximal at a daily intake of 123 mg/kg per day. These are in excess of current National Research Council (NRC)[1] recommendations by 38% and 36%, respectively. There was no consistent, significant effect of days on trial on phosphorus absorption or retention, which may have been due to inadvertent limited phosphorus intake. The efficiency of phosphorus retention systemically was over 94% to 98%. Phosphorus absorption and retention were not maximized at the highest intake (66 mg/kg/d), which is 32% over current NRC [1] recommendations. Similarly, there was no day effect on the efficiency of magnesium absorption or retention. Urinary excretion of magnesium was highest; thus, systemic efficiency of magnesium retention was lower on days 64 and 128 than on day 0. At day 64, magnesium retention was maximized at a daily intake of 35.6 mg/kg per day, which is 66% over NRC [1] recommendations. However, at day 128, magnesium retention was not maximized even at its highest intake (44 mg/kg/d), which is over 2 times the current NRC [1] recommendations. These data indicate that early race training affects the dietary requirements for calcium, phosphorus, and magnesium.

Introduction

The need for a marketable product at an early age in both competition and in sales places significant pressure on horse owners to start training or conditioning early in a horse's life. Training at an early age may exacerbate physiologic stress on young horses and increase nutritional requirements. The process of bone modeling/remodeling is necessary for the juvenile skeleton to adapt to the stresses of training. The horse must form new bone and remodel existing bone to bear the load being applied. During the demineralization process of bone remodeling, there is an increase in mineral excretion from the degradation of the bone matrix. Nielsen et al[2] reported this demineralization of the third metacarpal in conjunction with the introduction of speed in juvenile horses on a race-training regimen. The lack of time routinely given to the stressed bone of a juvenile horse to model and/or remodel according to the stresses placed upon it can cause serious and career-ending injuries. [3] While injury reduction may be achieved from a delay in the onset of training until the horse is mature, this is not feasible economically. Alterations in existing training methods and increasing physiologic stimulus to the skeleton are approaches being researched to minimize skeletal injuries to young horses.Mineral density increase and size of the third metacarpal would result in larger cortical bone mass, decreased strain on the bone, and decreased susceptibility for injury. Previous work in this area demonstrated that increased calcium and phosphorus intake above NRC[1] recommendations for juvenile horses in training enhanced bone density, but no quantitative estimates of requirements were made. [4] The NRC [1] developed an approximation of the requirements for juvenile horses in training using mineral intakes based on extrapolations from research conducted with sedentary and mature horses. This study was conducted to verify previous findings and to further quantify the dietary requirement for calcium, phosphorus, and magnesium during the bone modeling/remodeling process in juvenile athletic horses. The specific objectives of this study were to determine calcium, phosphorus, and magnesium balances in young horses during race training.

Materials and methods

Management of animals

Twenty-four long-yearling Quarter Horses were grouped according to age and sex, then randomly assigned to the diet treatments as shown in Table 1. Two horses from each group were randomly assigned to 1 of 4 diets with the condition that each treatment group would contain the same number of fillies and geldings. While at the Texas A&M University Horse Center, the horses were vaccinated against eastern and western equine encephalomyelitis, influenza, and tetanus and dewormed. All horses began the trial with a background period of at least 1 week, during which the horses were group-housed at the Texas A&M University Horse Center, fed hay ad lib, and offered concentrate at approximately 1% of body weight twice daily. Regular hoof care and deworming were provided throughout the course of the study. The horses were then moved from the Texas A&M University Horse Center in groups of 8 to Steephollow Farm in Bryan, Texas, a race-training facility, where they were separated and housed individually in 7 × 7-m stalls. The horses were moved to Steephollow Farm in 3 groups of 8 at an average age of 226 days for the group. Rations were formulated based on 60% concentrate and 40% Bermuda grass hay, with varying concentrations of calcium, phosphorus, and magnesium. The concentrate diets were provided by Consolidated Nutrition of Omaha, Nebraska (Table 1). All concentrates were mixed, pelleted, and bagged by Consolidated Nutrition and shipped to the Texas A&M University Horse Center. The horses were fed concentrate and hay at 12-hour intervals (7:00 and 7:00 ) for the duration of the trial. They were given until the next feeding to consume all concentrate and hay, and any feed refused was weighed and recorded. Refusals were very infrequent. Feed intake was adjusted weekly as needed to allow for normal growth and to maintain a body condition score of 5 to 6,[5] while maintaining a constant ratio of 60% concentrate and 40% hay. The protocol for management and treatment of the animals was approved by the Texas A&M University Agricultural Animal Care and Use Committee. Five horses were not able to complete the study because of lameness, injury, or sickness, and data from those horses were not included in the results of the study.  相似文献   

BRUCELLOSIS CONTROL IN LIGHTLY INFECTED AREAS     

W. H. Stephens  B.V.Sc. 《Australian veterinary journal》1953,29(10):284-287

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Associations between liveweight,body condition score and previous reproductive outcomes,and the risk of ewes bred at 18-months of age being dry at docking     

KJ Griffiths  AL Ridler  C Heuer  RA Corner-Thomas  PR Kenyon 《New Zealand veterinary journal》2018,66(6):290-296

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Serology of Campylobacter fetus fetus strains from four outbreaks of ovine abortion     

Bird MM  Stephens DJ  Wall EP  de Lisle GW 《New Zealand veterinary journal》1984,32(1-2):14-17

As a result of a Ministry of Agriculture & Fisheries survey on ovine abortions, 76 isolates of Campylobacterfetus fetus were obtained. These isolates were from four farms in the southern Hawkes Bay, with an abortion incidence of 2.8% to 9.1%. Antisera to eight different strains of C. fetus fetus were made in rabbits. Strains were then examined using whole cell tube agglutination tests and sensitised Staphylococcal Protein A slide agglutination tests. Heat labile antigens were examined by absorbing antisera with heat-treated bacteria. Two broad serogroups were found, but within-group variation was demonstrated by cross-absorbing antisera. The isolates from one farm were all of a single broad serogroup. Both serogroups were found on the remaining three farms. Evidence for the presence of two major serogroups was also obtained by immobilisation tests and antigen analysis by gel diffusion.  相似文献