A beef herd model for simulating feed intake, animal performance, and manure excretion in farm systems

A beef herd submodel was created for integration with other farm components to form a whole-farm model capable of simulating a wide range of beef production systems. This herd submodel determined the best available feed or feed mix to meet the fiber, energy, and protein requirements for each of up to six animal groups on the farm. The groups comprised any combination of cows, nursing calves, young heifers, yearling heifers, stockers, and finishing cattle. Protein, energy, and mineral requirements were determined for each group using the Cornell Net Carbohydrate and Protein System, Level 1. Diets were formulated to meet these requirements with available feeds, and the resulting feed intake, growth, and manure DM and nutrient (N, P, and K) excretions were predicted. Required feed characteristics included CP, ruminally degradable protein, acid detergent insoluble protein, NDF, P, and K concentrations. Feed intake was predicted by considering energy intake, potentially limited by fill, and exceeding a minimum roughage requirement. Fill and roughage limits were functions of feed NDF concentrations adjusted to consider particle size distribution and the relative rate of ruminal digestibility or the physical effectiveness of the fiber. The herd submodel was verified to predict feed intakes, nutrient requirements, diets, and manure excretions similar to those recommended or measured for beef animals. Incorporation of the beef herd submodel with other farm components, including crop growth (alfalfa, grass, corn, small grain, and soybean), harvest, storage, feeding, grazing, and manure handling, provided the Integrated Farm System Model. This comprehensive farm-simulation model is a useful research and teaching tool for evaluating and comparing the long-term performance, economics, and environmental impact of beef, dairy, and crop production systems.     

The effects of formulation on the immunostimulatory activity of dihydroheptaprenol

Holstein steer calves received a single injection of Miglyol (Sasol Chemical Industries, Ltd.) subcutaneously as a placebo, dihydroheptaprenol (DHP) (4 mg/kg) emulsified with lecithin subcutaneously, DHP in solution in Miglyol (4 mg/kg) subcutaneously, or DHP in solution in Miglyol (4 mg/kg) intranasally. The DHP emulsified in lecithin emulsion administered subcutaneously caused a substantial increase in body temperature, total leukocyte count, total neutrophil count, neutrophil cytochrome-c reduction, and neutrophil iodination 24 hours after administration and, for some of the parameters, at 48 hours. The DHP formulation in Miglyol did not have any of these effects when administered subcutaneously or intranasally. The carrier and formulation of DHP apparently have major effects on the biologic activity of DHP.     

Delayed acute capture myopathy in three roe deer

Delayed acute capture myopathy is the term used to describe the clinical syndrome observed in three roe deer captured by drive-nets and transported to an enclosure for scientific purposes. The animals died 48 h, 60 h and 8 days after being captured. The simultaneous deaths coincided with a previous episode of deliberate human disturbance. The histopathological findings were indicative of acute myopathy and myoglobinaemic nephrosis. These could be related to an ataxic myoglobinuric syndrome brought on by capture and transport operations. The lack of clinical signs and negative prognosis indicators in the period between capture and just before death. the absence of gross muscular lesions in the animal that died after 8 days post-capture, the simultaneous deaths of animals captured at different times and the evidence of deliberate human disturbance in the enclosure are suggestive of death triggered by a second stress episode.     

Meal size and starch content affect gastric emptying in horses

REASONS FOR PERFORMING STUDY: Feeding practices have been associated with colic in horses. If meal size and composition have an effect on gastric emptying, this could be one of the mechanisms by which feeding practices are related to the occurrence of colic. OBJECTIVES: To evaluate the effect of meal size and starch content on solid phase gastric emptying. METHODS: Solid phase gastric emptying of 3 different radiolabelled meals, small low-starch (SmLS), small high-starch (SmHS) and large high-starch (LgHS) meals, was measured in 5 horses by scintigraphy using 99mTc-disofenin. Data were compared among meals using nonlinear mixed-effects models and paired t tests. RESULTS: On a percentage basis, SmHS emptied significantly faster than LgHS and SmLS emptied significantly faster than SmHS meals. However, when meals of unequal size were compared by emptying rate in g/min and Kcal/min, LgHS emptied significantly faster than SmHS. CONCLUSIONS: Meal size and composition affect gastric emptying. POTENTIAL RELEVANCE: Further work needs to be performed in order to substantiate the possibility of a relationship between digestive functions and occurrence of colic and gastric ulcers.     

Vitamin and trace mineral content in feed of breeders and their progeny: effects of growth, feed conversion and severity of malabsorption syndrome of broilers

1. A study was conducted to investigate the effects of several vitamins and trace elements chickens and in chickens experimentally infected with malabsorption syndrome (MAS). 2. Vitamins and trace minerals in feed were varied. Breeders received either a basal amount of vitamins and trace minerals (low mix) or an increased amount (high mix). Their progeny also received either a low mix or a high mix. Effects of different breeder and broiler mix combinations on broiler performance, heamatology, spleen weight and humoral response were examined in control chickens. The effects of the different feeds and breeder, broiler combinations at the severity and recovery of MAS infection were also studied. 3. In general, the immune system can be stimulated by addition of vitamins and trace minerals, without affecting the growth potential of the controls. The number of leukocytes increased on d 1 in the broilers descended from breeders receiving high mix. The response to Newcastle disease virus boost was affected by the different amount of vitamins. 4. When breeders received a high mix the number of infiltrating polymorphonuclear leukocytes in the intestine was higher compared with breeders receiving basal amounts of minerals and vitamins. Also the recovery rate of intestinal lesions, cystic crypts of Lieberkühn and villus atrophy, as observed by histopathology, was faster in the groups where the breeders received high mix.     

Assessment of the metabolic effects of hydrocortisone on llamas before and after feed restriction

OBJECTIVE: To evaluate the effects of administration of hydrocortisone on plasma concentration of insulin and serum concentrations of glucose, triglyceride, and nonesterified fatty acids (NEFAs) in llamas before and after feed restriction. ANIMALS: 9 adult female llamas. PROCEDURE: Feed was withheld from llamas for 8 hours. Blood samples were collected before (0 minutes) and 120, 180, 240, and 300 minutes after IV injection of hydrocortisone sodium succinate (1 mg/kg) for determination of plasma insulin concentration and serum concentrations of glucose, triglyceride, and NEFAs. The llamas were then fed a limited diet (grass hay, 0.25% of body weight daily) for 21 days, after which the experimental procedures were repeated. RESULTS: Compared with llamas that were not feed-restricted, llamas after feed restriction had significantly higher plasma insulin concentration and serum concentrations of triglycerides and NEFAs. Feed-restricted llamas after hydrocortisone injection had a significantly smaller increase in serum glucose concentration, a decrease (rather than an increase) in serum concentration of NEFAs, and no change in blood concentrations of insulin or triglycerides. CONCLUSIONS AND CLINICAL RELEVANCE: Short-acting glucocorticoid hormones did not appear to increase blood lipid concentrations in healthy llamas, regardless of ongoing fat mobilization. Thus, these hormones appear unlikely to be major direct contributors to diseases such as hepatic lipidosis or hyperlipemia. Although administration of hydrocortisone reduced serum concentration of fatty acids in feed-restricted llamas, its use has not been evaluated in sick camelids and cannot be considered therapeutically useful.     

Developing a classification tool based on Bloom's taxonomy to assess the cognitive level of short essay questions

The cognitive level of short essay questions taken from assessments of two veterinary courses at the Faculty of Veterinary Medicine of Utrecht University (FVMU) was evaluated using a simplified classification tool based on the taxonomy of Bloom. Classifications were made by teaching staff members (subject matter experts, or SME) and by faculty members not involved in teaching the course (non-subject matter experts, or NSME). To compare the cognitive level assigned by raters in the SME group to that assigned by the NSME group, each test item was assigned a modal taxonomic level. The results indicate that the agreement level between a pair of raters within a group (SME or NSME) differed (34% to 77% and linear weighted Cohen's kappa coefficient 0.12 to 0.60). The agreement level on the modal taxonomic level between the SME and NSME groups for the two courses was 65% and 73%, with a linear weighted Cohen's kappa coefficient of 0.43 and 0.63 respectively. The requirement of expertise of a subject for classification is discussed. The introduction of the classification tool had a positive effect on teaching staff members' awareness of the importance of the cognitive level of assessments. Improvements to the classification tool to obtain higher agreement levels are proposed.     

Effect of anionic salt and highly fermentable carbohydrate supplementations on urine pH and on experimentally induced hypocalcaemia in cows

The objective of this experiment was to determine the effect of dietary grain on calcium homeostasis. Six rumen-fistulated dairy cows with 3 or more previous lactations and no history of parturient paresis were randomly assigned to a sequence of diets in a crossover study with 4 periods of 10 days each. Dietary treatments were: A control ration consisting of wrap grass silage alone (1), the control ration supplemented with ammonium chloride and ammonium sulphate salt solution (2), control ration following a period with supplementation (3) and control ration supplemented with increasing amounts of barley from 4 to 10 kg/cow per day, expected to produce subclinical rumen acidosis (4). Daily intake of the diets was adjusted to 14 kg DM/cow per day. On day 11, the calcium-regulating mechanisms in cows were challenged until recumbency by a standardized intravenous EDTA infusion and cows were left to recover spontaneously. Anion supplementation and the feeding of highly fermentable carbohydrate lowered urine pH below 7.0 due to subclinical acidosis. During spontaneous recovery from EDTA induced hypocalcaemia, the cows more quickly regained a whole blood free calcium concentration of 1.00 mmol/L if they had most recently been supplemented with either anionic salts or with increasing amounts of barley, as compared to the basic ration. It is concluded that so-called slug-feeding or 'steaming up' with highly fermentable carbohydrates before parturition in milk fever susceptible cows enhanced calcium homeostasis similar to the effect seen in cows on anionic diets.     

Development of an Immunobinding Assay with Monoclonal Antibodies to Diagnose Mycoplasma bovis in Semen

Veterinary Research Communications -     

An evaluation of mycophage therapy, chemotherapy and vaccination for control of Mycobacterium avium subsp. paratuberculosis infection

The control of ovine Johne's disease (OJD) is important for domestic trade, the viability of farming units and possibly also for public health. Current strategies in Australia have included quarantine and pasture spelling to decrease prevalence and shedding rates and reduce numbers of Mycobacterium paratuberculosis (Mptb) ingested by susceptible sheep. However, alternative procedures are needed and vaccination with Gudair has recently commenced. This review examines prospects for the control of OJD by chemotherapy, vaccination and mycophages. Current chemotherapeutic regimes for treatment of M. paratuberculosis in ruminants are prohibitively expensive and of dubious efficacy, and apart from environmental concerns, mycophage therapy lacks a track record of success against intracellular bacteria. There is substantial evidence that live and killed mycobacterial vaccines reduce the incidence of clinical disease and shedding rates in OJD. An appraisal of recent experimental results suggests that neonatal vaccination with a defined dose of M. paratuberculosis offers the best prospects for the induction of protective Th1-type immunity.