Legal responsibilities of veterinarians in the control of zoonotic diseases

This discussion of legal issues that may arise from the existence of zoonotic diseases is not meant to cause alarm; rather, it is meant to alert members of the profession to possibilities, not probabilities. The very nature of any discussion of legal issues, especially a discussion of case law in which someone is always suing somebody else, exaggerates the true-life situation. Although it is everyone's hope that they will not be involved in litigation, it is wise to be aware of the problems that may arise in connection with zoonotic diseases.     

Influence of breed and diet on growth, nutrient digestibility, body composition and plasma hormones of Brangus and Angus steers

Two split-plot designed experiments were conducted to determine the effects of breed (Angus, A, or Brangus, B) and diet (fescue hay, FH; corn silage, CS; or concentrate) on composition and rate of growth, diet digestibility and plasma hormones of steers. In Exp. 1, 10 steers (five of each breed) were fed a CS-based diet followed by a FH-based diet for two consecutive 60-d periods. Both breeds had lower (P less than .01) DM intake and digestibility when fed FH than when fed CS diets. The B steers had higher (P less than .01) plasma insulin concentrations than A steers when fed the CS diet. In Exp. 2, during two consecutive years, 10 steers previously fed CS- and FH-based diets were finished with a corn silage-whole shelled corn-based diet. During yr 1, A steers had higher (P less than .01) DM intake and plasma triiodothyronine (T3) and thyroxine (T4) concentrations (P less than .05) than B steers did. Although final weights were similar (P greater than .10), A steers had heavier (P less than .05) carcass weights than B steers did. During yr 2, A steers had higher (P less than .07) DM and starch digestibilities and higher (P less than .01) plasma T4 concentrations than B steers did. The greater (P less than .01) energetic efficiency of A steers was attributed to the greater rates of fat deposition during yr 2. Regardless of type of diet fed, A steers were more efficient at depositing energy. Higher circulating T4 concentrations of A than B steers may explain some of the physiological differences between these breeds.     

Drying times of umbilical cords of dairy calves

OBJECTIVE: To determine the distribution of drying times of umbilical cords of dairy calves and to determine if cord dryness is a reliable indicator of age. DESIGN: An observational study was undertaken in a spring calving herd in Victoria, of the umbilical cords of 188 calves (82 Friesian bulls, 82 Friesian heifers, 24 crossbreds). PROCEDURE: Umbilical cords were examined daily, visually and by palpation, until the cord to the junction of the skin on the abdomen of the calf was dry, shrivelled and inflexible. RESULTS: Drying times ranged from 1 to 8 days. By the fifth day of life, the umbilical cords of 96.7% of all calves, 97.5% Friesian heifer calves, 87.5% of Friesian bull calves and 100% of cross-bred calves were dry. If cord dryness only was used to select calves for sale, 91.3% of all calves, 86.4% of Friesian bull calves and 100% of cross bred calves could have been sold before their fifth day of life. If calves were selected on age only, 3.3% of all calves, 2.5% of Friesian heifer calves and 12.5% of Friesian bull calves would have been sold before their umbilical cord was dry. CONCLUSION: The dairy industry cannot rely on cord dryness alone as an indicator of age for selection of calves for sale and transportation. Cord dryness is a poor indicator of age.     

Diet modulates proteinuria in heterozygous female dogs with X-linked hereditary nephropathy

Young adult heterozygous (carrier) female dogs with X-linked hereditary nephropathy (XLHN) have glomerular proteinuria but are otherwise healthy. Because data regarding dietary influences on the magnitude of proteinuria in dogs with spontaneous glomerular disease are not available, 12 such dogs were studied in a double crossover experiment intended to determine effects of altering dietary protein intake for up to 6 weeks. Dogs were blocked by urine protein : creatinine ratio (UPC) and randomly assigned to receive 2 diets: high protein (34.6% dry matter [DM], HP) or low protein (14.1% DM, LP) fed in HP-LP-HP or LP-HP-LP sequence. Food intake was measured daily, body weight (BW) was measured twice weekly, and UPC, plasma creatinine, blood urea nitrogen, phosphorus, albumin, and protein concentrations were measured at 2-week intervals. Nutrient digestibility was measured during the third treatment period. Diet had a significant effect (P < .0001) on all measured variables except plasma phosphorus (P > .5), but unintended differences in digestibility of protein and energy (P < or = .01) prevented assignment of the diet effect exclusively to protein. Proteinuria was greater (UPC 4.7 +/- 2.2 versus 1.8 +/- 1.1, P < .0001) when the HP diet was fed, but the LP diet did not maintain starting BW or plasma albumin concentration within the normal reference range. Diet greatly affects the magnitude of proteinuria in XLHN carrier females. Dietary protein restriction can reduce proteinuria in dogs with glomerular disease, but BW and blood protein concentrations may not be maintained if the restriction is too severe.     

Variations in the dietary cation–anion difference and the acid–base balance of dairy cows on a pasture-based diet in south-eastern Australia

The variation in the dietary cation–anion difference (DCAD) and the urinary pH of dairy cows was examined over the year 1996–97 in Victoria, south-eastern Australia. Mineral concentrations in the pasture and dairy cow milk production were also examined. Three farmlets (A, B and C) under different feeding and management systems were used for the purpose of the study. Feeding management was based on grazed grass with stocking rates of 1·4, 2·5 and 4·7 cows ha^–1 for farmlets A, B and C respectively. Cows on farmlets B and C received more supplementary feed than those on the A farmlet.
The urine of the cows in each herd was sampled for pH twice monthly, after morning milking. A sample of the feed on offer the previous day was collected and analysed for crude protein, in vitro dry-matter digestibility and macrominerals. Milk yields were recorded on the same day as urine sampling and weather data for the previous day were also collected.
Pasture cation–anion difference was not greatly influenced by stocking rate or associated management practices, although mineral concentrations in pasture did vary. Urine pH was unaffected by changes in climate, management strategies (e.g. stocking rate), season and stage of lactation. Moreover, urine pH was also unaffected by changes in DCAD until the DCAD declined below approximately +15 mequiv. 100 g^–1 for two consecutive sampling periods.
It is concluded that when this threshold for DCAD (+15 mequiv. 100 g^–1) is breached, even in late lactation, a decrease in urine pH occurs. In south-eastern Australia, the DCAD offered to non-lactating cows in the last 2 weeks of pregnancy, in spring-calving herds, on a pasture-based diet is nearly always above that regarded as optimum in other feeding systems.