Survey of state veterinarians and state veterinary diagnostic laboratories for selenium deficiency and toxicosis in animals.

Surveys were performed in which the state veterinarian and the major state veterinary diagnostic laboratories in every state were asked about selenium (Se) deficiency and toxicosis in livestock and wildlife in their state. Selenium-deficiency diseases were diagnosed in 46 states and were reported to be an important livestock problem in regions of 37 states; deficiencies were diagnosed in wildlife in 10 states. Natural Se toxicosis was a rare problem, with only 7 states reporting naturally developing Se toxicosis. Oversupplementation with Se was reported as a cause of toxicosis in 15 states. Toxicoses in aquatic environments were reported from 4 states; in all cases, high-Se content in the water had resulted from agricultural irrigation or natural rainfall causing leaching of Se from high-Se soils. Current amounts of supplemental Se that can be fed to our major food-producing animals are being reviewed by the FDA because of speculation of potential environmental problems caused by Se supplementation in animals. Amounts of supplemental Se allowed in the western United States (states west of and including North Dakota, South Dakota, Nebraska, Kansas, Oklahoma, and Texas) are proposed by the FDA to have more potential for environmental Se enrichment and toxicosis. This premise was not supported by our data. Selenium supplementation in domestic livestock was not involved in wildlife toxicosis found by these surveys.

Evaluation of multiple reticulorumen selenium pellets as a health risk in growing Hereford steers.

Five groups of Hereford steers were monitored for 293 days. One group of 3 was not given selenium supplementation; the other 4 groups of 3 steers each were given 2, 4, 6, or 8 reticulorumen selenium pellets. Health, body weight, and blood selenium concentration were monitored during the study. At the finish, steers were slaughtered, and various tissues from the carcasses were analyzed for selenium content. Initial blood selenium concentration did not differ significantly among groups. However, significant (alpha = 0.01) difference among means was detected during the early period of rapid increase in blood selenium concentration in steers of supplemented groups. Means of maximal blood selenium concentration also differed among groups; however, even the highest value, 0.253 micrograms/g, was lower than the 3 micrograms/ml reported in chronic clinical cases of toxicosis in the literature. Carcass analysis indicated significant (alpha = 0.05) differences in selenium concentrations among treatment groups for almost all tissues tested. Only kidney samples (7.9 micrograms/g) from steers of the 8-pellet treatment group exceeded published normal values (7.6 micrograms/g). Health variables for most dates were not significantly different among groups, and selenium toxicosis was not evident in any steer. Analysis did not indicate risk to human beings consuming tissues from these steers.

Detection of antibiotic and sulfonamide residues in bob veal calf tissues: 967 cases (1987-1988).

The data on antimicrobials in bob veal calves obtained by USDA-Food Safety Inspection Service (FSIS) during the fiscal year 1988 were reviewed. Of 3,095 calf antibiotic and sulfonamide test (CAST)-positive carcass submissions, 967 were chosen by FSIS for antimicrobial residue analyses. Specimens of muscle, liver, and kidney were obtained at abattoirs as a part of the FSIS program, and the results were reviewed by calf submission. At least 1 tissue from each of 425 submissions contained neomycin. Unidentified microbial inhibitors were found in 291 submissions. Streptomycin was found in 86 carcass submissions, penicillin in 81, sulfamethazine in 73, tetracycline HCl in 59, and gentamicin in 53. Other monitored agents were found in less than 50 submissions each. Only 257 submissions included evaluation for sulfonamides, but sulfamethazine was found in 28.4% of them. Chloramphenicol was not detected. Concentrations of neomycin in kidney specimens ranged from 0.25 to greater than 100 ppm, and differed among the 3 regional laboratories (West, Midwest, and East). The western region had the greatest proportion of low-concentration specimens, whereas the midwestern laboratory had the largest proportion of specimens with very high concentrations (greater than or equal to 100 ppm) of neomycin in kidney tissue. Data to identify the sources and causes of the residues were not available. However, the western laboratory evaluated CAST-positive submissions from calves certified to be antimicrobial-free, whereas the other laboratories evaluated submissions from certified and noncertified calves; therefore, this may partially explain regional patterns for neomycin quantities in kidney specimens. Neomycin predominated among CAST-positive verifications. A high prevalence of unidentified microbial inhibitors suggests further identification may be warranted.

Antibiotic and sulfonamide residues from Food Safety Inspection Service bob veal calf tissues by region, from October 1987 to September 1988.

Of 3,095 bob veal carcasses declared positive to the calf antibiotic and sulfonamide test (CAST) performed by USDA-FSIS personnel during the fiscal year 1988, 967 were submitted to USDA-FSIS laboratories for intensified antimicrobial evaluation of kidney, liver, and muscle specimens. In the western region, CAST-positive specimens were analyzed from certified calves, that is, calves declared free of antimicrobials by their producers. In the midwestern and eastern regions, 20% of the CAST-positive carcass submissions were certified and 20% had not been certified. Among the regions, neomycin was the most commonly reported agent from kidney specimens; however, there were some distinct differences among regions (24.6% of the specimens in the Midwest, 37.4% in the East, and 46.8% in the West). Reports of gentamicin in specimens also were different among regional laboratories (9.0% in the Midwest, 12.1% in the East, 3.1% in the West). Sulfamethazine was less frequently reported by the western laboratory, never exceeding 2% among the 3 tissues tested, whereas the eastern and midwestern laboratories had at least 1 tissue type that was greater than or equal to 9%. Not all specimens were subjected to sulfonamide evaluation. Regional patterns were noticed for unidentified microbial inhibitors, which were most evident for liver in which 24.6% of the specimens at the western laboratory were classified as having unidentified microbial inhibitors, and only 6.3% of specimens at the eastern laboratory were classified as having unidentified microbial inhibitors.

Antibiotic and sulfonamide agents in bob veal calf muscle, liver, and kidney.

During the fiscal year 1988, USDA-FSIS detected 3,095 antimicrobial violations in bob veal calves, using the calf antibiotic and sulfonamide test. Of the 3,095 carcass submissions involved, 945 were tested further to identify the causative agents. The results of tests on the available kidney, liver, and muscle specimens are reported. Kidney specimens yielded a specific agent most often (71.2%), with neomycin (42.6%) being cited most among agents found in kidneys. Neomycin was found less frequently in liver (4.5%) and muscle (0.2%). Among all tissues, unidentified microbial inhibitors were either the largest or second largest category found (kidney, 10.5%; liver, 27.1%; muscle, 7.8%), and no other agent exceeded 7.0% (streptomycin in kidney). The proportion of liver and muscle specimens that had unidentified microbial inhibitors is particularly important because the next most common classes were streptomycin in liver at 5.5% and sulfamethazine in muscle at 2%. The frequency of unidentified microbial inhibitors may justify the addition of tests to the FSIS battery for identification of agents. Not all tissues were tested for sulfonamides, hence these agents are likely to have been underreported. Less than 10% of the muscle specimens evaluated yielded an agent, suggesting most calf antibiotic and sulfonamide test-positive carcasses may have been safe with regard to residues in meat, although organs might have been adulterated. Specimens for verification were not selected completely randomly from the population of all calf antibiotic and sulfonamide test-positive animals and calves selected for testing were not chosen strictly by random sampling; therefore, extrapolation of the contents of this report to the bob veal calf industry must be done with caution.

Safety and efficacy of two sustained-release intrareticular selenium supplements and the associated placental and colostral transfer of selenium in beef cattle.

One hundred fifty Se-deficient, pregnant, crossbred beef cows were assigned to 1 of 4 treatment groups: group A, Se-deficient control; group B, 1 Se bolus at 0 and 119 days; group C, 1 Se bolus at 0 days; and group D, 2 Se pellets at 0 days. The Se bolus is an osmotic pump designed to release 3 mg of Se/d into the reticulorumen. The Se pellets weight approximately 30 g and contain 10% elemental Se, which is liberated in the reticulorumen. The Se bolus is designed to provide Se supplementation for 120 days and the Se pellets provide supplementation for up to 18 months. Cattle were maintained on Se-deficient pasture or forages prepared from these pastures for the duration of the experiment. Blood samples were collected from cows prior to treatment (time 0) and at 28, 52, 119, and 220 days thereafter and analyzed for blood Se (BSe) concentration. Body weights were recorded at each sampling time. Blood Se concentration of cows from all supplemented groups were significantly (P less than 0.01) higher than control values at all sample dates after treatments began. By the end of the 220-day study, treatment group-B cattle had significantly (P less than 0.01) higher BSe concentrations than any other group. Body weights of treatment groups fluctuated throughout the study, but did not differ (P greater than 0.05) between groups. One cow and 6 calves born to cows during the experimental period died. Necropsy of 5 calves provided no evidence linking these deaths to treatments.(ABSTRACT TRUNCATED AT 250 WORDS)

Compensatory weight gain in steers recovered from oak bud toxicosis.

Cattle that had recovered from clinical oak bud toxicosis (as assessed by normal BUN and serum creatinine values and good appetite) performed better than did clinically normal herdmates when weight gain and feed efficiency were compared. Both groups had a rate of weight gain (oak bud-exposed cattle, 1.76 kg/steer/d; control cattle, 1.57 kg/steer/d) that exceeded the feedlot mean value (approximately 1.4 kg/d) for cattle (of similar starting weight and diet) that had zeranol implants, and the difference was significant (P less than 0.005) for both groups. The difference in weight gain performance of oak bud-exposed cattle, compared with control cattle, was not highly significant; however, the improved feed efficiency was significantly (P less than 0.05) better than that in controls (2.57 kg of feed/kg of weight gain vs 3 kg of feed/kg of weight gain). On the basis of accepted criteria (increased rate of weight gain and efficiency of feed conversion), the group of oak bud-exposed cattle of this study had compensatory weight gain. Thus, cattle with good evidence of clinical recovery from oak bud toxicosis can be expected to perform in the feedlot at least as well as cattle not exposed to oak bud toxicosis, and may have compensatory weight gain.

Bovine adenovirus type-3 infection in feedlot calves.

The frequency of bovine adenovirus type-3 (BA3) infection in 84 of 165 light feeder calves and the possible role of BA3 in inducing febrile disease and affecting weight gain performance were studied for 56 days after the calves entered a feedlot. Samples of blood for serotesting were obtained periodically, and samples for virus isolation were collected on days 28 and 56. At the time the calves entered the feedlot, 17.8% (15 of 84) had serum virus-neutralizing antibodies to BA3. During 56 days, 54.8% (46 of 84) seroconverted to BA3. Of these seroconversions, 87% took place during the first 28 days. Bovine adenovirus type-3 was isolated from 2 calves (1 isolate each on days 28 and 56). Pyrexia (greater than or equal to 39.2 C) was observed more often in BA3-infected calves than in noninfected calves. However, there was no significant (P less than 0.05) difference in weight gain between the BA3-infected and noninfected calves.

Oak toxicosis in cattle in northern California: clinical and pathologic findings.

Sixteen calves (3 to 8 months old) affected with oak toxicosis were studied. Clinical, laboratory, and pathologic findings during the peracute through chronic stages were documented. Of the calves studied, 1 died, and 9 others were euthanatized because death was imminent. To evaluate chronic effects, the 6 remaining cattle were euthanatized after 2 months. One calf with acute toxicosis was treated successfully with diuretics and fluid volume replacements containing sodium chloride and calcium. Clinical and laboratory data were compared between survivors and nonsurvivors. A statistically significant (P less than 0.02) difference was found only in serum creatinine concentration at the time of initial reexamination. A decrease in BUN and creatinine values during the next 7 days and the lack of anorexia after the acute phase were the best prognostic indicators for survival.

B-vitamin supplementation of diets for feedlot calves.

B-vitamin supplementation of diets for 144 shipping-stressed crossbred calves (116 kg) at levels up to 10 times that recommended for growing pigs did not influence (P greater than .20) weight gain or feed conversion during a 56-d receiving trial. However, vitamin supplementation tended (P less than .10) to reduce morbidity. In a second trial, supplemental B-vitamins had no effect (P greater than .20) on efficiency of microbial growth or site and extent of digestion of organic matter, acid detergent fiber and N. Supplemental dietary riboflavin, niacin, folic acid, B12 and ascorbic acid were largely metabolized [degraded and (or) absorbed] anterior to the small intestine, with escape values of 1, 3, 10 and 0% of added vitamins, respectively, while dietary B6 and biotin largely escaped the rumen. Thiamine and pantothenic acid were intermediate in ruminal escape (52 and 22%, respectively). Small intestinal absorption of thiamine, niacin, riboflavin, B6 and B12 averaged 75, 79, 25, 79 and 48%, respectively. Coefficients for ruminal escape and microbial synthesis for each B-vitamin were calculated using the slope-ratio technique. Measured flows for thiamine, riboflavin and B12 in a third experiment were similar to flows predicted from escape and synthesis equations, though flow of niacin and B6 were under-predicted by 37 and 44%, respectively. Results are interpreted to indicate that intestinal B-vitamin supply can be predicted based on dietary composition and intake.

Effects and use of a modified live Anaplasma marginale vaccine in beef heifers in California.

Eighty-one 11-month-old, nonpregnant, Anaplasma marginale-seronegative beef heifers were allotted to 2 groups for evaluation of a modified live A marginale vaccine (n = 50 for vaccinated group and n = 31 for nonvaccinated group). The vaccine induced a mild form of anaplasmosis, as evidenced by a significant (P less than 0.01) decrease in the packed cell volume (PCV) between days 31 and 46 after vaccination. The lowest PCV was 11%, and 3 heifers had a PCV less than 20%. Slight lethargy was evident in some of the vaccinated heifers between days 30 and 45 after vaccination. All vaccinated heifers became seropositive to A marginale, as measured by the complement fixation test and the card test on days 35 and 42 after vaccination, respectively. All nonvaccinated heifers remained seronegative.

An economic evaluation of metabolic and cellular profile testing in calves to be raised in a feedlot.

The economic value of the metabolic and cellular profile test as a predictor of feedlot calves' performance was determined. The economic technique used in this evaluation was decision tree analysis. Results showed that in a case study evaluation such as this one, the metabolic and cellular profile test would not be recommended. Further, under the assumptions used, even if the test were perfected, the cost of the test should not exceed $2.79. The application of decision tree analysis demonstrated how questions concerning the economics of animal health issues may be formulated and solved.

Metabolic and cellular profile testing in calves maintained under feedlot conditions: protein fractions and lactate dehydrogenase isoenzymes--changes over time.

Mean concentrations for total serum protein and serum protein fractions, and mean activities for total lactate dehydrogenase (LDH) and LDH isoenzymes were determined in 114 crossbred yearling cattle during a 56-day feeding trial. These values were to be used as predictors of performance (weight gain). The mean total serum protein concentration on day 0 was high (7.27 g/dl), reached a low on days 7 and 14 (6.47 and 6.50 g/dl), and then equilibrated toward the end of the study. The mean concentration for the albumin fraction also reached a low on days 7 and 14 (2.83 and 2.84 g/dl) and then increased, remaining steady until termination of the feeding trial. The alpha-, beta-, and gamma-globulin fractions fluctuated throughout the study. The mean for total LDH activity peaked on day 21 (1,363 IU) and then remained relatively constant through day 56. Mean serum activities for the LDH3 activity peaked on day 7 (27%) and then decreased progressively to day 56 (17%). The overall trend for LDH4 and LDH5 activities seemed to be a steady increase.

Metabolic and cellular profile testing in calves under feedlot conditions, using discriminant analysis to identify calves with low potential for weight gain.

Thirty-eight variables were measured in blood samples of 48 calves at the beginning (day 0) of a feed trial. After 56 days, the calves were assigned (according to weight gain) into three groups: high gainers, medium gainers, and low gainers. Discriminant analysis was used on the variables that were measured to classify the calves into three groups. When the mean values for three overlapping groups of 16 calves each were analyzed, blood urea nitrogen data alone correctly classified 68.7% of the low gainers. Overall, correct classification never exceeded 58.3%. When three nonoverlapping groups of nine calves each were used, inorganic phosphate data (used first and alone) correctly classified 66.7% of the low gainers. After seven steps, 81.5% of the animals were correctly classified, including 88.9% of the low gainers. The two-group discriminant analysis identified 78% of the nine lowest gainers, and 90% of the remaining animals were correctly classified.

Metabolic and cellular profile testing in calves under feedlot conditions: minerals, electrolytes, and biochemical components--reference values.

Blood serum samples were obtained from 114 crossbred calves on a feed trial under feedlot conditions at the end of a 56-day feeding period. Average values for 19 blood components were determined. The effects of the 3 trial rations and 2 electrolyte treatments were analyzed. Except for inorganic phosphates, urea nitrogen, cholesterol, glucose, alanine aminotransferase, and alkaline phosphatase most mean values were similar to those in dairy cattle. Urea nitrogen values differed significantly (P less than 0.05) in animals fed different rations apparently reflecting the crude protein content of each ration. The mean values presented can be used as base-line data for comparison with other similar studies or with values from diseased animals.

Metabolic and cellular profile testing in calves under feedlot conditions: minerals, electrolytes and biochemical components--changes over time in feedlot.

The concentration of 19 mineral, electrolyte, and biochemical components in blood serum of 114 calves under feedlot conditions were measured or calculated over a 58-day period (2 days before and 56 days during a feed trail). The purpose was to evaluate the variability in the concentration of these components over time. The blood was collected on 7 sampling dates and analyzed on the day following sampling. Generally, the serum concentrations of the components that were measured varied considerably over the first 3 weeks of the feeding period and then had a tendency to level off during the 2nd part of that period.

Metabolic and cellular profile testing in calves uncer feedlot conditions: blood cellular components--reference values and changes over time in feedlot.

The cellular components of the blood of 114 calves were measured under feedlot conditions. The results suggest that certain cellular components of the blood of a group of crossbred feedlot-type calves which are homogeneous only with regard to weight are reasonably uniform. More specifically, all red blood cell components have coefficients of variation of less than 10%. The white blood cell counts underwent drastic changes over the first 2 sampling dates, ie, before and after transport and processing of the calves. Later, in the feeding period, the cell counts readjusted to more stable levels. The results were compared with such values obtained from dairy cattle. The total erythrocyte count, total leukocyte count, and red blood cell components were found to be slightly higher in these feedlot calves than in dairy cattle. The difference might partly be due to age. The mean values reported can be used as a base for comparison with values obtained from other such studies or from studies of disease processes in cattle under feedlot conditions (or both).