Five studies were performed to determine factors affecting progesterone concentration in skim milk. Results of the first study indicated that progesterone concentration was higher in skim milk of samples kept 16 hours in an ice bath (0 C) than of those left at room temperature (21 C). In the second study, this temperature effect was found to be reversible, with skim milk progesterone concentration increasing when whole milk samples were cooled prior to centrifugation. In the third study, [3H]-labeled progesterone was used to determine the relationship between fat content of foremilk (the first milk obtained from the teats), midmilk (milk obtained through milking), and strippings (milk obtained immediately after milking machines have been removed) samples and temperature (4 C and 21 C) on the percentage of progesterone in the skim milk fraction. The relationship between percentage of butterfat and percentage of progesterone in skim milk was linear when the log of these variables was used for calculations. In the fourth study, assayable progesterone in the skim milk fraction of foremilk, midmilk, and strippings was affected by temperature. In the fifth study, a multiple-regression procedure was used to determine the amount of variation in percentage of radioactive progesterone in the skim milk fraction. Independent variables (whole milk butterfat and temperature of incubation [1, 3, 13, 22, 37, and 50 C]) and the natural log of each variable, were entered into a stepwise multiple-regression analysis. The log of the temperature and percentage of butterfat of whole milk at the time of centrifugation accounted for 89.2% (r2 = 0.892) of the variation in the log of the progesterone concentration in the skim milk fractions. The equation describing this relationship was: log percentage of progesterone in the skim milk fraction = 4.046 - 0.144 X (log of temperature of whole milk sample) - 0.688 X (log percentage of butterfat in whole milk sample). The loss of progesterone from skim milk fractions of warm whole milk samples is possibly a physical phenomenon dependent on the temperature of the sample and its percentage of butterfat. A nomograph was created to allow others to use these variables in making adjustments in progesterone concentrations.

The effect of dietary copper deficiency on T-cell mitogenic responsiveness and phenotypic profile of blood mononuclear cells (MNC) in weaned pigs was examined. Outbred, weaned pigs were fed a semipurified diet containing adequate (6.4 mg/kg of body weight) or deficient (0.8 mg(kg) amounts of Cu. Pigs fed the low Cu diet for 10 weeks had markedly decreased concentrations of Cu in liver and plasma, and hypertrophic hearts. In vitro reactivity of MNC from Cu-deficient pigs to phytohemagglutinin and concanavalin A was significantly suppressed. This functional impairment was not associated with a decrease in the percentages of T cells, CD4 or CD8 cell subsets, or B cells. Expression of SLA-DQ and SLA-DR class II major histocompatibility complex (MHC) antigens was increased by Cu deficiency, the former significantly. Unlike rodents, in which inadequate Cu nutriture induces functional T cell deficiency that is associated with a decrease in the CD4 T-cell subset, swine fed inadequate Cu diets for 10 weeks had no changes in MNC subsets yet clearly manifested functional impairment of T-cell responses.

The purpose of this study was to experimentally reproduce swine infertility and respiratory syndrome (SIRS). Six multiparous sows were intranasally inoculated at 93 days of gestation with lung homogenates from clinically affected pigs, and 3 additional sows were similarly inoculated with a virus isolated in cell culture from the lung homogenate (SIRS virus, isolate ATCC VR-2332). Inoculated sows developed transient anorexia, farrowed up to 7 days prematurely, and delivered a mean of 5.8 live pigs and 6.0 dead fetuses/litter. Clinical signs of disease were not observed in 3 sham-inoculated control sows that delivered a mean of 12.7 live pigs and 0.3 stillborn fetuses/litter. The sirs virus was isolated from 50 of 76 live-born and stillborn fetuses from the 9 infected fitters. Virus was not isolated from 26 autolyzed fetuses or 15 control pigs. Six of 9 inoculated sows developed neutralizing antibodies to SIRS virus. The reproductive effects found in these experiments were identical to those found in field cases. On the basis of our findings, virus isolate ATCC VR-2332 causes the reproductive failure associated with SIRS.

The study reported here was part of a long-term investigation of the effects of genotype on growth, reproduction, and metabolism in cattle grazing common Bermuda grass and endophyte-infected fescue pastures. In June 1990, blood samples were collected from the tail vein of yearling heifers and steers (Angus [AA], Brahman [BB], and their reciprocal crosses [AB, BA], n = 97). Serum amylase activity was assayed enzymatically; serum Ca and Mg concentrations were determined by atomic absorption spectrophotometry. The effects of endophyte-infected fescue depended on genotype (P < 0.001). In yearlings having at least 1 Angus parent (AA, AB, BA), grazing endophyteinfected fescue was associated with higher serum amylase activity than was grazing Bermuda grass. But serum amylase activities of BB yearlings consuming either forage were similar. Moreover, for either forage, substantial differences were related to genotype (P < 0.007) and gender (P < 0.05). Angus yearlings had higher serum amylase activity than did Brahman yearlings; AB and RA yearlings had intermediate values. Heifers had higher amylase activity than did steers. The relationship among serum values of amylase, Ca, and Mg depended on forage. Yearlings consuming endophyte-infected fescue and having at least 1 Angus parent had a moderate negative correlation between serum amylase activity and Ca concentration (r = -0.53; P < 0.0005); that is, in calves of genotypes with increased amylase activity while consuming endophyte-infected fescue (AA, AB, BA), the higher the amylase activity, the lower the serum Ca concentration. However, in yearlings consuming Bermuda grass, serum amylase and Ca values were not correlated. Conversely, grazing Bermuda grass was associated with moderate positive correlation between Ca and Mg concentrations (r = 0.46; P < 0.0003), but in yearlings grazing endophyte-infected fescue, Ca and Mg concentrations were independent. The cause, pathophysiologic mechanism, and clinical importance of these effects remain to be determined. In conclusion, serum amylase activity in yearling cattle was influenced by genotype, gender, and consumption of endophyte-infected fescue. We speculate that yearlings having at least 1 Angus parent may develop a persistent subclinical derangement of the exocrine portion of the pancreas when exposed to common environmental toxins associated with endophyte-infected fescue grass, and that purebred Brahman yearlings can resist this aspect of fescue toxicosis.

Intranasal (IN) and intratracheal (IT) oxygen administration techniques were compared by measuring inspired oxygen concentrations (FI(O2)) and partial pressures of arterial oxygen (Pa(O2)) in 5 healthy dogs at various IN (50, 100, 150, and 200 ml/kg of body weight/min) and IT (10, 25, 50, 100, 150, 200, and 250 ml/kg/min) oxygen flow rates. Intratracheal administration of oxygen permitted lower oxygen flow rates than IN administration. Each IT oxygen flow rate produced significantly higher FI(O2) and Pa(O2), than the corresponding IN flow rate. An IT oxygen flow-rate of 25 ml/kg/min produced FI(O2) and Pa(O2) Values equivalent to those produced by an IN oxygen flow rate of 50 ml/kg/min. An IT oxygen flow rate of 50 ml/kg/min produced FI(O2) and Pa(O2) values equivalent to those produced by IN oxygen flow rates of 100 and 150 ml/kg/min. All IT oxygen flow rates greater than or equal to 100 ml/kg/min produced FI(O2) and Pa(O2) values that were greater than FI(O2) and Pa(O2) values produced by IN oxygen flow rates of 200 ml/kg/min. The lowest flow rates studied (50 ml/kg/min, IN, and 10 ml/kg/min, IT) produced Pa(O2), capable of maintaining 97% hemoglobin saturation, which should be adequate for most clinical situations. Arterial blood gas analysis and FI(O2) measurements are necessary to accurately guide oxygen flow adjustments to achieve the desired Pa(O2) and to prevent oxygen toxicity produced by excessive FI(O2).

Plasma cortisol and immunoreactive (IR)-ACTH responses to 125 microg of tetracosactrin and cosyntropin--the formulation of synthetic ACTH available in Europe and the United States, respectively--were compared in 10 clinically normal cats. After administration of tetracosactrin or cosyntropin, mean plasma cortisol concentration reached a peak and plateaued between 60 and 120 minutes, then gradually decreased to values not significantly different from baseline concentration by 5 hours. Mean plasma IR-ACTH concentration reached a maximal value at 15 minutes after administration of tetracosactrin or cosyntropin and was still higher than baseline concentration at 6 hours. Difference between mean plasma cortisol and IR-ACTH concentrations for the tetracosactrin or cosyntropin trials was not significant at any of the sample collection times. Individual cats had some variation in the time of peak cortisol response after administration of either ACTH preparation. About half the cats had peak cortisol concentration at 60 to 90 minutes, whereas the remainder had the peak response at 2 to 4 hours. In general, however, peak cortisol concentration in the cats with delayed response was not much higher than the cortisol concentration at 60 to 90 minutes. Overall, these results indicate that tetracosactrin or cosyntropin induce a comparable, if not identical, pattern of adrenocortical responses when administered to healthy cats.

Sixteen healthy ponies were inoculated IV with Ehrlichia risticii-infected P388D1 mouse monocytes. Of the 16 ponies, 15 developed clinical signs of equine ehrlichial colitis. Twenty-four hours after onset of fever (rectal temperature > 38.8 degrees C), 7 ponies were treated with 25 mg of erythromycin stearate/kg of body weight and 10 mg of rifampin/kg, given orally every 12 hours for 5 days. The remaining 8 ill ponies served as nontreated controls. All ponies were observed for progression of clinical signs typical of equine ehrlichial colitis. Within 12 hours of initiation of treatment, 4 of the 7 treated ponies had rectal temperature < 38.4 C and, within 24 hours, 6 of the 7 ponies had rectal temperature < 38.3C. In contrast, all control ponies had rectal temperature > 39.2 C at 24 hours (P < 0.05). Of the 7 treated ponies, 4 no longer had signs of mental depression after the second day of treatment, and only 1 of the 7 ponies had mild signs of depression after the third day of treatment. In contrast, control ponies had high mental depression score during the observation period (P < 0.05). Feed intake improved in ponies of the treatment group, with feed intake of 4 of the 7 ponies returning to normal; the other 3 ponies were only mildly anorectic by the second day of treatment. Control ponies progressively decreased their feed intake during the observation period (P < 0.05). One control pony and 2 treated ponies developed diarrhea before the treatment/observation period began. Only 1 treated pony developed diarrhea after treatment began. Of the 8 control ponies, 7 developed diarrhea. Profound decrease in borborygmal sounds with silent periods lasting longer than 3 minutes was observed in 7 of the 8 control ponies. Only 1 of the 7 treated ponies had such profound decrease in borborygmi (P < 0.05). The decrease in borborygmal sounds progressed in the control ponies during the observation period. None of the treated ponies continued to have decreased borborygmi after treatment day 2 (P < 0.05). Of the 8 control ponies, 2 were euthanatized; all treated ponies survived. In survivors, signs lasted 8 to 17 (mean, 10) days in control ponies but only 1 to 5 (mean, 2.9) days in treated ponies.

Four diets were formulated to contain: 16% protein and 0.4% phosphorus-diet 1; 16% protein and 1.4% phosphorus-diet 2; 32% protein and 0.4% phosphorus-diet 3; and 32% protein and 1.4% phosphorus-diet 4. Forty-eight dogs were fed diet 1 for 3 months after surgical reduction of renal mass, then were allotted to 4 groups of 12 dogs each, with equal mean values for glomerular filtration rate (GFR). Dog of groups 1-4 were fed diets 1-4, respectively, for 24 months. Data collected from the dogs during and at termination of the study were analyzed statistically for effects of dietary protein, phosphorus (P), time, and interactions between these factors. During the 24 months of study, 24 dogs developed uremia and were euthanatized for necropsy. Necropsy also was performed on the remaining 24 dogs after they were euthanatized at the end of the study. Dog survival was significantly enhanced by 0.4% P diets (vs 1.4% P diets), but survival was not significantly influenced by amount of dietary protein. The 0.4% P diets (vs 1.4% P diets) significantly increased the period that GFR remained stable before it decreased, but dietary protein did not have significant effect. Significant blood biochemical changes attributed to P, protein, and time were identified during the study. Terminally, plasma parathyroid hormone concentration was significantly increased from prediet values in all groups of dogs. Urine protein excretion was not significantly affected by dietary amount of either protein or P, when measured by either timed urine collection or urine protein-to-creatinine ratio. A tendency was seen for increased protein excretion with passage of time. Histologic and mineral analyses of kidneys removed at necropsy revealed some significant difference attributable to diet, but differences were more marked when diet was ignored, and the 24 surviving dogs were compared with the 24 that developed uremia. Overall, amount of dietary P was more important than amount of dietary protein for preventing adverse responses. However, because renal damage specifically attributable to either dietary component was not obvious, it is possible that the effects of P were manifested by extrarenal mechanisms.

Glycoprotein I (gI) phenotypes and genotypes of 4 pseudorabies viral diagnostic isolates were evaluated by use of in vitro DNA amplification, monoclonal antibody binding, gI-specific serodiagnostic responses, and in vivo virulence approaches. Three viruses were avirulent and did not elicit gI-specific serologic responses, react with gI-specific monoclonal antibodies, or contain gI epitope-encoding DNA sequences. The fourth virus was virulent and did elicit a gI-specific serodiagnostic response. Compared with reference virulent pseudorabies viruses, however, the fourth isolate had reduced reactivity with a group of gI monoclonal antibodies and had a single nucleotide sequence substitution with a corresponding putative amino acid change in the epitopically dominant portion of the gI molecule. Presumably, the first 3 isolates represented diagnostic recoveries of viruses derived from gI-deleted modified-live pseudorabies viral vaccines, whereas the fourth isolate was a virulent but gI-aberrant wild-type virus. Thoroughly assessing the gI status of pseudorabies viral diagnostic isolates was considered to be essential in evaluating the epidemiologic importance of these viruses and in monitoring the validity of gI-based vaccine companion tests now used worldwide in pseudorabies control and eradication programs.

A commercially available Salmonella bacterin was administered to Holstein calves starting at 1 to 19 weeks of age. Serum samples were obtained before administering bacterin and at 2-week intervals thereafter. An ELISA with Salmonella dublin lipopolysaccharide (LPS) or S dublin whole cells as antigen, was used to measure specific IgG and IgM responses. Antibody responses to LPS were not detected from calves < 12 weeks old inoculated with killed bacterin. Immunoglobulin responses to whole-cell antigen were detected from all age groups of calves inoculated with the same killed Salmonella bacterin. Calves < 11 weeks old are able to produce immunoglobulins to some whole-cell antigens, but are unable to produce anti-LPS immunoglobulins when inoculated with killed Salmonella bacterin. This age-related response to killed Salmonella antigens may account, in part, for increased susceptibility to salmonellosis in calves < 12 weeks old. In comparison to the response for killed antigen, 8 calves given modified-live aromatic-dependent S dublin bacterin at 1 to 3 weeks of age had detectable anti-LPS immunoglobulin after immunization, although the response was not as rapid and was of a lesser magnitude than that of older calves given killed Salmonella bacterin.