Detection of rotavirus antigen in diarrhoeic and non-diarrhoeic piglets in Nigeria

Faecal samples from 96 piglets with acute gastroenteritis and 41 samples from non-diarrhoeic piglets were investigated for porcine rotavirus (PRV) antigens by enzyme-linked immunosorbent assay (ELISA). PRV was detected in 43 of 96 (44.8%) in the diarrhoeic group whilst none of the samples in the non-diarrhoeic group was positive for PRV (P less than 0.01). Age distribution of infection showed a higher infection rate of 30.2% in piglets aged 1-3 weeks, which was significantly higher (P less than 0.05) than in piglets aged 4-6 weeks, where the infection rate was 14.6 per cent. No PRV antigen was detected in diarrhoeic piglets above 6 weeks of age. Titration of 10 randomly selected ELISA-positive samples showed titres ranging from 512 to greater than or equal to 4.096.     

Isolation of Salmonella enteritidis from internal organs of experimentally infected hens

Tissues from experimentally infected hens were examined for the presence of Salmonella enteritidis (SE). SE was recovered from internal organs of both orally inoculated hens and hens infected by horizontal contact transmission. SE was isolated from 58% of the ceca, 51% of the livers, 47% of the spleens, 17% of the ovaries, and 17% of the oviducts of hens sampled during the first 5 weeks after exposure. SE was recovered at a low frequency from all internal organs sampled for as long as 22 weeks after exposure.     

Influence of ambient temperature on prolactin concentrations in serum of Holstein and Brahman x Hereford heifers

Four Holstein and four Brahman x Hereford heifers about 8 mo of age were used in a study to determine whether breed influences the effects of ambient temperature on concentrations' of prolactin in serum. Two heifers of each breed were stanchioned in each of two environmental chambers at 21 C for 7 d, after which chamber temperatures were changed to 7 or 31 C during 6 h. After 5 d at 7, 21 or 31 C, heifers were injected with 60 micrograms thyrotropin-releasing hormone (TRH). A switch-back design was used and each heifer was exposed to all treatments. Concentrations of prolactin in serum of heifers during exposure to 7, 21 or 31 C for 5 d were related to ambient temperature (9.0, 20.9 and 29.5 ng/ml, respectively; P less than .001), but the response was not influenced by breed. Heifers of both breeds responded similarly to treatment with TRH, and prolactin in serum increased (P less than .001) within 5 min from 7.0 +/- 3.2 to 45.7 +/- 8.2 ng/ml in heifers at 7 C, from 13.1 +/- 1.6 to 97.2 +/- 9.6 ng/ml in heifers at 21 C and from 18.2 +/- 3.5 to 96.2 +/- 11.3 ng/ml in heifers at 31 C. We conclude that concentrations of prolactin in serum of heifers are positively associated with ambient temperature and that the effects of temperature on basal and TRH-stimulated concentrations of prolactin do not differ significantly between Holstein and Brahman x Hereford heifers. Thus, differences in tolerance to heat were not related to differences in prolactin secretion.     

EFFECT OF STRESS ON STEROID HORMONE LEVELS IN RACEHORSES

SUMMARY Cortisol and testosterone were measured by radioimmunoassay in plasma samples from race horses. None of 6 stressed male horses had Iow cortisol levels but testosterone levels (0.81 ± 0.15 nmol/l) were significantly lower than in healthy horses (1.86 ± 0.31 nmol/l). The conclusion was made that adrenocortical insufficiency is not a common association of stress in race horses. The reduction in testosterone levels is probably a nonspecific response similar to that seen in other species.     

EVALUATION OF A HARDJO-POMONA VACCINE TO PREVENT LEPTOSPIRURIA IN CATTLE EXPOSED TO A NATURAL CHALLENGE WITH LEPTOSPIRA INTERROGANS SEROVAR HARDJO

SUMMARY The efficacy of a vaccine against Leptospira interrogans serovar pomona and Leptospira interrogans serovar hardjo was evaluated in a group of dairy heifers that were serologically negative at the time of vaccination and later subjected to natural challenge with L. interogans serovar hardjo. Thirty-nine heifers were vaccinated twice, at a one-month interval, with a commercially prepared bivalent vaccine, while 43 unvaccinated heifers were used as controls. After vaccination, microscopic agglutination (MA) titres of serums to L. interrogans serovar hardjo ranged from 32 to 512, and those to L. interrogans serovar pomona ranged from 32 to 2048. Titres resulting from vaccination were short-lived and after the first vaccination the serums of 95% of vaccinated heifers did not react in the MA test by 24 weeks. The first indication of infection in the heifers was noted at week 6, and by week 16, elevated MA titres (≥128) to L. interrogans serovar hardjo had occurred in 62% of unvaccinated heifers and had increased to 85% by week 24. At week 18, 18% of the vaccinated heifers and 56% of the unvaccinated heifers had leptospiruria (p<0.01); after 22 weeks, 13% of the vaccinated heifers and 58% of the unvaccinated heifers showed evidence of leptospiruria (p<0.01).     

A SURVEY OF CLINICAL MASTITIS IN SOUTH-EAST QUEENSLAND DAIRY HERDS

SUMMARY A survey of clinical mastitis in 26 South-East Queensland dairy herds supplying more than 300,000 litres of milk annually, revealed a quarter incidence of 2.6% with a cow incidence of 9% over a 3-month period. Secretion samples from cows yielded Staphylococcus aureus, Streptococcus agalactiae, Streptococcus dysgalactiae, Streptococcus uberis, coliforms, Pseudomonas spp and other bacteria in 38.5%, 12.5%, 6.6%, 3.4%, 2.6%. 0.6% and 2.0% of cases respectively. Samples from 38% of the cases were culturally negative while at least 38% of the clinical quarters had shown a previous clinical episode of mastitis. There was a significant association (P < 0.025) between herd and the likelihood of a negative culture result on samples from clinical cases. Twenty-one percent of cases occurred in the first month of lactation and 10.3% in the first week. There was a significant association (P < 0.005) between the age of cow and the stage of lactation in which clinical cases occurred in that cows in the 2 to 5 year age group were more likely to suffer attacks in the earlier part of lactation. There was a highly significant relationship (P < 0.005) between cow age group and the proportion of affected quarters and it was calculated that the change with each year of age was a 55% increase over the previous year. Forty-five percent of the isolates of S. aureus were resistant to penicillin.     

A national survey of the occurrence of infectious bovine keratoconjunctivitis

SUMMARY A national mail survey of 4880 beef and dairy producers was undertaken to record details of infectious bovine keratoconjunctivitis. One thousand four hundred and fifty eight (29.8%) questionnaires were returned. The survey confirmed the widespread nature of the disease with higher prevalence in the summer months, in calves and dairy cattle, and in Bos taurus breeds. The constant prevalence contrasts with the disease in New Zealand where it is increasing.     

The pharmacokinetics and tissue levels of polymyxin B, colistin and gentamicin in calves

Following a single intravenous injection of polymyxin B, colistin (5 mg/kg, each) and gentamicin (3 mg/kg) to calves, the decline in serum antibiotic concentration generally suggested a three-compartment (open system) pharmacokinetic model. Tissue binding is a dominant factor in the distribution and elimination kinetics of the drugs. Less than 65% of the dose of polymyxin B and colistin was recovered in the urine during 48 h after treatment. Concentrations of nonbound polymyxin B and colistin in the kidney, liver, lung, heart, and skeletal muscles were similar to total (free and bound) serum drug levels, but considerably higher concentrations were found, in bound form, in chloroform-ethanol extracts of these organs.
At 24 h after treatment, more than 50% of the doses of polymyxin B and colistin were present bound to the tissues; the largest amount was in the skeletal muscles. Gentamicin was concentrated in the kidney, predominantly in the free form. At 48 h after treatment the amount of gentamicin in the kidney was 6.3% of the administered dose, being more than five times greater than the corresponding amounts of polymyxin B and colistin.
The extent of tissue uptake of polymyxin B and colistin limits the usefulness of kinetic values, which are derived from the analysis of serum drug levels, for the purpose of designing dosage schedules. The strong affinity of the polymyxins to the muscle tissue, and gentamicin to the kidney, can result in drug residues persisting in the body for several weeks.     

Effects of grain type, roughage level and monensin level on finishing cattle performance

Interactions among grain type (grain sorghum, corn or wheat), roughage level and monensin level were studied in four feedlot trials using pen-fed crossbred yearling cattle. In Trial 1, cattle fed high-moisture corn (HMC) were more efficient (.1537 vs .1406 for gain/feed; P less than .01) than cattle fed dry-rolled grain sorghum (DRGS). As level (0, 3, 6, 9%) of dietary roughage was increased, feed efficiency (gain/feed) decreased (.1566, .1461, .1479, .1382; linear, P less than .01). In Trial 2, a grain type (DRGS; dry-rolled corn, DRC; dry-rolled wheat, DRW) x roughage level interaction was observed for daily gain and feed efficiency. Feed efficiency (gain/feed) was decreased when roughage was added to diets containing DRC (.1608 vs .1750) or DRGS (.1674 vs .1465), but not to the diet containing DRW (.1664 vs .1607). In trial 3, a grain type x roughage level x monensin level interaction (P less than .08) was observed for feed efficiency. The addition of 27.5 mg of monensin per kilogram of the 0% roughage-DRC diet tended to improve feed efficiency (.1633 vs .1531), but the addition of monensin to the 7.5% roughage-DRC diet tended to depress feed efficiency (.1476 vs .1575). The addition of either roughage (.1493 vs .1420) or monensin (.1500 vs .1413) to the DRW diet improved feed efficiency. In Trial 4, cattle fed a combination of 75% DRW and 25% DRC were more efficient (.1618 vs .1591; P less than .06) than cattle fed DRC. As level of roughage (0, 3.75, 7.5%) increased, feed efficiency decreased linearly (.1645, .1599, .1569; P less than .0001). Monensin had no effect on feed efficiency. The value of feeding roughage and monensin was variable both across grain types and within similar grain types.