Plasma beta-endorphin and adrenocorticotrophin in young horses in training

A controlled period of submaximal exercise on a treadmill was used as a standardised stress test in 6 young horses to monitor the effects of training. Circulating plasma concentrations of immunoreactive beta-endorphin (IR beta-EP) were measured before, during and after the exercise period. The stress test was conducted on 3 occasions during an intensive training program lasting 14 weeks. In week 3 a marked increase in plasma IR beta-EP (P = 0.003) was demonstrated as a result of training, but by the last exercise test performed in week 9 no significant increase in plasma IR beta-EP concentrations could be detected. During the training period the basal concentrations of plasma IR beta-EP significantly decreased (P = 0.0059). Plasma adrenocorticotrophin (ACTH) did not increase during exercise, although there was a trend of decreasing basal plasma ACTH by the end of the training period. It was concluded that a standardised work test acted as a mild stress to unfit horses, but as the horses' fitness increased the hormonal response to exercise diminished. Basal plasma beta-EP concentrations were decreased with increasing fitness.     

Effects of antibiotic therapy at drying off on mastitis in the dry period and early lactation

Four strategies for selecting cows for intramammary therapy with benzathine cloxacillin at drying off were compared in 12 Victorian dairy herds. The bacteriological status of all quarters of all (1044) cows was determined just before drying off, within 2 d of calving, and again 3 to 5 months after calving. All cases of clinical mastitis (from calving to mid-lactation) were recorded. Cows not infected at drying off were allocated randomly to 2 subgroups of approximately 350 cows each: not infected, not treated (NI-NT), or not infected, all quarters treated (NI-AT). New infection rates in the dry period (3.8% for NI-NT vs 2.1% for NI-AT) and in early lactation (4.1% for NI-NT vs 3.9% for NI-AT) were low and these differences were not significant. Incidence of clinical mastitis in early lactation was almost 50% higher for the treated group of uninfected cows compared with the untreated group (0.05 less than p less than 0.1). Cows infected in one or more quarters at drying off were split randomly into 2 subgroups of approximately 170 cows each: infected, all quarters treated (I-AT), or infected quarters treated only (I-QT). The new infection rate during the dry period was nearly 4 times higher for I-QT (15.3%) due to significantly more new infections by Staphylococcus aureus and Streptococcus uberis.(ABSTRACT TRUNCATED AT 250 WORDS)     

Eclogitic diamond formation at jwaneng: No room for a recycled component

Eclogitic diamonds have a large range of delta13C values, whereas peridotitic diamonds do not. Paired delta15N-delta13C-N variations in 40 eclogitic diamonds from the Jwaneng kimberlite in Botswana show that neither the influence of recycled biogenic carbon nor the global and primordial heterogeneity of mantle carbon are likely for the origin of the large delta13C range; the data instead support a fractionation process. It is proposed that carbonatitic mantle melts from which diamonds crystallize undergo different evolutions before diamond precipitation, when percolating through either a peridotite or an eclogite. These different evolutions, reflecting the presence or absence of olivine, can account for their respective delta13C distributions.     

Congenital biliary atresia and jaundice in lambs and calves

An outbreak of congenital biliary atresia and jaundice is described, in which approximately 300 crossbred lambs and 9 crossbred calves died. The affected animals failed to thrive, developed jaundice and white scours and died within 4 weeks of birth. A common feature of this outbreak and a similar occurrence 24 years previously was the grazing of plants growing on the exposed silt foreshores of Burrinjuck Dam by ewes and cows in the early stages of pregnancy. Epidemiological and pathological findings suggested that a toxic insult to the foetus in early gestation caused choledysgenesis and biliary atresia, leading to diffuse, subacute to chronic cholangiohepatopathy and cirrhosis.     

Strategies for mastitis control: dry cow therapy and culling

SUMMARY The effects of three selection strategies for dry cow therapy on prevention of new infections and rate of antibiotic usage were compared. Quarter infection status of 1044 cows in 12 herds was determined by bacteriological methods at drying off, calving and three to five months into the following lactation. Cows that were uninfected at drying off were randomly allocated to treatment (whole udder, dry cow therapy) and non-treatment groups. Infected cows were randomly allocated to whole udder or infected quarter only treatments. The strategies compared were blanket treatment (treat all quarters of all cows), selective cow treatment (treat all quarters of any cow infected in one or more quarters) and selective quarter treatment (treat infected quarters only). Selective cow treatment was identified as the preferred strategy. Blanket treatment resulted in increased antibiotic usage (15.5 vs 6.4 tubes per infection eliminated) with no additional benefit, and selective quarter treatment resulted in a higher new infection rate (6.4%vs 3.9% quarters) in the dry period. The prevalence of infection within a herd at drying off had no influence on new infection rates in the dry period or early lactation. The cure rate after dry cow treatment (mean of 66%) decreased significantly with increasing age (P < 0.001). Cows infected in the previous lactation contributed over 76% of infections at calving and nearly 70% at mid-lactation. To lower the incidence of mastitis in a herd, a greater emphasis on culling of older infected cows and prevention of new infections during lactation is needed.     

Time Empty and Ketone Body Status in the Early Postpartum Period of Dairy Cows

This study aimed to assess the effect of ketone body status early postpartum on time empty in 74 multiparous dairy cows under field conditions. Animals were equally distributed across eight farms and were controlled by the same herd‐fertility‐monitoring programme. Cows were visited twice antepartum and six times postpartum at weekly intervals between 0530 and 0830 a.m. On these occasions, body condition scores and milk yields were measured, blood and milk samples were taken, cows were gynaecologically examined, and parameters of reproduction were recorded. Cows with a time empty of less or more than 80 days were classified as early and late conceiving cows (EC and LC, respectively). A time empty of 80 days results in calving‐to‐calving intervals of 1 year and classification based on this threshold value resulted in groups of equal size and equal distribution of EC and LC within farms. Ketone bodies measured were β‐hydroxybutyrate in blood and acetoacetate and acetone in blood and milk. Blood and milk ketone body concentrations, as well as the ratios of acetoacetate and acetone to β‐hydroxybutyrate, over the first 6 weeks postpartum were higher in LC than in EC, whereas plasma glucose and non‐esterified fatty acids and milk fat, protein and urea concentrations did not exhibit clear differences between groups. Ketone body concentrations were as good predictors of time empty as ketone body ratios and might have practical impact in herd‐fertility‐monitoring programmes.     

Effect of zinc and molybdenum supplementation of the feed concentrate on the storage of copper in the liver of lambs

Summary During a 98-day trial, eight groups of eight male weanling Texel x Friesian milk sheep lambs were fed the same hay and concentrates, the latter differing only in the contents of Cu, Zn, and Mo. At high (± 30 ppm) and moderately low (± 15 ppm) copper levels in the concentrates, additions of Zn (respectively 0, 150, and 340 ppm) and Mo (0 and 16 ppm) to the concentrates were studied with regard to effect on the accumulation of copper in the liver. At the higher copper level, the addition of 150 or 340ppm Zn resulted in a significant decrease of the Cu accumulation in the liver, while at a moderately low copper level the effect of these additions on the Cu accumulation was only slight. The two Zn doses given appeared to be equally effective in reducing the Cu accumulation. Additions of zinc did not increase liver and kidney Zn. The addition of Mo. resulted in higher levels of Mo in liver and kidney. At either copper level the addition of 16 ppm Mo was more effective in reducing the Cu accumulation in the liver than the addition of 150 or 340 ppm Zn. The additions of Zn and Mo, had no visible influence on the health of the lambs. This agrees with the finding that the blood parameters (determination of haemoglobin, haematocryt, protein, copper, zinc, enzymes) and the growth of the lambs were in the normal range. These results suggest that zinc may be a useful alternative to the somewhat toxic molybdenum as an additive to concentrates for sheep in preventing Cu intoxication.