Evaluation of maternal bromoform supplementation in late gestation on blood parameters of cows and their progeny.

Bromoform supplementation has been successful in reducing enteric methanogenesis in ruminants; however, the impacts on the health of these animals are still limited. The current study evaluates the impact of maternal bromoform supplementation on the health of late-gestation cows and their progeny. Pregnant Angus cows (n = 42) were allocated into a control or bromoform group (n = 21 cows per treatment). Bromoform extracted from Asparagopsis armata (7,372 mg/kg) was supplemented once daily. Blood samples were collected from cows before supplementation (baseline). Within 24 h of parturition, blood and colostrum samples were collected from each cow and blood from neonates. Colostrum brix was measured to indicate immunoglobulin content. All data was analysed using the MIXED procedure in SAS. Supplementation of cows with bromoform resulted in increased blood urea to creatinine ratio (P = 0.048), base excess (P = 0.049), total carbon dioxide (TCO2; P = 0.048) and a decrease in blood glutamate dehydrogenase (GLDH; P = 0.031) compared to the control group. For cows in the bromoform group, a trend was observed for higher levels of partial pressure of carbon dioxide (pCO2; P = 0.070) and bicarbonate (HCO3-; P = 0.052), and lower levels of partial pressure of oxygen (pO2; P = 0.058) compared to the control group. Blood gamma-glutamyl transferase (GGT) was elevated in offspring of cows fed bromoform (P = 0.050). The lower blood pO2 of pregnant cows fed bromoform and elevated blood GGT levels in offspring are not well understood and highlight the need for further investigation. Additionally, the low-dose bromoform supplementation affected various blood gas parameters of cows and calves, demonstrating the importance of monitoring these parameters when using different doses of halogenated compounds in livestock.

Seropositivity to Campylobacter and association with abortion and lamb mortality in maiden ewes from Western Australia, South Australia and Victoria.

This case-control study investigated associations between Campylobacter fetus or Campylobacter jejuni titre and reproductive outcomes in 22 flocks of Merino and non-Merino maiden ewes aged 1-2 years old. Campylobacter titres were also determined for multiparous ewes aged 3 years or older on the same farms. C. fetus 'positivity' (titre ≥1:80) was detected for 12% (57/462; 95% confidence interval [95% CI] 9.6 to 15.6) of maiden ewes and 31% (65/210; 95% CI 25.0 to 37.4) of mature ewes. The odds for failing to rear a lamb in C. fetus-'exposed' maiden ewes (titre ≥1:10) was 2.01 times that of seronegative ewes (95% CI 1.09 to 3.77; P = 0.027), but there was no association between C. fetus-'positivity' (titre ≥1:80) and failure to rise (OR 1.69; 95% CI 0.77 to 3.76; P = 0.191). C. fetus abortions were confirmed with microbial culture in one maiden ewe flock. In this flock, C. fetus titres fluctuated and often waned by lamb marking, highlighting the value of necropsies during abortion investigations. C. jejuni-'positivity' (titre ≥1:80) was detected for 44% (204/462; 95% CI 39.7 to 48.7) maiden ewes, but odds of failing to rear were decreased for C. jejuni-'positive' ewes (OR 0.52; 95% CI 0.32 to 0.83; P = 0.007). The association between Campylobacter serology and the reproductive outcome was inconsistent in these flocks. Serology should be considered in the context of other risk factors and used in conjunction with other strategies to investigate the impact of Campylobacter exposure on ewe reproductive performance such as monitoring for abortions and lamb necropsies to determine aetiological diagnosis, and vaccination trials.

Measurement of phase gradients in the EEG.

Previous research has shown that spatio-temporal waves in the EEG are generally of long spatial wavelength and form smooth patterns of phase gradients at particular time-samples. This paper describes a method to measure smooth phase gradients of long spatial wavelength in the EEG. The method depends on the global pattern of phase at a given frequency and time and is therefore robust to variations, over time, in phase-lag between particular sites. Phases were estimated in the EEG signal using wavelet or short time-series Fourier methods. During an auditory oddball task, phases across the scalp tend to fall within a limited circular range, a range that is not indicative of phase-synchrony nor waves with multiple periods. At times the phases tended to maintain a spatially and temporally ordered relationship. The relative phases were analysed using three phase gradient basis functions, providing a measure of the amount of variance explained, across the electrodes, by smooth changes in relative phase from a single minimum or single maximum. The data from 586 adult subjects were analysed and it was found that the probability of phase gradient events varies with time and frequency in the stimulus-locked average, and with task demands. The temporal extent of spatio-temporal waves was measured by detecting smoothly changing patterns of phase latencies across the scalp. The specific spatial pattern and timing of phase gradients correspond closely to the latency distributions of certain ERPs.

Separating individual skin conductance responses in a short interstimulus-interval paradigm.

We describe a new method for measuring skin conductance responses, designed to overcome the problem of overlapping skin conductance responses. The method relies on the assumptions that the underlying sudomotor nerve signal has a shorter time-constant than the skin conductance signal itself, and that the sudomotor bursts arrive as discrete, separated events. By converting the skin conductance signal into a time-series with a shorter time-constant, we are able to extract the separated peaks in the estimated underlying driver signal. The separated driver peaks are then used to re-estimate each individual skin conductance response. The method is automated and applied to a normative database of 735 subjects, for which skin conductance was measured during an auditory oddball paradigm.

Trace element supplementation of sheep: evaluation of various copper supplements and a soluble glass bullet containing copper, cobalt and selenium.

The effect of 5 different copper supplements on copper status of Merino sheep at pasture was examined. Transient increases in plasma copper concentrations occurred following treatment with copper calcium EDTA, copper sulphate, and glass bullets impregnated with copper, cobalt and selenium, but these increases were not considered to be a reliable indication of changes in liver copper reserves. Sheep receiving the glass bullet or 2.5 g oxidised copper wire particles orally or 50 mg copper as copper calcium EDTA parenterally had liver copper concentrations significantly greater than those of untreated sheep for periods up to 51 weeks. Oral doses of 30 mg copper as copper oxychloride, or 300 mg copper as copper sulphate did not alter the liver copper reserves at any stage. The bodyweight and greasy fleece weights were not significantly altered by any of the copper supplements. Plasma vitamin B12 concentrations in sheep given the glass bullet were increased for about 5 months. Thereafter increased plasma vitamin B12 concentrations were observed in all sheep. Blood selenium concentrations were also high during the experiment thereby preventing the evaluation of the glass bullet as a source of selenium.

Copper supplementation of sheep.

The effect of 6 methods of copper supplementation on copper status was examined in Merino sheep at pasture. Plasma copper concentrations were not affected by any of the treatments. Liver copper concentrations in sheep given an oral dose of 3 g of oxidised copper wire particles were significantly greater than those of untreated sheep for the duration of the experiment of 80 weeks. Subcutaneous injections of 18 mg of copper as diethylamino cupro -oxyquinoline sulphonate produced small, transient increases in liver copper. Single oral doses of 150 mg of copper as copper sulphate or 30 mg of copper as copper oxychloride produced little or no detectable increase in liver copper. Liver copper concentrations of untreated sheep were lowest in winter, apparently associated with increased damage to the abomasum, as indicated by raised plasma pepsinogen activities.

Clinical field study to evaluate the efficacy and safety of the amino-acetonitrile derivative, monepantel, compared with registered anthelmintics against gastrointestinal nematodes of sheep in Australia.

OBJECTIVE: To determine the efficacy of monepantel, a developmental compound from the amino-acetonitrile derivative class of anthelmintics, against field infections of gastrointestinal nematodes in sheep. PROCEDURES: Comparisons of efficacy (using standard faecal worm egg count reduction tests) and safety (on the basis of visual observations) were made in a large-scale field study in Australia, between groups of sheep treated with either an oral solution of monepantel or a registered anthelmintic. The sheep were naturally infected with the major gastrointestinal nematode genera present in Australia. RESULTS: The post-treatment efficacy results for monepantel were: at 7 days (+/-1 day) efficacy was >98%; at 14 days (+/-1 day) it was generally close to or >99%; and at 21 days (+/-1 day) efficacy was consistently >99%. A high proportion of the targeted nematode populations were confirmed as being resistant to one or more of the currently available anthelmintic classes. CONCLUSIONS: Monepantel when used under field conditions at a minimum dose rate of 2.5 mg/kg was highly effective against mixed-genus natural field infections of the major gastrointestinal nematode genera including Haemonchus, Teladorsagia (Ostertagia), Trichostrongylus, Nematodirus, Chabertia and Oesophagostomum. This result included efficacy against some populations resistant to the currently available broad-spectrum anthelmintics. Few Cooperia spp. were present to allow confirmation of efficacy against this genus. On no occasion after treatment did any commercial anthelmintic-treated groups have significantly lower faecal egg counts than the monepantel-treated groups. Monepantel was safe for the target animals and human operators when used in a field situation.