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Bovine trichomoniasis, caused by the protozoal parasite Tritrichomonas foetus, is a highly contagious venereal disease characterised by early pregnancy loss, abortion and pyometra. Persistently infected bulls and cows are the primary reservoirs of infection in infected herds. This research investigated the prevalence of T. foetus infection in bulls from properties located across northern Australia and New South Wales. Preputial samples were collected from 606 bulls at slaughter and tested for T. foetus using the VetMAX-Gold Trich Detection Kit (Thermo Fisher Scientific). The apparent prevalence of T. foetus infection varied between regions, with northern regions in the Northern Territory, Queensland and Western Australia showing a prevalence of 15.4%, 13.8% and 11.4%, respectively. There was some evidence of an association between infection and postcode (P = 0.06) and increasing bull age (P = 0.054). This study confirms that T. foetus infection is likely to be present in many beef breeding herds and contributing to lower than expected reproductive performance, particularly across northern Australia., (© 2022 Thermo Fisher Scientific Australia Pty Ltd. Australian Veterinary Journal published by John Wiley & Sons Australia, Ltd on behalf of Australian Veterinary Association.)

Objective: To assess the effect on healing and pain-associated behaviours of covering exposed sinuses after horn amputation under extensive production conditions in northern Australia., Methods: Horned, weaned Brahman-cross heifers (n = 50) aged approximately 6 months were alternately allocated to have their dehorning wounds either patched with a dry, non-sterile gauze swab or left untreated. Adherence of swabs and growth rates, healing and pain-associated behaviour were monitored for 88 days post-surgery., Results: Half of the patches were lost by 24 h post-surgery, with most of the rest falling off 2-6 weeks later. Patching resulted in healing 5.5 days earlier (P = 0.018). Sealing of exposed frontal sinuses occurred in most heifers within 3 weeks and full healing occurred within 13 weeks. Patching reduced haemorrhage (P < 0.01) regardless of when the patches were dislodged, prevented insect invasion of the wound and reduced the incidence of secondary infection (P < 0.01). Wound patches did not affect behaviour in the weeks following surgery. In the days after surgery, the heifers did not eat and showed a high incidence of behaviours indicating pain. Behaviour was relatively normal by 2 weeks after surgery, although the heifers avoided social interaction with other unbranded calves for 4 weeks., Conclusion: The application of gauze swabs to dehorning wounds advanced healing, reduced the incidence of haemorrhage and secondary infections, and may reduce deaths. Efficacy is expected to improve if high rates of 24-h retention of patches can be achieved. The prolonged time to healing and the pain-associated behaviours highlight the need for better welfare of dehorned calves through improvements in analgesia, surgical procedures and post-surgical care., (© 2018 Australian Veterinary Association.)

Objective: To identify measures that most closely relate to hydration in healthy Brahman-cross neonatal calves that experience milk deprivation., Methods: In a dry tropical environment, eight neonatal Brahman-cross calves were prevented from suckling for 2-3 days during which measurements were performed twice daily., Results: Mean body water, as estimated by the mean urea space, was 74±3% of body weight at full hydration. The mean decrease in hydration was 7.3±1.1% per day. The rate of decrease was more than three-fold higher during the day than at night. At an ambient temperature of 39°C, the decrease in hydration averaged 1.1% hourly. Measures that were most useful in predicting the degree of hydration in both simple and multiple-regression prediction models were body weight, hindleg length, girth, ambient and oral temperatures, eyelid tenting, alertness score and plasma sodium. These parameters are different to those recommended for assessing calves with diarrhoea. Single-measure predictions had a standard error of at least 5%, which reduced to 3-4% if multiple measures were used., Conclusion: We conclude that simple assessment of non-suckling Brahman-cross neonatal calves can estimate the severity of dehydration, but the estimates are imprecise. Dehydration in healthy neonatal calves that do not have access to milk can exceed 20% (>15% weight loss) in 1-3 days under tropical conditions and at this point some are unable to recover without clinical intervention., (© 2015 Australian Veterinary Association.)

Objective: To compare reproduction in extensively managed, tropically adapted beef cows that were either seropositive or seronegative to Neospora caninum., Design: Longitudinal study of cows within management groups., Methods: Compare pregnancy with weaning outcomes for 502 seropositive and 3255 seronegative cows in 25 management groups., Results: We found N. caninum in all herds, with an average of 20% of 2640 tested animals seropositive within management group; prevalence varied between 0% and 94%. At 7 of 10 sites assessed, there was evidence of horizontal transmission of N. caninum. There was no overall difference in pregnancy rate (79% vs 75%; P > 0.05), reproductive wastage after confirmed pregnancy diagnosis (11% vs 10%; P > 0.05) or weaning rate (67% vs 68%; P > 0.05) between seronegative and seropositive cows, respectively. In one herd where a combination of risk factors for N. caninum was present, a significant reduction in pregnancy rate occurred after the 6 months mating (85% vs 69%; P < 0.05). The fetal and calf losses observed were lowest in south-east Queensland (4.3% of 117 pregnancies), highest in north-west Queensland (15.5% of 413 pregnancies) and intermediate in north-east Queensland (10.2% of 1625 pregnancies). Other infectious agents that are known to cause reproductive wastage were endemic in many herds, though none appeared to cause significant fetal or calf loss in this study., Conclusion: Despite a high prevalence of N. caninum, there was no apparent effect on beef cattle reproduction, but there is potential to cause reproductive wastage if known risk factors to neosporosis are in effect., (© 2013 Australian Veterinary Association.)

Objective: To compare the Willis dropped ovary technique with traditional spaying methods in extensive beef cattle herds in northern Australia., Procedure: Three field trials were conducted simultaneously at different sites in northern Australia in 1996-97. Brahman and Brahman-Shorthorn cross heifers (n = 219, 2 years, 250 to 378 kg) and cows (n = 211, 3 to 16 years, 256 to 540 kg) were allocated by stratified randomisation to three treatments: spaying using the Willis dropped ovary technique (WDOT); spaying using traditional paralumbar and vaginal methods; and unspayed. Following these procedures, these nonpregnant, nonlactating cattle were then exposed to bulls (4 per 100 females) under extensive rangeland conditions for 12 months during which time weight, body condition, pregnancy and ovarian function were monitored and compared., Results: Pregnancy rates varied from 60 to 90% for entire heifers and 80 to 100% for entire cows depending on site. The traditional spay methods were 100% successful in preventing pregnancy; the WDOT was 92 to 97% effective, depending on operator experience. The number of deaths was the same or higher in Willis spayed animals than other groups. Weight changes were similar in all groups at the three sites over the trial period. The time taken to spay using the WDOT was similar to or less than that required for the traditional methods. Uterine abnormalities were not observed in animals spayed with the WDOT, there were however 30 (12.4%) animals where excision of the ovary was incomplete; the still-attached ovarian remnant presumably accounting for the three pregnant animals in this group., Conclusion: The WDOT suffers from requiring a high degree of skill in transrectal ovarian manipulation. There were more deaths and more pregnancies than with traditional spay methods. More experienced operators can be expected to achieve lower mortalities, better contraception and higher processing rates. Pregnancy will occur as a consequence of ovarian remnants unless care is taken to ensure removal of the entire ovary.

This experiment evaluated intra-testicular injection of a sclerosing drug, lactic acid, for castration of bulls. Its use was compared in 58 Brahman cross calves (50 to 128kg) with the general practice of open surgical castration. Chemical castration appeared to be more painful than surgical castration, though post-operative swelling and pain appeared similar for both methods. Chemical castration took 3 times longer than surgical castration (58 sec v 20 sec; P less than 0.01). Scrotal necrosis occurred in 25% of chemically-castrated calves and appeared due to drug leakage from the testes under the high pressure of injection. Healing time for chemical castrates was approximately twice that for surgical castrates. Five chemically-castrated calves (18%) retained one testis. Though all 5 were rendered sterile, each maintained androgenesis. This led to secondary male behaviour which caused management problems. Castration method did not influence post-operative growth. It is concluded that lactic acid administration is not a suitable alternative to the open surgical technique for castration of Brahman cross calves.