Ecological role of the giant root‐rat (Tachyoryctes macrocephalus) in the Afroalpine ecosystem

Rodents with prevailing subterranean activity usually play an important role in the ecosystems of which they are a part due to the combined effect of herbivory and soil perturbation. This is the case for the giant root‐rat Tachyoryctes macrocephalus endemic to the Afroalpine ecosystem of the Bale Mountains, Ethiopia. We studied the impact of root‐rats on various ecosystem features within a 3.5‐ha study locality dominated by Alchemilla pasture, which represents an optimal habitat for this species, in 2 periods of a year. The root‐rats altered plant species composition, reducing the dominant forb, Alchemilla abyssinica, while enhancing Salvia merjame and a few other species, and reduced vegetation cover, but not the fresh plant biomass. Where burrows were abandoned by root‐rats, other rodents took them over and A. abyssinica increased again. Root‐rat burrowing created small‐scale heterogeneity in soil compactness due to the backfilling of some unused burrow segments. Less compacted soil tended to be rich in nutrients, including carbon, nitrogen and phosphorus, which likely affected the plant growth on sites where the vegetation has been reduced as a result of root‐rat foraging and burrowing.     

Management of equine skull fractures using fixation with polydioxanone sutures

Ten horses presented with severe distortion of the facial contour, crepitus on palpation and mild to moderate epistaxis. Individual horses also showed ocular damage, ptosis, severe dyspnoea and movement of the facial bones concurrent with respiration. The fracture fragments were exposed using a large curvilinear incision and elevated using a retractor, periosteal elevator, chisel or Steinmann pin. The fracture fragments were unstable following reduction and fixation was necessary. Stabilisation was achieved with polydioxanone sutures placed through holes drilled in opposing sides of the fracture lines. Polydioxanone sutures provided good stability and had better handling properties than wire. There was good apposition of fracture edges and minimal complications. Use of polydioxanone sutures can also avoid the expense and complexity of plate fixation in selected cases, and should be considered as an alternative to fixation with stainless steel wire in any facial fracture that adjoins stable bone.     

The Anti‐Müllerian Hormone Profile is Linked with the In Vitro Embryo Production Capacity and Embryo Viability after Transfer but Cannot Predict Pregnancy Outcome

The current study investigated the possibility of using the AMH concentration as a predictor of the ability of Korean Hanwoo cows to produce cumulus‐oocyte complexes, embryos that survive after transfer as well as the pregnancy outcome of surrogates. Eight sessions of ovum pick‐up (OPU) were performed with 19 donor cows at an interval of 3–4 days. Antral follicle count (AFC), oocyte quality and in vitro embryo development were recorded for each cow. Embryos produced from cows with different AMH profiles were transferred into recipients (n = 96). Cows in the high (≥0.25 ng/ml) and intermediate (0.1≥ to <0.25 ng/ml) AMH groups had a significantly higher AFC per OPU session (20.40 ± 1.36 and 16.91 ± 1.52, respectively; mean ± standard deviation) than cows in the low AMH group (<0.1 ng/ml; 12.19 ± 2.14). In addition, more cumulus‐oocyte complexes per donor were recovered in the high (11.46 ± 1.22) and intermediate (7.38 ± 0.83) AMH groups than in the low AMH group (4.77 ± 0.44). The percentage of oocytes reached blastocyst stage was significantly higher in the intermediate (47.0%) and high (38.5%) AMH groups than in the low AMH group (32.3%). The number of embryos produced per cow was higher in the high (3.9 ± 0.2) and intermediate (6.9 ± 0.6) AMH groups than in the low AMH group (2.2 ± 0.3). The percentage of embryos that gave birth to viable calves when transferred into recipients was higher for those derived from cows in the intermediate AMH group (50.7%) than for those derived from cows in the low (35.7%) and high (36.4%) AMH groups. In conclusion, a single measurement of AMH concentration predicted the in vitro embryo production potential of donor Korean native cows before OPU and is linked with embryo viability after transfer into recipients.     

Communicating the risks of handling bats: analysing approaches used by Australian stakeholders in the context of Australian bat lyssavirus

Australian bat lyssavirus (ABLV) is a member of the Lyssavirus genus of the Rhabdoviridae family and is found in Australian bat species. It is of public health concern because of the rabies-like syndrome it causes in humans, resulting in government health and wildlife agencies using varied communication approaches to inform targeted audiences about zoonotic risks associated with handling bats. Despite these warnings, the number of reports of human-bat interactions remains high. This paper details a survey conducted to analyse the approaches utilised by a range of stakeholders to educate and communicate warnings to their target audiences. The survey focused on identifying the target audiences, communication methods used, along with the message frequency, content, and perceived effectiveness. Analysis of the top three messages delivered by stakeholders revealed that over half were information-focused messages and over a third, instruction-focused. Stakeholders identified the need to balance messaging about bat handling risks with information regarding the vulnerable status of bats and their environmental significance. Whilst the most common and (perceived) effective method of communication was one-on-one discussions, it was also identified to be ineffective for targeting mass audiences leading stakeholders to recognise the need to adapt to more efficient means of communication. The outcomes of this study may be useful to improve risk communication strategies regarding ABLV in Australia.     

The effects of lactation on the fertility of dairy cows

Lactation has been negatively associated with fertility because pregnancy rates in maiden heifers exceed those obtained after first or subsequent calvings. The extent of this difference is less in pasture-fed dairy cows (<10%) than in American Holsteins (>20%) fed grain and conserved forages. The latter cows have pregnancy rates to first insemination and oestrus detection rates of only 40 to 45%. This suggests that the subsequent fertility of inherently fertile Holstein heifers may be severely compromised by high levels of milk production. International comparisons show that pasture-fed dairy cows may experience extended periods of anovulatory anoestrum but have normal fertility (60% pregnancy rate to first insemination) once cycling. The high-producing American Holstein may ovulate within 4 weeks postpartum but is more likely to continue ovulating without being detected in oestrus. Both situations are associated with negative energy balances (NEB) during early lactation. The severity and duration of this NEB may vary with body condition at calving, age or parity, ration formulation, production level and environmental factors. Relative daily milk yield is not an absolute indicator of NEB, because some lower producing cows within a herd have lower feed intakes and more severe energy deficits. NEB is not simple to measure; nonetheless, it is correlated with genetic improvement for milk yield. A positive energy balance, greater weight gain and higher body condition score have all been shown to be positively correlated with plasma progesterone concentrations in early lactation. No studies have investigated the possibility that the rapid increase in metabolic rate at this time may also alter steroid concentrations with consequent effects on oestrous behaviour and fertility. Studies to more precisely define the effects of increasing milk yields in early lactation, especially in Holsteins, may need to be completed in Australia and New Zealand. Oestrus detection rates and pregnancy rates for American Holsteins of less than 50% are accepted widely in the USA. Such low detection rates confound studies on fertility. The objective should be to increase these 2 rates to at least 80% and 60% respectively. This may involve the use of controlled breeding, especially if oestrous behaviour is less overt in high-producing Holstein cows.     

Persistent efficacy of abamectin and doramectin against gastrointestinal nematodes of cattle

Objective To assess the persistent activity of injectable formulations of abamectin and doramectin against gastrointestinal nematodes of cattle.
Design Controlled slaughter study assessing residual efficacy.
Procedure Nematode-free calves were treated with abamectin or doramectin (each at a dose of 200 μg/kg) and infections then induced with repeated doses of infective larvae of Trichostrongylus axei, Haemonchus placei, Ostertagia ostertagi and Cooperia species. The duration of challenge ranged from 14 to 28 days. The calves were slaughtered at either 38/39 or 45/46 days after the treatments and nematodes recovered from the gastro-intestinal tract.
Results Significant reductions in numbers of O ostertagi occurred for both abamectin and doramectin treatments (> 93%) relative to counts in untreated calves, when challenge was administered up to 21 days after treatment. For T axei and Cooperia spp significant reductions occurred when the challenge occurred for 14 days after treatment (99%). Although differences from untreated animals were not significant, the results for H placei suggested high efficacy (> 85%) for up to 21 days for doramectin and up to 28 days for abamectin.
Conclusion There was no significant difference between abamectin and doramectin for any parasite at any challenge point, indicating that there is equivalent persistent activity of doramectin and abamectin against important gastrointestinal nematodes of cattle.