Roberta Bencini

Ultrasound technique for measuring mammary cistern size of dairy ewes.

Sarda ewes, ∼4·5 million animals producing 500 000 tonnes milk annually, are one of the most important breeds of dairy sheep in the Mediterranean area. Several studies (Casu & Labussiere, 1972; Labussiere et al . 1981; Gallego et al . 1983; Rebello de Andrade et al . 1989; Bencini, 1993) have shown that milk production is influenced by mammary gland size and cistern dimension. The size of the mammary cistern affects both milk secretion rate and milk emission kinetics during milking. Milk secretion rate is controlled at the mammary gland level mainly by a protein feedback inhibitor of lactation (FIL), which is produced by mammary epithelial cells and secreted together with milk into the alveoli (Wilde & Peaker, 1990). As the alveoli are the site of action of the FIL (Henderson & Peaker, 1984), the FIL affects the rate of secretion when the milk is stored in the secretory tissue, whereas it is inactive in the milk stored in the cistern. As a consequence, the action of the FIL should be less in animals with a greater cistern volume, because a large proportion of milk is stored in the mammary cistern and the time during which the milk is in contact with the alveoli is reduced. This hypothesis is supported by the finding that the milk production of cows (Dewhurst & Knight, 1992; Knight & Dewhurst, 1992, 1994) and sheep (Karam et al . 1971; Enne et al . 1972) with large cistern storage capacities was almost unaffected by changes in the frequency of milking. Cistern volume also affects milk emission kinetics and the proportion of stripped milk obtained at milking (Labussiere, 1988). Cisternal milk is immediately available for removal, whereas alveolar milk is available only after operation of the ejection reflex, necessary in dairy ewes for complete udder emptying (Bruckmaier et al . 1997). Therefore, in animals readily able to expel alveolar milk into the cistern before the whole cisternal milk fraction is removed (Pazzona et al . 1978; Bruckmaier et al . 1997), a larger cistern volume enables milking time to be reduced by eliminating or restricting the need for stripping. On the basis of the above considerations, the volume of the mammary gland cistern could be proposed as a selection objective to improve milk production and milking ability of dairy ewes. For this purpose, a quick, accurate and economic method for measuring it is needed. The ultrasound technique allows the internal structure of the mammary gland cistern to be observed clearly in sheep (Ruberte et al . 1994; Pulina et al . 1996; Bruckmaier et al . 1997), cows (Bruckmaier et al . 1994 b ) and goats (Bruckmaier et al . 1994 a ). Cistern size has been measured by ultrasound in dairy cows (Bruckmaier et al . 1994 b ) and sheep (Pulina & Nudda, 1996), where a positive correlation between milk yield and cistern area calculated from the ultrasound images of mammary glands was found. However, area estimation requires the use of expensive ultrasound equipment or of a digitizing tablet. In both cases, area measurement is difficult owing to the irregular shape of the cistern. The aim of this study was to test the use of linear measurements taken directly from ultrasound images to estimate cistern size in dairy ewes.

New evidence for facultative male die-off in island populations of dibblers, Parantechinus apicalis

The post-mating mortality of males in dasyurid species is thought to be a specific life-history strategy, associated with a tightly synchronised breeding season, that may enhance survivorship of juveniles. Parantechinus apicalis has been reported to exhibit male die-off in island populations but not in mainland populations, and males originating from both island and mainland populations are known to survive post-mating in captivity. However, males in the island populations have been reported to sometimes survive to breed in a second year. This study monitored captive and island populations over a three-year period (April 1997 – May 2000) to examine the extent of male die-off. In captivity, males showed no evidence of post-mating mortality. Males on one island were also found to survive post-mating, while another island population appeared to have high mortality of males in three years, and a complete male die-off after the 1999 breeding season. We conclude that P. apicalis may warrant inclusion in a new category of life-history strategy for species exhibiting facultative male die-off.

Multiple individual southern brown bandicoots (Isoodon obesulus fusciventer) and foxes (Vulpes vulpes) use underpasses installed at a new highway in Perth, Western Australia

Context. Although wildlife crossing structures are often included when new roads are built, their effectiveness at reconnecting wildlife populations is still largely unknown. A new highway was built in 2005 through an area of remnant vegetation in Perth, Western Australia. Assessment of the area before construction identified potential impacts on a population of southern brown bandicoots (Isoodon obesulus fusciventer). Aims. We aimed to determine the use by bandicoots of three underpasses constructed to provide a linkage between habitats that were fragmented by the highway, focussing on how many different individuals used them, which is an essential step to demonstrate their effectiveness at reconnecting fragmented populations. Methods. We used detection of tracks in sand pads for 1 year to establish the use of the underpasses by bandicoots. We then captured 56 bandicoots and fitted them with passive integrated transponders (PIT), and installed a Trovan 650 scanner/decoder within the most frequently used underpass to establish whether multiple individuals used it. Key results. By using sand pads, we demonstrated that bandicoots used the underpasses, with a total of 278 passes between August 2005 and August 2006. One underpass accounted for 71% of these passes and was used already during construction. Eight different bandicoots were recorded using this underpass between August 2006 and August 2007, demonstrating use by multiple individuals. A dramatic decline in the use of this underpass was observed after foxes (Vulpes vulpes) also started using it in August 2006, and a fox built a den near the entrance of this structure. Because we also failed to recapture any of the bandicoots implanted with PITs we suspect that they had been killed by foxes. Conclusions. A severe decline in bandicoots coinciding with underpass use by foxes raises questions as to the long-term success of fauna crossings. Clearly, the relationship between underpass use by predators and the target species, in this case bandicoots, needs to be examined further. Implications. Our work demonstrated that although underpasses have the potential to reconnect populations because multiple individuals used them, their installation may be detrimental to wildlife populations if predators are not controlled.

Increasing the target-specificity of ERADICAT® for feral cat (Felis catus) control by encapsulating a toxicant

ERADICAT®, a sausage-type meat bait, has been developed for use in managing feral cat (Felis catus) populations throughout Western Australia. However, concern about potential exposure of non-target species to bait-delivered toxicants has led to the development of a technique to more specifically target feral cats using a pellet. Research into the consumption, by cats and native animals, of toxic pellets implanted within the ERADICAT® bait has been simulated using ball bearings as a substitute pellet. Results from our work indicate that encapsulating the toxicant may pose less risk of poisoning to chuditch (Dasyurus geoffroii), woylies (Bettongia pencillata) and southern brown bandicoots (Isoodon obesulus) as they consumed significantly fewer ball bearings (P = 0.003, <0.001, <0.001) than semi-feral cats (P = 0.07). Theoretically, a toxic pellet will not reduce the effectiveness of the ERADICAT® bait as there was no significant difference between consumption of baits and the consumption of ball bearings in feral cats (P = 0.07). Therefore, baits containing a toxic pellet have the potential to be a more selective method to control feral cats.

Deslorelin implants control fertility in urban brushtail possums (Trichosurus vulpecula) without negatively influencing their body-condition index

Wild brushtail possums (Trichosurus vulpecula) occur in large numbers in the grounds of Perth Zoo, Western Australia. These possums are a problem because they consume feed the zoo buys for its captive animals, damage seedlings and trees and many need to be treated for injuries sustained during fights with conspecifics. A contraceptive implant, which contains the gonadotrophin releasing hormone (GnRH) agonist deslorelin, could be a potential method of managing this population. We tested the efficacy of the implant and its impact on the body-condition index of treated possums with Kaplan–Meier analysis and a mixed model with residual maximum likelihood. We implanted 60 female possums with deslorelin and monitored reproductive success of treated and untreated possums for the following 18 months. At the conclusion of the study, 80% of 20 treated females recaptured had shown no evidence of breeding activity, giving an average minimum duration of effective contraception of 381 days. The implant did not have a negative impact on the body-condition index of treated possums during the course of the study. Our results suggest that deslorelin implants could be an effective management tool for brushtail possums at Perth Zoo and in other urban environments.

Quantification of naltrexone and 6,β-naltrexol in plasma and milk using gas chromatography-mass spectrometry. Application to studies in the lactating sheep

A selective gas chromatography-mass spectrometry method using solid-phase extraction has been developed for the detection and quantification of naltrexone and its metabolite, 6,beta-naltrexol in plasma and milk from humans and sheep at pharmacologically relevant concentrations. Di- or tri-acetyl derivatives were formed and quantified by selected-ion monitoring. Recoveries of naltrexone (30 microg/l) and 6,beta-naltrexol (250 microg/l) from both human plasma and milk were greater than 70%. Intra-assay and inter-day precision ranged from 3 to 21% for naltrexone and 2-18% for 6,beta-naltrexol for all matrices investigated, with an overall mean accuracy of 104% for naltrexone, and 99% for 6,beta-naltrexol. Human samples containing these analytes were stable for at least 3 weeks at -20 degrees C or 6 weeks at -80 degrees C. Analysis of the plasma and milk from the lactating sheep showed mean milk-to-plasma ratios of 55 for naltrexone and 3 for 6,beta-naltrexol.

Multipronged strategy including genetic analysis for assessing conservation options for the snow leopard in the central Himalaya

Abstract The snow leopard (Panthera uncia) is an endangered carnivore of southern and central Asia. Approximate 10% of the global population occurs in the Himalayan region of Nepal. The snow leopard is thought to be in decline because of human–snow leopard conflicts, poaching, habitat loss and fragmentation, decreasing prey populations, and a lack of awareness and enforcement of conservation legislation. In this study, we used habitat surveys and genetic analyses of putative snow leopard scats to estimate the abundance, habitat preferences, and diet profile of the snow leopard in the Annapurna Conservation Area, Nepal. Cliffs, grassland, and shrubland at high elevation (3,000–5,000 m) were the preferred habitats of snow leopards. Eighty-three percent of collected scats collected were verified to be from snow leopards using mitochondrial DNA cytochrome-b species-specific polymerase chain reaction assays. Sixty-two percent of the scats were successfully genotyped using 6 microsatellite markers, and identified as having originated from 5 different individuals. The dispersion of multiple scats from the same individual suggested minimum movement ranges of 89.4 km2 for males and 59.3 km2 for females. Estimated population density was 1.9 individuals/100 km2 and 22 snow leopards were estimated to inhabit the upper Mustang region. Microhistological analysis of scats (n = 248) revealed that blue sheep (Pseudois nayaur) was the primary wild prey (63%), and livestock also contributed significantly (18%) to snow leopard diet. We used a multipronged strategy for assessing conservation options for this rare carnivore and compared our findings with those pertaining to other predators of the region that share similar habitats and resources. The findings from this study will be helpful in managing snow leopards and similar carnivore populations across the snow leopards entire geographic range.

Secretion of milk and milk components in sheep

The effect of milking intervals of 4-20 h and of milking frequencies of 1-6 times a day on the rate of secretion of milk and milk components was determined in 2 breeds of sheep unselected for dairy production, the Australian Merino and the New Zealand Poll Dorset. The rate of milk secretion was greater after short intervals and after increased milking frequencies, indicating that in sheep the rate of milk secretion in the short term is regulated by a local feedback mechanism. After short intervals between milkings, the fat concentration in the milk was higher (99.5 ± 6.21 g/kg) and the protein concentration was lower (about 65 ± 2.89 g/kg) than after long intervals between milkings. This was not due to the presence of residual milk left in the mammary glands as subsequent experiments gave similar results when the residual milk was removed with the aid of oxytocin. We obtained similar responses if ewes were exposed to a series of 4 consecutive milkings to remove possible carry-over effects of the previous interval and achieve a constant volume of residual milk. We concluded that in sheep the rate of secretion of fat decreases while that of protein increases with time after milking and that the synthesis of fat and protein are controlled by at least 2 different mechanisms. This might be due to the fact that, unlike dairy cows and goats, sheep have not been subjected to selective pressure for dairy production.

Habitat and diet of the dibbler (Parantechinus apicalis) on two islands in Jurien Bay, Western Australia

Trapping was conducted over three years on Boullanger and Whitlock Islands in Jurien Bay (Western Australia), to establish the habitat and diet of the dibbler (Parantechinus apicalis), an endangered marsupial. Habitat preference was determined by conducting a single-factor ANOVA of the trapping success rate for P. apicalis captured at each trap site. The diet was investigated by scat analysis. On Boullanger Island there was no significant difference between trapping success rate in the different habitats. However, on Whitlock Island, significantly greater trapping success rates were recorded in the dunal scrubland dominated by Nitraria billardierei and foredune heath than in succulent heath. Scats contained arthropod (65%) and some vegetable (25%) matter, confirming that island P. apicalis are chiefly insectivorous and rarely eat vertebrate prey.

Food availability for the dibbler (Parantechinus apicalis) on Boullanger and Whitlock Islands, Western Australia

The aim of this study was to assess food availability for the dibbler (Parantechinus apicalis) on Boullanger and Whitlock Islands in different habitats and seasons. This was assessed by capturing ground-dwelling invertebrates in pitfall traps in winter, spring and autumn. A quantitative faecal-pellet analysis was conducted to determine the composition of the diet. There were no significant differences in the number of invertebrates captured in the different seasons, or in the different habitat types on the islands. The proportion of plant versus animal matter in the faecal pellets did not change significantly between the seasons. The diet consisted of ~20% plant material. The scat analysis showed that dibblers consumed at least 10 orders of invertebrates ranging in length from 0.1 mm to 25 mm with an average size of 4.5 ± 0.4 mm. The dibblers did not select for a particular size or taxon of prey, but fed on any invertebrates that were readily available to them. This suggests that dibblers are essentially insectivorous dietary generalists and opportunists. The information gathered in this study could be applied when considering available food resources at future translocation sites for dibblers.