Performance and Consistency of Circulating Warm Water Blankets for Rodents

General anesthesia as used for rodent research can have adverse effects on physiologic mechanisms. Thermoregulation is often greatly inhibited, with resultant deleterious effects on cardiac and respiratory function. These potential effects can be mitigated by providing external heat support. The circulating warm water blanket and associated heat pump are often used in rodent procedures. The current study demonstrated that the heating pump and water blanket require quality control assessment to ensure adequate function. Our data showed that of the 6 pumps tested, 5 were able to achieve a temperature thatmet or exceeded the documented thermoneutral zone for mice. Pumps required 20 min of warming to reach their maximal attainable temperatures for the designated user setting. Although the pumps reached a temperature that was sufficient toprovide external thermal support, only 1 of the 6 pumps reached the temperature that was set by the user during the trial.Surface temperatures across the water blanket were recorded to analyze whether a difference in heat support was influencedby animal placement along the water blanket; however, the location points did not yield statistically different results. Two pumps were eliminated from the study due to failure to pass the preparation phase of the trial. The results of this studysupport the need for facilities to establish quality control measures to ensure that heat support systems are functioning at a level required to maintain normothermia during anesthetic procedures.

Effects of Reduced Space Allowance and Heat Stress on Behavior and Eye Temperature in Unweaned Lambs: A Pilot Study

Current European animal transportation law contains only a few and vague indications concerning how to move lambs of less than 26 kg. Moreover, little information is available in the literature about factors affecting these lambs’ welfare. We investigated the effect of space allowance and ambient temperature on the welfare of unweaned Lacaune lambs during a simulation of long-distance transportation (19 h). Three groups of lambs (N = 130) were housed in equally sized pens for 19 h, Control (C; n = 39; 0.27 m2 per head), Low Space Allowance (LSA; n = 52; 0.20 m2 per head), and Heat Stress (HS; n = 39; 0.27 m2 per head) groups. LSA lambs had lower space allowance than C but were tested at the same temperature, within their Thermoneutral zone (range = 12–18 °C). The HS lambs were, instead, subjected to higher temperatures (range = 19–30 °C). Scan sampling of behavior was conducted, eye temperature and body weight were also recorded. LSA and HS lambs showed more discomfort behaviors (p < 0.05) and higher eye temperatures (p < 0.001) compared to C lambs, while HS lambs additionally showed a decrease in body weight over the experimental period (p < 0.001). This study indicates that lower space allowances and higher temperatures impact negatively the welfare of lambs transported for slaughter suggesting that the regulation should be implemented taking these factors into account.

Significance of variation in basal metabolic rate in laboratory mice for translational experiments

The basal metabolic rate (BMR) accounts for 60–70% of the daily energy expenditure (DEE) in sedentary humans and at least 50% of the DEE in laboratory mice in the thermoneutral zone. Surprisingly, however, the significance of the variation in the BMR is largely overlooked in translational research using such indices as physical activity level (PAL), i.e., the ratio of DEE/BMR. In particular, it is unclear whether emulation of human PAL in mouse models should be carried out within or below the thermoneutral zone. It is also unclear whether physical activity within the thermoneutral zone is limited by the capacity to dissipate heat generated by exercise and obligatory metabolic processes contributing to BMR. We measured PAL and spontaneous physical activity (SPA) in laboratory mice from two lines, divergently selected towards either high or low level of BMR, and acclimated to 30 °C (i.e., the thermoneutral zone), 23 or 4 °C. The mean PAL did not differ between both lines in the mice acclimated to 30 °C but became significantly higher in the low BMR mouse line at the lower ambient temperatures. Acclimation to 30 °C reduced the mean locomotor activity but did not affect the significant difference observed between the selected lines. We conclude that carrying out experiments within the thermoneutral zone can increase the consistency of translational studies aimed at the emulation of human energetics, without affecting the variation in physical activity correlated with BMR.

Impact of environmental conditions on the levels of stress and breeding performance in Wistar rats: conventional environment versus environmentally controlled housing.

It has been established that providing comparable and standard environmental conditions to house experimental rats is of high importance. However, there is growing evidence that rats prefer higher temperatures owing to their thermoneutral zone that lies between 28-34°C. This experiment validates the stress levels of Wistar rats of both sexes housed in conventional conditions about 24-31°C and a relative humidity of 70-92% in a tropical animal facility when compared to rats housed in controlled temperatures of 20-24°C with humidity maintained between 30-70%. Adequate air-changes to maintain ammonia-free environment was provided with a power-exhaust system in a conventional setup and with the individually ventilated caging system in the environmentally controlled group. To assess stress, faecal corticosteroid metabolite assay was done in naïve animals and in a set of animals that underwent retro-orbital bleeding under general anaesthesia. Mothering ability, fecundity and preweaning mortality were also compared between animals housed in two different conditions. Results showed no differences in stress hormone levels between the groups. However, faecal weights differed between males and females in both naïve and orbital bled groups. Animals housed in controlled environment clearly had better breeding data with lesser preweaning mortality in comparison to the conventionally housed rats. Further studies are required to elucidate whether the results are comparable when conducted during all seasons of the year at different locations across the globe.

Cool birds: facultative use by an introduced species of mechanical air conditioning systems during extremely hot outdoor conditions

Rapid climate change across the globe is having dramatic effects on wildlife. Responses of organisms to shifting thermal conditions often include physiological and behavioural accommodations, but to date these have been largely viewed and studied as naturally evolved phenomena (e.g. heat avoidance, sweating, panting) and not necessarily as strategies where animals exploit other anthropogenic conditions or resources. Moreover, the degree to which native versus introduced species show thermal plasticity has generated much conservation and ecological interest. We previously have observed introduced rosy-faced lovebirds ( Agapornis roseicollis ) perching in the relief-air vents on building faces in the Phoenix, Arizona, USA, metropolitan area, but doing so only during summer. Here, we show that such vent-perching events are significantly associated with extreme outdoor summer temperatures (when daily local highs routinely exceed 40°C). In fact, the temperature threshold at which we detected lovebirds starting to perch in cool air vents mirrors the upper range of the thermoneutral zone for this species. These results implicate novel, facultative use of an anthropogenic resource—industrial air-conditioning systems—by a recently introduced species (within the last 35 years) to cool down and survive extremely hot conditions in this urban ‘heat-island' environment.

Pigs fed various levels of crude protein and raised above the thermoneutral zone: effects on protein metabolism and nitrogen balance

We evaluated performance, nutrient balance, nitrogen balance, and serum parameters in pigs in the nursery phase raised in environmental conditions above the thermoneutral zone that were fed with diets containing various levels of crude protein (CP). A total of 15 barrows (22.75 ± 1.58 kg) were housed in metabolism pens and distributed in a completely randomized design with three treatments: 15.5%, 18.3%, and 21.0% of CP, designated T15, T18, and T21, respectively. There was a gradual increase of temperature over the first three days from 25 to 29.1 ± 2.3 °C. From d18 to d20 of the experiment, pigs received the same diet (18% CP) and thermoneutral conditions were reestablished (22.9 ± 1.9 ºC). There were higher values of urinary, excreted, and absorbed nitrogen in T21, followed by T18 and T15. Blood urea levels were higher in treatments with higher protein levels. On d4 (adaptation period), cholesterol levels were higher in the T15 group than in the T21 group, antioxidant power of iron reduction values were lower in the T18 group than the T21 group. Advanced oxidation protein products (AOPP) on day 16 were higher in the T15 group, associated with the accumulation of heat stress and lower CP diets. Similar results were obtained for T18 with higher AOPP values on d16 than on d8 and d12. However, there were greater AOPP values in the T21 group on d20 (when the CP level was reduced to 18%) than on d8. Amino acid supplementation and reduction of CP in the diet to levels of 15.5% in piglets raised above the thermoneutral zone improved the use of CP. Furthermore, 15.5% of CP in the diet reduced the excretion of urinary nitrogen. The N-retention was not affected by dietary CP level, using the ideal protein concept. The use of 21%-CP in the diet efficiently avoided exacerbation of protein oxidation for pigs raised above thermoneutrality.

Cloacal temperature responses of broiler chickens administered with fisetin and probiotic (Saccharomyces cerevisiae) and exposed to heat stress

There is dearth information on the role of fisetin as an antistress agent in ameliorating heat stress in broiler chickens. Here, we experimentally compared probiotic, an antioxidant and antistress agent, with fisetin, an antioxidant agent with little or no report on its antistress effect. Sixty-day-old broiler chickens (Arbo Acre breed) were allotted into 4 groups of 15 birds each as follows; control, fisetin, probiotic, and fisetin + probiotic groups, respectively. All administrations were performed orally through gavage for the treatment groups. The environmental and cloacal temperature (CT) parameters were measured bi-hourly at Days 21, 28, and 35 from 7:00 to 7:00 hr, during the period of study. The environmental parameters exceeded the thermoneutral zone for broiler chickens. The probiotic-supplemented group had the least overall mean CT values all through the experimental period. Based on our findings, fisetin was not a potent antistress agent in mitigating heat stress in birds.

Calf jackets: a review of science and practice

In the ideal world in which we do not live, where all births are easy, all nutrition balanced, and environmental conditions clean and without thermal stress, calf jackets would never be needed. In reality, however, calves — particularly those born in the winter months in the UK — will likely fall below their thermoneutral zone, requiring a solution. While some added insulation for a cold period might have positive physiological responses, trial data on the value of calf jackets do not often show clear benefits, despite the confidence of some UK producers that they produce benefits for their farms. There are also concerns about the extent of effective hygiene routinely applied to jackets. This article presents and discusses literature related to calf jacket use, and suggests protocols for safe use.