A reduced core to skin temperature gradient,not a critical core temperature,affects aerobic capacity in the heat

The purpose of this study was to determine the impact of the core to skin temperature gradient during incremental running to volitional fatigue across varying environmental conditions. A secondary aim was to determine if a “critical” core temperature would dictate volitional fatigue during running in the heat. 60 participants (n=49 male, n=11 female; 24±5 yrs, 177±11 cm, 75±13 kg) completed the study. Participants were uniformly stratified into a specific exercise temperature group (18 °C, 26 °C, 34 °C, or 42 °C) based on a 3-mile run performance. Participants were equipped with core and chest skin temperature sensors and a heart rate monitor, entered an environmental chamber (18 °C, 26 °C, 34 °C, or 42 °C), and rested in the seated position for 10 min before performing a walk/run to volitional exhaustion. Initial treadmill speed was 3.2 km h⁻¹ with a 0% grade. Every 3 min, starting with speed, speed and grade increased in an alternating pattern (speed increased by 0.805 km h⁻¹, grade increased by 0.5%). Time to volitional fatigue was longer for the 18 °C and 26 °C group compared to the 42 °C group, (58.1±9.3 and 62.6±6.5 min vs. 51.3±8.3 min, respectively, p<0.05). At the half-way point and finish, the core to skin gradient for the 18 °C and 26 °C groups was larger compared to 42 °C group (halfway: 2.6±0.7 and 2.0±0.6 vs. 1.3±0.5 for the 18 °C, 26 °C and 42 °C groups, respectively; finish: 3.3±0.7 and 3.5±1.1 vs. 2.1±0.9 for the 26 °C, 34 °C, and 42 °C groups, respectively, p<0.05). Sweat rate was lower in the 18 °C group compared to the 26 °C, 34 °C, and 42 °C groups, 3.6±1.3 vs. 7.2±3.0, 7.1±2.0, and 7.6±1.7 g m⁻² min⁻¹, respectively, p<0.05. There were no group differences in core temperature and heart rate response during the exercise trials. The current data demonstrate a 13% and 22% longer run time to exhaustion for the 18 °C and 26 °C group, respectively, compared to the 42 °C group despite no differences in beginning and ending core temperatures or baseline 3-mile run time. This capacity difference appears to result from a magnified core to skin gradient via an environmental temperature advantageous to convective heat loss, and in part from an increased sweat rate.     

Thermoregulatory responses of Holstein cows exposed to experimentally induced heat stress

Heat stress (HS) adversely influences productivity and welfare of dairy cattle. We hypothesized that the thermoregulatory mechanisms vary depending on the exposure time to HS, with a cumulative effect on the adaptive responses and thermal strain of the cow. To identify the effect of HS on adaptive thermoregulatory mechanisms and predictors of caloric balance, Holstein cows were housed in climate chambers and randomly distributed into thermoneutral (TN; n=12) or HS (n=12) treatments for 16 days. Vaginal temperature (VT), rectal temperature (Tre), respiratory rate (RR), heart rate (HR), and dry matter intake (DMI) were measured. The temperature and humidity under TN were 25.9±0.2 °C and 73.0±0.8%, respectively, and under HS were 36.3±0.3 °C and 60.9±0.9%, respectively. The RR of the HS cows increased immediately after exposure to heat and was higher (76.02±1.70bpm, p<0.001) than in the TN (39.70±0.71bpm). An increase in Tre (39.87±0.07 °C in the HS vs. 38.56±0.03 °C in the TN, p<0.001) and in VT (39.82±0.10 °C in the HS vs. 38.26±0.03 °C in the TN, p<0.001) followed the increase in RR. A decrease (p<0.05) in HR occurred in the HS (62.13±0.99bpm) compared with the TN (66.23±0.79bpm); however, the magnitude of the differences was not the same over time. The DMI was lower in HS cows from the third day (8.27±0.33 kg d⁻¹ in the HS vs. 14.03±0.29 kg d⁻¹ in the TN, p<0.001), and the reduction of DMI was strongly affected (r=−0.65) by changes in the temperature humidity index. The effect of environmental variables from the previous day on physiological parameters and DMI was more important than the immediate effect, and ambient temperature represented the most determinant factor for heat exchange. The difference in the responses to acute and chronic exposure to HS suggests an adaptive response. Thus, intense thermal stress strongly influence thermoregulatory mechanisms and the acclimation process depend critically on heat exposure time.     

Cryopreservation of Bangladeshi ram semen using different diluents and manual freezing techniques

A study was conducted to establish a sustainable and effective manual freezing technique for cryopreservation of Bangladeshi ram semen. Three diluents and freezing techniques were tested, both as treatment combinations (diluent × freezing technique) and fixed effects (diluent or freezing technique) on post-thaw sperm motility (SM), viability (SV), plasma membrane integrity (SPMI) and acrosome integrity (SAI). Ten rams were selected, based on semen evaluation. Eight ejaculates were used for each treatment combination. Semen samples were diluted using a two-step protocol for home-made Tris-based egg yolk (20%, v/v) diluents: D1 (7% glycerol, v/v) and D2 (5% glycerol, v/v), and one-step for commercial diluent: D3 (Triladyl^®, consists of bi-distilled water, glycerol, tris, citric acid, fructose, spectinomycin, lincomycin, tylosin and gentamycin) at 35 °C. Fraction-A (without glycerol) was added at 35 °C, and following cooling of sample to 5 °C (−0.30 °C/min), Fraction-B (with glycerol) was added. The diluted semen samples were aspirated into 0.25 ml French straws, sealed, and equilibrated at 5 °C for 2 h. The straws were frozen in liquid nitrogen (LN) vapour, in a Styrofoam box. The freezing techniques were; One-step (F1): at −15.26 °C/min from +5 °C to −140 °C; Two-step (F2): at −11.33 °C/min from +5 °C to −80 °C, and −30 °C/min from −80 °C-140 °C; and Three-step (F3): at −11.33 °C/min from +5 °C to −80 °C, at −26.66 °C/min from to −80 °C to −120 °C, and at −13.33 °C/min from −120 °C to −140 °C. Two semen straws from each batch were evaluated before and after freezing. The group F3D3 exhibited significantly higher (p < 0.05) post-thaw SM 63.1 ± 2.5%, SV 79.0 ± 2.1% and SPMI 72.9 ± 1.7%, whereas SAI 72.9 ± 1.7% was significantly higher (p < 0.05) in group F3D2. The freezing technique F2 and F3 had significantly higher (p < 0.05) post-thaw sperm values compared to F1. The post-thaw SM and SV were above 50% and 65% with the freezing technique F2 and F3 but differed non-significant. The SPMI 67.6 ± 2.0% and SAI 76.1 ± 1.4% were significantly higher (p < 0.05) with F3. Likewise, the diluent D2 and D3 had significantly higher (p < 0.05) post-thaw sperm values compared to D1. The post-thaw SM, SV and SPMI were above 50%, 65% and 55% with the diluents D2 and D3 but differed non-significant. The SAI 76.1 ± 1.1% was significantly higher (p < 0.05) with D3. We concluded that the use of a simple home-made Tris-based diluent containing 20% (v/v) egg yolk and 5% glycerol (v/v), two-step dilution and a three-step freezing technique is a sustainable and effective method for freezing ram semen. For further validation, the fertility of ewes artificially inseminated with the frozen semen will be observed.     

The effect of heat stress on intestinal integrity and Salmonella invasion in broiler birds

The intestinal mucosa works as a barrier to protect the internal environment of the animal from bacteria and bacterial toxins found in the gut lumen. Heat stress may harm this function. Therefore, we designed the current experiment to investigate the effect of heat stress on intestinal integrity, physiological and immunological responses and Salmonella invasion in broiler chickens. At 26 days of age, 72 birds were randomly distributed into 3 treatments, with 8 replicates per treatment and 3 birds per replicate. The three treatments were control treatment; kept at thermoneutral environmental conditions (20 ± 2 °C), chronic heat stress treatment (exposed to 30 ± 2 °C; 24 h/day) and acute heat stress treatment (exposed to 35 ±2 °C from 09:00 to 13:00 and kept at 20 ± 1 °C from 13:00 to 09:00). The heat stress exposure was conducted for 10 successive days. Compared with the control treatment, birds subject to chronic and acute heat stress had reduced (P < 0.05) body weight and body gain and increased (P < 0.05) feed conversion ratio. However, feed intake and mortality rate were only increased (P < 0.05) in the acute heat stress treatment. Rectal temperature and Δ rectal temperature (°C/h) increased (P < 0.05) sharply during the first 2 days of exposure followed by gradual decreases until a plateau was achieved. Heat-stressed birds had increased (P < 0.05) serum concentrations of corticosterone, endotoxin lipopolysaccharide and the systemic inflammatory cytokine: TNF-α and IL-2, as well as a higher (P < 0.05) prevalence of Salmonella spp. in meat and livers, as compared with control treatment. It can be concluded that heat stress impaired intestinal integrity which resulted in increased intestinal permeability to endotoxin, translocation of intestinal pathogens (Salmonella spp.) and serum inflammatory cytokines. Therefore, avoiding thermal dysfunction of intestinal barrier is a significant factor in maintaining welfare, immune status and meat safety of broiler birds.     

Heat acclimation does not modify autonomic responses to core cooling and the skin thermal comfort zone

Exercise heat acclimation (HA) is known to magnify the sweating response by virtue of a lower threshold as well as increased gain and maximal capacity of sweating. However, HA has been shown to potentiate the shivering response in a cold-air environment. We investigated whether HA would alter heat loss and heat production responses during water immersion. Twelve healthy male participants underwent a 10-day HA protocol comprising daily 90-min controlled-hyperthermia (target rectal temperature, T_re 38.5 °C) exercise sessions. Preceding and following HA, the participants performed a maximal exercise test in thermoneutral conditions (ambient temperature 23 °C, relative humidity 50%) and were, following exercise, immersed in 28 °C water for 60 min. Thermal comfort zone (TCZ) was also assessed with participants regulating the temperature of a water-perfused suit during heating and cooling. Baseline pre-immersion T_re was similar pre- and post-HA (pre: 38.33 ± 0.33 °C vs post: 38.12 ± 0.36 °C, p = 0.092). The T_re cooling rate was identical pre-to post-HA (−0.03 ± 0.01 °C·min⁻¹, p = 0.31), as was the vasomotor response reflected in the forearm-fingertip temperature difference. Shivering thresholds (p = 0.43) and gains (p = 0.61) were not affected by HA. TCZ was established at similar temperatures, with the magnitude in regulated water temperature being 7.6 (16.3) °C pre-HA and 5.1 (24.7) °C post-HA (p = 0.65). The present findings suggest that heat production and heat loss responses during whole body cooling as well as the skin thermal comfort zone remained unaltered by a controlled-hyperthermia HA protocol.     

Sperm cryostorage in a dry tank: An accurate alternative

This prospective study aimed to determine the effects of dry nitrogen cryostorage on human sperm characteristics in comparison with liquid nitrogen cryostorage. For this purpose, 42 men undergoing routine semen analysis (21 normozoospermia and 21 with altered semen parameters) were analyzed. After slow freezing, half of the straws of each sample were randomly stored in liquid and dry tanks, at the top and bottom levels of the latter. After 6 months storage, thawed samples were treated by density gradient centrifugation and sperm characteristics were compared. There was no difference in sperm progressive motility (15.1% ± 14.2% vs. 15.1% ± 12.7%; p = 0.76), sperm vitality (25.5% ± 17.7% vs. 26.2% ± 19%; p = 0.71), percentages of acrosome-reacted spermatozoa (38% ± 8.5% vs. 38.5% ± 7.4%; p = 0.53) and DNA fragmentation spermatozoa (27.3% ± 12.4% vs. 28.5% ± 12.9%, p = 0.47) after cryostorage in the dry or the liquid nitrogen tank. Moreover, we did not observe differences between either cryostorage system for normal and altered sperm samples. This lack of difference was also observed whatever the floor level of cryostorage in the dry tank. The temperature measurement of the dry tank showed a stable temperature at −194 °C throughout storage whatever the storage floor level, guaranteeing the stability of the low temperatures suitable for human sperm storage. Because of its greater safety, dry storage without contact with the liquid phase should be preferred and can be a useful alternative for the cryostorage of human sperm samples.     

Effect of change in ambient temperature on core temperature during the daytime

In this study, the hypothesis is tested that continuous increases in ambient temperature (T_a) during daytime would give elevated core and skin temperatures, and consequently better thermal sensation and comfort. Rectal temperature (T_re), skin temperatures and regional dry heat losses at 7 sites were continuously measured for 10 Japanese male subjects in three thermal conditions: cond. 1, stepwise increases in T_a from 26 °C at 9 h00 to 30 °C at 18 h00; cond. 2, steady T_a at 28 °C from 9 h00 to 18 h00 and cond. 3, stepwise decreases in T_a from 30 °C at 9 h00 to 26 °C at 18 h00. Oxygen consumption was measured and thermal sensation and comfort votes were monitored at 15 min intervals. Body weight loss was measured at 1 h intervals. While T_re increased continuously in the morning period in any condition, it increased to a significantly greater (p?<?0.05) 36.9?±?0.3 °C at 18 h00 in cond. 1 relative to 36.7?±?0.28 °C in Cond. 2 and 36.5?±?0.37 °C in cond. 3. Better thermal comfort was observed in the afternoon and the evening in Cond.1 as compared with the other 2 conditions. Thus, a progressive and appropriate increase in T_a may induce optimal cycle in core temperature during daytime, particularly for a resting person.     

Thermoregulatory responses of lower limb amputees during exercise in a hot environment

Lower limb amputees (LLAs) have less skin surface required for sweating; thus, the ability to dissipate heat from the body may decrease and the risk of heat illness may increase during exercise in a hot environment. However, no study has compared the thermoregulatory responses during exercise between LLAs and able-body (AB) individuals with different body surface areas. This study aimed to compare the thermoregulatory responses of LLAs with those of AB individuals during exercise in a hot environment. Seven LLAs (LLA group) and 7 able-body individuals (AB group) participated in the study. A 60% peak power output of arm crank upper-body exercise was performed for 60 min in a hot environment (32 °C, 50% relative humidity). There was no difference in the increase in rectal temperature (LLA: 0.8 ± 0.2 °C, AB: 0.8  ± 0.2 °C) and mean skin temperature between the groups during the 60-min exercise. In the LLA group, the accumulated local sweat rate of the thigh during exercise was significantly higher on the non-cut side than on the cut side (64.6 ± 43.0 mg/h vs. 37.0 ± 27.2 mg/h, p < 0.05). The total sweat rate was significantly higher in the LLA group than in the AB group (1.18 ± 0.37 kg/h vs. 0.84 ± 0.10 kg/h, p < 0.05). Thermal sensation and comfort were lower in the LLA group than in the AB group. Different heat loss responses were observed in the AB and LLA groups during exercise in the heat. The LLA group compensates for sweating on the cut side due to an increase in sweat loss on the intact limb, thereby preserving appropriate thermoregulation during exercise.     

Changes in the acid-base balance and lactate concentration in the blood in amateur ultramarathon runners during a 100-km run

The aim of this study was to analyse the acid-base balance and partial pressure of blood gases of participants during a 100-km run. Fourteen experienced amateur ultramarathon runners (age: 43.36±11.83 years; height: 175.29±6.98 cm; weight: 72.12±7.36 kg) completed the 100-km run. Blood samples were taken before the run; after 25, 50, 75, and 100 km; and 12 and 24 hours after the run. There were significant differences (p<0.05) between the mean values registered for acid-alkaline balance, buffering alkalies, and current bicarbonate in each segment of the run, especially during the third, fourth, and fifth segments of the run (i.e., between 50 and 100 km), and there were only significant differences associated with buffering alkalies and current bicarbonate during the recovery. However, all the changes were within the physiological norm. A significant decrease in the compressibility of oxygen was observed after 100 km (from 92.80±15.67 to 88.36±13.71 mmHg) and continued during the recovery to 75.06±8.60 mmHg 12 h after the run. Also there was a decrease in saturation to a mean value of 93.78±3.10 at 12 h after the run. Generally the amateurs runners are able to adjust their running speed so as not to provoke a significant acid-base imbalance or lactate acid accumulation.     

Influence of larval rearing temperature on the quality of cold‐stored Oomyzus sokolowskii Kurdjumov (Hymenoptera: Eulophidae)

Oomyzus sokolowskii, an important parasitoid of Plutella xylostella, has great potential for use in biological control. Storage at suboptimal temperature is valuable for increasing the shelf‐life of insect parasitoids. In this study, O. sokolowskii larvae were reared at 30/25, 25/25 and 25/20°C light/dark (65 ± 5% RH, 16 : 8 h L : D) until pupation. The pupae were then cold‐stored at 4 ± 1°C (60 ± 5% RH, full darkness). The pupae were removed out from the storage at 10, 20, 30 and 40 days after storage (DAS) and maintained at 25 ± 2°C until adults emerged or pupae died. Quality of the emerging adults and their F₁ offspring were assessed. Incidence of parasitism by O. sokolowskii was higher at 30/25°C than at 25/20°C. Cold storage of O. sokolowskii pupae greatly affected the fitness of the parasitoid: adult emergence rates were lower in the 40 DAS treatment than in other treatments; when O. sokolowskii larvae developed at 25/25°C, female proportions of the emerged adults were lower in the 40 DAS treatment than in the 0 and 10 DAS treatments. Larval rearing temperature mildly affected the adult emergence rate, post‐storage developmental time and female proportion with a few exceptions. Number of parasitoids emerged per host pupa, and incidence of parasitism by the females were neither affected by larval rearing temperature nor cold storage duration. Trans‐generational effects on F₁ offspring were evident in adult emergence rate, egg‐adult developmental time and female proportion which were negatively affected by long duration of storage (40 days), but not by larval rearing temperature with a few exceptions. In conclusion, O. sokolowskii pupae could be stored at 4°C for up to 30 days without significant fitness loss.     

High subzero cryofixation: A technique for observing ice within tissues

While various fixation techniques for observing ice within tissues stored at high sub-zero temperatures currently exist, these techniques require either different fixative solution compositions when assessing different storage temperatures or alteration of the sample temperature to enable alcohol-water substitution. Therefore, high-subzero cryofixation (HSC), was developed to facilitate fixation at any temperature above −80 °C without sample temperature alteration. Rat liver sections (1 cm²) were frozen at a rate of −1 °C/min to −20 °C, stored for 1 h at −20 °C, and processed using classical freeze-substitution (FS) or HSC. FS samples were plunged in liquid nitrogen and held for 1 h before transfer to −80 °C methanol. After 1, 3, or 5 days of −80 °C storage, samples were placed in 3% glutaraldehyde on dry ice and allowed to sublimate. HSC samples were stored in HSC fixative at −20 °C for 1, 3, or 5 days prior to transfer to 4 °C. Tissue sections were paraffin embedded, sliced, and stained prior to quantification of ice size. HSC fixative permeation was linear with time and could be mathematically modelled to determine duration of fixation required for a given tissue depth. Ice grain size within the inner regions of 5 d samples was consistent between HSC and FS processing (p = 0.76); however, FS processing resulted in greater ice grains in the outer region of tissue. This differed significantly from HSC outer regions (p = 0.016) and FS inner regions (p = 0.038). No difference in ice size was observed between HSC inner and outer regions (p = 0.42). This work demonstrates that HSC can be utilized to observe ice formed within liver tissue stored at −20 °C. Unlike isothermal freeze fixation and freeze substitution alternatives, the low melting point of the HSC fixative enables its use at a variety of temperatures without alteration of sample temperature or fixative composition.     

Some reproductive characteristics of endangered Caspian Lamprey (<Emphasis Type="Italic">Caspiomyzon wagneri</Emphasis> Kessler, 1870) in the Shirud River southern Caspian Sea,Iran

Migration and reproduction of the Caspian Lamprey, Caspiomyzon wagneri, in the Shirud River were investigated during late-March to early-May at water temperatures ranging from 11 to 21.25°C. We examined the effect of water temperature on timing of spawning migrations. There was a significant negative relationship between temperature and intensive migration of Caspian Lamprey (p < 0.05). The most intensive migration of lampreys was at night (21:00–3:00 h) and when the water temperatures averaged 16°C (34.43%). The overall sex ratio (male to female) was 1.07 to 1. The individual absolute fecundity was 31 ‘758–51’ 198 eggs (mean±SD—41,924 ± 5,382). The egg diameter was 0.780–1.151 (0.92 ± 0.081) mm. The individual relative fecundity varies from 80.3 to 148.1 (107.2 ± 15.1) eggs per 1 mm of length and from 260.8 to 677.4 (397.6 ± 93) eggs per 1 g of weight. The gonadosomatic index (GSI) of females was 5.83–31.44 (11.22 ± 4.30).     

Two-step accelerating freezing protocol yields a better motility,membranes and DNA integrities of thawed ram sperm than three-steps freezing protocols

The present study compares a protocol that mimics freezing of ram semen in static nitrogen vapor with two protocols with an initial low cooling rate in the first step, followed by higher cooling rates where ice nucleation occurs. Semen ejaculates, obtained from twelve adults rams, were diluted with TEST-based extender and frozen with either Protocol 1 (three-step decelerating cooling): from +5 °C to −35 °C (40 °C/min), from −35 °C to −65 °C (17 °C/min), and then from −65 °C to −85 °C (3 °C/min); or Protocol 2 (three-step accelerating cooling): from +5 °C to −5 °C (4 °C/min), from −5 °C to −110 °C (25 °C/min), and then from −110 °C to −140 °C (35 °C/min); or Protocol 3 (two-step accelerating cooling), from +5 °C to −10 °C (5 °C/min), and then from −10 °C to −130 °C (60 °C/min). Post-thaw sperm quality was reduced for all protocols (p < .05) compared with fresh semen. Post-thaw percentages of sperm motility characteristics and sperm with intact plasma membrane, intact acrosome, and intact mitochondrial membrane were greater using Protocol 3 than Protocol 2 (p < .05) and Protocol 1 (p < .01). In addition, the post-thaw percentage of sperm with fragmented DNA was lower (p < .05) using Protocol 3 compared with Protocol 1. The present results indicate that a cooling rate of 60 °C/min around and after the time point of ice nucleation provided better post thaw survival and function of ram sperm than lower (and/or decelerating) cooling rates.     

Vaginal temperature is not related to the time of ovulation in sows

The relationship between vaginal temperature and ovulation time was studied in sows. The vaginal temperature was measured continuously between Day 4 and Day 10 after Altrenogest-treatment in 10 sows. Oestrus was checked with a vasectomized boar at 8-h intervals, and during oestrus, ovulation time was checked with transrectal ultrasonography at 2-h intervals between 07:00 h and 23:00 h. Two sows ovulated between 23:00 h and 07:00 h, and these sows were taken out of the experiment. In the eight remaining sows, a clear day/night rhythm in vaginal temperature was found: between 03:00 h and 09:00 h, vaginal temperature (LSM ± sem, corrected for sow) was on average 38.2 ± 0.01°C; between 15:00 h and 21:00 h, vaginal temperature was on average 38.5 ± 0.01°C (P < 0.001). Between 4 days before ovulation and 2 days after ovulation, no changes in temperature could be found that were related to ovulation time in any of the sows. Therefore, in sows, changes in vaginal temperature cannot be used as a predictor for ovulation time, and consequently cannot be used to predict the best time for insemination.     

Predicting military working dog core temperature during exertional heat strain: Validation of a Canine Thermal Model

Military working dogs (MWDs) operate under a wide range of conditions, including hot environments. Predicting how long a MWD can safely work without overheating is important for both health and performance. A Canine Thermal Model (CTM) was developed to predict core temperature (Tc) of MWDs. The CTM calculates heat storage from the balance of heat production from metabolism and heat exchange with the environment. Inputs to the CTM are: meteorological conditions (ambient temperature, relative humidity, solar radiation and wind speed), physical characteristics of the dog (mass, length), and metabolic activity (MET level, estimated from accelerometer data). The CTM was validated against Tc measured in 23 MWDs during training sessions (11.6 ± 5.0 min (mean ± standard deviation), range 4–26 min) in October (24 °C, 52% RH), March (14 °C, 74% RH), or August (28 °C, 64% RH), and 24 kennel MWDs during a standard exercise walk (11.4 ± 3.3 min, range 5.6–18 min) in July (26 °C, 77% RH). The CTM was considered acceptable if predicted Tc was within ±0.5 °C of measured Tc at the end of exercise. Compared to Tc at the end of training sessions (39.8 ± 0.6 °C, range 38.4–41.1 °C) and exercise walks (40.0 ± 0.7 °C, range 38.9–41.4 °C), the CTM-predicted Tc was within ±0.5 °C for 71 of 84 cases (85%) and 19 of 24 cases (79%), respectively. The mean difference between CTM-predicted and measured final Tc during training was -0.04 ± 0.43 °C, with 80 of 84 cases (95%) within the range of ±2 SD (Bland Altman comparison). During exercise walks the mean difference was -0.15 °C ± 0.57, with 23 of 24 cases (96%) within ±2 SD. These results support the use of the CTM to predict Tc of MWDs for the types of physical activities described above.     

The relative roles of the parasol-like tail and burrow shuttling in thermoregulation of free-ranging Cape ground squirrels,Xerus inauris

As small arid-zone mammals, Cape ground squirrels (Xerus inauris) are unusual in being diurnally active. It is postulated that they remain active during the day by using their parasol-like tails to shade their bodies whilst foraging. However, no studies have continuously measured body temperature to determine the effect of using the tail as a parasol, relative to other thermoregulatory behaviours, such as burrow retreat. We caught four free-ranging Cape ground squirrels (673 ± 36 g) and surgically implanted miniature temperature-sensitive data loggers into their abdomens, to record body temperature every 5 min to an accuracy of 0.04 °C, before they were released back into their home range and observed for two weeks. Mean daily peak black globe temperature was 41 °C, and daily peak body temperature reached 40 °C. Ground squirrels raised their tails significantly more often at globe temperatures above 30 °C, but raising the tail did not decrease body temperature, nor prevent body temperature rising. Ground squirrels retreated to burrows, at 18 °C, significantly more often at high body temperatures and body temperature dropped 1–2 °C before re-emergence. We believe that the tail was raised to provide thermal comfort during high solar radiation exposure, and that burrow retreat was employed to dissipate a heat load and remain active diurnally.     

Life cycle and morphology of Anisops sardeus Herrich-Schaeffer, 1849 (Heteroptera: Notonectidae)

The life cycle of Anisops sardeus was studied by rearing individuals from egg to adult stage in laboratory conditions at a water temperature of 23.2 ± 1.4 °C during the wet season (May-June) and 19 ± 1.8 °C during the dry season (December-February). The incubation period averaged 8 ± 0.8 and 11.5 ± 1.7 days during the wet and dry seasons, respectively. Duration of the five instars averaged 3.4 ± 0.5, 4.4 ± 0.5, 4.8 ± 0.8, 5 ± 0.7, and 6.9 ± 0.7 days, respectively during the wet season, and 4.9 ± 0.7, 6.5 ± 1.1, 7.5 ± 1.1, 8.1 ± 0.7, and 9.4 ± 1.1 days, respectively during the dry season. Total developmental time averaged 32.5 ± 2 and 47.9 ± 2.8 days in the wet and dry seasons, respectively. The average period of incubation and developmental time of the five instars were shorter in the wet season as compared to those in the dry season. But individuals were larger in the dry season. The variations in morphometric ratios of different characteristic features of laboratory reared specimens among different developmental stages in both the wet and dry seasons, and field collected specimens in the wet season were highly significant as revealed by one-way MANOVA (F = 95.45, p < 0.001; F = 124.38, p < 0.001; F = 5022.85, p < 0.001, respectively). Five instars are described in detail with emphasis on 29 morphometric ratios. This study discerned six morphometric ratios such as length of wing pad/ width of wing pad (WL/WW), length of wing pad/body length (WL/BL), length of head/length of body (HL/BL), length of meso femur/length of meso tibia (FE2L/TI2L), synthlipsis/width of head (S/HW), and vertex/synthlipsis (V/S) which can be used for discriminating instars I-V.     

Combined effects of spray‐drying conditions and postdrying storage time and temperature on Salmonella choleraesuis and Salmonella typhimurium survival when inoculated in liquid porcine plasma

The objective of this study was to determine the effectiveness of the spray‐drying process on the inactivation of Salmonella choleraesuis and Salmonella typhimurium spiked in liquid porcine plasma and to test the additive effect of immediate postdrying storage. Commercial spray‐dried porcine plasma was sterilized by irradiation and then reconstituted (1:9) with sterile water. Aliquots of reconstituted plasma were inoculated with either S. choleraesuis or S. typhimurium, subjected to spray‐drying at an inlet temperature of 200°C and an outlet temperature of either 71 or 80°C, and each spray‐drying temperature combinations were subjected to either 0, 30 or 60 s of residence time (RT) as a simulation of residence time typical of commercial dryers. Spray‐dried samples were stored at either 4·0 ± 3·0°C or 23·0 ± 0·3°C for 15 days. Bacterial counts of each Salmonella spp., were completed for all samples. For both Salmonella spp., spray‐drying at both outlet temperatures reduced bacterial counts about 3 logs at RT 0 s, while there was about a 5·5 log reduction at RT 60 s. Storage of all dried samples at either 4·0 ± 3·0°C or 23·0 ± 0·3°C for 15 days eliminate all detectable bacterial counts of both Salmonella spp.

Significance and Impact of the Study

Safety of raw materials from animal origin like spray‐dried porcine plasma (SDPP) may be a concern for the swine industry. Spray‐drying process and postdrying storage are good inactivation steps to reduce the bacterial load of Salmonella choleraesuis and Salmonella typhimurium. For both Salmonella spp., spray‐drying at 71°C or 80°C outlet temperatures reduced bacterial counts about 3 log at residence time (RT) 0 s, while there was about a 5.5 log reduction at RT 60 s. Storage of all dried samples at either 4.0 ± 3.0°C or 23.0 ± 0.3°C for 15 days was effective for eliminating detectable bacterial counts of both Salmonella spp.     

Effect of thermal exposure on physiological adaptability and seminal attributes of rams under semi-arid environment

Thermal stress in hot semi-arid environment is a major limitation of sheep production in tropical and sub-tropical climatic condition. The animals tend to maintain homeostasis through physiological adjustments in a hot environment (maximum temperature reaches up to 47.5 °C). Therefore, the present study was carried out to assess the effect of thermal exposure on physiological adaptability and seminal attributes of rams under semi-arid environment. The experiment was conducted for eight weeks involving sixteen Malpura crossbred rams (GMM: Garole X Malpura X Malpura). The rams were divided equally into two groups, designated as G1 and G2, respectively. The rams in G1 (Control) group were kept in a sheep shed under naturally prevailing environment without artificial manipulation of ambient temperature (Temperature 30.48±0.38 °C; Relative Humidity 28.59±1.15%). The rams of G2 group were exposed to different temperature at different hours of the day (38 °C at 1000–1100 h; 40 °C at 1100–1200 h; 42 °C at 12:00–1300 h; 43 °C at 1300–1400 h; 44 °C at 1400–1500 h and 42 °C at 1500–1600 h) in a climatic chamber for thermal exposure. Physiological responses, blood biochemical profile, blood endocrine profile, sexual behavior and seminal attributes were measured for both the groups. Thermal exposure significantly (P<0.05) increased the water intake; respiration rate, rectal temperature and skin temperature at afternoon in rams. Exposure of rams to thermal stress (G2) significantly (P<0.05) increased cortisol level and decreased tri-ido-thyronine level. The latency period after the first ejaculation, decreased significantly (P<0.05) in G2. The percentage of rapid motile sperm, linearity and average path velocity of sperm were also altered significantly (P<0.05) in thermal exposed rams as compared to control. However, comparable feed intake, body weight, and major blood biochemical parameters, as well as acceptable semen quality attributes of all the rams indicated that the Fec B gene introgressed Malpura cross rams adapted to the thermal exposure under semi-arid tropical climate.     

Biology of Lysiphlebus fabarum following cold storage of larvae and pupae

Cold storage is one means of preserving parasitoids prior to release in augmentation biological control programs. This study examined the feasibility of storing larval and pupal stages of a sexual population of Lysiphlebus fabarum Marshall (Hymenoptera: Braconidae: Aphidiinae) at 6 ± 1 and 8 ± 1 °C, 50–60% r.h., and L14:D10 photoperiod. These life stages were stored for periods of 1, 2, and 3 weeks under fluctuating thermal regimes (2 h daily at 21 ± 1 °C). Generally, pupae gave better results than larvae, and 6 °C was better than 8 °C, considering wasp survival, wasp size (tibial and antennal lengths), egg load, and egg size. The best results were obtained with pupae stored for 2 weeks under a fluctuating temperature regime at 6 °C. Females emerging from this treatment did not differ from controls (developing directly at 21 °C) in body size, egg size, or progeny sex ratio, and suffered less than 20% mortality. Egg loads were reduced in these wasps, but the reductions were substantially less than occurred in other 2‐week‐storage treatments. Wasps stored in this manner successfully parasitized similar numbers of aphids as controls and produced similar progeny sex ratios. These results reveal a suitable set of low‐temperature conditions that can be used to delay the development of L. fabarum for 2 weeks with minimal impact on wasp fitness.