Comparing the responses of grain-fed feedlot cattle under moderate heat load and during subsequent recovery with those of feed-restricted thermoneutral counterparts: blood cells and inflammatory markers.

Given the climate projections for livestock rearing regions globally, understanding the inflammatory status of livestock under various heat loads will be informative to animal welfare and management. A survey of plasma inflammatory markers was conducted, and blood leucocyte counts followed to investigate the capacity of the ~ 500 kg grain fed Black Angus steer to respond to and recover from a moderate heat load challenge. Two sequential cohorts of 12 steers were housed in climate-controlled rooms (CCR) for 18 days. A thermally challenged (TC) group (n = 2 × 6) experienced five consecutive periods: PreChallenge, Challenge, and Recovery within the CCR, and 40 days in outdoor pens (PENS and Late PENS). PreChallenge (5 days) and Recovery (7 days) delivered thermoneutral conditions, whereas in Challenge the TC steers experienced a diurnal temperature range of 28-35 °C. A feed-restricted thermoneutral (FRTN) treatment (n = 2 × 6) was run concurrently to differentiate between responses to reduced feed intake alone and moderate heat stress. Blood neutrophil counts were particularly sensitive to moderate heat load with higher numbers during Challlenge and in PENs. The plasma concentrations of TNFα and IL-1ß were depressed in the TC group compared to the FRTN counterparts and remained so for 40 days after Challenge. Linear relationships of the concentrations of IL-1ß, IL-10, and haptoglobin with rumen temperature or dry matter intake detected in the FRTN group were altered or absent in the TC group. The findings suggest significant impacts of moderate heat load on the inflammatory status of feedlot cattle.

The effect of day-only versus day-plus-night cooling of dairy cows.

The aim of this study was to assess effects on milk yield (MY), rumen temperature, and panting score when lactating dairy cows were cooled during the day only or during the day and night. The study was conducted over 106 d during using 120 multiparous Holstein-Friesian cows assigned to 2 treatments (60 cows/treatment; 2 pens/treatment): (1) day cooling (DC): overhead sprinklers (large droplet) and fans while in the dairy holding yard only, shade and fans at the feedpad, and a shaded loafing area; and (2) enhanced day+night cooling (EDN): overhead sprinklers (large droplet) and fans in dairy holding yard, ducted air blowing onto cows during milking, plus thorough wetting (shower array) on exit from dairy; shade and fans at feedpad (turned off at night); and shaded loafing area + ducted fan-forced air blowing onto cows at night. The ducted air at night was manually activated at 2030 h when the maximum daily temperature-humidity index exceeded 75 and remained on until 0430 h the next day. The cows were fed a total mixed ration ad libitum, and feed intake was determined on a pen basis. Rumen temperature and cow activity were obtained from each cow at 10-min intervals via rumen boluses. Panting scores were obtained by direct observation 4 times a day at approximately 0430, 0930, 1530, and 2030 h. Cows were milked twice daily: 0500 to 0600 h and 1600 to 1700 h. Individual MY were obtained at each milking and combined to give individual daily totals. The EDN cows had greater daily MY (+2.05 kg/cow per day) over the duration of the study compared with DC cows. Rumen temperature during the third heat wave was lower for EDN (39.51 ± 0.01°C) than for DC (39.66 ± 0.01°C) cows. During the most severe heat wave (heat wave 3), MY for the 2 groups was similar, but over the 6 d following the heat wave, EDN cows had greater daily MY (+3.61 kg/cow per day). Rumen temperature was lower for EDN (39.58 ± 0.01°C) than for DC (40.10 ± 0.01°C) cows.

Comparing the responses of grain fed feedlot cattle under moderate heat load and during subsequent recovery with those of feed restricted thermoneutral counterparts: metabolic hormones.

We set out to determine the impact of moderate heat load on the plasma concentrations of a suite of hormones involved in regulating energy metabolism and feed intake. The responses of the thermally challenged (TC) feedlot steers were compared to those of feed restricted thermoneutral (FRTN) steers. Two sequential cohorts of twelve 518 ± 23 kg Black Angus steers on finisher grain ration were housed in climate-controlled rooms (CCR) for 18 days and returned to outdoor pens for 40 days. The TC group was subjected to a diurnal range of 28-35 °C for 7 days (Challenge) but held in thermoneutral conditions beforehand (PreChallenge), and in Recovery (after Challenge). The FRTN group was held in thermoneutral conditions and feed restricted throughout. Blood was collected over the three periods in CCR and two periods in outdoor pens for 40 days (PENS and Late PENS). Plasma concentrations of prolactin, thyroid stimulating hormone, insulin, leptin, adiponectin and thyroxine (T4) were determined during the five periods. Whilst the pituitary hormones were relatively stable, there were differences in plasma leptin, adiponectin and T4 between the two groups during Challenge and Recovery, and occasionally in PENS. The interaction of the plasma hormone concentrations and rumen temperature and DMI were also investigated. Whilst the positive relationship between DMI and leptin was confirmed, we found a strong negative relationship between adiponectin and rumen temperature, and a strong positive relationship between adiponectin and dry matter intake (DMI) in the TC steers only.

The influence of shade availability on the effectiveness of the Dairy Heat Load Index (DHLI) to predict lactating cow behavior, physiology, and production traits.

Numerous climatic indices have been utilized to predict the effect of hot, and cold, climatic conditions on animal production and welfare. To date, the dairy industry has relied extensively on the Temperature Humidity Index (THI) to predict adverse climatic conditions; however, neither solar radiation nor air movement is accounted for in the THI equation. The Dairy Heat Load Index (DHLI) was initially developed as an alternative climate index. In its current format, the DHLI does not account for the effects of heat load mitigation strategies, such as shade, which decreases the negative effects of hot climatic conditions on lactating cows. Therefore, this experiment aimed to determine the effectiveness of the DHLI as a predictor of heat load responses in both shaded and unshaded cows, as compared with the THI. Forty lactating Holstein Friesian (n = 40) cows were selected and paired based on live weight, milk yield, and days in milk. One cow from each pair was randomly allocated to one of two treatments: shaded (n = 20) or unshaded (n = 20). Cows were given 7 days to acclimate prior to the commencement of data collection. After 28 days, cows were transitioned into the alternate treatment in a crossover design and given 7 days to acclimate prior to data collection. Behavioral observations (0800, 1200, 1400, and 1800 h daily), daily milk yield (kg), milk composition (various days), and vaginal temperature (TVAG, °C; 5 pairs/week, over a 4-week rotation) were recorded. Overall, data from this experiment indicated that the DHLI was a better predictor of standing and feeding behaviors in unshaded cows and drinking behaviors in shaded cows. Conversely, the THI was a better predictor of standing behavior and shade usage in shaded cows. Furthermore, the THI was a better predictor of mean panting score (MPS) in shaded cows, whereas the DHLI performed better in unshaded cows. Additionally the DHLI was a better predictor of TVAG in these cows. Finally, when evaluating the 7-day average of each climatic index, the DHLI was a better predictor of change in milk yield. Incorporation of additional animal and management factors is required if the DHLI is to become an effective heat load management tool.

Influence of feeding Saccharomyces cerevisiae on the heat load responses of lactating dairy cows during summer.

The objective of this study was to evaluate the influence of supplementing lactating dairy cows with Saccharomyces cerevisiae on milk production and composition, cow behavior, and physiological responses during summer. Twenty primiparous cows were used and two treatments were imposed: (1) control (CON); and (2) probiotic supplementation (PRO; S. cerevisiae, providing 1010 colony forming units (CFU) per day). Rumen temperature (TRUM, °C) and pH were obtained via rumen boluses. Rumen temperatures were obtained from all cows (n = 20) at 10-min intervals and ruminal pH were obtained from five cow pairs (n = 10) at 10-min intervals. Ambient temperature (TA; °C), relative humidity (RH; %), wind speed (WS; m/s), and solar radiation (SR; W/m2) were recorded at 10-min intervals. The temperature humidity index (THI) was calculated using TA and RH. Cows were milked twice daily. Milk fat (%), protein (%), lactose (%), and somatic cell count (SCC, '000) were evaluated on 16 occasions. Cows were observed three times (0800 h; 1200 h; and 1400 h) daily for panting score (PS); respiration rate (RR); posture (standing/lying); shade utilization; and cow activity (eating/drinking/ruminating). Individual PS were used to calculate a mean panting score (MPS) for CON and PRO treatments for each observation. S. cerevisiae did not influence milk yield (P = 0.87), fat (P = 0.82), protein (P = 0.26) or SCC (P = 0.19), although there was a tendency for PRO cows to have higher lactose (P = 0.06). Probiotics did not influence the proportion of cows utilizing shade (P = 0.42); standing (P = 0.41); ruminating (P = 0.72); or drinking (P = 0.40). All cows exhibited an increase in RR (> 24 bpm) at 1200 h and RR showed a steady increase as THI increased (P < 0.0001), regardless of treatment (P = 0.96). Both CON (35.8%) and PRO (40.2%) exhibited an increase in MPS as THI increased from thermoneutral (THI ≤ 74) to very hot (THI ≥ 84.1; P < 0.001). However, PRO cows had lower (2.19 ± 0.09; P < 0.0001) MPS compared with CON (2.54 ± 0.22) cows when THI was categorized as very hot (THI ≥ 84.1). Rumen pH were not influenced by treatment (P = 0.38), however TRUM of PRO cows were 0.2 °C lower across days (P < 0.0001) and hours (P < 0.0001). These results suggest that supplementing cows with S. cerevisiae may support thermoregulation via decreased TRUM and MPS; however, further studies are required.

Thermoregulation of the bovine scrotum 2: simulated acute and chronic heat waves reduces the scrotal thermoregulatory capability of Wagyu bulls.

The objective of this study was to investigate the effect of acute and chronic heat load events on scrotal temperature (ST), body temperature (BT) and bull behaviour, and to examine the interrelationship between these parameters; the underlying hypothesis was that adverse heat treatments delivered in a temperature controlled environment will lead to thermoregulatory dysfunction of the bull scrotum. Six sexually mature Wagyu bulls were used in this study with data loggers surgically implanted into the abdominal cavity and scrotum. Body temperate and ST were recorded at 30-min intervals for the duration of the study. There were two housing locations used throughout the study, outdoor pens and climate control rooms. The study was designed as a four-phase crossover design with two heat treatments: (1) a 5-day acute challenge, and (2) a 14-day chronic challenge. The study was also blocked by phase to control for systematic change between phases with a thermoneutral (TN) phase in outdoor pens between each heat challenge. Observations within the climate rooms were conducted at 1-h intervals and data on panting scores (PS), respiration rate (RR), posture (standing or lying) and general behaviours (feeding, drinking, ruminating) recorded. Ambient temperature (AT, °C) and relative humidity (RH, %) were obtained at 10-min intervals and used to calculate the temperature humidity index (THI). Multiple models were conducted using a linear mixed effects model that contained different permutations of date and time factors and interactions as well as inclusion of an autoregressive parameter. The strongest model based on Akaike's information criterion (AIC) was selected and further analysed. Ambient conditions during heat treatments were consistent with heat load and bulls showed typical physiological symptoms of the same. Maximum ST for acute and chronic treatments occurred once AT had exceeded 34 °C for at least 3 h (acute 35.59 °C at 1500 h; chronic 35.18 °C at 1400 h), whereas during TN conditions, maximum ST was at 2100 h. All phases showed variation in ST throughout the day. There were strong cross correlations between ST and RR during the heat treatments (acute r = 0.918, P < 0.0001; chronic r = 0.916, P < 0.0001), but not during TN (r = 0.411, P < 0.05). Our results confirmed that the ST of the bulls used in this study was not held at a constant temperature and that there was a possible connection between ST and RR. We have shown that during a period of heat load, the thermoregulatory mechanisms thought responsible for maintaining bovine ST appear to breakdown.

Comparing the responses of grain fed feedlot cattle under moderate heat load and during subsequent recovery with those of feed restricted thermoneutral counterparts: plasma biochemistry.

Responses to heat stress in ruminants reflect the integration of local climatic conditions, environment/production system and the animal's homeostatic and homeorhetic capacities. Thus, the goal of ameliorating heat stress requires experimental settings that, within limits, closely resemble the target production system and cohort. We investigated the blood biochemical changes of two sequential cohorts of twelve 518 ± 23 kg grain fed Black Angus steers. Each cohort consisted of two treatments of 6 head/group: a thermally challenged (TC) treatment and a feed restricted thermoneutral (FRTN) treatment. Both groups were housed in climate controlled rooms for 19 days, with the TC group experiencing three distinct periods: PreChallenge, Challenge and Recovery. PreChallenge and Recovery delivered thermoneutral conditions, while Challenge consisted of 7 days of moderate diurnal heat load. The FRTN group was maintained in thermoneutral conditions at all times. Both groups were then relocated to outdoor pens for a further 40 days to detect any enduring change to metabolism as a consequence of the treatments. We compared blood biochemical responses of the treatments and inferred likely metabolic changes. Relative to the FRTN group, the TC animals experienced limited supply of triglycerides, cholesterol and glutamine during moderate heat load, suggesting constraints to energy metabolism. Lower blood urea during Recovery and in outdoor pens implied a requirement to capture N rather than allow its excretion. Altered liver enzyme profiles indicated a higher level of hepatic stress in the TC group. By the completion of feedlot finishing, the groups were not separable on most measures.

Development of a Model for Abdominal Aortic Aneurysms in Swine.

INTRODUCTION: Producing a reliable large-animal model of AAA has proven challenging. We sought to create a reproducible swine model of AAA using enzymatic degradation of the aortic wall. METHODS: Twelve male Yorkshire swine received periadventitial injections of type 1 collagenase and porcine pancreatic elastase into a 4 cm segment of infrarenal aorta. Nine survived until postoperative day (POD) 21. Aortic growth was monitored at 7 and 14 days using ultrasound. The animals were euthanized on POD 21, and the suprarenal (control) and infrarenal aorta were harvested for analysis, after gross measurement of aortic diameter (AD). Tensile strength was measured and additional segments were collected for histopathological analysis. PCR of matrix metalloproteinases (MMP9) was conducted. Groups were compared with paired t-tests, or ANOVA, where appropriate. RESULTS: Average percent growth of AD at POD 21 for treated segments was 27% versus 4.5% for control tissue. The average difference in AD by subject, was 26.7% (P<0.001). Aortic medial thickness was decreased in treated tissue; 235 µm versus 645 µm (P<0.0001). Quantities of both medial elastin fibers, and smooth muscles cells were decreased in treated tissue; 1.8% compared to 9.9% (P<0.0001), and 24% versus 37.4%, respectively. Tensile strength was also decreased in treated tissue; 16.7 MPa versus 29.5 MPa (P=0.0002). A 12-fold increase in expression of MMP9 mRNA was also demonstrated in aneurysmal tissue (P=0.002) CONCLUSION: A reproducible, large-animal model of AAA, with anatomical, histopathological, and biomechanical properties that are clinically translatable, can be achieved with extraluminal enzymatic degradation.

Heat load increases the risk of clinical mastitis in dairy cattle.

The study was aimed at assessing heat load-related risk of clinical mastitis (CM) in dairy cows. Records of CM for the years 2014 and 2015 were obtained from a large conventional dairy farm milking about 1,200 Holstein cows in central Italy. A case of CM was defined by the presence of clinical signs and veterinary confirmation. Quarter milk samples were collected and bacteriological investigated for each CM. Etiological agents were identified and classified as environmental or contagious pathogens. Hourly weather data from the nearest weather station were used to calculate heat load index (HLI). Upper and lower thresholds of HLI, at which the animal accumulates or dissipates heat, were settled and used to measure heat load balance through the accumulated heat load (AHL) model. Zero and positive values of AHL indicate periods of thermo-neutral and heat accumulation, respectively. Each case of CM was associated with HLI-AHL values recorded 5 d before the event. The risk of CM was evaluated using a case-crossover design. A conditional logistic regression model was used to calculate the odds ratio and 95% confidence intervals of CM recorded in thermo-neutral (AHL = 0) or heat load (AHL > 0) days, pooled or stratified for pathogen type (environmental or contagious). Classes of AHL as low (<6.5), medium (6.6-34.9), and high (>35) were included in the model. Other variables included in the model were milk yield as liters (<20, 20-30, and >30), days in milk (<60, 60-150, and >150), and parity (1, 2-3, and >3). A total of 1,086 CM cases were identified from 677 cows. Escherichia coli, Streptococcus spp., and Streptococcus uberis were the environmental pathogens isolated with the highest frequency; Staphylococcus aureus prevailed within contagious species. The analysis of pooled data indicated a significant effect of heat load on the occurrence of CM in the contagious pathogen stratum. Higher milk yield, middle and late stage of lactation, and older parity increased the risk of CM under heat load conditions. However, the association between pathogen type and these factors was not clear because the model provided significant odds ratios within all pathogen categories. The present study provided the first evidence of an association between HLI and CM in dairy cattle and suggested the ability of the AHL model to assess the risk of mastitis associated with heat load.

Body temperature of free-ranging koalas (Phascolarctos cinereus) in south-east Queensland.

The distribution of the koala (Phascolarctos cinereus) in Queensland is predicted to contract as a result of climate change, driven by the frequency, intensity and duration of heatwaves and drought. However, little is known about the physiological responses of this species to environmental extremes under field conditions. This study aimed to establish the efficacy of surgically implanted thermal radio transmitters and data loggers to measure the body temperature of free-ranging koalas across a range of environmental conditions and ambient temperatures. Five free-ranging koalas in southeast Queensland were implanted with thermal transmitters and data loggers waxed together as a single package. Body temperatures were recorded for variable periods ranging from 3 to 12 months. Diurnal rhythms in body temperature were detected irrespective of season. The long-term diurnal body temperature peak for all koalas occurred between 16:00 and 17:00 h and body temperature was 36.7-36.9 °C, the long-term nadir occurred between 07:00 and 08:00 h and body temperature was 35.4-35.7 °C. Koala body temperatures as low as 34.2 °C and as high as 39.0 °C were recorded. Thermolability became apparent when ambient temperatures were outside the deduced thermal neutral zone for koalas (14.5-24.5 °C): heat was accumulated during the day and dissipated during the cool of the night. While this study is the first to report on body temperature of free-ranging koalas in their normal behavioural context, further investigations are necessary to determine the physiological boundaries of the thermal niche for this species, in order to better equip models that will more accurately predict the impacts of climate change on koalas.

Evaluating rumen temperature as an estimate of core body temperature in Angus feedlot cattle during summer.

This study was conducted to determine the relationship between rectal temperature (TREC) and rumen temperature (TRUM) and to assess if TRUM could be used as a proxy measure of core body temperature (TCORE) in feedlot cattle. Eighty Angus steers (388.8 ± 2.1 kg) were orally administered with rumen temperature boluses. Rumen temperatures were recorded at 10-min intervals over 128 days from all 80 steers. To define the suitability of TRUM as an estimation of TCORE, TREC were obtained from all steers at 7-day intervals (n = 16). Eight feedlot pens were used where there were 10 steers per pen (162 m2). Shade was available in each pen (1.8 m2/animal; 90% solar block). Climatic data were recorded at 30-min intervals, including ambient temperature (TA; °C); relative humidity (RH; %); wind speed (WS; m/s) and direction; solar radiation (SR; W/m2); and black globe temperature (BGT; °C). Rainfall (mm) was recorded daily at 0900 h. From these data, temperature humidity index (THI), heat load index (HLI) and accumulated heat load (AHL) were calculated. Individual 10-min TRUM data were converted to an individual hourly average. Pooled mean hourly TRUM data from the 128-day data were used to establish the diurnal rhythm of TRUM where the mean minimum (39.19 ± 0.01 °C) and mean maximum (40.04 ± 0.01 °C) were observed at 0800 h and 2000 h respectively. A partial correlation coefficient indicated that there were moderate to strong relationships between TRUM and TREC using both real-time (r = 0.55; P < 0.001) and hourly mean (r = 0.51; P < 0.001) TRUM data. The mean difference between TREC and TRUM was small using both real-time (0.16 ± 0.02 °C) and hourly mean TRUM (0.13 ± 0.02 °C) data. Data from this study supports the hypothesis that TRUM can be used as an estimate of TCORE, suggesting that TRUM can be used to measure and quantify heat load in feedlot cattle.

A panting score index for sheep.

When exposed to hot conditions, heat dissipation via an increase in respiration rate (RR) is an important thermoregulatory mechanism for sheep. However, evaluating RR under field conditions is difficult. In cattle, a viable alternative has been to assess panting score (PS); therefore, the objective of this study was to evaluate the relationship between RR and PS to determine if a PS index can be used to evaluate heat load in sheep. One hundred and forty-four Merino wethers (44.02 ± 0.32 kg) were used within a climate-controlled study. The study was replicated twice over 29 days, where each replicate consisted of two treatments: (1) thermoneutral (TN) and (2) hot (HOT). Ambient temperature (TA) and relative humidity (RH) were maintained between 18 and 20 °C and 60 and 70% respectively for the TN treatment. For the HOT treatment, heat load increased steadily over the 29 days. Minimum TA was 22.5 °C and maximum was 38.5 °C, while RH decreased (60 to 30%) as TA increased in the HOT treatment. A comprehensive PS classification was developed by enhancing the current sheep PS index and aligning the descriptors with the current PS index utilized in beef cattle studies. Respiration rate and PS were obtained for each animal at 3-h intervals between 0800 h and 1700 h daily. These data were used to determine the mean RR for each PS, across the study and within the TN and HOT treatments. The relationship between PS and RR was evaluated using a Pearson's correlation coefficient. Data were also analyzed using a general linear model to determine the impact of PS, posture and animal identification (animal ID) on RR within each PS. Unsurprisingly, RR increased as PS increased, and PS, 0 and RR, 2.5 were 30.7 ± 0.59 and 246.8 ± 12.20 bpm respectively. There was a strong relationship between RR and PS (r = 0.71; P < 0.0001). As RR increased, sheep were more likely to be observed standing (P < 0.001). Mean PS of sheep within the HOT treatment (1.49 ± 0.02) were greater (P = 0.0085) when compared to the TN (1.17 ± 0.02) sheep. Individual animal ID accounted for approximately 7-37% of the variation observed for RR across PS, indicating that animal ID and climatic conditions were influencing RR and PS. These results suggest that the comprehensive PS index described here can be used as a visual appraisal of the heat load status of sheep.

Prediction models, assessment methodologies and biotechnological tools to quantify heat stress response in ruminant livestock.

Livestock industries have an important role in ensuring global food security. This review discusses the importance of quantifying the heat stress response of ruminants, with an emphasis on identifying thermo-tolerant breeds. There are numerous heat stress prediction models that have attempted to quantify the response of ruminant livestock to hot climatic conditions. This review highlights the importance of investigating prediction models beyond the temperature-humidity index (THI). Furthermore, this review highlights the importance of incorporating other climatic variables when developing prediction indices to ensure the accurate prediction of heat stress in ruminants. Prediction models, particularly the heat load index (HLI) were developed to overcome the limitations of the THI by incorporating ambient temperature (AT), relative humidity (RH), solar radiation (SR) and wind speed (WS). Furthermore refinements to existing prediction models have been undertaken to account for the interactions between climatic variables and physiological traits of livestock. Specifically, studies have investigated the relationships between coat characteristics, respiration rate (RR), body temperature (BT), sweating rate, vasodilation, body weight (BW), body condition score (BCS), fatness and feed intake with climatic conditions. While advancements in prediction models have been occurring, there has also been substantial advancement in the methodologies used to quantify animal responses to heat stress. The most recent development in this field is the application of radio frequency identification (RFID) technology to record animal behaviour and various physiological responses. Rumen temperature measurements using rumen boluses and skin temperature recording using infrared thermography (IRT) are making inroads to redefine the quantification of the heat stress response of ruminants. Further, this review describes several advanced biotechnological tools that can be used to identify climate resilient breeds of ruminant livestock.

Short communication: using infrared thermography as an in situ measure of core body temperature in lot-fed Angus steers.

Thirty-six Black Angus steers were used in a replicated study; three replicates of 12 steers/replicate. Steers had an initial non-fasted BW of 392.3 ± 5.1, 427.5 ± 6.3, and 392.7 ± 3.7 kg for each replicate, respectively. Steers were housed outside in individual animal pens (10 m × 3.4 m). Each replicate was conducted over a 6-day period where infrared thermography (IRT) images were collected at 3-h intervals, commencing at 0600 h on day 1 and concluding at 0600 h on day 6. Rumen temperatures (T RUM) were measured at 10-min intervals for the duration of each replicate using a radio-frequency identification (RFID) rumen bolus. These data were used to determine the relationship with surface temperature of the cattle, which was determined using IRT. Individual T RUM were converted to an hourly average. The relationship between T RUM and surface temperature was determined using Pearson's correlation coefficient. There were no linear trends between mean hourly T RUM and mean surface temperature. Pearson's correlation coefficient indicated that there were weak associations (r ≤ 0.1; P < 0.003) between T RUM and body surface temperature. These data suggest that there was little relationship between the surface temperature and T RUM.

Effect of heat stress on rumen temperature of three breeds of cattle.

Thirty-six steers (12 of each Angus, Charolais, and Brahman) with an initial BW of 318.5 ± 6.7 kg were used in a 130-day study. Two treatments were imposed: un-shaded and shaded (3 m2/animal; 90% solar block shade cloth). On day 1, steers were administered with rumen temperature boluses. Rumen temperatures (T RUM) were obtained at 10 min intervals over the duration of the study to determine differences in T RUM between Bos indicus and Bos taurus cattle. Six feedlot pens (162 m2) were used with six steers (2/breed) per pen with three pens/treatment. Ambient dry bulb temperature (T A; °C), relative humidity (RH; %), wind speed (WS; m/s) and direction, and solar radiation (SR; W/m2) were recorded at 10 min intervals. Rainfall (mm) was collected daily at 0900 h. From these data, black globe temperature (BGT; °C), temperature humidity index (THI), heat load index (HLI), and accumulated heat load (AHL) were calculated. Individual T RUM were converted to an hourly average and then mean hourly T RUM were converted to a mean within hour T RUM across the 130 days. Rumen temperatures were analyzed using an autoregressive repeated measures model. The model analyzed the effect of breed (P < 0.0002), treatment (P = 0.3543), time of day (hour, h; P < 0.0001), breed × treatment (P < 0.3683), breed × h (P < 0.0001), treatment × h (P < 0.0001), breed × treatment × h (P = 0.0029), pen within treatment (P = 0.0195), and animal × breed × treatment within pen (P = 0.1041). Furthermore, there were breed × treatment × hour differences in T RUM (P = 0.0036), indicating that Bos indicus and Bos taurus regulate T RUM differently.

Evaluation of the Walking Index for Spinal Cord Injury II (WISCI-II) in children with Spinal Cord Injury (SCI).

STUDY DESIGN: Mixed methods were used in this study. The appropriateness of the levels of the Walking Index for Spinal Cord Injury II (WISCI-II) for application in children was critically reviewed by physical therapists using the Modified Delphi Technique, and the inter- and intra-rater reliability of the WISCI-II in children was evaluated. OBJECTIVES: To examine the construct validity, and to establish reliability of the WISCI-II related to its use in children with spinal cord injury (SCI). SETTING: United States of America. METHODS: Using a Modified Delphi Technique, physical therapists critically reviewed the WISCI-II levels for pediatric utilization. Concurrently, ambulatory children under age 18 years with SCI were evaluated using the WISCI-II on two occasions by the same therapist to establish intra-rater reliability. One trial was photographed and de-identified. Each photograph was reviewed by four different physical therapists who gave WISCI-II scores to establish inter-rater reliability. Summary and descriptive statistics were used to calculate the frequency of yes/no responses for each WISCI-II level question and to determine the percent agreement for each question. Inter- and intra-rater reliability was calculated using interclass correlation coefficients (ICCs) with 95% confidence intervals (CI). RESULTS: Construct validity was confirmed after one Delphi round during which at least 80% agreement was established by 51 physical therapists on the appropriateness of the WISCI-II levels for children. Fifty-two children with SCI aged 2-17 years completed repeated WISCI-II assessments and 40 de-identified photographs were scored by four physical therapists. Intra- and inter-rater reliability was high (ICC=0.997, CI=0.995-0.998 and ICC=0.97, CI=0.95-0.98, respectively). CONCLUSION: This study demonstrates support for the use of the WISCI-II in ambulatory children with SCI. SPONSORSHIP: This study was funded by the Craig H Neilsen Foundation, Spinal Cord Injury Research on the Translation Spectrum, Senior Research Award #282592 (Mulcahey, PI).

Measurement of bovine body and scrotal temperature using implanted temperature sensitive radio transmitters, data loggers and infrared thermography.

Synchronous and continuous measurement of body (BT) and scrotal temperature (ST) without adverse welfare or behavioural interference is essential for understanding thermoregulation of the bull testis. This study compared three technologies for their efficacy for long-term measurement of the relationship between BT and ST by means of (1) temperature sensitive radio transmitters (RT), (2) data loggers (DL) and (3) infrared imaging (IRI). After an initial pilot study on two bulls to establish a surgical protocol, RTs and DLs were implanted into the flank and mid-scrotum of six Wagyu bulls for between 29 and 49 days. RT frequencies were scanned every 15 min, whilst DLs logged every 30 min. Infrared imaging of the body (flank) and scrotum of each bull was recorded hourly for one 24-h period and compared to RT and DL data. After a series of subsequent heat stress studies, bulls were castrated and testicular tissue samples processed for evidence of histopathology. Radio transmitters were less reliable than DLs; RTs lost >11 % of data, whilst 11 of the 12 DLs had 0 % data loss. IRI was only interpretable in 35.8 % of images recorded. Pearson correlations between DL and RT were strong for both BT (r > 0.94, P < 0.001) and ST (r > 0.80, P < 0.001). Surgery produced temporary minor inflammation and scrotal hematoma in two animals post-surgery. Whilst scar tissue was observed at all surgical sutured sites when bulls were castrated, there was no evidence of testicular adhesion and normal active spermatogenesis was observed in six of the eight implanted testicles. There was no significant correlation of IRI with either DL or RT. We conclude that DLs provided to be a reliable continuous source of data for synchronous measurement of BT and ST.

Thermoregulation of the bovine scrotum 1: measurements of free-range animals in a paddock and pen.

The bull's scrotum and scrotal cord vasculature has traditionally been regarded as a thermoregulatory device for maintaining optimal testicular temperature for normal spermatogenesis. This assumption has mostly been derived from discrete measurements using thermocouples with limited data correlating continuous scrotal temperature (ST) to body temperature (BT). From mid-summer to early autumn, four Wagyu bulls (9-18 months) were surgically implanted with two data loggers (DL) logging at 30 min intervals: one on the right hand side flank and the other was attached to the visceral vaginal tunic of the mid-testis. Bulls were firstly housed in a paddock (PK) for 13 days and then moved to individual pens (IP), again for 13 days. Repeated measures analysis modelled the long-term and diurnal trends in BT and ST. While both day and time of day (TOD) were significant effects for ST at both housing locations (P < 0.005), only TOD showed significance for BT at both locations (P < 0.0001). Significant effects were seen between bulls with ST (F = 167.2, P < 0.001) but not BT (F = 0.03, P = 0.863), suggestive of variation in individual bull thermoregulatory capacity. Dual peaks were observed in ST at 0500 and 2130 h when housed in PK but not IP, suggesting ST may be influenced by external stimuli such as postural or behavioural changes. Reporting concurrent and continuous BT and ST will allow further investigation into factors influencing bovine ST and should be useful in selecting bulls with high degrees of thermoregulation capacity.

Comparison of the impact of six heat-load management strategies on thermal responses and milk production of feed-pad and pasture fed dairy cows in a subtropical environment.

Exposure to hot environments affects milk yield (MY) and milk composition of pasture and feed-pad fed dairy cows in subtropical regions. This study was undertaken during summer to compare MY and physiology of cows exposed to six heat-load management treatments. Seventy-eight Holstein-Friesian cows were blocked by season of calving, parity, milk yield, BW, and milk protein (%) and milk fat (%) measured in 2 weeks prior to the start of the study. Within blocks, cows were randomly allocated to one of the following treatments: open-sided iron roofed day pen adjacent to dairy (CID) + sprinklers (SP); CID only; non-shaded pen adjacent to dairy + SP (NSD + SP); open-sided shade cloth roofed day pen adjacent to dairy (SCD); NSD + sprinkler (sprinkler on for 45 min at 1100 h if mean respiration rate >80 breaths per minute (NSD + WSP)); open-sided shade cloth roofed structure over feed bunk in paddock + 1 km walk to and from the dairy (SCP + WLK). Sprinklers for CID + SP and NSD + SP cycled 2 min on, 12 min off when ambient temperature >26°C. The highest milk yields were in the CID + SP and CID treatments (23.9 L cow-1 day-1), intermediate for NSD + SP, SCD and SCP + WLK (22.4 L cow-1 day-1), and lowest for NSD + WSP (21.3 L cow-1 day-1) (P < 0.05). The highest (P < 0.05) feed intakes occurred in the CID + SP and CID treatments while intake was lowest (P < 0.05) for NSD + WSP and SCP + WLK. Weather data were collected on site at 10-min intervals, and from these, THI was calculated. Nonlinear regression modelling of MY × THI and heat-load management treatment demonstrated that cows in CID + SP showed no decline in MY out to a THI break point value of 83.2, whereas the pooled MY of the other treatments declined when THI >80.7. A combination of iron roof shade plus water sprinkling throughout the day provided the most effective control of heat load.

Body temperature and respiratory dynamics in un-shaded beef cattle.

In this study body temperature (BT, °C) and panting score (PS, 0-4.5; where 0 = no panting/no stress and 4.5 = catastrophic stress) data were obtained from 30 Angus steers housed outside over 120 days Steers were implanted with a BT transmitter on day -31, BT was recorded at 30-min intervals to a data logger and downloaded each day to a database. The cattle were housed in ten outdoor un-shaded pens with an earthen floor, eight of which had a pen floor area of 144 m2 (three transmitter steers plus five non-transmitter steers; 18 m2/steer) and two had an area of 168 m2 (three transmitter steers and six non-transmitter steers; 18.7 m2/steer). Only data from the transmitter steers were used in this study. The PS of the steers was obtained daily (± 15 min) at 0600 hours (AM), 1200 hours (MD) and 1600 hours (PM). At the same times climate variables (ambient temperature, black globe temperature, solar radiation, relative humidity, wind speed and rainfall) were obtained from an on-site weather station. PS observations were made from outside the pens so as not to influence cattle responses. The two closest BT values to the time when PS was obtained were downloaded retrospectively from a logger and averaged. A total of 8,352 observations were used to generate second order polynomial response curves: (AM) y = 39.08 + 0.009 x + 0.137x2 (R2 = 0.94; P < 0.001) (MD) y = 39.09 + 0.914x − 0.080x2 (R2 = 0.89; P < 0.001) and (PM) y = 39.52 + 0.790x − 0.068x2 (R2 = 0.83; P < 0.001) where y = BT (°C) and x PS. These data suggest that PS is a good indicator of body temperature. The BT at MD corresponded to slightly lower PS compared with PM, e.g., for PS 1; BT at MD = 39.1 ± 0.05 °C whereas BT at PM = 39.5 ± 0.05 °C. However during AM, BT was lower (P < 0.05) at PS 1, 2 and 2.5 compared with MD and PM. For example, when PS was 2.5 the BT at AM was 40.2 ± 0.04 °C, at MD it was 40.9 ± 0.04 °C and at PM BT was 41.1 ± 0.04 °C. When PS was 0 the BT at AM and MD were similar. The AM response curve suggests animals attempt to increase heat dissipation during the cooler AM period relative to MD and PM. Morning observation of cattle (before feeding) are crucial for effective heat load management especially on days when high heat load is expected. The MD and PM observations provide a good indication of the impact of high environmental heat load on cattle. Differences in PS between AM and PM observations suggest that more research is needed to determine the effect of night time conditions on BT, PS and overall respiratory dynamics of cattle during periods of hot weather.