J.R. Webster

Eye temperature and heart rate variability of calves disbudded with or without local anaesthetic.

The possibility that pain can be detected from changes in eye temperature and heart rate variability (HRV) during disbudding was examined in thirty calves, randomly assigned to four treatments: 1) sham handling (control), 2) local anaesthetic (LA, cornual nerve injection) and sham disbudded, 3) sham LA and disbudded, 4) LA and disbudded. During a 40 min sampling period, maximum eye temperature, behavior and HRV parameters were recorded continuously. One week later, twelve disbudded calves were injected with adrenocorticotrophic hormone (ACTH) or saline and maximum eye temperature was recorded. There was a rapid drop in eye temperature during the 5 min following disbudding without LA (P<0.05). Eye temperature then increased and was higher than baseline over the remaining sampling period following both disbudding procedures (P<0.001), a response which could not be explained by increased physical activity LA increased eye temperature prior to disbudding (P<0.001). Heart rate increased (P<0.001) during the 5 min following disbudding with and without LA, however, LF/HF ratio only increased during this time (P<0.01) following disbudding without LA. Eye temperature did not change following ACTH, suggesting that hypothalamus-pituitary-adrenal axis (HPA) activity is not responsible for the changes in eye temperature following disbudding. The increase in LF/HF ratio following disbudding without LA suggests an acute sympathetic response to pain, which could be responsible for the drop in eye temperature via vasoconstriction. HRV and eye temperature together may be a useful non-invasive and more immediate index of pain than HPA activity alone.

Non-invasive measurement of stress in dairy cows using infrared thermography

The possibility that changes in eye temperature, measured using infrared thermography (IRT), can detect stress in dairy cattle was examined by six different stimulations of the stress axis. Six cows were given six treatments in a random Latin-square design: 1) Control (saline) 2) ACTH (0.05 mg Synacthen) 3) bCRH (20 mug) 4) bCRH (40 mug) 5) epinephrine (1.4 mug /kg liveweight) and 6) social isolation. Treatments were administered at time 0 and blood samples were taken at -30, -15, 0, 5, 10, 15, 20, 30, 40, 50, 60, 75, 90, 120, 180 and 240 min except for epinephrine which was sampled at -30, -15, -10, -5, 0, 2, 5, 10, 15, 20, 30, 45, 60, 90 and 120 min. Core body temperature was recorded every 10 min and eye images collected every 2 min. Eye temperature and cortisol increased following catheterization (P<0.05). ACTH increased following bCRH, cortisol increased following ACTH and bCRH (P<0.001) and NEFA increased following epinephrine (P<0.001). Core body temperature was unaffected by treatments. Eye temperature was unaffected by CRH and epinephrine but was higher 30 and 60 min following control and ACTH (P<0.001). Our results provide evidence that exogenous HPA stimulation does not increase eye temperature. The increases in eye temperature following catheterization however raise the possibility that a cognitive component may be required for an eye temperature response to occur.

Noninvasive assessment of autonomic activity for evaluation of pain in calves, using surgical castration as a model

The role of the autonomic nervous system (ANS) in mediating eye temperature responses during painful procedures was examined in thirty 4-mo-old bull calves randomly assigned to 4 treatments: 1) sham handling control (C; n=8), 2) surgical castration (SC; n=6), 3) local anesthesia with sham handling (LAC; n=8), and 4) local anesthesia with surgical castration (LASC; n=8). Maximum eye temperature ( degrees C), measured by infrared thermography, heart rate (HR), and heart rate variability (HRV) were recorded continuously from 25 min before to 20 min after castration. The HRV was analyzed by examining segments of 512 interbeat intervals before and after treatments and comparing the root mean square of successive differences (RMSSD), high and low frequency (HF and LF, respectively) power, and the ratio of LF and HF powers (LF:HF). Jugular blood samples were analyzed for norepinephrine and epinephrine in C and SC treatments and for cortisol during all treatments. There was an immediate increase in HR following castration in SC (+15.3+/-2.8 beats/min) and LASC (+6.3+/-2.4 beats/min) calves. Eye temperature increased during the 20-min observation period in SC and LASC calves (+0.47+/-0.05 degrees C and +0.28+/-0.05 degrees C, respectively), and there was a small increase in C calves (+0.10+/-0.05 degrees C). Following castration in SC calves, there was an increase in RMSSD (+25.8+/-6.4) and HF power (+11.0+/-6.5) and LF:HF decreased (-2.1+/-0.7). Following castration in LASC, there was an increase in RMSSD (+18.1+/-4.9) and a decrease in LF power (-10.2+/-5.0). Cortisol increased above baseline within 15 min following treatment in both castrated groups, but was greater for SC calves (+18.4+/-2.3 ng/mL) than for LASC calves (+11.1+/-1.9 ng/mL). After castration, norepinephrine increased 3-fold and epinephrine increased by half in SC calves but not in C calves. There were no changes in HR, HRV, or cortisol responses to C or LAC treatments. Local anesthetic reduced, but did not eliminate, responses to surgical castration. The synchronized increase in catecholamine and HR responses immediately following SC treatment suggests the initial response was mediated by the sympathetic branch of the ANS. The subsequent changes in RMSSD, HF power, and LF:HF ratio indicated this was followed by an increase in parasympathetic activity. The use of HR, HRV, and infrared thermography measurements together provide a noninvasive means to assess ANS responses as indicators of acute pain in cattle.

Dairy cattle prefer shade over sprinklers: Effects on behavior and physiology

Cattle will readily use shade in warm weather, but less is known about voluntary use of sprinklers. We examined preferences of 96 Holstein-Friesian dairy cows (milk yield: 12.7±3.48 kg per day; mean±SD) for sprinklers, shade, or ambient conditions after walking 2.0 km or 0.3 km before afternoon milking (n=48 cows/distance). Each cow was individually tested on 3 consecutive days with a different paired choice each day: 1) shade or sprinklers, 2) shade or ambient conditions, 3) sprinklers or ambient conditions. Average air temperature during testing was 22.3°C. Cows preferred shade over sprinklers (62 vs. 38% ± 5.0%; mean ± SE) and shade over ambient conditions (65 vs. 35% ± 5.1%; mean±SE). Cows showed no preference between sprinklers and ambient conditions (44% of the cows chose sprinklers, SE=5.3%). The preference for shade over sprinklers and ambient conditions increased with air temperature, solar radiation, and wind speed. Walking distance did not influence the preference for any treatment. Respiration rate was decreased most by sprinklers (38% decrease) but also decreased in shade and ambient conditions (17 and 13% decrease, respectively; standard error of the difference=4.7%). Similarly, surface temperature was decreased most by sprinklers (11.4% decrease), compared with that by shade (1.0% decrease), or that by ambient conditions (1.4% increase; standard error of the difference=1.82%). Furthermore, sprinklers reduced insect avoidance behaviors, including number of tail flicks and hoof stamps. In conclusion, dairy cattle preferred to use shade in summer despite sprinklers being more efficient in decreasing heat load and insect avoidance behavior.

Body condition score at calving affects systemic and hepatic transcriptome indicators of inflammation and nutrient metabolism in grazing dairy cows.

Calving body condition score (BCS) is an important determinant of early-lactation dry matter intake, milk yield, and disease incidence. The current study investigated the metabolic and molecular changes induced by the change in BCS. A group of cows of mixed age and breed were managed from the second half of the previous lactation to achieve mean group BCS (10-point scale) that were high (HBCS, 5.5; n=20), medium (MBCS, 4.5; n=18), or low (LBCS, 3.5; n=19). Blood was sampled at wk -4, -3, -2, 1, 3, 5, and 6 relative to parturition to measure biomarkers of energy balance, inflammation, and liver function. Liver was biopsied on wk 1, 3, and 5 relative to parturition, and 10 cows per BCS group were used for transcript profiling via quantitative PCR. Cows in HBCS and MBCS produced more milk and had greater concentrations of nonesterified fatty acids and β-hydroxybutyrate postpartum than LBCS. Peak concentrations of nonesterified fatty acids and β-hydroxybutyrate and greater hepatic triacylglycerol concentrations were recorded in HBCS at wk 3. Consistent with blood biomarkers, HBCS and MBCS had greater expression of genes associated with fatty acid oxidation (CPT1A, ACOX1), ketogenesis (HMGCS2), and hepatokines (FGF21, ANGPTL4), whereas HBCS had the lowest expression of APOB (lipoprotein transport). Greater expression during early lactation of BBOX1 in MBCS and LBCS suggested greater de novo carnitine synthesis. The greater BCS was associated with lower expression of growth hormone/insulin-like growth factor-1 signaling axis genes (GHR1A, IGF1, and IGFALS) and greater expression of gluconeogenic genes. These likely contributed to the higher milk production and greater gluconeogenesis. Despite greater serum haptoglobin around calving, cows in HBCS and MBCS had greater blood albumin. Cows in MBCS, however, had a higher albumin:globulin ratio, probably indicating a less pronounced inflammatory status and better liver function. The marked decrease in expression of NFKB1, STAT3, HP, and SAA3 coupled with the increase in ALB on wk 3 in MBCS cows were consistent with blood measures. Overall, results suggest that the greater milk production of cows with higher calving BCS is associated with a proinflammatory response without negatively affecting expression of genes related to metabolism and the growth hormone/insulin-like growth factor-1 axis. Results highlight the sensitivity of indicators of metabolic health and inflammatory state to subtle changes in calving BCS and, collectively, indicate a suboptimal health status in cows calving at either BCS 3.5 or 5.5 relative to BCS 4.5.

Calving body condition score affects indicators of health in grazing dairy cows

The objectives of this study were to determine the effect of calving body condition score (BCS) on cow health during the transition period in a pasture-based dairying system. Feed inputs were managed during the second half of the previous lactation so that BCS differed at drying off (BCS 5.0, 4.0, and 3.0 for high, medium, and low treatments, respectively: a 10-point scale); feed allowance was managed after cows were dried off, such that the BCS differences established during lactation remained at the subsequent calving (BCS 5.5, 4.5, and 3.5; n=20, 18, and 19, for high, medium, and low treatments, respectively). After calving, cows were allocated pasture and pasture silage to ensure grazing residuals >1,600 kg of DM/ha. Milk production was measured weekly; blood was sampled regularly pre- and postpartum to measure indicators of health, and udder and uterine health were evaluated during the 6 wk after calving. Milk weight, fat, protein, and lactose yields, and fat content increased with calving BCS during the first 6 wk of lactation. The effect of calving BCS on the metabolic profile was nonlinear. Before calving, cows in the low group had lower mean plasma β-hydroxybutyrate and serum Mg concentrations and greater mean serum urea than cows in the medium and high BCS groups, which did not differ from each other. During the 6 wk after calving, cows in the low group had lower serum albumin and fructosamine concentrations than cows in the other 2 treatment groups, whereas cows in the low- and medium-BCS groups had proportionately more polymorphonucleated cells in their uterine secretions at 3 and 5 wk postpartum than high-BCS cows. In comparison, plasma β-hydroxybutyrate and nonesterified fatty acid concentrations increased linearly in early lactation with calving BCS, consistent with a greater negative energy balance in these cows. Many of the parameters measured did not vary with BCS. The results highlight that calving BCS and, therefore, BCS through early lactation are not effective indicators of functional welfare, with the analyses presented indicating that both low and high BCS at calving will increase the risk of disease: cows in the low group were more prone to reproductive compromise and fatter cows had an increased risk of metabolic diseases. These results are important in defining the welfare consequences of cow BCS.

Effect of milking frequency and feeding level before and after dry off on dairy cattle behavior and udder characteristics.

The effects of 2 common dry-off management procedures, feed restriction [8 vs. 16 kg of dry matter (DM)/d] and reduced milking frequency (once, 1x vs. twice, 2x/d), on the behavior and udder characteristics of dairy cattle were assessed in late lactation and the early dry period. Milking cows 1x instead of 2x in the week before dry off reduced milk yield (7.0 vs. 8.9 +/- 0.95 kg/d for 1x and 2x, respectively), but had little effect on behavior before or after cessation of milking. In comparison, feed restriction reduced milk yield (6.9 vs. 9.1 +/- 0.95 kg/d for 8 and 16 kg of DM/d, respectively), udder firmness after dry off (7.3 vs. 8.0 +/- 0.24 g force for 8 and 16 kg of DM/d, respectively), milk leakage (2 d after dry off, 14% of cows offered 8 kg of DM/d were leaking milk compared with 42% cows offered 16 kg of DM/d), and the likelihood of Streptococcus uberis intramammary infection (nonclinical mastitis; 12.5 vs. 62.5% of groups with at least 1 cow with a new intramammary infection for 8 and 16 kg of DM/d, respectively). Despite these benefits, cows offered only 8 kg of DM/d spent less time eating (7.3 vs. 8.3 +/- 0.28 h/d for 8 and 16 kg DM/d, respectively), more time lying (8.8 vs. 7.3 +/- 0.24 h/d), and vocalized more before dry off than cows offered 16 kg of DM/d (0.8 vs. 0.2 +/- 0.15 calls/min for 8 and 16 kg of DM/d, respectively). These behavioral changes indicate that this level of feed restriction may cause hunger. Information is needed about alternative dry-off procedures that maintain the health benefits and comfort associated with lower milk yield before dry off but prevent hunger, such as feeding low quality diets ad libitum.

Quantification of temperament in weaned deer calves of two genotypes (Cervus elaphus and Cervus elaphus × Elaphurus davidianus hybrids)

Two experiments were carried out on farmed deer calves at weaning (at 3–4 months of age) to compare individual temperament. In Experiment 1, 30 male red deer calves were confined indoors in groups of 15. On Days 1–27 following weaning they were subjected to the following tests: time taken to feed in the presence of a human (n=15 trials); time taken to sniff a novel object (n=5 trials); drafting order (n=8 trials); aggression during feeding (n=3 trials); isolation in a novel pen with and without a human; individual confinement (n=5 trials). Individual rangkings within groups within the same type of test revealed some consistency in individual behaviour. Principal components analysis indicated behavioural variability in fear of humans and exploratory behaviour. In Experiment 2, 22 red deer×Pere David deer and 34 red deer calves were tested in pairs of the same genotype, on either Day 1 or Day 2 after weaning. Each pair was confined for 20 min in an unfamiliar pen, with a stationary human in the pen during the last 10 min of the test. Hybrid calves showed a tendency to avoid the human more and to be less active in the presence of the human compared with red deer calves. This tendency was significant for nosing activities directed at the walls and floor of the pen (P<0.05). Principal components analysis indicated that the genotypes differed most in their nosing frequency and mobility within the pen, with hybrid calves nosing less than red deer at the same level of mobility. Thus both experiments indicated variability in the degree to which deer calves avoided humans and exhibited exploratory behaviour in new surroundings.

Technical note: Effects of an epinephrine infusion on eye temperature and heart rate variability in bull calves

Changes in autonomic nervous system (ANS) activity are one of the first phases of a stress response, but they are rarely used to assess the welfare of farm animals. Eye temperature measured using infrared thermography (IRT) is proposed as an indicator of ANS activity because it may reflect changes in blood flow in the capillary beds of the conjunctiva. The aim was to determine whether epinephrine infusion would initiate eye temperature changes in calves. Sixteen 4-mo-old Friesian calves (124±5 kg) were assigned randomly to receive a jugular infusion of either epinephrine (4 μg/kg per min for 5 min) or saline. Eye temperature (°C), heart rate (HR), and HR variability (HRV) were recorded from 15 min before infusion until 10 min after it was completed. Blood samples collected via jugular catheter were assayed for epinephrine, norepinephrine, and cortisol concentrations, and packed cell volume (PCV) was measured. No changes in any variable were observed with the saline infusion. Plasma epinephrine concentrations increased 90-fold with epinephrine infusion, which was associated with a decrease in eye temperature of 1.4±0.05°C. During epinephrine infusion, plasma norepinephrine concentrations decreased by half and HR decreased by 9.3±3.3 beats/min. The HRV measure, the root mean square of successive differences, increased by 49.7±9.2 ms, indicating a compensatory increase in parasympathetic activity. After epinephrine infusion, plasma cortisol concentrations increased by 10.4±1.7 ng/mL and PCV was higher (38 vs. 31±0.1%, epinephrine vs. saline, respectively). These results support the hypothesis that changes in eye temperature are mediated by the sympathetic component of the ANS. Infrared thermography is a noninvasive method to assess ANS activity for evaluating welfare of cattle.

Effects of melatonin implants on insulin-like growth factor 1 in male red deer (Cervus elaphus)

Red deer stags have a seasonal pattern of growth, alternating between periods of summer weight gain and winter weight loss that are influenced by photoperiod and by exogenous melatonin. A seasonal pattern of plasma insulin-like growth factor 1, also influenced by photoperiod, underlies the seasonal growth pattern. The present studies aimed to determine the influence of exogenous melatonin, administered at various times of the year, on plasma IGF1 in adult red deer stags in New Zealand at 45 degrees S. In one study, 7-year-old stags (N = 9) were allocated to one of three treatment groups, either control or subcutaneous melatonin (3 x 18-mg coated implants (Regulin) per month) from November to February or from December to February. Blood was sampled, the stags were weighed, and antler status was recorded over 17 months. Melatonin treatment advanced the seasonal patterns of rise and fall of plasma IGF1 and of weight gain and loss. The cessation of melatonin treatment in February produced early antler casting and a second (out-of-season) antler and increased IGF1. In a second study, 4-year-old stags (N = 30) were allocated to one of six treatment groups as follows: three melatonin implants per months for 6 consecutive months beginning on 22 June, i.e., winter solstice, 4 August, 16 September, and 23 October; three melatonin implants per month for 12 months beginning on 22 June; and an untreated group. All animals were sampled as before for 12 months. Melatonin treatment beginning in July and August did not prevent the seasonal peak in IGF1, but the amplitude was lowered and antler casting delayed.