Donald C. Lay

Effects of freeze or hot-iron branding of Angus calves on some physiological and behavioral indicators of stress

Twenty-four Angus calves averaging 293 ± 38 kg were either hot-iron branded (H), freeze branded (F), or served as a sham (S). Calves were blocked for temperament, weight, and sex, and randomly assigned to day and order in which treatments were applied. To reduce stress from handling at treatment time, each calf was herded through the squeeze chute for 5 days prior to the experiment. Jugular cannulae were established in each calf 1 day prior to application of treatment. Blood samples and heart rate were obtained at −5 and −3 min prior to and 0, 0.5, 1, 3, 5, 10, 15 and 20 min after calves were branded on the hip. Mean plasma cortisol concentration increased for all treatments during the sampling times (P = 0.0001). Mean plasma epinephrine concentration was greater (P < 0.01) for H calves at 0.5 min after branding than either S or F calves. Hot-iron branded calves had greater (P < 0.02) mean heart rate during branding and 30 s post-branding than did either S or F calves. The escape-avoidance reaction of H calves, quantified as the amount of vertical movement the calf exhibited during branding, was also greater (P < 0.05) than either the F or S calves. Five H calves, four F calves, and no S calves vocalized during treatment. The greater escape-avoidance reaction as well as the elevated heart rate and plasma epinephrine concentration of the H calves indicate that a greater pain sensation is perceived by hot-iron branded Angus cattle.

Behavioral responses of mares to short-term confinement and social isolation

Thirty-six mares, blocked by age and temperament score, were assigned to one of three treatment groups: pasture (P); confinement stalls (C), allowing social contact; isolation stalls (ISS), allowing no contact with conspecifics. After 48 h on treatment, the mares were observed in situ for 1 h. Medium temperament and highly reactive ISS mares spent more time eating grain (P<0.01) and exhibited more grain-eating bouts (P<0.03) than P and C mares. Calm P mares had longer forage-eating bouts than C and ISS mares (P<0.02). During a 15 min open-field test in a 23 m × 23 m pen after 72 h on treatment, ISS mares traveled farther (P<0.005) than C and P mares, spent more total time trotting (P<0.01) than C and P mares, and exhibited a greater number of trotting bouts (P<0.01) than both C and P mares. Isolated mares spent less total time standing during the open-field test than C (P<0.05) and P (P<0.01) mares, but exhibited a greater number of standing bouts than C (P<0.05) and P (P<0.01) mares. Isolated mares also exhibited a greater number of total activity bouts (P<0.01) during the open-field test than both C and P mares; P mares also exhibited fewer activity bouts than C mares (P<0.1). Results indicate that mares kept in confined and isolated environments showed greater motivation for movement and performance of a greater number of activities than those maintained on pasture with conspecifics.

Effects of restricted nursing on physiological and behavioral reactions of Brahman calves to subsequent restraint and weaning1

The influence of restricted nursing on physiological and behavioral reactions to later restraint and weaning was examined in Brahman (Bos indicus) calves. The calves were blocked for sex and randomly assigned at birth to one of two treatments: restricted nurse (RN), or ad libitum nurse (ALN). The RN calves were separated from their dams at 21 days of age and allowed to nurse once daily (2-h duration) for 19±3 days. The ALN calves remained with their dams from birth until weaning. The ALN calves were brought in and worked through handling facilities for the same amount of time each day as the RN calves. At 192±4 days of age each calf was restrained while blood samples (5) were taken and heart rate monitored via telemetry. Two weeks later, the calves were weaned and blood samples and behavioral observations were taken. Mean plasma cortisol concentration (MC) increased over time for both treatments (P<0.004) in response to restraint, but was greater for RN than for ALN calves after 15 min of restraint (P<0.03). In response to restraint, RN calves had overall greater heart rates than did ALN calves (P<0.02). In response to weaning, ALN calves tended to travel more (P<0.07), and included more calves who ate (P<0.05), and vocalized (P<0.05). The effects of the restricted nursing regimen, which inherently includes handling, appears to alter the calfs later response to restraint and weaning. However, due to the lack of a uniform response further research is required to determine the meaning of and causal factors for this alteration.

Confinement of lambs ( Ovis aries) in metabolism stalls increased adrenal function, thyroxine and motivation for movement*

Eighteen, 8-week-old Rambouillet wether lambs were habituated to human contact for 2 months prior to data collection. The lambs were maintained in a paddock prior to being placed in individual 41 cm × 95 cm metabolism stalls for 9 days. Blood samples were taken via jugular cannulae 7 days prior to, and after 2 and 9 days of confinement. After two basal blood samples were drawn, 1 iu kg−1 adrenocorticotrophic hormone (ACTH) was administered to each lamb via the cannulae and serial blood samples were drawn over the next 3 h. A 5-min open-field test was conducted the day before the lambs were placed in stalls and again after Day 9, following the last blood sampling. Response to ACTH, measured as the integrated cortisol concentrations, was greater when the lambs were housed in stalls than maintained in the paddock (P < 0.01). Confinement did not affect plasma concentrations of triiodothyronine (P < 0.37), but lambs in stalls had higher concentrations of thyroxine after 2 and 9 days than when on pasture (P < 0.001). Lambs traveled further during the open-field tests, after 9 days in the metabolism stalls, than they did before confinement (P < 0.001). These results indicate that lambs maintained in metabolism stalls can be physiologically and behaviorally altered. Such alterations may affect the applicability of certain types of data derived from these lambs compared with lambs in more extensive housing situations.

Novel breeding box has variable effects on heart rate and cortisol response of cattle

In seven experiments, cattle of different sex classes (bulls, steers, and cows), age (2–10 years), and breed (Augus, Hereford, and Braford) were subjected, one at a time, to restraint by a standard squeeze chute (cattle crush) or a novel ‘breeding box’ in order to compare each methods effects on heart rate and cortisol. The breeding box held two cattle in adjacent stalls and was covered with plywood to limit outside disturbances and light. The cattle were held in either the squeeze chute or the breeding box for 3 min while five heart rate samples were recorded at 0.5, 1, 1.5, 2, and 2.5 min after entering the treatment; in four of the experiments, one tail vein blood sample was taken at 3 min for plasma cortisol analysis. In one of the experiments, heart rate responses were greater for the chute restrained cows than for the cows restrained in the breeding box (P<0.04). In a second experiment, cortisol response was also greater (P<0.03) for the chute restrained cows than for the cows restrained in the breeding box. No differences were found for cortisol and heart rate responses in the other five experiments. Because breed, sex, and age were consistent between four of the experiments, data were combined and the results indicate that mean plasma cortisol concentrations were greater for the squeeze chute treatment than for the breeding box (P<0.01), but no differences were found for heart rate. Angus cattle tended to have greater mean plasma cortisol concentrations than Hereford cattle for the combined experiments (P<0.07). The Angus cattle also had greater heart rates than the Hereford cattle in one experiment (P<0.05). The results from this research indicate that restraining cattle in a breeding box that was novel to them was as stressful as being restrained in a squeeze chute in which they had been subjected to routine production procedures. The stress resulting from being restrained in a novel breeding box when cattle are artificially bred may contribute to the variable conception rates reported by ranchers.

The effect of naloxone on nursing behavior in Brahman calves

Abstract The influence of subcutaneous injections of naloxone on nursing behavior of Brahman calves was determined in three experiments. In Experiment I, 30 calves averaging 194 days of age received either 1.5 mg kg −1 body weight (BW) naloxone, 3 mg kg −1 BW naloxone, or saline. Following a 2 h separation, dams and calves were observed for 15 min. Although no treatment effects were found for time spent nursing ( P =0.25), the means suggested a trend for naloxone-treated calves to nurse less than the saline-treated calves: saline, 8.13 min; 1.5 mg kg −1 , 4.95 min; 3 mg kg −1 , 4.28 min. In Experiment II, 24 calves, averaging 83 days of age, received either 3 mg kg −1 BW naloxone or saline. During the 15 min observation period following a 2 h separation, as in Experiment I. No treatment effects were found ( P =0.41); but trends for means were indicated: saline, 6.78 min; 3 mg kg −1 , 4.97 min. In Experiment III, 18 calves received either 1 mg kg −1 BW naloxone, 2 mg kg −1 BW naloxone, or saline immediately after birth. Observations conducted for 8 h postpartum revealed no treatment effects for latency to nurse ( P =0.33, log 10 transformation), but again means suggested a trend: saline, 145 min; 1 mg kg −1 , 247 min; 2 mg kg −1 , 331 min. Naloxone does not appear to break social bonds between dam and calf and therefore it would not be useful in reducing weaning stress.

Evaluation of a commercial stencil/aerosol — Coolant technique for freeze branding horses

SUMMARY A study was conducted to evaluate a commercial stencil/aerosol-coolant freeze branding technique for horses. Forty five (45) mares were branded with one of five treatments to determine which combination of pre-treatment application of alcohol on the brand site, number of coolant spray applications or drying methods produced the most acceptable brands. Reactions indicative of pain were quantitated for all treatments. Kit equipment and recommended procedures were evaluated. Non-alcohol pre-treated digits tended to be more acceptable than alcohol pretreated digits (P .20), number of applications (P >.10) or drying method (P >.12). The stencil/aerosol-coolant technique is safe and convenient, but at least three applications of spray are necessary to produce acceptable brands.