Ten foals were used to determine effects of handling during different ages on their ability to perform a halter training test. Early-handled (EH) foals (n = 5) were handled in 10 min sessions 5 days weekly from 24 h after birth until 42 days of age, then were not handled from 43 to 84 days of age, Later-handled (LH) foals (n = 5) were not handled from birth to 42 days of age, then were handled in 10-min sessions 5 days weekly from 43 to 84 days of age. At 85 days of age, each foal was subjected to a 10-min halter training test for 5 consecutive days, The test consisted of an unfamiliar handler placing a halter on each foal and attempting to make the foal walk forward for 20 m, Data recorded during each day of the halter training were duration of initial struggle, number of lunges into the air, time to first forward step, time to five consecutive forward steps, and time to travel 20 m, At the end of the 5 day halter training test, the handler assigned a subjective test rating score to each foal based on ease of training, Split-plot analysis indicated that EH foals took less time (P < 0.05) to take one step forward, five consecutive steps forward, and to travel 20 m than LH foals, One-way ANOVA indicated that EH foals had a lower (more desirable) test ratings than LH foals (P < 0.01). Results indicate that handling throughout the first 42 days of life increased foal performance on this halter training task compared to handling from 43 to 84 days of age. These results may imply the existence of a critical handling period during the first 42 days of age or a phenomenon similar to learned helplessness.

Twenty-three foals were used to determine if different amounts of handling between birth and weaning affected their later learning ability and manageability. Foals were assigned to one of three treatments: non-handled (NH) foals were not handled except for necessary maintenance procedures; intermediately handled (IH) foals were handled daily in two 10-min sessions for 7 days after birth and then not handled except for necessary maintenance procedures; extensively handled (EH) foals were handled daily for 7 days as were IH foals and then handled for 10 min once weekly until weaning. Foals were weaned at 120 +/- 10 days of age. On Days 1, 3, and 15 after weaning, foals were subjected to a one-trial learning test. The learning test consisted of placing the foal in a familiar pen with an apparatus of 1.5 m x 0.6 m containing 40 compartments of 15 cm X 15 cm. Number of visits to the apparatus and compartment visited were recorded for 5 min. A small amount of concentrate feed then was placed in a target compartment, and visits were recorded for an additional 5 min. On Day 16 after weaning, foals were subjected to a manageability test in which flight distance from an unfamiliar handler and reaction to a novel stimulus were recorded. Split-plot analysis of variance revealed no treatment differences in performance on the learning test (P>0.05). Foal performance on the test was improved on Day 15 compared with Day 1 or Day 3 (P<0.01). Analysis of variance indicated handling treatment had no effect (P>0.05) on foal performance during the manageability test. Results indicate that this preweaning handling regimen has no effect on foal learning ability or manageability as measured by these procedures.

Fourteen Arabian foals were used to determine if a one-trial appetitive conditioning task, developed for laboratory rats, could be adapted for use in equine learning research. The learning apparatus consisted of a 1.5 m × 0.6 m wooden grid containing 40 compartments. Seven foals received a complete learning test which consisted of placing a foal in a pen with the learning apparatus on one wall, recording the foal's behavior for 5 min and then placing a food reinforcer in a target compartment (TC). After location of the food, the foal's behavior was recorded for an additional 5 min. Total visits made to the apparatus and compartments visited by the foal were recorded. The remaining seven foals received a test in which no reinforcer was placed in the TC. These foals were re-tested the next day with reinforcement. After location of the food reinforcer, all foals exhibited more visits to the apparatus, visits to the TC, visits one compartment from the TC, and visits greater than one and less than or equal to two compartments from the TC (P<0.05). Mean distance of visits from the TC decreased after location of the reinforcer (P<0.05). Increased frequency of visits to the apparatus and concentration of visits around the TC after finding the reinforcer suggest that foals had learned the location of the reinforcer. Results suggest that a one-trial appetitive conditioning test may be applicable in equine learning research.

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.

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, log10 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.

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.

Thirty-six pastured mares, blocked by age and temperament, were assigned to one of three housing treatment groups: pasture (P); confinement stalls (C), allowing social contact; and isolation stalls (ISS), allowing no contact with conspecif- ics. Forty-eight hours post-placement on treatment, the mares were injected intmdermally with a solution of.1 mg phytohe- magglutinin-P (PHA) in .1 ml saline in one side of the neck. After 65 h on treatment, each mare was fitted with a jugular cannula from which a blood sample was drawn and analyzed for plasma concentrations of thyroid hormones and cortisol, complete blood cell counts, and differential leukocyte counts. Blood hemoglobin was elevated for ISS mares, and mean corpuscular hemoglobin content (MCHC) was depressed for ISS mares. Interactions (P<.001) indicated that older and younger, but not middle aged, as well as calm ISS mares had depressed mean corpuscular hemoglobin content. No differences were found (P>.10) in leukocyte counts, but trends were evident. The dermal response to PHA had a treatment by age interaction (P<.02) with older mares on treatment C and ISS having a higher response than P mares. After 1 h, a second blood sample was drawn and 1.02 IU ACTH/kg.75 was administered via the jugular cannula. Plasma cortisol concentrations from blood samples drawn 20, 40, 60, 80, 100, 120,150, 180, and 210 min post ACTH administration were then integrated to determine adrenal function (AF). No differences in AF were found (P<.52). No differences were seen for concentrations of thyroxine (T4) and triiodothyronine (T3), although for C and ISS mares the concentrations of these hormones were higher than the normal values reported in the literature. Concentrations of 3, 3, 5'triiodothyronine (rT3) were higher in ISS mares than in C and P mares. Physiological data suggest that C and ISS mares exhibited evidence of a mild stress reaction with increasing c0nfmement and isolation.