Biomedical subjects

D C Lay

Publications and source records attributed to D C Lay.

10 recordsLinked to original sources

PubMed2000

Few differences found between early- and late-weaned pigs raised in the same environment.

Segregation and medicated early weaning are technologies used to optimize the productivity and health of pigs, but these practices may also cause aberrant behaviors indicative of stress. Thus, differences in early- (=10 d of age) and late- (=30 d of age) weaned pigs were investigated. At weaning, pigs were housed in groups of four in 16 pens (eight pens per treatment) in the same facility, and, thus, they were not segregated. Body weights were recorded at birth, weaning, and at approximately 42, 65, 102, 137, and 165 d of age (at slaughter). One-minute, instantaneous scan samples during a 10-min period (at 0600, 1000, 1400, and 1800) were used to record the frequency of lying, standing, and sitting, total number of drinks, feeder investigations, and time spent playing/fighting on 2, 3, and 4 d after weaning. Five-minute, direct observations of each pig were conducted at approximately 40, 60, 80, and 150 d of age. Direct observations were also made of the entire pen for 10 min at approximately 50, 95, 123, and 160 d of age to record aberrant behaviors. At 62 d of age, a handling and blood collection stress was imposed. At 165 d of age, a second stress test was conducted in response to rough handling and transport. Early-weaned pigs spent more time playing/ fighting (P < .006) than late-weaned pigs during the 4 d after weaning, manipulated conspecifics more often at 40 d of age (P < .002), had greater percentage of hemoglobin (P < .03) during Stress Test 1, had greater ADG at 42 d of age (P < .03), and had greater hypothalamic growth hormone-releasing hormone receptor mRNA at slaughter (P < .06). Late-weaned pigs had greater ADG between 137 and 165 d of age (P < .03) and greater pro-opiomelanocortin at slaughter (P < .04). Overall, most differences found between early-weaned and late-weaned pigs were evident soon after weaning, but they disappeared before slaughter.

Animals↗

PubMed2000

Administration of ACTH to restrained, pregnant sows alters their pigs' hypothalamic-pituitary-adrenal (HPA) axis.

This study was designed to examine the physiology and behavior of pigs whose dams were snared and then injected with ACTH during gestation. Administration of ACTH to dams during pregnancy has been shown to replicate the effects of prenatal stress in other species. Control sows (n = 8) were given no treatment, whereas the treatment sows (ACTH, n = 8) were immobilized by snaring the snout and then administered an i.v. injection of ACTH (1 IU/kg BW) weekly from 6 to 12 wk of gestation. A pig was killed from each sow at 1, 30, and 60 d of age. The hypothalamus, pituitary gland, adrenal glands, and liver were immediately obtained to determine the amounts of corticotropin-releasing hormone (CRH), beta-endorphin, and mRNA for pro-opiomelanocorticotropin (POMC), the ACTH receptor (ACTH-R), and insulin-like growth factor I (IGF-I). Pituitary corticotrope and somatotrope cell numbers and adrenal cortex-to-medulla area ratios (CORT:MED) were also determined. Pigs' behaviors were recorded at 6 and 8 wk of age. At 75 d of age, a blood sample was taken and a biopsy puncture was created on one pig from each litter, then pigs were stressed by mixing. Blood was sampled every other day for 10 d to determine plasma cortisol concentrations and differential leukocyte counts. Biopsy damage was evaluated for healing. At 1 d of age, control pigs tended to weigh more (P = .09), have a lower expression of ACTH-R mRNA (P = .01) and IGF-I mRNA (P = .01), and a lower CORT:MED (P = .04) than ACTH pigs. At 30 d of age, control pigs had a greater concentration of beta-endorphin (P = .01) and tended to have a lower concentration of CRH (P = .09) and IGF-I mRNA (P = .10) than ACTH pigs. At 60 d of age, control pigs tended to have lighter pituitary glands (P = .08), a lower expression of POMC mRNA (P = .02), and a CORT:MED (P = .003) than ACTH pigs. At 8 wk of age, control pigs performed a higher frequency of belly nosing (P = .07) and oral vice behaviors (P = .01) than ACTH pigs. In response to mixing stress, control pigs had lesser concentrations of plasma cortisol (P = .03) and healed faster (P = .006) than ACTH pigs. Thus, exogenous ACTH and restraint during gestation alters the HPA axis of the sow's offspring, and during stressful situations later in life health, and therefore welfare, may be compromised.

Adrenal Glands↗

PubMed1999

Butorphanol tartrate acts to decrease sow activity, which could lead to reduced pig crushing.

The objective of this study was to determine whether administration of an analgesic to sows immediately after farrowing would allow them to lie more restfully. Sows lying on their pigs, causing them to be "crushed," is a major cause of pig mortality. Most deaths due to crushing occur during the first 3 d postpartum. For modern, lean-type sows, farrowing crates are relatively hard and unforgiving, even though they may be equipped with plastic-coated, expanded metal flooring. Indeed, many sows develop pressure sores on their shoulders, and this may contribute to the sows' discomfort. These sores may cause a sow to change position frequently to alleviate pain, thus increasing its chances of crushing pigs. Sixteen production sows were assigned to either a control group (C, n = 8) with litter size 11.71+/-.78 or an experimental group (B, n = 8) with litter size 11.63+/-1.22. Pigs born to C and B sows weighed 1.60+/-.04 and 1.37+/-.04 kg, respectively. The C sows were given no treatment, whereas the B sows were administered an i.m. injection of butorphanol tartrate at a dose of .15 mg/kg BW every 6 h until 3 d after farrowing. Data were collected on all sows using time-lapse photography (1 frame/.4 s) for a 3-d duration upon the initiation of farrowing. To assess the degree of comfort of each sow, body position changes were recorded when sows switched between lying, sitting, and standing. Data were analyzed by 12-h periods using Wilcoxon-Mann-Whitney equations. During the 72-h period, B sows tended to perform fewer position changes than C sows (P = .10). Specifically, position changes were fewer for B sows from 48 to 72 h postpartum (P<.06). There were no differences in position changes between treatments from 0 to 48 h postpartum (P>.50). There was no difference in the rate of crushing between treatments (C = 5, B = 5). The butorphanol did not seem to affect pig activity or normal behaviors or to create adverse effects, such as diarrhea. Although the sows given butorphanol showed a reduced number of position changes, the dose was intermediate, and a higher dose may have a greater effect. If pig mortality can be decreased, an analgesic protocol that is simple to administer and readily available to producers can be developed. Alternatively, using of more pliable flooring or an increase in sow body fat may allow sows to lie more stationary.

Analgesics, Opioid↗

PubMed1999

Danger to pigs due to crushing can be reduced by the use of a simulated udder.

Sows that lie on their young, pig "crushing", is a significant cause of pig mortality in current production systems. Although mortality rates of pigs in farrowing crates are lower than mortality rates of pigs in pens, loss due to crushing is still estimated to be between 4.8 and 18%. During the first few days after parturition, pigs are highly attracted to the odor of their dam's udder. Thus, our research was designed to move the pigs away from the sow by competing with the sow's udder using a "simulated" udder. Fifteen Yorkshire x Landrace sows and their litters (11.4+/-.78 pigs) were assigned to either a control (C, n = 9) or an experimental group (SU, n = 6). The C pigs had access to a heat lamp, whereas the SU pigs' crate had a simulated udder. Data were collected using time-lapse photography (1 frame/.4 s) for a 3-d duration at the initiation of farrowing. When a sow stood, data were recorded by 1-min scan samples to record the number of pigs using either the heat lamp or the simulated udder. In addition, stillborn pigs, pig crushing, and death by other means also were recorded. Data were analyzed by 12-h periods using generalized estimating equations. Results indicate that from 12 to 72 h postpartum, excluding 24 to 36 h postpartum, the estimated probability that pigs were in a safe area (simulated udder or heat lamp) was .89 for SU pigs, compared with only .72 for C pigs (P = .005). During the 24- to 36-h period, it was more probable to find pigs on a simulated udder (.77) than under only a heat lamp (.61, P = .016). Stillborn pigs, pig crushing, and death by other means were not different between treatments (mean = .87, .60, 1.2; P>.20). The simulated udder drew pigs away from the sow's udder better than heat lamps alone. Considering these findings, mortality of pigs due to crushing may be decreased substantially using a simulated udder. These results are promising, but further refinement should be done, including improved udder design and investigation of the attractiveness of various stimuli.

Animal Husbandry↗

PubMed1997

Effects of prenatal stress on the fetal calf.

Twelve pregnant Brahman cows were randomly assigned to one of two treatment groups: 1) transported in a stock trailer for 24.2 km, unloaded at a second farm and penned for 1 hr, and then returned to the original farm (TRANS, n = 6); or 2) walked through the handling facilities (SHAM, n = 6). Treatments were repeated at 60, 80, 100, 120, and 140 d of gestation. Calves were delivered by cesarean section on d 266 of gestation. The male:female ratio was 4:2 and 5:1 for the TRANS and SHAM treatment groups, respectively. Before calf removal and severance of the umbilical blood flow, a blood sample was collected from the calf to determine plasma concentrations of adrenocorticotropin (ACTH) and cortisol. The calf was then sedated and exsanguinated, after which pituitary and adrenal glands were collected. The adrenals were immediately weighed, and a cross-section from the left adrenal was stored in 4% paraformaldehyde until being embedded in paraffin. Eight sections from each adrenal were sliced (5 microns), fixed, and then stained with Harris' hematoxylin and eosin. Areas of the cortex and medulla were calculated with a computerized digitizing unit and tracing of the viewed section. The TRANS calves had heavier body weights (BW) (28.7 vs. 23.9 +/- 1.8 kg; P < 0.07), pituitary glands (12.63 vs. 8.24 +/- 1.10 g/kg BW; P < 0.008), and heart weights (5.58 vs. 5.17 +/- 0.58 g/kg BW; P < 0.05) than did the SHAM calves. Plasma concentrations of ACTH and cortisol did not differ between SHAM and TRANS calves (57 vs. 82 +/- 14 pg/ml and 7.0 vs. 6.7 +/- 0.9 ng/ml, respectively; P > 0.2). Adrenal gland weight and medulla-to-cortex ratio did not differ between SHAM and TRANS calves (0.61 and 0.73 +/- 0.03 g and 0.97 and 0.99 +/- 0.12 g, respectively; P > 0.2). These results suggest that the altered response to stress in prenatally stressed calves is not associated with morphological changes in the adrenal gland but may be due to effects of prenatal stress on the fetal pituitary.

Adrenal Glands↗

PubMed1997

Effects of prenatal stress on suckling calves.

Pregnant Brahman cows (n = 42), bred to either Brahman or Tuli bulls, were randomly assigned to one of three treatments: 1) transported in a stock trailer for 24.2 km, unloaded at a second farm and penned for 1 h, and then returned to the original farm (TRANS); 2) i.v. injection of ACTH, 1 IU/kg BW (ACTH); or 3) walked through the handling facilities (SHAM). Treatments were initiated on d 60 and repeated at 80, 100, 120, and 140 d of gestation. The calves from these cows were subjected to tests to measure their capacity to react to stress. In Test 1, Tuli-sired calves were restrained at 10 and 150 d of age for 3.5 h. In Test 2, Brahman-sired calves were restrained for 3.5 h and given an injection of ACTH (.125 IU ACTH/kg of BW). In Test 3, Test-2 calves were restrained at 180 d of age and hot-iron branded. In Test 4, Test-1 calves were restrained at 180 d of age and given an injection of cortisol (6.7 ng/kg BW) to estimate cortisol clearance rate. During all tests, calves were restrained for 3.5 h, and heart rates were recorded and blood samples were taken at -15, 0, 15, 30, 45, 60, 90, 120, and 180 min. The 10- and 150-d-old TRANS calves maintained greater plasma cortisol in Test 1 (restraint) than the ACTH and SHAM calves (P < .01). The ACTH challenge (Test 2) increased plasma cortisol and ACTH, but cow treatment did not alter the response (P > .4). In response to branding (Test 3), the TRANS, ACTH, and SHAM calves' overall mean plasma cortisol was not affected by treatment (52, 51, and 43 +/- 3 ng/mL, respectively; P > .1), nor was the calves' overall heart rate (91, 94, and 86 +/- 3 beats/min, respectively; P > . 1). In Test 4, TRANS calves cleared plasma of cortisol at a slower rate than did the SHAM calves (P < .01), but not the ACTH calves (261, 374, and 473 +/- 50 mL/min, respectively; P > .1). The TRANS calves had an overall greater heart rate than did the ACTH or the SHAM calves (91, 79, and 77 +/- 2 beats/min, respectively; P < .001). Exposing cows to repeated transportation stress during gestation altered their calf's physiological response to stress, and these alterations could have a profound influence on the calfs ability to adapt to stress, thereby influencing its welfare. Further research should examine the growth, immune function, and reproductive function of prenatally stressed calves to determine whether these changes in plasma cortisol are beneficial or deleterious.

Adrenocorticotropic Hormone↗

PubMed1996

Adrenocorticotropic hormone dose response and some physiological effects of transportation on pregnant Brahman cattle.

The appropriate dose and the ability of exogenous ACTH to mimic the physiological effects of a real stressor need to be determined. In Exp. 1, 25 pregnant Brahman heifers were injected i.v. with either 0 (saline), .125, .25, .5, or 1 i.u. of ACTH/kg BW. Plasma cortisol was determined in blood samples collected during a 5-h period, and an integrated cortisol response was calculated for each cow. The greater the dose of ACTH, the greater was the integrated cortisol response (P < .001). However, peak plasma cortisol in response to the four doses of ACTH did not differ (P > .6). The plasma cortisol concentrations returned to baseline more slowly in those cows receiving the greater doses of ACTH, making their integrated areas of response greater. In Exp. 2, pregnant Brahman cows were either transported 48 km (n = 28), injected with 1 i.u. of ACTH/kg BW (n = 21), or served as shams (n = 28). Each treatment was repeated at 60, 80, 100, 120, and 140 d of gestation. Shrink was greater for the transported cows than for either the ACTH-treated or sham cows, 14.3, 6.0, and 5.2 kg (P < .001). Shrink also decreased in response to each subsequent application of treatment for all three treatment groups (P < .001). Transported cows had lower plasma cortisol concentrations after the first two applications of treatments (P < .006). The range of doses of ACTH caused a similar peak cortisol release; however, it took cortisol longer to return to baseline as ACTH dose increased. Repeated administration of exogenous ACTH did not cause the same amount of shrinkage as transportation, and the resultant cortisol concentrations remained consistent for each administration. There was no apparent carryover effect of repeated administration of ACTH at 20-d intervals. Maximal plasma cortisol concentrations in Brahman cattle can be obtained with doses of ACTH much smaller than those traditionally injected. However, larger doses of ACTH maintained plasma cortisol concentrations for a longer duration. Repeated transportation caused a decrease in cortisol release and shrinkage indicative of psychological habituation. Injections of ACTH did not cause the same physiological response as transportation.

Adrenocorticotropic Hormone↗

PubMed1994

Wisconsin's "stale calf" issue and a study designed to resolve some of the animal welfare concerns.

A unique law (Act 201) requiring livestock markets to place an identifying mark on calves up to 90 kg each time they are sold went into effect in Wisconsin in 1993. The intent of the law is to reduce the number of times calves are resold and hence become "stale." The original proponents of the law proposed that calves be ear-notched each time they are sold. Ear notching, however, was resisted by Wisconsin regulatory agencies partly because of fear of an adverse public reaction. These authors then conducted a study to determine the approximate amount of discomfort experienced by young Holstein calves during ear notching. Six 2-mo-old Holstein calves were used to determine heart rate and behavioral responses to a standard "V" pig ear notcher (6 mm wide x 14 mm deep) applied between the tip and halfway down the dorsal edge of the left ear. Five other calves were given 30 s of access to a rubber nipple to provide a comparison to a desirable stimulus. Ear notching only elicited a mild startle response that lasted 1 to 2 s followed by resumption of normal behavior. The calves presented with the nipple suckled or butted the nipple for the full 30 s. The mean heart rate for the 30-s period in which treatments occurred was 95 +/- 4.8 bpm and 110 +/- 5.8 bpm for the notched and suckled calves, respectively, and was not influenced by treatments (P = .50).(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Husbandry↗

PubMed1992

Behavioral and physiological effects of freeze or hot-iron branding on crossbred cattle.

Twenty-seven crossbred calves (1/2 Simmental, 1/4 Hereford, 1/4 Brahman) averaging 257 +/- 11 d of age were either hot-iron-branded (H), freeze-branded (F), or sham-branded (S). Calves were blocked for temperament, weight, and sex and were 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 daily for 5 d before the experiment. Jugular cannulas were inserted in each calf 1 d before application of treatment. Blood samples and heart rate measures were obtained at -5, -3, 0, .5, 1, 3, 5, 10, 15, and 20 min after application of the treatments. Mean concentrations of plasma epinephrine (EPI) were higher for H calves at time .5 min than for either S or F calves (P = .10). To account for individual differences, prebranding heart rates and hormone concentrations were subtracted from subsequent samples and were also used to calculate a proportion for each subsequent sample. Analyses of subtracted values found that EPI concentrations were greater for H calves than for either S or F calves (P = .007) at .5 min postbranding. No other differences were found for the subtracted analyses. Analyses of proportion data also revealed that H calves had greater EPI than did either S or F calves (P = .027) at .5 min postbranding. Only three animals vocalized during branding, one H calf and two F calves. Despite the 5-d acclimation period, handling and restraint elevated plasma cortisol concentrations and heart rate.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Identification Systems↗

PubMed1992

A comparative physiological and behavioral study of freeze and hot-iron branding using dairy cows.

A public debate has recently arisen, largely surrounding the issue of pain, over whether freeze or hot-iron branding should be the preferred method of permanently identifying cattle. This study addressed that question by quantifying the following accepted measures of distress and pain over a 25-min sampling period: elevated heart rate, concentrations of cortisol, epinephrine, and norepinephrine, and escape-avoidance reactions and vocalizations. Twenty-four dairy cows (15 Holsteins and 9 Jerseys) were assigned to one of three treatments: freeze-branded (F), hot-iron-branded (H), or sham-branded (S), in which a room-temperature brander was applied. Plasma epinephrine and norepinephrine concentrations showed no discernible trends. Plasma cortisol concentrations were elevated in the F and H cows from 5.5 min to 25.5 min postbranding (P = .04). Heart rate, analyzed as a proportion of the prebranding mean, showed that H cows had a greater, more acute, response than did F cows (P = .04), which exhibited a more prolonged response (P = .07). No cows vocalized during branding; however, H cows had a greater escape-avoidance reaction toward branding than did the F and S cows. Both methods of branding produced elevated heart rates and cortisol concentrations indicative of pain sensations. Because the cows exhibited a greater escape-avoidance reaction and heart rate proportions to hot-iron branding, freeze banding would be preferable to hot-iron branding when feasible.

Animal Identification Systems↗