Biomedical subjects
B A Becker
Publications and source records attributed to B A Becker.
Effect of a hot environment on performance, carcass characteristics, and blood hormones and metabolites of pigs treated with porcine somatotropin.
A study was conducted to compare the effects of a single 100-mg recombinant porcine somatotropin (rpST) implant on performance, carcass characteristics, and blood hormones and metabolites of 40 finishing pigs exposed to either a thermoneutral (TN; 18 to 21 degrees C) or hot environment (H; 27 to 35 degrees C) for 28 or 35 d. Pigs in H gained at a slower rate (P less than .01) than pigs in TN. Control and rpST-treated pigs gained at similar rates in respective environments. The rpST-treated pigs consumed 13% less feed (P less than .01) than the control pigs in both environments, and pigs in H consumed 19% less feed (P less than .01) than pigs in TN. Feed efficiency for rpST-treated pigs was 15% better (P less than .01) than that for control pigs; environment had no effect on feed efficiency. When slaughtered, pigs treated with rpST had less (P less than .01) leaf fat and less (P less than .01) 10th rib backfat than control pigs. Pigs in H had a lower (P less than .01) final BW and less leaf fat and backfat than pigs in TN. The rpST and H had various effects on blood hormones and metabolites. The results demonstrated that the benefits of this form of rpST treatment achieved under TN were also achieved in H with no interactions between the hormone and environment.
Physiologic and immune responses associated with 48-hour fast of pigs.
We sought to determine the effect of 48 hours of fasting on physiologic and immune responses of pigs. Sixteen crossbred barrows, approximately 8 weeks of age, were housed in a controlled environment (21 degrees C, 45% RH) with feed and water ad libitum. After 10 days, eight pigs were fasted for 48 hours with water available ad libitum; the remaining eight received feed and water ad libitum. Blood samples were obtained by venipuncture before fasting, at the end of 48-hour fasting, and 3 and 10 days later. No significant differences in responses to mitogens PHA or Con A were noted in whole blood or isolated lymphocyte cultures. Changes in numbers of leukocytes, neutrophils, and serum cortisol concentrations, but not of lymphocytes, were significant. The results suggested that short-term fasting transiently reduces the number of neutrophils and increases serum cortisol concentrations, with no effect on blastogenic responses of lymphocytes to selected mitogens.
Assessment of thermal status of somatotropin-injected lactating Holstein cows maintained under controlled-laboratory thermoneutral, hot and cold environments.
Two experiments, with a single-reversal design and 12 cows per experiment, were conducted to study the effects of somatotropin on thermal status of lactating cows under laboratory thermoneutral (18 to 22 degrees C, 30-50% relative humidity), hot (24-35 degrees C, 30-50% relative humidity) and cold (-5 (-) +5 degrees C, 50-55% relative humidity) conditions. Throughout the experiment six cows were injected with somatotropin (25 mg/d) and six with sodium bicarbonate. All injections were started the first day of the 30-d natural environmental period (22-35 degrees C and 41-97% relative humidity for summer experiment, and -5 (-) +5 degrees C and 4-25% relative humidity for winter experiment) before the cows were exposed alternatively to laboratory thermoneutral and hot or cold environments. The somatotropin-treated cows had higher energy intake (13 and 17%), heat production (19 and 25%), heat loss (36 and 24%) and milk energy (40 and 49%), than control cows under thermoneutral and hot conditions, respectively. The somatotropin-treated cows had higher heat production (18 and 10%), respiratory heat loss (27 and 17%) and milk energy (14 and 25%) than control cows under thermoneutral and cold conditions, respectively. The increased heat production associated with somatotropin was accompanied by increased heat losses. Part of the increased heat production was attributed to the increased milk energy and energy intake. These results suggest that increased heat production during somatotropin treatment was within the range that could be dissipated by the cows.
Effects of temperature on the performance of finishing swine: I. Effects of a hot, diurnal temperature on average daily gain, feed intake, and feed efficiency.
Ninety-six crossbred barrows and gilts weighing 90 +/- .67 kg were used during a 21-d study to determine the effects of a hot, diurnal temperature (H; 22.5 to 35 degrees C) compared with a constant, thermoneutral temperature (TN; 20 degrees C) and the effects of sex (barrows vs gilts) on performance. A secondary objective included the determination of weight loss as a result of a 24-h fast immediately after the 21-d feeding study of commingled vs not commingled hogs of both environmental treatments (TN and H). Pigs housed in the hot, diurnal temperature gained 16.3% more slowly (P less than .001;.77 vs. .92 kg/d) than those in the constant, thermoneutral environment. Feed intake (FI) for the H pigs was 10.9% less (P less than .001; 3.01 vs 3.38 kg/d) than that for the TN pigs. The H pigs gained 17.6 g/d less and consumed 43.5 g/d less feed for every C degrees above 20 degrees C; however, no differences were observed for feed efficiency (F/G; 3.86 vs 4.19 kg for the TN and H pigs, respectively). Average daily gain and feed/gain (F/G) were not affected by sex. Likewise, no significant interactions of temperature x sex were observed for ADG, FI, or F/G. Weight loss (shrinkage) during the 24-h fast was not affected by commingling; however, the H pigs lost 17.5% more weight (P less than .05) than the TN pigs (3.82 vs 3.25%, respectively).
Effects of temperature on the performance of finishing swine: II. Effects of a cold, diurnal temperature on average daily gain, feed intake, and feed efficiency.
Forty-eight crossbred barrows and gilts weighing 84.5 +/- .33 kg were used during two 21-d trials to investigate the effects of a cold, diurnal temperature (CD; -5.0 to 8.0 degrees C) compared with a constant, thermoneutral temperature (TN; 20 degrees C) and the effects of sex (barrows vs gilts) on performance. A second objective was to determine shrinkage as a result of a 24-h fast immediately after the 21-d study of hogs commingled vs those not commingled for both environmental treatments (CD vs TN). Pigs housed in the CD chamber gained 27.2% more slowly (P less than .001; 75 vs 1.03 kg/d) than those in the TN environment and consumed 5.7% more feed (P less than .05; 3.88 vs 3.67 kg/d). The lower ADG and higher feed intake (FI) exhibited by the CD pigs resulted in poorer (P less than .05) feed efficiency (F/G; 5.33 vs 3.73, respectively). A temperature x sex interaction occurred for ADG but not for FI or F/G. Twenty-four-hour shrink for the CD pigs was 16.4% less than for the TN pigs (3.72 vs 4.45%, respectively); however, commingling did not affect shrinkage.
Effects of somatotropin on milk yield and physiological responses during summer farm and hot laboratory conditions.
The effects of bST on performance and physiological responses of lactating cows was studied under farm summer and laboratory heat conditions. Twelve cows, 90 to 50 d postpartum, were injected with either bST or vehicle solution for 30 d under farm summer and 10 d under either laboratory thermoneutral or heat conditions. Somatotropin increased milk yield by 6.1 (21%), 8.1 (32%), and 7.3 kg (35%) under the farm summer, laboratory thermoneutral, and heat conditions, respectively. Somatotropin also increased milk fat by 15 and 19% and dry matter intake by 16 and 18% under laboratory thermoneutral and heat conditions, respectively. Somatotropin increased the efficiency of feed conversion into milk without any significant changes in body weight and temperatures. Somatotropin reduced plasma concentrations of triiodothyronine and cortisol and had no effect on plasma prolactin and insulin concentrations. Somatotropin did not increase water intake; however, hematocrit was decreased. The results suggest that stimulatory effects of bST on milk production are still observed on heat-stressed cows without any significant indications of additional heat stress.
Effect of farm and simulated laboratory cold environmental conditions on the performance and physiological responses of lactating dairy cows supplemented with bovine somatotropin (BST).
A study was conducted to evaluate the effect of bovine somatotropin (BST) supplementation in twelve lactating dairy cows maintained in cold environmental conditions. Six cows were injected daily with 25 mg of BST; the other six were injected with a control vehicle. Cows were maintained under standard dairy management during mid-winter for 30 days. Milk production was recorded twice daily, and blood samples were taken weekly. Animals were then transferred to environmentally controlled chambers and exposed to cycling thermoneutral (15 degrees to 20 degrees C) and cycling cold (-5 degrees to +5 degrees C) temperatures for 10 days in a split-reversal design. Milk production, feed and water intake, body weights and rectal temperatures were monitored. Blood samples were taken on days 1, 3, 5, 8 and 10 of each period and analyzed for plasma triiodothyronine (T3), thyroxine (T4), cortisol, insulin and prolactin. Under farm conditions, BST-treated cows produced 11% more milk than control-treated cows and in environmentally controlled chambers produced 17.4% more milk. No differences due to BST in feed or water intake, body weights or rectal temperatures were found under laboratory conditions. Plasma T3 and insulin increased due to BST treatment while no effect was found on cortisol, prolactin or T4. The results showed that the benefits of BST supplementation in lactating dairy cows were achieved under cold environmental conditions.
Suppressed peripheral blood lymphocyte blastogenesis in pre- and postpartal sheep by chronic heat-stress, and suppressive property of heat-stressed sheep serum on lymphocytes.
Phytohemagglutinin (PHA) and concanavalin A (Con A)-induced blastogenesis of peripheral blood lymphocytes was examined in heat-stressed pre- and postpartal sheep. The peak responses of lymphocytes to PHA and Con A in heat-stressed sheep revealed significant reduction before and after parturition compared with those in the corresponding control animals kept under thermoneutral conditions. Furthermore, the effect of serum from control or heat-stressed sheep on PHA-induced lymphocyte blastogenesis was examined. Supplementation of serum from heat-stressed sheep significantly suppressed the blastogenesis of lymphocytes obtained from healthy sheep, bovine, and human donors. Unlike dexamethasone, heat-stressed sheep serum did not inhibit IL-2 production by PHA-stimulated human peripheral blood lymphocytes. These results indicate that the immunosuppression of heat-stressed sheep is in part mediated by serum factor(s) that can modulate T-cell function in a species nonspecific manner.
Physiologic and body composition changes in feeder pigs under simulated marketing conditions.
Two experiments were conducted to determine changes in body composition and various physiologic variables in feeder pigs under simulated marketing conditions. In the first experiment, pigs were assigned to 1 of 4 treatment groups for 48 hours: (1) no water and feed; (2) water ad libitum, no feed; (3) no water, feed ad libitum; or (4) water and feed ad libitum. During a 48-hour recovery period, all pigs were allowed feed and water ad libitum. Plasma triiodothyronine decreased (P less than 0.01) within the first 24 hours in groups-1 and -2 pigs, but increased (P less than 0.01) within the first 6 hours of the recovery period. The circadian rhythm of plasma cortisol was disrupted in groups-1 and -3 pigs and during recovery in group-1 pigs. Packed cell volume increased (P less than 0.05) in groups-1 and -3 pigs and returned to initial values within the first 24 hours of the recovery period. In the second experiment, body composition was estimated by the 40K technique for fat-free body mass, percentage of nitrogen, and percentage of fat. Body composition was determined before and after pigs were allotted to 1 of 2 groups for 48 hours: group-1 pigs were given feed and water ad libitum and group-2 pigs were not given feed and water. Group-1 pigs gained 2.2 kg of body weight (P less than 0.01), 0.6% fat (P less than 0.01), 0.7 kg of fat-free body mass, and 0.02% nitrogen (P greater than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)
Adrenal and behavioral responses of swine restricted to varying degrees of mobility.
Adrenal and behavioral responses in swine restricted to varying degrees of mobility were examined to determine what component may impose chronic stress. The components of restriction considered were the inability to turn around and/or move freely. For 5 to 6 weeks 32 pigs were restrained such that pigs A) could move freely; B) could not turn around or move freely; C) could not turn around but could move back and forth the same distance as pigs in A; or D) could turn around but not move freely. After 4 weeks no significant differences due to degree of restraint were found in the profile of serum cortisol concentrations, neutrophil:lymphocyte ratio and ambulatory abilities; however overall cortisol concentrations were higher in pigs that could turn around but not move freely. Increases in serum cortisol due to ACTH injection were higher in pigs that could turn around but not move freely. No alterations in the manner in which gilts stood up and layed down could be observed. Collectively these data suggest that swine adapt when mobility is restricted to not turning around and not moving freely but cannot when animals can turn around but not move freely.
Atypical plaquelike staphylococcal folliculitis in human immunodeficiency virus-infected persons.
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Effect of fasting and transportation on various physiological parameters and meat quality of slaughter hogs.
Forty-nine slaughter hogs were transported and fasted or fasted with no transport for 0 (no transport), 24, 48 and 72 h. Blood samples were taken before treatments were imposed and again prior to slaughter. Soft tissues of the ham were chemically analyzed and loin samples were evaluated by a sensory panel. Fasting and transportation decreased plasma triiodothyronine and hematocrit and increased plasma osmolality. Preslaughter treatment did not affect juiciness or desirability of cooked chops or percentage of fat in the ham soft tissues. These data suggest that although fasting and transporting of slaughter hogs may disrupt homeostasis of pigs, such physiological changes do not negatively affect meat quality.
The phenomenon of stress: concepts and mechanisms associated with stress-induced responses of the neuroendocrine system.
'Stress', 'stressors' and the 'stress response' are terms which represent concepts rather than being precisely definable. No single theory of stress has been universally accepted. Selye's General Adaptation Syndrome of stress remains the primary theory for the basis of stress research in food-producing animals; however, other concepts and theories have been developed. This paper reviews current theories and suggests that the complexity of research on stress in food-producing animals can be attributed to the lack of concrete theories and concepts regarding identifiable stressors, the endocrine responses stimulated by potential stressors and the complex and integrated biological changes in the neuro-endocrine system resulting from exposure to hypothesized stressors.
Prolactin and its involvement in fluid regulation in the bovine.
Plasma prolactin (PRL) concentrations, osmolality, water consumption, feed intake, urine excretion, and fecal water output were determined in twelve steers of 3 breeds exposed to 5 feed and water regimes. Breed differences were found in water intake and plasma PRL concentrations when feed and water were ad lib., however, during any of the other 4 treatments, responses were similar between breeds. During dehydration and feed restriction, water intake, urine, fecal water, and plasma prolactin decreased; however, during hydration and refeeding such changes were not as clearly related. No consistent relationships between plasma prolactin and osmolality were found. Data suggests that PRL's role in fluid regulation in the bovine is most likely associated with alterations in renal hemodynamics rather than by changes in plasma osmolality.
Plasma antidiuretic hormone (ADH) concentrations in cattle, during various water and feed regimes.
Twelve steers of three different breeds were exposed to five feed and water regimes in order to characterize changes in plasma antidiuretic hormone (ADH) concentrations. No breed differences were found in plasma ADH concentration. Plasma ADH concentration rose (4.2 to 22.0 pg/ml) during dehydration. By 3 hr hydration, plasma ADH concentrations dropped dramatically (over 50%) to 9.2 pg/ml. No changes in plasma ADH concentrations occurred during feed restriction and refeeding. Hematocrit percentages were also determined and differences are hypothesized to relate to probable differences in environmental adaptability and genetic selection for meat or milk production among the three breeds.
Cortisol response of gilts in tether stalls.
Several experiments were conducted to evaluate serum cortisol concentrations and the circadian rhythm of this hormone in gilts tethered in stalls. Control animals were penned individually. In the initial experiment, 18 nongravid gilts were placed in tether stalls after being in either tether stalls or individual pens for 2 wk. No significant differences were found in serum cortisol concentrations. In a second experiment, 16 ovariectomized gilts were placed in tether stalls or individual pens for up to 5 wk. Estrus was induced during wk 3 and 4. During the first day in tether stalls, serum cortisol concentrations increased (P less than .05) and the circadian rhythm of cortisol was disrupted for 4 d. During estrus, the circadian rhythm of cortisol was interrupted for several days in the gilts, regardless of housing. After 4 wk, morning concentrations of cortisol were higher for gilts in tether stalls. The results indicate that: 1) the initial response to tethering varies according to previous penning and handling experience, 2) although the circadian rhythm of cortisol was either altered or disrupted during estrus, such disruptions were not influenced by type of penning and 3) tether stalls may chronically increase cortisol concentrations in gilts.
Peripheral concentrations of cortisol as an indicator of stress in the pig.
Twenty-four crossbred gilts (7 to 9 months old) were exposed to 3 different stressors to evaluate changes in peripheral concentrations of the adrenal hormone cortisol. Gilts were confined in a box for 1 hour, electrically stimulated for 6 minutes, or heat-stressed for 6 hours; these stressors were imposed for 3 consecutive days. Blood samples were collected repeatedly, and serum cortisol concentrations were determined by radioimmunoassay. Peak cortisol concentrations for pigs in the box, electrically stimulated, and heat-stressed were 67.8 +/- 9.9 ng/ml (mean +/- SEM), 43.2 +/- 5.8 ng/ml, and 25.2 +/- 3.0 ng/ml greater than the control concentrations. The times at which these peaks occurred varied with each stressor. Overall serum cortisol concentrations decreased from day 1 to day 3, but the response to a given stressor was not diminished. Our data substantiate the use of cortisol as an indicator of stress in swine and emphasize consideration for the interval between exposures to stressors.