Salivary cortisol in pigs following adrenocorticotrophic hormone stimulation: comparison with plasma levels

Four prepubertal pigs were prepared with venous catheters and housed in metabolism cages. Plasma and saliva samples were taken at 15-min intervals over a 105-min period and analysed by radioimmunoassay for total (i.e. free and bound) cortisol content. Adrenocorticotrophic hormone (ACTH) was given i.v. at three different doses (0.5, 1.0 and 2.0 mg) after the second sample and the cortisol responses were compared with pretreatment values and levels observed after saline vehicle administration. Basal levels of salivary cortisol were approximately 10% of those in plasma. ACTH induced significant increases in plasma and salivary cortisol but in no case was a dose/response relationship detected. Plasma cortisol showed a maximum increase of approximately 230% whereas salivary cortisol increased only by about 130%, indicating that salivary cortisol is a less sensitive indicator of adrenal activity than plasma cortisol in this species. Estimation of salivary cortisol concentrations may offer practical advantages for the assessment of stress responses in intensively housed pigs.     

Changes in serum concentrations of luteinizing hormone and follicle-stimulating hormone following injection of gonadotropin-releasing hormone during pregnancy and after parturition in mares

High concentrations of estrogens in the peripheral circulation during late gestation inhibit synthesis of LH and markedly reduce pituitary content of LH at the end of pregnancy in most domestic species. Because blood concentrations of estrogen peak shortly before mid-gestation in the mare and then gradually decrease until parturition, we hypothesized that pituitary content of LH may increase during late gestation. To test this hypothesis 10 horse mares were challenged with a maximally stimulatory dose (2 micrograms/kg) of GnRH on d 240 and 320 of gestation and d 3 after parturition. A separate group of four mares were treated with GnRH on d 2 or 3 estrus. Blood samples were collected at -2, -1, 0, .25, .5, .75, 1, 1.5, 2, 2.5, 3, 3.5, 4, 5, 6, 7 and 8 h relative to injection of GnRH and serum was analyzed for concentration of LH and FSH. Basal serum concentration and total quantity of LH released after GnRH stimulation (assessed by determining the area under the response curve) were not different on d 240 and 320 of gestation or on d 3 after parturition (12.5 +/- 3.5, 5.7 +/- 1.5 and 29.1 +/- 12.1 ng.min/ml, respectively) and were less (P less than .05) than on d 3 of estrus (311.0 +/- 54.0 ng.min/ml). There was little difference in the basal serum concentration of FSH at any of the time points examined. In contrast, GnRH-induced release of FSH continually decreased (P less than .05) from d 240 of gestation (559.8 +/- 88.9 ng.min/ml) to d 3 of estrus (51.8 +/- 6.2 ng.min/ml).(ABSTRACT TRUNCATED AT 250 WORDS)     

Ceftiofur distribution in plasma and joint fluid following regional limb injection in cattle

The objective of this study was to evaluate the efficacy of regional intravenous (i.v.) injection of ceftiofur in delivery of this drug to joint fluid and plasma in a limb distal to a tourniquet in five, healthy, adult, mixed breed beef cattle. A tourniquet was positioned in the mid-metacarpal region, and 500 mg of ceftiofur was administered through a catheter in the dorsal common digital vein (DCDV). Plasma samples were collected from the catheter at 15, 30 and 45 min postinjection, and from the abaxial proper palmar vein (APPV) at 15 min postinjection. Synovial fluid was collected from the metacarpal phalangeal joint at 45 min postinjection. Ceftiofur concentrations were estimated in plasma and synovial fluid using high-pressure liquid chromatography (HPLC) and a microbiological assay utilizing Pasteurella haemolytica as the test organism. Both assays indicated highest plasma concentrations of ceftiofur at 15 min, with the concentrations declining with time. Concentrations of ceftiofur in plasma obtained from the DCDV were not significantly different from APPV levels, indicating rapid distribution of ceftiofur within the limb. Microbiological assay always demonstrated higher concentrations of ceftiofur compared with HPLC assay, because the former probably also detected the active metabolites of ceftiofur as well as the parent compound. At 45 min, ceftiofur concentrations determined by HPLC were 251+/-97 and 15+/-5 microg/mL in plasma and synovial fluid, respectively. Regional intravenous injection appears to be a feasible technique to produce rapid distribution of ceftiofur within the limb well above therapeutic concentrations.     

日粮ADF水平对妊娠母兔繁殖性能、血清生化指标及激素水平的影响

为探讨妊娠母兔适宜的酸性洗涤纤维(ADF)需要量,选用80只体质量相近的经产新西兰肉兔,随机分为4组,分别饲喂4种ADF水平(13%、16%、19%和22%)的日粮。结果表明:日粮ADF水平显著影响妊娠母兔窝产活仔数、产活仔率和初生窝质量(P0.05)。随ADF水平升高,血清尿素氮浓度(P0.05)和谷丙转氨酶、谷草转氨酶活性(P0.05)逐渐升高,血清胆固醇(P0.05)和甘油三酯含量(P0.05)逐渐降低,血清总蛋白和血糖含量先升高后降低(P0.05);血清胰岛素样生长因子-1、雌二醇、孕酮(P0.05)和胰岛素、生长激素(P0.05)水平也呈先升高后降低趋势,胰高血糖素水平则呈先降低后增加趋势(P0.05),泌乳素水平逐渐降低(P0.05)。综合分析认为,妊娠母兔适宜的ADF水平为16%。     

Plasma steroid profiles following follicle-stimulating hormone or equine chorionic gonadotropin injection in cows chronically treated with gonadotropin-releasing hormone agonist

Plasma steroid profiles following follicle-stimulating hormone (FSH) or equine chorionic gonadotropin (eCG) injection were studied in chronically gonadotropin releasing hormone agonist (GnRH-A)-treated cows. Follicular development and irINH secretion were stimulated by FSH or eCG injection. The plasma concentrations of estradiol-17 beta (E(2)) and testosterone (T) were markedly increased following eCG injection. However, significant increases of the plasma E(2) and T concentrations were not detected in FSH-treated cows. Ovulation of developed follicles were depended on the hCG injection in both groups. These results show: 1) Follicular response to an exogenous gonadotropin is still remained, 2) Ovulation of developed follicles is induced by hCG injection and 3) FSH and eCG cause disparate plasma steroid profiles, under the influence of repeated GnRH-A treatment.     

Changes in plasma melanocyte-stimulating hormone,ACTH, prolactin,GH, LH,FSH, and thyroid-stimulating hormone in response to injection of sulpiride,thyrotropin-releasing hormone,or vehicle in insulin-sensitive and -insensitive mares

Six insulin-sensitive and 6 insulin-insensitive mares were used in a replicated 3 by 3 Latin square design to determine the pituitary hormonal responses (compared with vehicle) to sulpiride and thyrotropin-releasing hormone (TRH), 2 compounds commonly used to diagnose pituitary pars intermedia dysfunction (PPID) in horses. Mares were classified as insulin sensitive or insensitive by their previous glucose responses to direct injection of human recombinant insulin. Treatment days were February 25, 2012, and March 10 and 24, 2012. Treatments were sulpiride (racemic mixture, 0.01 mg/kg BW), TRH (0.002 mg/kg BW), and vehicle (saline, 0.01 mL/kg BW) administered intravenously. Blood samples were collected via jugular catheters at −10, 0, 5, 10, 20, 30, 45, 60, 90, and 120 min relative to treatment injection. Plasma ACTH concentrations were variable and were not affected by treatment or insulin sensitivity category. Plasma melanocyte-stimulating hormone (MSH) concentrations responded (P < 0.01) to both sulpiride and TRH injection and were greater (P < 0.05) in insulin-insensitive mares than in sensitive mares. Plasma prolactin concentrations responded (P < 0.01) to both sulpiride and TRH injection, and the response was greater (P < 0.05) for sulpiride; no effect of insulin sensitivity was observed. Plasma thyroid-stimulating hormone (TSH) concentrations responded (P < 0.01) to TRH injection only and were higher (P < 0.05) in insulin-sensitive mares in almost all time periods. Plasma LH and FSH concentrations varied with time (P < 0.05), particularly in the first week of the experiment, but were not affected by treatment or insulin sensitivity category. Plasma GH concentrations were affected (P < 0.05) only by day of treatment. The greater MSH responses to sulpiride and TRH in insulin-insensitive mares were similar to, but not as exaggerated as, those observed by others for PPID horses. In addition, the reduced TSH concentrations in insulin-insensitive mares are consistent with our previous observation of elevated plasma triiodothyronine concentrations in hyperleptinemic horses (later shown to be insulin insensitive as well).     

Changes in hormone and metabolite concentrations in plasma of steers during a prolonged fast

Two Brown Swiss and two Holstein steers, average weight of 226 kg, were fasted 8 d. Two days before the fast, jugular vein catheters were installed. Blood samples were collected every 15 min from 0800 to 1400 h on d 0, 2, 5 and 8 of fasting. Plasma from each sample was analyzed for concentrations of growth hormone, and from selected samples for insulin, glucagon, glucose, beta-hydroxybutyrate, free fatty acids, urea N and glycerol. Both growth hormone and insulin concentrations decreased by d 2 of the fast and remained at that concentration. Glucagon, however, remained constant. From d 0 to 2, concentrations of beta-hydroxybutyrate, free fatty acids and glycerol increased but then changed little for d 5 and 8. From d 0 to 2, glucose decreased and urea N increased. In contrast to the other metabolites, glucose and urea N concentrations stabilized between 3 and 5 d of fasting. The ratio of growth hormone to insulin decreased threefold and the ratio of glucagon to insulin decreased fivefold from d 0 to 2; both ratios remained constant during the rest of the fast. The data indicate that fasting cattle adapt by decreasing concentrations in plasma of growth hormone and insulin but not glucagon. These endocrine changes, therefore, seem responsible for greater rates of free fatty acid mobilization and glucose sparing during an energy deficit.     

Adrenocorticotrophic hormone fails to alter plasma fibrinogen and fibronectin values in calves but does so in rabbits

The intramuscular administration of adrenocorticotrophic hormone (ACTH) to calves, in either a short-acting form (cosyntrophin) or a longer-acting form (ACTHAR Gel), failed to induce any alteration in circulating fibrinogen or fibronectin values, despite marked elevations in plasma cortisol concentrations. With the longer-acting ACTH, plasma cortisol was elevated for at least 12 h following treatment and induced the expected physiological response of an elevation in blood glucose. In contrast, both forms of ACTH induced marked increases (p<0.01) in plasma fibrinogen and fibronectin when administered to rabbits. The elevation in the circulating levels of these proteins was first observed 24 h after ACTH administration, by which time plasma corticosteroid values had returned to pre-treatment values. With both ACTH preparations the increases in the circulating levels of these proteins were sustained for at least 96 h. The results suggest that, in cattle, the well-recognized increases in plasma fibrinogen values following stress are not associated with the concomitant increase in plasma cortisol. Further, the results clearly illustrate the marked species differences in the response of acute-phase reactant proteins to elevated glucocorticoids.     

Changes in plasma follicle-stimulating hormone, luteinizing hormone, estrogen and progesterone during growth of ovulatory follicles in the pig

This experiment was conducted to determine the changes in secretion of LH, FSH, estrogen and progesterone during follicle maturation. Ovaries were recovered from 11 non-treated (control) gilts, three on day 13, four on day 16, and four on day 19 of the estrous cycle, and from four altrenogest-treated gilts on day 19. Altrenogest, a progesterone agonist, was fed at a dose of 20 mg once daily from days 13 to 18 to block spontaneous follicle maturation. Gilts were bled daily from day 12 until slaughter. For control gilts, the number of follicles/gilt 1-6 mm in diameter decreased (P less than .05) from 93.5 on day 13 to 21.5 on day 19, and the number of large (greater than 6 mm) follicles increased (P less than .05) from 5.3 to 13.2. Altrenogest treatment blocked loss of small follicles and growth of large follicles between days 13 and 19. Plasma progesterone decreased (P less than .001) between days 12 and 16 in both control and altrenogest-treated gilts. Plasma FSH decreased (P less than .05) between days 12 and 16 only in control gilts. Plasma LH was not significantly affected by day or altrenogest treatment. Plasma estrogen increased (P less than .05) between days 15 and 19 only in control gilts. These results indicate that 1) no increased LH secretion was detected in conjunction with emergence of ovulatory follicles, and 2) atresia of nonovulatory follicles was associated with decreased secretion of FSH. Both atresia and decreasing FSH secretion began before estrogen concentration increased in the systemic circulation.     

Changes in plasma fibrinogen levels in experimental Mycoplasma bovis arthritis in calves

Plasma fibrinogen levels were measured as a means of following the course of an intravenous and intraperitoneal challenge of vaccinated and non-vaccinated animals in an experimental Mycoplasma bovis arthritis in calves. Intraperitoneal challenge failed to induce as much elevation of fibrinogen concentration as intravenous challenge in both the vaccinated and non-vaccinated groups.The elevation of fibrinogen levels among the vaccinated calves remained within the normal range of 300–800 mg% throughout, irrespective of the route of challenge. In contrast, the level rose to over 1600 mg% ten days postchallenge in all but one of the non-vaccinated calves that were challenged intravenously. The relatively low plasma fibrinogen levels in non-vaccinated calves that were challenged intraperitoneally correlated with the absence of arthritis in this group. In general, there was an inverse correlation between high fibrinogen levels and protection from M. bovis arthritis.     

Changes in plasma ghrelin and growth hormone concentrations in mature Holstein cows and three-month-old calves

We measured changes in plasma ghrelin and GH concentrations in mature Holstein cows and 3-mo-old female Holstein calves fed at scheduled times. Our objective was to determine the characteristics of ghrelin secretion in dairy cattle and its influence on GH. Animals were fed at 0800 and 1600 for 2 wk before and during experiments. Plasma was sampled for 24 h at 2-h intervals in Exp. 1. In mature cows, plasma ghrelin concentrations decreased (P < 0.01) just after 0800 but not at the 1600 feeding. Ghrelin concentrations were lower (P < 0.01) in calves than in mature cows and they did not decrease after feeding in calves. The temporal relationship between ghrelin and GH remained unclear. In Exp. 2, plasma was sampled 2 h before and after both morning and evening feedings at 20-min intervals. Plasma ghrelin concentrations decreased (P < 0.05) 40 min after 0800 feeding and 60 min after 1600 feeding in mature cows. These results indicate that in mature cows, plasma ghrelin concentration decreased after feeding, but this decrease was not evident in 3-mo-old calves. Further studies are required to define the relationship between plasma ghrelin and GH concentrations.