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).     

Characterization of Glucose Response Curves after Insulin Injection in Sensitive versus Insensitive Mares

The glucose responses to intravenous injections of a range of doses of recombinant human insulin were determined for six mares known to be insulin sensitive and six mares known to be insulin insensitive, with the goal of better characterizing the regression lines resulting from the two categories of mares. Insulin doses between 8 and 198 mU of insulin per kg of body weight (mU/kg BW) were administered intravenously between September 13 and 26, 2010, starting with 50 mU/kg BW on the first day. Higher and lower doses were administered on alternate days to obtain percentages of decreases in blood glucose concentrations between 10% and 70%. Linear regression analysis revealed that insulin-insensitive mares have glucose response curves with higher y intercepts (P = .066), less steep slopes (P = .0003), and less goodness of fit (P = .053) in addition to the expected greater dose required to produce a 50% reduction in blood glucose concentrations (ED50; P = .006), despite the similarities between their body weights and those of insulin-sensitive mares. Linear and nonlinear regression of responses to the 32, 50, and 79 mU/kg BW insulin doses with the overall estimates of ED50 and the natural log of ED50 indicated that the 50 mU/kg BW dose had the greatest coefficient of determination (>0.95). Generally, it appears that estimates of insulin sensitivity based on a single injection of insulin or on multiple injections of insulin are least variable for insulin-sensitive mares.     

Plasma progesterone concentration in beef heifers receiving exogenous glucose, insulin, or bovine somatotropin

Three experiments were conducted to evaluate plasma concentrations of glucose, insulin, IGF-I, and progesterone (P4) in pubertal beef heifers receiving exogenous glucose, insulin, or sometribove zinc. All heifers used had no luteal P4 synthesis but received a controlled internal drug-releasing device containing 1.38 g of P4 to estimate treatment effects on hepatic P4 degradation. In Exp. 1, 8 pubertal, nulliparous Angus × Hereford heifers (initial BW = 442 ± 14 kg; initial age = 656 ± 7 d) were randomly assigned to receive, in a crossover design containing 2 periods of 10 h, intravenous (i.v.) infusions (10 mL) of insulin (1 μg/kg of BW; INS) or saline (0.9%; SAL). Treatments were administered via jugular venipuncture in 7 applications (0.15 μg insulin/kg BW per application) 45 min apart (from 0 to 270 min). Blood samples were collected immediately before each infusion as well as at -120, -60, 330, 390, and 450 min relative to the first infusion. Heifers receiving INS had greater (P < 0.01) plasma insulin, reduced (P ≤ 0.04) plasma glucose and IGF-I, and similar (P = 0.62) plasma P4 concentrations compared with SAL heifers. In Exp. 2, the same heifers were assigned to receive, in a similar experimental design as Exp. 1, i.v. infusions (10 mL) of 1) insulin (1 μg/kg BW) and glucose (0.5 g/kg BW; INS+G) or 2) SAL. Heifers receiving INS+G had greater (P ≤ 0.02) plasma insulin, glucose, and P4 but reduced (P = 0.01) plasma IGF-I concentrations compared with SAL heifers. In Exp. 3, the same heifers were assigned to receive, in a crossover design containing 2 periods of 14 d, subcutaneous (s.c.) injections of 1) 250 mg of sometribove zinc (BST) or 2) SAL. Blood samples were collected 3 h apart (0900, 1200, 1500, and 1800 h) from heifers on d 6, 8, and 10 relative to treatment administration (d 1). Heifers receiving BST had greater (P < 0.01) plasma glucose and IGF-I and similar (P ≥ 0.67) plasma insulin and P4 concentrations compared with SAL heifers. Results from this series of experiments suggested that concurrent increases in glucose and insulin are required to reduce hepatic catabolism and increase plasma concentrations of P4 in bovine females.     

Factors Affecting the Glucose Response to Insulin Injection in Mares: Epinephrine, Short- and Long-Term Prior Feed Intake, Cinnamon Extract, and Omega-3 Fatty Acid Supplementation

Five experiments were conducted with mares to better define factors that might affect the assessment of insulin sensitivity via direct insulin injection, and to then apply this method of assessing insulin sensitivity to trials which tested two potential supplements for improving poor insulin sensitivity in horses. The experiments assessed the effects of the following: (1) previous administration of epinephrine, (2) overnight feed deprivation versus hay or pasture consumption, (3) 10-day acclimatization to hay in a dry lot versus pasture grazing, (4) cinnamon extract supplementation, and (5) fish oil supplementation on insulin sensitivity. Mares of known high and low insulin sensitivities were used in the first three experiments, whereas mares with low insulin sensitivities were used in the supplement trials. Epinephrine administration increased blood glucose concentrations (P < .05) and prevented the insulin-induced decrease in blood glucose concentrations in both sensitive and insensitive mares. Overnight feed deprivation decreased (P < .06) insulin sensitivity relative to overnight ad libitum access to hay, and both regimens resulted in reduced insulin sensitivity relative to overnight pasture availability; sensitive and insensitive mares responded similarly except when kept on pasture (P = .0854). Ten days of hay consumption in a dry lot reduced (P < .05) insulin sensitivity in insensitive mares, but not in sensitive mares, relative to pasture grazing. Supplementation with cinnamon extract or fish oil had no effect on insulin sensitivity of mares with known low insulin sensitivity under the conditions of these experiments.     

The Effect of Feeding Two or Three Meals Per Day of Either Low or High Nonstructural Carbohydrate Concentrates on Postprandial Glucose and Insulin Concentrations in Horses

Eight mature idle gelding horses (mean body weight [BW], 558 ± 45 kg) were used in a replicated 2 × 2 Latin square design study. Horses received either two or three meals per day (MPD) for 7 days, of either a high (H; 43%; 215 g/100 kg BW) or low (L; 18%; 90 g/100 kg BW) nonstructural carbohydrate (NSC) concentrate feed to achieve four treatment groups: low NSC in two MPD (L2), low NSC in three MPD (L3), high NSC in two MPD (H2), and high NSC in three MPD (H3). On day 7 of the treatments, blood was collected before (baseline) and for 5 hours after feeding the morning meal (10, 20, 30, 40, 50, 60, 90, 120, 150, 180, 210, 240, 270, and 300 minutes after feeding). Baseline insulin concentrations tended (P = .093) to be higher for horses fed high NSC than low NSC, and horses fed two MPD tended (P = .092) to have higher baseline insulin concentrations than horses fed three MPD. In addition, baseline glucose-to-insulin ratio (GIR) was higher in horses fed high NSC compared with low NSC (P < .001). Horses fed high NSC had higher area under the curve of insulin and higher peak insulin after feeding than those fed low NSC. These findings suggest that NSC content of a concentrate feed has an impact on baseline insulin and GIRs and on postprandial insulin concentrations. Meanwhile, the number (and therefore size) of MPD had fewer impacts on glucose metabolism.     

Plasma ghrelin concentration is decreased by short chain fatty acids in wethers

To examine the effects of short chain fatty acids (SCFAs) on plasma ghrelin concentration, 4 wethers were injected intravenously with SCFA solutions [acetate (ACE), propionate (PRO), and butyrate (BUT) (0.8 mmol/kg BW)] and saline. The experiment was conducted after a 4 × 4 Latin square design. Each solution was injected into the jugular vein catheter with blood samples taken at −10, 0, 5, 10, 15, 20, 25, 30, 40, 50, and 60 min relative to the injection time also from this catheter. Plasma ghrelin concentrations decreased after injection with ACE, PRO, and BUT. Although plasma glucose concentrations increased after injection with PRO and BUT (P < 0.05), the increment areas were greater with BUT than with PRO. Plasma insulin concentrations increased after injection with PRO and BUT (P < 0.05). The decrement areas in plasma ghrelin concentrations were equal in ACE, PRO, and BUT. These data suggest that SCFAs inhibit ghrelin secretion in wethers and not through increased circulating glucose and insulin as previously proposed.     

Postprandial Blood Glucose and Insulin Responses of Horses to Feeds Differing in Soluble Fiber Concentration

In humans, the consumption of soluble fibers reduces glycemic response after a meal. We hypothesized high soluble fiber diets would reduce and delay postprandial glucose and insulin responses in horses. In a 4 × 4 Latin square design experiment, four Quarter Horse geldings were adapted to diets containing orchardgrass hay (ORCH) or ORCH with 1 of 3 treatment ingredients: molassed sugar beet pulp (BEET), almond hulls (HULL), or steam-crimped oats (OATS). Blood was serially sampled for 6 hours after feeding 0.15% body weight (BW) of the treatment ingredient (meal test) or 1.1 g starch/kg BW from oats plus the treatment ingredient (starch test) to evaluate glycemic and insulinemic responses. Glycemic response during the meal test peaked between 60 and 90 min after feeding (P < .05) and tended to be altered by diet (P = .071) and diet × time (P = .076). Serum insulin was affected by diet (P = .008), time (P < .001), and diet × time (P < .001) during the meal test, with concentrations lower in ORCH compared with BEET and OATS (P < .05). In the starch test, glucose was lower (P < .05) in ORCH and HULL compared with BEET and insulin was lower (P = .046) in ORCH compared with BEET. In both tests, horses took longer (P < .05) to consume HULL, likely influencing postprandial responses. Future research integrating the functional properties of feeds with physiological responses will be necessary to elucidate how soluble fiber affects postprandial glucose metabolism in horses.     

Characteristics of prolactin-releasing response to salsolinol in vivo in cattle

The aims of the present study were to clarify the effect of salsolinol (SAL), a dopamine (DA)-derived endogenous compound, on the secretion of prolactin (PRL) in cattle. The experiments were performed from April to June using calves and cows. A single intravenous (i.v.) injection of SAL (5 mg/kg body weight [BW]) or sulpiride (a DA receptor antagonist, 0.1 mg/kg BW) significantly stimulated the release of PRL in male and female calves (P < 0.05), though the response to SAL was smaller than that to sulpiride. The secretory pattern of PRL in response to SAL or sulpiride in female calves resembled that in male calves. A single i.v. injection of SAL or sulpiride significantly stimulated the release of PRL in cows (P < 0.05). There was no significant difference in the PRL-releasing response between the SAL- and sulpiride-injected groups in cows. A single intracerebroventricular injection of SAL (10 mg/head) also significantly stimulated the release of PRL in castrated calves (P < 0.05). These results show that SAL is involved in the regulatory process for the secretion of PRL, not only in male and female calves, but also in cows. The results also suggest that the potency of the PRL-releasing response to SAL differs with the physiological status of cattle.     

Impact of feeding on growth performance,blood biochemical and mineral profiles of pre-pubescent camels under pastoral management in arid western Rajasthan

The experiment was undertaken on 20 pre-pubescent dromedary camels of 300?±?7.0 kg average bodyweight (BW) and 1.5–2 years of age to determine change in body weight, blood biochemical and mineral profiles and morphometric parameters on rangeland grazing (GR) and supplementary stall feeding (GS) at arid northwestern part of Rajasthan over a period of 80 days. GR camels were maintained only on grazing, while GS camels were fed semi-intensively ad-lib groundnut haulms along with formulated concentrate and mineral mixture to meet maintenance requirement. Intake of young camels was determined using chromium(III) oxide as internal marker. The biomass yield of rangeland estimated was 0.54 t DM/ha. Dry matter intake (kg/day) by GR camels on rangeland grazing was lower than that by GS camels fed on supplementary feeding. The nutrient digestibility of dry matter and organic matter (P?<?0.05) and crude protein was higher in GS camels than that in GR camels. Likewise, intake of digestible crude protein (P?<?0.05) and metabolizable energy were higher in stall-fed young camels. Pre-pubescent camels fed on grazing had significantly (P?<?0.01) low glucose and higher urea concentration compared to stall-fed camels. Final body weight of camels differed significantly (P?<?0.05) between groups. The camels fed on supplementary stall feeding had significantly (P?<?0.01) higher total gain (kg) and average daily gain (ADG) compared to camels on grazing. Among morphometric parameters, body length and body height showed more significant increase in GS compared to GR camels. Intake of digestible crude protein (DCP) by GR group was 43 % low compared to the requirement for growing camel of 300 kg body weight. Despite this, GR camels were able to maintain body weight due to better recycling of urea which was significantly higher in comparison to GS camels. The findings of significantly (P?<?0.01) low serum glucose and higher urea concentration and lower body weight gain of GR camels suggest the need of locally available protein and energy supplement in addition to grazing for better growth performance.     

Markers for Predicting Overweight or Obesity of Broodmares

Obesity has become of great concern to all equine community from both veterinary and welfare points of view. For estimating obesity markers of brood mares, 17 mares with body conditions were subjected to blood sampling and ultrasound examination to measure rump fat for 6 consecutive weeks. Body length (L), girth (G), and height (H) were measured to estimate body weight (BW), body fat %, body fat mass (BFM) and body mass index (BMI). Mares were classified into three groups according to body condition score (BCS) and rump fat thickness (RF). Overweight mares (O) had BCS >7 and RF >7 mm, moderate (M) had BCS and RF >3 to ≤7, and emaciated (E) had BCS and RF ≤ 3 mm. Glucose, triglycerides, nitric oxide (NO), insulin, insulin-like growth factor-I (IGF-1), leptin, ovarian hormones, and thyroid hormones were measured. Results revealed that BCS, G, L, L × G × H, BW, RF, fat %, and BFM correlated significantly (P < .0001) with body condition. Tetraiodothyronine concentrations of E mares were significantly high (P = .04), but triiodothyronine concentrations tended (P = .07) to be low. Insulin (P = .06) and IGF-1 (P = .07) concentrations tended to be high in O mares. Moderate mares had the highest leptin concentrations (P = .007), but E mares had the lowest P4 concentrations (P = .01). Overweight mares had nonsignificantly high glucose, NO, and triglycerides. In conclusion, back fat and morphometric measurements are the easiest and simple assessment of overweight and obesity. Obese and overweight mares showed slight hyperinsulinemia, hypertriglyceridemia, and hyperglycemia. Hyperleptinemia alone is not indicative of obesity.     

Associations between meal size,gastric emptying and post‐prandial plasma glucose,insulin and lactate concentrations in meal‐fed cats

Plasma glucose and insulin concentrations are increased for 12–24 h in healthy cats following moderate‐ to high‐carbohydrate meals. This study investigated associations between gastric emptying time and post‐prandial plasma glucose, insulin and lactate concentrations in cats fed an extruded dry, high‐carbohydrate, moderate‐fat, low‐protein diet (51, 28, 21% metabolizable energy, respectively) once daily by varying meal volume. Eleven healthy, non‐obese, neutered adult cats were enrolled in a prospective study and fed to maintain body weight. Ultrasound examinations were performed for up to 26 h, and blood collections over 24 h after eating meals containing approximately 100% and 50% of the cats’ daily caloric intake (209 and 105 kJ/kg BW, respectively). Gastric emptying time was increased after a meal of 209 kJ/kg BW compared with 105 kJ/kg BW (median gastric emptying times 24 and 14 h, respectively; p = 0.03). Time for glucose to return to fasting was longer after the 209 kJ/kg BW meal (median 20 h; 25th and 75th percentiles 15 and 23 h, respectively) than the 105 kJ/kg BW meal (13, 12 and 14 h; p < 0.01); however, peak glucose was not higher after the 209 kJ/kg BW meal compared with the 105 kJ/kg BW meal [(mean ± SD) 6.6 ± 0.6 and 7.8 ± 1.2 mmol/l, respectively, p = 0.07]. Times for insulin to return to fasting were not significantly longer after the 209 kJ/kg BW meal than the 105 kJ/kg BW meal (p = 0.29). d ‐ and l ‐lactate concentrations were not associated with gastric emptying time or post‐prandial blood glucose and insulin. Based on results obtained, prolonged gastric emptying contributes to prolonged post‐prandial hyperglycemia in cats meal fed a high‐carbohydrate, low‐protein, dry diet and fasting times for cats’ meal‐fed diets of similar composition should be 14–26 h, depending on meal size.     

Long-term Treatment of Insulin-insensitive Mares with Cabergoline: Effects on Prolactin and Melanocyte Stimulating Hormone Responses to Sulpiride and on Indices of Insulin Sensitivity

The main experiment assessed whether the inhibitory effects of the dopamine agonist, cabergoline, on prolactin and α-melanocyte stimulating hormone (MSH) concentrations would persist throughout a longer-term administration (65 days). The possible effect of cabergoline on insulin sensitivity was also studied. Ten mares known to be insulin insensitive were allotted to two groups (treated vs. control). An insulin challenge, a glucose tolerance test, and a sulpiride challenge were administered before treatment. On day 0, treated mares (n = 5) received an injection of 5 mg cabergoline in slow-release vehicle; control mares (n = 5) received an equivalent vehicle injection. Injections were repeated every 10 days for a total of seven injections. Sulpiride challenges were done 1 day before each cabergoline treatment to assess possible refractoriness to the treatment. Behavior and hair coat density were also monitored. Plasma prolactin was suppressed (P < .01) to undetectable levels in mares receiving cabergoline; control mares had robust prolactin responses to each sulpiride injection. There was no indication of refractoriness to cabergoline over time. Plasma MSH concentrations after sulpiride were also suppressed (P < .05) by cabergoline. After treatment, neither the glucose response to insulin nor the insulin response to glucose differed (P > .1) between groups. No behavioral changes were noted because of treatment. Weight of hair samples indicated that cabergoline perturbed (P < .05) winter coat growth. It is concluded that 5 mg of cabergoline in slow-release vehicle administered every 10 days is an effective way of delivering dopaminergic activity to mares that results in no noticeable detrimental effects and no refractoriness to the drug.     

Dose-Response of Prolactin to Increasing Doses of the Dopamine Receptor Antagonist,Sulpiride, in Horses: Effect of Season in Mares and Stallions of Estradiol Pretreatment in Geldings

Two experiments were performed to determine whether dopaminergic input to the adenohypophysis (1) differs across seasons in mares and stallions proportionally with changes in prolactin secretion and (2) is altered by estradiol administration in geldings. In experiment 1, prolactin responses to increasing doses of l-sulpiride in eight mares and eight stallions in March, June, September, and December were used to estimate the theoretical dose equivalent to 50% of maximal response. Prolactin areas increased (P < .001) with increasing doses of sulpiride and were greatest (P < .05) in March for stallions, but in June for mares. Mean half-maximal dose, which was assumed to be proportional to the dopaminergic input to the pituitary, was lowest (P < .05) in June and greatest in September. Experiment 2 used the same approach to determine whether the stimulatory effect of estradiol pretreatment on prolactin secretion was associated with an alteration of the half-maximal response. Geldings (n = 6/group) were administered 100 mg of estradiol cypionate in oil, or oil alone, on day 0 (October 3) and increasing doses of l-sulpiride starting on day 6. Estradiol treatment increased (P < .08) the prolactin response to l-sulpiride at 0.41 μg/kg body weight and all higher doses (P < .05); mean half-maximal dose did not differ (P > .1) between groups. We conclude that dopaminergic input to the adenohypophysis of mares and stallions varies with season and that the stimulatory effect of estradiol on prolactin secretion is not associated with a decrease in dopaminergic input to the adenohypophysis.     

Glycemic and Insulinemic Responses Are Affected by Age of Horse and Method of Feed Processing

The objective of this study was to examine age-related differences in glycemic and insulinemic responses of horses that were fed various feedstuffs, with particular attention to method of feed processing. A 16 × 16 Latin square design was used with eight 2-year-olds and eight mature Arabians. Horses were maintained on a roughage diet and were subjected to a glycemic response test once weekly. A control treatment consisted of an oral dextrose drench (0.25 g dextrose/kg of BW). Ten treatments consisted of variously processed feed ingredients fed at the rate of 1.5 g/kg of BW. Five other treatments were commercial feeds of a proprietary nature and are not reported. Fasting blood samples were taken once a week for 16 weeks. Thirty minutes later, another baseline sample was taken and horses were administered their respective treatment. Further blood samples were taken every 30 minutes through four hours. Samples were analyzed for glucose and insulin concentrations. Differences in glucose response between 2-year-olds and mature horses were minimal. However, mature horses had a higher insulin response (P < .01) suggesting young horses had greater insulin sensitivity. Additionally, differences (P < .05) existed between treatments with pelleted steam-processed corn having the highest glycemic response and cracked corn the lowest. Results from this study confirm that mature horses have reduced insulin sensitivity and that both glycemic and insulinemic responses are altered with feed processing techniques. Thermal processing produces the greatest response; however, a low glycemic response may not be desirable if starch escapes into the hindgut.     

Factors Affecting the Rate and Measurement of Feed Intake for a Cereal-Based Meal in Horses

The rapid intake of high-cereal, low-roughage meals may cause gastrointestinal and behavioral disorders. We investigated some of the factors that can affect the rate of intake (ROI) in four separate studies. Study 1 investigated the effect of chaff length and addition rate on the ROI of oats. The ROI decreased as more chaff was added to the diet, attaining significance (P < .05, n = 6) at levels above 15% addition and reaching a plateau at ∼50%. This was independent of stalk length (1.4 cm vs. 4.1 cm). Study 2 showed that meal size (varying from 0.5 to 4 g/kg BW) did not affect the ROI for a cereal-based meal, nor was ROI altered by the addition of 10% molasses (n = 6). Study 3 demonstrated that ROI changed markedly over the course of a meal, commencing at an average rate of 74 g/minute for the first 5 minutes and decreasing to 15.8 g/minute after 30 minutes (n = 6). Study 4 examined the effects of breed, BW, exercise, and gender in 71 horses. In Clydesdales, BW affected ROI (P < .05), and Clydesdales had a faster ROI than Thoroughbreds of similar BW (81.8 ± 6.8 vs. 66.0 ± 3.35 g/minute; P < .05). Exercise level, age, and gender did not impact ROI significantly. The results highlight the effectiveness of feeding chaff to slow ROI and demonstrate the need for a standardized protocol if ROI is to be compared between different studies.     

Effect of ω-3 Fatty Acid Supplementation to Gestating and Lactating Mares: On Milk IgG,Mare and Foal Blood Concentrations of IgG,Insulin and Glucose,Placental Efficiency,and Fatty Acid Composition of Milk and Serum From Mares and Foals

Limited research has been conducted to evaluate effects of fatty acid (FA) supplementation on mare and foal FA profiles and foal immunity. Dietary polyunsaturated FAs, particularly ω-3 FAs, increase fluidity of intestinal cell membranes. Fluidity of mammary tissues may also be altered to allow more incorporation of immunoglobulin G (IgG) into milk. Therefore, the goal of this study was to determine effects of incorporating dietary ω-3 FAs on mares, her milk, and her subsequent foal. Pregnant mares were assigned to one of three diets beginning 28 days before expected foaling date until 84 days after foaling. Diet 1 was a commercial feed (CON); diet 2 was diet 1 plus a fish oil blend (FO); and diet 3 was diet 1 plus a blend of fish and soybean oil (FSO). Mare serum FA concentrations were not affected by treatment (P > .05) with the exception of 20:5, which had a treatment × time interaction (P < .05). Mare milk FA concentrations were not affected by treatment (P > .05) with the exception of 16:1 and 20:5. Foal serum FA concentration was not affected by treatment with the exception of 18:2, which had a treatment × time interaction, and 20:5 (P < .0001), which was greatest in FO foals and least in CON foals. Dietary supplementation of ω-3 FAs did increase 20:5 in mare serum, milk, as well as serum of their subsequent foals. No differences were found for mare plasma IgG (P = .1318), serum insulin (P = .3886), plasma glucose (P = .2407), or milk IgG (P = .1262) concentrations for treatment. Foal plasma IgG (P = .2767), serum insulin (P = .4843), or plasma glucose (P = .1204) were not affected by treatment. Omega-3 FA in mare serum, milk, and foal serum were able to be manipulated by diet; however, IgG concentration was unchanged.     

Effect of phentolamine mesylate on regression of lidocaine–epinephrine epidural anaesthesia in sheep

ObjectiveTo determine the impact of epidural phentolamine on the duration of anaesthesia following epidural injection of lidocaine–epinephrine.Study designBlinded randomized experimental study.AnimalsA group of 12 adult ewes weighing 25.7 ± 2.3 kg and aged 8–9 months.MethodsAll sheep were administered epidural lidocaine (approximately 4 mg kg^–1) and epinephrine (5 μg mL^–1). Of these, six sheep were randomized into three epidural treatments, separated by 1 week, administered 30 minutes after lidocaine–epinephrine: SAL: normal saline, PHE1: phentolamine (1 mg) and PHE2: phentolamine (2 mg). The other six sheep were administered only epidural lidocaine–epinephrine: treatment LIDEP. Each injection was corrected to 5 mL using 0.9% saline. Noxious stimuli were pinpricks with a hypodermic needle and skin pinch with haemostatic forceps to determine the onset and duration of sensory and motor block. Heart rate, noninvasive mean arterial pressure (MAP), respiratory rate and rectal temperature were recorded.ResultsThe onset times were not different among treatments. Duration of sensory block was significantly shorter in SAL (57.5 ± 6.2 minutes), PHE1 (60.7 ± 9.0 minutes) and PHE2 (62.0 ± 6.7 minutes) than in LIDEP (81.7 ± 13.4 minutes) (p < 0.05). Duration of motor blockade was significantly shorter in PHE1 (59.4 ± 5.4 minutes) and PHE2 (54.3 ± 4.0 minutes) than in SAL (84.8 ± 7.0 minutes) and LIDEP (91.5 ± 18.2 minutes) (p < 0.01). MAP in PHE2 was decreased at 10 minutes after administration of phentolamine (p < 0.05).Conclusion and clinical relevanceEpidural administration of 5 mL normal saline after epidural injection of lidocaine–epinephrine reduced the duration of sensory but not motor block in sheep. Epidural administration of phentolamine diluted to the final volume of 5 mL diminished both the duration of sensory and motor block in sheep administered epidural lidocaine–epinephrine.     

Effects of 2 different medetomidine infusion rates on selected neurohormonal and metabolic parameters in dogs

The effects of 2 different 8-hour continuous rate infusions (CRIs) of medetomidine on epinephrine, norepinephrine, cortisol, glucose, and insulin levels were investigated in 6 healthy dogs. Each dog received both treatments and a control as follows: MED1 = 2 μg/kg bodyweight (BW) loading dose followed by 1 μg/kg BW per hour CRI; MED2 = 4 μg/kg BW loading dose followed by 2 μg/kg BW per hour CRI; and CONTROL = saline bolus followed by a saline CRI. Both infusion rates of medetomidine decreased norepinephrine levels throughout the infusion compared to CONTROL. While norepinephrine levels tended to be lower with the MED2 treatment compared to the MED1, this difference was not significant. No differences in epinephrine, cortisol, glucose, or insulin were documented among any of the treatments at any time point. At the low doses used in this study, both CRIs of medetomidine decreased norepinephrine levels over the 8-hour infusion period, while no effects were observed on epinephrine, cortisol, glucose, and insulin.     

Associations between endotoxin‐induced metabolic changes and temperament in Brahman bulls,

The influence of temperament on the alteration of metabolic parameters in response to a lipopolysaccharide (LPS) challenge was investigated. Brahman bulls were selected based on temperament score. Bulls (10 months; 211 ± 5 kg BW; n = 6, 8 and 7 for Calm, Intermediate and Temperamental groups, respectively) were fitted with indwelling jugular catheters to evaluate peripheral blood concentrations of glucose, blood urea nitrogen (BUN), non‐esterified fatty acids (NEFA), insulin, epinephrine and cortisol before and after LPS administration (0.5 μg/kg BW LPS). Feed intake was also recorded. Intermediate bulls consumed more feed than the Temperamental bulls during the challenge (p = 0.046). Pre‐LPS glucose (p = 0.401) and BUN (p = 0.222) did not differ among the temperament groups. However, pre‐LPS insulin (p = 0.023) was lower, whereas pre‐LPS NEFA (p < 0.001), cortisol (p < 0.001) and epinephrine (p < 0.001) were greater in Temperamental than in Calm and Intermediate bulls. Post‐LPS glucose was increased in Calm and Intermediate bulls but not in Temperamental bulls (p < 0.001). Insulin concentrations post‐LPS were greater in Calm than in Intermediate and Temperamental bulls (p < 0.001). Concentrations of NEFA post‐LPS were greater in Temperamental than in Calm and Intermediate bulls (p < 0.001). Serum BUN concentration increased post‐LPS, with values being greater in Calm and Intermediate than in Temperamental bulls (p = 0.012). Collectively, these data demonstrate that animal temperament is related to the metabolic responses of Brahman bulls following a provocative endotoxin challenge. Specifically, Temperamental bulls may preferentially utilize an alternate energy source (i.e. NEFA) to a greater degree than do bulls of Calm and Intermediate temperaments. The use of circulating NEFA from lipolysis may reduce the negative metabolic consequences of an immune response by allowing for a prompt answer to increasing energy demands required during immunological challenge, compared with the time required for glycogenolysis and gluconeogenesis.     

Nutritional strategies for heifers under grazing system: productive and nutritional performance,metabolic profile and ovarian activity

The objective of this study was to evaluate the effects of nutritional strategies on productive and nutritional performance, metabolic profile, and ovarian activity in heifers under grazing in the tropics in Brazil. Forty Nellore heifers averaging 8.5?±?0.06 months and 248.6?±?3.3 kg body weight (BW) were distributed in a completely randomized 2?×?2 factorial design with four treatments and ten replicates. The evaluated strategies consisted of different amounts of energetic-protein supplement: (1) 4 g/kg of BW of supplement in the pre-weaning and post-weaning; (2) 4 g/kg of BW of supplement pre-weaning and 6 g/kg in the post-weaning; (3) 6 g/kg of BW of supplement in the pre-weaning and 4 g/kg of BW in the post-weaning and; (4) 6 g/kg of BW of supplement in the pre-weaning and post-weaning. Crude protein (CP) and organic matter (OM) intake were increased (P?<?0.05) by increasing the amounts of supplement in the post-weaning. Additionally, increasing supplement amounts in the post-weaning increased the digestibility of OM and CP (P?<?0.05). Means insulin and glucose concentrations were greater (P?<?0.05) for heifers that received higher amounts of supplement in the post-weaning. Average daily gain and fat thickness in the rump were increased (P?<?0.05) by increasing supplement amounts in the post-weaning. Amounts of supplement did not influence the body growth of heifers. However, follicular number, diameter, and progesterone concentration were greater (P?<?0.05) for heifers that received higher amounts of supplement in the post-weaning. In summary, increasing supplement amounts in the post-weaning improve the performance, energy and metabolic status, and ovarian activity in beef heifers under grazing in the tropics. Due to higher intake of supplement, the heifers receiving 6 g/kg of BW post-weaning had greater responses, independently of the supplement amount received pre-weaning.