Secretion and clearance rates of glucagon in dairy cows

Eight Holstein cows were sampled to examine plasma concentrations of hormones and some energy related metabolites. Sampling was every hour for 12 h at about 2 wk prepartum, at 3 wk postpartum, during an energy restriction ketonemia, and after a recovery period. Cows were fed ad libitum except for four cows induced into ketonemia by restricting feed intake 50%. Pulse doses of glucagon were injected intravenously during each period. Feed restriction increased concentrations of growth hormone, acetoacetate, beta-hydroxybutyrate, and free fatty acids in blood plasma. Concentrations of insulin and glucose showed some tendencies to decrease. Distribution space and turnover rate of glucagon were not different between periods, and pool size was increased in the dry period. Metabolic clearance rate of glucagon was not significantly different between periods. Insulin and glucose concentrations were increased 1 to 2 min after injection of glucagon and remained increased for 25 min. Covariance analysis showed that glucagon injection caused glucose concentration to increase proportionally in all periods, suggesting that cows had equal gluconeogenic capacity in all periods. Basal concentration, pool size, and secretion rate of glucagon showed some tendency to be decreased during ketonemia.     

Effect of six Korean plants on glucagon like peptide-1 release

Food Science and Biotechnology - Glucagon like peptide-1 (GLP-1) plays a major role in the regulation of energy homeostasis as it causes satiety and suppresses appetite. Angelica dahurica,...     

Potential treatment of fatty liver with 14-day subcutaneous injections of glucagon

Fatty liver is a major metabolic disease of dairy cows in early lactation that can be treated with 14-d continuous, intravenous infusions of 10 mg/d of glucagon. The objective was to test whether similar effects can be obtained with 14-d subcutaneous 7.5- or 15-mg daily dosages of glucagon beginning at d 8 postpartum. Multiparous Holstein cows (n = 32) were grouped on the basis of their liver triacylglycerol concentration at d 8 postpartum into "normal" (n = 8; triacylglycerol < 1% liver wet wt) and "susceptible" (n = 24; triacylglycerol > 1% liver wet wt) cows. Susceptible cows were assigned randomly to three groups and beginning at d 8 postpartum received 0, 2.5, or 5 mg of glucagon in 60 ml of saline by subcutaneous injections every 8 h for 14 d. Beginning at d 8 postpartum, normal cows received 60 ml of saline by subcutaneous injections every 8 h for 14 d. Both dosages of glucagon increased concentrations of plasma glucose and insulin and decreased concentrations of plasma nonesterfied fatty acids. Glucagon injections of 15 mg/d decreased concentrations of liver triacylglycerol in cows older than 3.5 yr, but not in younger multiparous cows. Our results document that subcutaneous injections of glucagon have the potential to decrease the degree of fatty liver in older dairy cows in early lactation.     

Prevention of fatty liver in transition dairy cows by subcutaneous injections of glucagon

The main objective of this study was to test the extent to which injecting glucagon subcutaneously for 14 d beginning at d 2 postpartum would prevent fatty liver development in transition dairy cows. Twenty-four multiparous Holstein cows were fed 6 kg of cracked corn in addition to their standard diet during the last 30 d of a dry period to induce postpartum development of fatty liver. Glucagon at either 7.5 or 15 mg/d or saline (control) was injected subcutaneously 3 times daily for 14 d beginning at d 2 postpartum. Glucagon at 15 mg/d prevented liver triacylglycerol accumulation in postpartum dairy cows. Glucagon at 7.5 mg/d showed potential for fatty liver prevention. Glucagon increased concentration of plasma glucose and insulin and decreased plasma nonesterified fatty acid concentrations. No effects of glucagon were detected on plasma β-hydroxybutyrate concentrations. Glucagon affected neither feed intake nor milk production. Moreover, milk composition was not altered by glucagon. Milk urea N concentrations decreased, and plasma urea N concentrations tended to decrease during glucagon administration, indicating that glucagon may improve protein use. Liver glycogen concentrations were not affected by glucagon. No significant differences in body condition scores were detected among treatments throughout the study. These results indicate that subcutaneous glucagon injections can prevent fatty liver in transition dairy cows without causing major production and metabolite disturbances.     

Metabolic responses of lactating dairy cows to single and multiple subcutaneous injections of glucagon

Continuous, intravenous infusions of glucagon improve carbohydrate status in lactating dairy cows without increasing concentrations of plasma NEFA. The objective was to test whether single subcutaneous injections and multiple subcutaneous injections of glucagon delivered at 8-h intervals over 14 d improve the carbohydrate status in lactating dairy cows without increasing concentrations of plasma BHBA and NEFA. In a single-injection experiment, four midlactation cows each were injected with 2.5 and 5 mg of glucagon 1 wk apart. In a multiple-injection experiment, nine cows, assigned randomly to three treatments, were injected subcutaneously with 0, 2.5, or 5 mg of glucagon every 8 h for 14 d, beginning at d 8 postpartum. Single subcutaneous injections of glucagon increased concentrations of plasma glucagon and single and multiple subcutaneous injections of glucagon increased concentrations of plasma glucose, with larger increases at the 5-mg dosage. Injections of 5 mg of glucagon increased concentrations of plasma insulin in both experiments, whereas the 2.5-mg dosage increased plasma insulin only in the multiple-injection experiment. The response of glucose and insulin to injections of 5 mg of glucagon persisted throughout the 14-d injection period. Concentrations of plasma NEFA decreased in the single-injection experiment, and concentrations of BHBA decreased after 5 mg of glucagon was injected in the multiple-injection experiment. These results document that both single and multiple injections of 5 mg of glucagon over 14 d consistently improve the carbohydrate status of dairy cows and decrease concentrations of plasma NEFA and BHBA.     

Effects of exogenous glucagon on lipids in lipoproteins and liver of lactating dairy cows

Decreased concentrations of phospholipids, free cholesterol, and cholesteryl ester in plasma and liver are associated with fatty liver, a major metabolic disease of dairy cows in early lactation. The objective was to test whether daily subcutaneous injections of 7.5 and 15 mg of glucagon, which can decrease concentrations of liver triacylglycerol, affect concentrations of plasma lipoprotein components and liver lipids other than triacylglycerol. Multiparous Holstein cows (n = 32) were grouped on the basis of liver triacylglycerol concentrations at d 8 postpartum into "normal" (n = 8; triacylglycerol <1% liver wet wt) and "susceptible to fatty liver" (n = 24; triacylglycerol >1% liver wet wt) cows. Susceptible cows were assigned randomly to three groups and beginning at d 8 postpartum received 0 (same for Normal cows), 2.5, or 5 mg of glucagon by subcutaneous injections every 8 h for 14 d. In comparison to saline injections, subcutaneous injections of glucagon either increased or tended to increase concentrations of phospholipids and free cholesterol in liver, with greater increases of the latter during ambient temperatures below 35 degrees C. Glucagon injections decreased or tended to decrease concentrations of very low-density lipoprotein-triacylglycerol, high-density lipoprotein1-phospholipids, and high-density lipoprotein2-free cholesterol in plasma, with no changes of the latter two during ambient temperatures below 35 degrees C. The results indicate that subcutaneously administered glucagon has only minor effects on the lipid transport in plasma of dairy cows in early lactation with more beneficial effects occurring during ambient temperatures below 35 degrees C and, most importantly, no indications that glucagon has negative effects.     

Metabolic responses of lactating dairy cows to 14-day intravenous infusions of glucagon.

Twenty cows were assigned at parturition to two groups to study metabolic effects of continuous intravenous infusions of glucagon. Groups were control cows and cows treated with glucagon at 10 mg/d for 14 d starting at d 21 postpartum. Daily blood samples and nine liver biopsies were taken from d 7 to 49 postpartum. Plasma glucagon increased six- to seven-fold during infusions of treated cows. Plasma insulin was increased heterogeneously by glucagon infusions. Plasma glucose increased 11.5 and 9.0 mg/dl during wk 1 and 2 of glucagon infusions. No other plasma metabolites tested (nonesterified fatty acids, beta-hydroxybutyrate, and urea N) were affected by glucagon infusions. Liver glycogen decreased by d 2 of glucagon infusion but was repleted to preinfusion values by d 7 and increased to 169% of the preinfusion baseline values at 3 d after cessation of glucagon. Milk production decreased transiently during glucagon infusions. Both milk production and milk protein percentage decreased during glucagon infusion, which could imply a decreased availability of amino acids for milk protein synthesis. Feed intakes did not increase during glucagon infusions, which was in contrast to the control group. Results indicated that glucagon infusions caused liver glycogenolysis initially and probably enhanced gluconeogenesis but glucagon did not appear to increase lipolysis from adipose tissue in these early lactating dairy cows.     

Metabolic responses of dairy cows and heifers to various intravenous dosages of glucagon.

To evaluate the ability of glucagon to improve carbohydrate status in dairy cows without an increase in blood lipids, glucagon was infused intravenously for 48 h into lactating cows and spayed heifers in three crossover experiments. During Experiment 1, glucagon (5 and 20 mg/d) was infused into four midlactation cows. Experiment 2 involved the infusion of 0, 2.5, 5.0, or 10 mg/d of glucagon into eight heifers; each heifer received two of the dosages. In Experiment 3, four early lactation cows were treated with 5 and 10 mg/d of glucagon. Glucagon consistently increased plasma glucose concentrations in a dose-dependent fashion throughout the 48-h periods. Plasma insulin was increased in a nondose-dependent manner by glucagon in Experiment 1. Plasma urea N was increased when glucagon was administered at 5 mg/d during Experiment 2 and tended to be decreased during Experiment 3. Nonesterified fatty acids in plasma were, in most cases, not affected; however, they were increased by glucagon at 10 mg/d during Experiment 2. Concentrations of beta-hydroxybutyrate were increased only by the 20-mg/d dosage. During Experiment 1, liver glycogen concentrations decreased by 2.1% (wet weight basis) for both dosages of glucagon, and concentrations of total lipid in the liver were increased by 0.6% (wet weight basis) by 20 mg/d of glucagon. Milk fat percentage was increased by glucagon, but milk volume and milk protein production were decreased during Experiment 1. Glucagon improved carbohydrate status over the 48-h periods in all experiments but did not increase plasma nonesterified fatty acids except at the 10-mg/d dosage in Experiment 2.     

Alleviation of fatty liver in dairy cows with 14-day intravenous infusions of glucagon.

Twenty multiparous cows were fed additional concentrate during the final 30 d prepartum to cause susceptibility to fatty liver. From 14 to 42 d postpartum, all cows were subjected to a protocol to induce fatty liver and ketosis. To test glucagon as a treatment for fatty liver, either glucagon at 10 mg/d or excipient was infused via the jugular vein from 21 to 35 d postpartum. All cows had fatty liver at 14 d postpartum and became ketonemic and hypoglycemic during the induction of ketosis. Glucagon increased plasma glucose to 142% of that of controls throughout the 14-d treatment. The hypoinsulinemia present in cows with fatty liver was not affected by glucagon. Plasma beta-hydroxybutyrate and nonesterified fatty acids were decreased by glucagon. At 6 d postpartum, liver triacylglycerol averaged 12.9% of liver (wet weight basis). Glucagon had decreased triacylglycerol content of livers by 71% at d 35. Glycogen was 1.0% of the wet weight of livers at 6 d in milk, but it was decreased by glucagon to 0.5% at 2 d after glucagon began. Glycogen then increased in cows treated with glucagon until at 38 d in milk liver glycogen was 3.7% versus 1.6% in controls. Our results document that glucagon decreases the degree of fatty liver in early lactation dairy cows, which also decreases the incidence of ketosis after alleviation of fatty liver.     

Effects of short-term glucagon administration on gluconeogenic enzymes in the liver of midlactation dairy cows

During lactation, the dairy cow experiences an increased demand for glucose to support milk production. Increased glucose demand can be met through increased capacity for gluconeogenesis, increased supply of glucose precursors, or a combination of both processes. Glucagon, a key hormone in glucose homeostasis, acts to promote gluconeogenesis and increase glucose output from liver. The objective of this study was to determine the effect of short-term administration of glucagon on expression of gluconeogenic enzymes in lactating dairy cattle. Sixteen multiparous Holstein cows were selected from the Purdue University Animal Sciences Dairy Research Center herd. Cows were stratified on the basis of milk production and days in milk and randomly assigned to either a saline or glucagon injection group (n = 8 per group). Cows were injected subcutaneously at −21, −14, −7, and 0 h relative to final glucagon and saline injections with either 3.75 mg of lyophilized bovine glucagon (15 mg/d) dissolved in 60 mL of 0.15 M NaCl (pH 10.25) or 60 mL of 0.15 M NaCl. Liver biopsy samples were obtained 1 wk before injection to establish baseline values and at 3 h after cows received final glucagon and saline injections. Biopsy samples were analyzed for mRNA abundance, enzyme activity, protein abundance, and in vitro measures of gluconeogenesis. Glucagon did not alter pyruvate carboxylase or cytosolic phosphoenolpyruvate carboxykinase (PEPCK) mRNA abundance, enzyme activity, or protein abundance, although there was a tendency for greater mRNA expression with the glucagon treatment (4.69 vs. 6.78, arbitrary units). Glucagon injections did not change mitochondrial PEPCK mRNA expression. Gluconeogenesis from 2.5 mM [2-¹⁴C]propionate and 2.0 mM [U-¹⁴C]lactate was similar in liver biopsy samples from glucagon-treated and control cows. There was no effect of glucagon on dry matter intake and milk production. Glucose, nonesterified fatty acids, β-hydroxybutyrate acid, and insulin were not altered by glucagon. Blood glucagon was elevated, 76.09 vs. 96.14 pg/mL, for cows receiving glucagon injections. The data indicate that 24-h administration of glucagon does not alter cytosolic PEPCK mRNA expression or result in immediate alterations in total PEPCK enzyme activity and gluconeogenic capacity.     

Effects of glucagon infusions on protein and amino acid composition of milk from dairy cows

Changing the composition of milk proteins and AA affects the nutritional and physical properties of dairy products. Intravenous infusions of glucagon decreases milk protein production and concentration by promoting the use of gluconeogenic blood AA for hepatic glucose synthesis. Little is known about how the diversion of AA to gluconeogenesis affects the composition of milk proteins and AA. The objective was to quantify changes in composition of milk protein and AA in response to i.v. glucagon infusions. Three separate experiments were used: 1) 8 Holstein cows were fed ad libitum and infused with glucagon at 10 mg/d for 14 d, 2) 7 Holstein cows were feed restricted and infused with glucagon at 10 mg/d for 14 d, and 3) 4 Brown Swiss cows were infused with glucagon at 5 and 10 mg/d for 2 d each. Milk and milk component yields and milk protein and amino acid composition of samples, collected with blood samples at the first and last day of the glucagon infusion period, were compared with those collected 1 d before and after the glucagon infusion period. Glucagon infusions decreased milk protein production and concentration in each experiment by at least 0.2 ± 0.05 kg/d and 4 ± 0.4 g/L, respectively. The decrease was accompanied by changes in milk protein composition, the most consistent being an increase in κ-casein (1.68 ± 0.27%). Overall, glucagon infusions resulted in higher proportions of κ-casein and α_S2-casein (1.34 ± 0.51%) and smaller proportions of α_S1-casein (−3.83 ± 1.75%) and α-lactalbumin (−0.91 ± 0.32%). Glucagon had little impact on milk AA composition except an increase in glycine (0.26 ± 0.11%). The results suggest that milk protein synthesis is regulated by many factors including AA and glucose availability.     

Effect of food on blood levels of insulin, glucagon and C-peptide in gastroduodenal pathology]

Insulin, glucagon and C-peptide content in the blood was assayed with the use of commercial radioimmune kits (Diagnostic, USA, and Oris, France). A total of 93 peptic ulcer patients (35 with duodenal peptic ulcer, 28 with gastric ulcer, 16 after Billroth-I resection, and 14 after Billroth-II resection) and 25 patients with chronic gastritis attended by secretory insufficiency were investigated. The study was conducted on empty stomach and after a test breakfast containing 57 g of protein, 63 g of fat, 103 g of carbohydrates that comprised 1212 kcal. The highest changes in hormone incretion were recorded in patients with peptic ulcer disease after Billroth-I and Billroth-II resection, the lowest--in patients with chronic gastritis attended by secretory insufficiency.     

Regulation of messenger ribonucleic acid expression for gluconeogenic enzymes during glucagon infusions into lactating cows.

The effects of glucagon infusions on expression of mRNA for enzymes that regulate gluconeogenesis were studied in lactating cows. Normal cows and cows with fatty liver that were susceptible to ketosis were assigned to either glucagon-treated or control groups. Glucagon at 0 or 10 mg/d was infused for 14 d beginning at d 21 postpartum. In normal cows, glucagon infusions increased concentrations of both plasma glucagon and glucose, which caused plasma insulin to increase. Consequently, hepatic phosphoenolpyruvate carboxykinase mRNA decreased during wk 1 of glucagon infusions. Glucagon infusions into cows with fatty liver also increased plasma glucagon and glucose, but concentrations of plasma insulin and hepatic phosphoenolpyruvate carboxykinase mRNA did not change. More phosphoenolpyruvate carboxykinase mRNA was present in the livers of cows with fatty liver than in livers of normal cows. In a follow-up experiment with midlactation cows, 3.5-h infusions of glucagon at 14 mg/d increased plasma glucose and insulin and decreased plasma nonesterified fatty acids and hepatic glycogen. Hepatic phosphoenolpyruvate carboxykinase mRNA was decreased 41%, pyruvate carboxylase mRNA was increased 50%, but fructose-1,6-bisphosphatase mRNA did not change. We conclude that the expression of the hepatic phosphoenolpyruvate carboxykinase gene in normal cows is inhibited by insulin to balance elevated carbohydrate status during glucagon infusions; however, inhibited expression of hepatic phosphoenolpyruvate carboxykinase mRNA probably is not involved in the pathogenesis of lactation ketosis.     

Effect of carbohydrate structure on glucose utilization and biosynthesis of lipids, proteins and glucagon in rats]

It was established that utilization of labelled glucose depended on food carbohydrate structure. Saccharose increased 1.5-fold the labelling of lipids in the liver and lowered insignificantly glycogen labelling. Similar quantity of invert sugar sharply reduced glycogen labelling. When starch was substituted for corn syrup lipid labelling increased two-fold, while glycogen labelling decreased down to 26% of the control level. Lipid/glycogen labelling ratio in saccharose feeding was 2, in invert sugar--4, in corn syrup--17.     

Chronic metabolic responses of postpartal dairy cows to subcutaneous glucagon injections, oral glycerol, or both

We examined the long-term effects of daily subcutaneous injections of 15 mg of glucagon during the first 14 d postpartum with or without coadministration of 400 mL of pure glycerol orally on blood metabolites and hormones and liver composition of Holstein dairy cows during early lactation. Fourteen multiparous cows with body condition score of ≥3.5 points (1-5 point scale) were assigned randomly to one of 4 treatment groups—saline, glucagon, glycerol, or glucagon plus glycerol. Fatty liver syndrome was induced by feeding cows a dry-cow ration supplemented with 6 kg of cracked corn daily during the last 6 wk of the dry period. Compared with saline treatment (n = 3), coadministration of glucagon and glycerol (n = 4) increased plasma glucose and insulin and decreased plasma nonesterified fatty acid concentrations in both treatment weeks, whereas glucagon alone (n = 3) produced similar changes plus a decrease in plasma β-hydroxybutyrate in the second week only. No significant changes were observed for the glycerol alone treatment (n = 4). We conclude that a single daily dose of glycerol for the first 14 d postpartum may potentiate the action of glucagon in the first treatment days to alleviate some symptoms of fatty liver syndrome, such as the increase in plasma nonesterified fatty acids and the decrease in plasma glucose and insulin, in Holstein dairy cows after parturition.     

Acute metabolic responses of postpartal dairy cows to subcutaneous glucagon injections, oral glycerol, or both

This study examined the effects of multiple subcutaneous glucagon injections with or without co-administration of oral glycerol on energy status-related blood metabolites and hormones of Holstein dairy cows in the first 2 wk postpartum. Twenty multiparous cows were fed a dry cow ration supplemented with 6 kg of cracked corn during the dry period to increase the likelihood of developing postpartal fatty liver syndrome. Cows with a body condition score of ≥3.5 points (1- to 5-point scale) were assigned randomly to 1 of 4 treatment groups: saline, glucagon, glycerol, or glucagon plus glycerol. Following treatment, serial blood samples were collected over an 8-h period to determine the effects of glucagon and glycerol on blood metabolites and hormones. Treatment effects were determined by comparing the concentrations of metabolites and hormones during the first 4-h period and the entire 8-h period after treatment administration (time 0) with the concentration of the same compounds at time 0 on d 1, 7, and 13 postpartum. Administration of glucagon alone increased concentrations of plasma glucagon and insulin on d 1, 7, and 13 and increased plasma glucose and decreased plasma nonesterified fatty acids (NEFA) on d 7 and 13 postpartum relative to the saline group. Administration of glycerol alone increased plasma glucose on d 7 and plasma triacylglycerols on d 1 postpartum. Glycerol administration also decreased plasma glucagon and NEFA on d 1, 7, and 13 and plasma β-hydroxybutyrate (BHBA) on d 1 postpartum relative to the saline group. Administration of glucagon plus glycerol increased and sustained concentrations of plasma glucagon, glucose, and insulin on d 1, 7, and 13 and decreased plasma NEFA on d 1, 7, and 13 and BHBA on d 1 and 7. Early postpartal treatment of dairy cows with glucagon plus glycerol increased plasma glucose and insulin, decreased plasma NEFA and BHBA, and increased secretion of liver NEFA as plasma triacylglycerols. This suggests that glucagon and glycerol, when co-administered, act to decrease the likelihood of metabolism-related syndrome development in dairy cows.     

Response of insulin, glucagon, and growth hormone to intravenous glucose challenge in cows fed high fat diets

Effect of feeding high fat diets on peripheral plasma concentrations of immunoreactive insulin, glucagon, and growth hormone following intravenous glucose challenge (100 mg D-glucose/kg body weight) at 50 and 100 d of lactation in 16 multiparous Holstein cows was evaluated. The high fat diet contained 18.5% whole cottonseed on a dry matter basis as the source of extra dietary fat. Feeding the high fat diet had no apparent effect on energy balance. Basal plasma insulin and insulin:glucagon ratio were increased in cows fed the high fat diet relative to those of controls. Glucagon, insulin, and insulin:glucagon ratio response to glucose challenge were not affected by diet. Response of growth hormone to glucose challenge at 50 d of lactation was depressed in cows fed the high fat diet. Plasma glucose peaked at greater concentrations in cows fed the high fat diet. Feeding a high fat diet to dairy cows appears to increase basal insulin concentration and insulin:glucagon ratio, which has actions opposed to glucose synthesis. Thus, endocrine effects of a high fat diet appear to favor decreased milk production.     

The effect of different treatments for early-lactation hyperketonemia on blood β-hydroxybutyrate,plasma nonesterified fatty acids,glucose, insulin,and glucagon in dairy cattle

Despite increased efforts in preventing the occurrence of metabolic disorders in transition cows, hyperketonemia remains a frequent early-lactation metabolic disease affecting an average of 40% of cows in herds in the United States. Despite the demonstrated economic effect of this disorder, controlled clinical trials comparing different treatment strategies in affected cows are lacking. The objective of our study was to investigate the effect of treatment with intravenous glucose, oral propylene glycol, or a combination of both on the reduction in blood β-hydroxybutyrate (BHB) concentrations of early-lactation hyperketonemic dairy cows. Multiparous Holstein cows between 3 to 9 d in milk were screened for hyperketonemia using a handheld meter 3 times per week, and enrolled at whole blood BHB concentration ≥1.2 mmol/L to 1 of 4 treatment groups: (1) 500 mL of a 50% dextrose solution i.v. once daily for 3 d (GLU, n = 9), (2) 300 mL of propylene glycol as a drench once daily for 3 d (PG, n = 9), (3) a combination treatment of a 500 mL of 50% dextrose solution i.v. and 300 mL of propylene glycol orally once daily for 3 d (GLU+PG, n = 8), or (4) an untreated control group (CTRL, n = 8). Blood samples were collected immediately before as well as at 1, 2, 4, 8, 12, 24, 36, 48, 60, and 72 h after administration of the first treatment through a jugular catheter and 3 times per week thereafter from coccygeal vessels. Concentrations of BHB were measured in whole blood, and plasma samples were analyzed for glucose, fatty acid (NEFA), insulin, glucagon, and electrolyte concentrations. The EDTA-anticoagulated blood samples were assessed for red blood cell indices, and smears were made for evaluation of red blood cell morphology. Outcomes were analyzed using repeated measures analysis. Overall least squares means (95% CI) of whole blood BHB concentrations between 1 h and d 11 relative to first treatment were 1.11 (0.95 to 1.30), 1.26 (1.07 to 1.47), 0.96 (0.81 to 1.13), and 1.53 (1.30 to 1.80) mmol/L for the GLU, PG, GLU+PG, and CTRL groups, respectively. Treatment with both glucose and propylene glycol led to a greater magnitude and more prolonged decrease in BHB concentrations compared with individual treatments. The NEFA and glucagon concentrations were lower immediately after treatment in GLU and GLU+PG groups compared with CTRL, and treatment with both glucose and propylene glycol was associated with a greater increase in glucose and insulin concentrations immediately after treatment compared with CTRL and GLU treatment alone. Treatments did not lead to differences in plasma mineral concentrations. We conclude that treatments varied in the magnitude of decreasing blood BHB concentrations in hyperketonemic postpartum cows, with the greatest decline after treatment with a combination of intravenous glucose and oral propylene glycol.     

Effects of jugular infusions of isoleucine,leucine, methionine,threonine, and other amino acids on insulin and glucagon concentrations,mammalian target of rapamycin (mTOR) signaling,and lactational performance in goats

The supply and profile of absorbed AA may affect milk protein synthesis through hormonal changes and mammalian target of rapamycin (mTOR) signaling pathways; and Ile, Leu, Met, and Thr (ILMT) are the 4 AA that have been reported to have the greatest effect on mammary mTOR signaling. The extent to which ILMT and the other remaining AA (RAA) differ in their effects on milk protein synthesis needs to be systematically investigated. In this study, 5 lactating goats, averaging 120 ± 10 d in milk, fitted with jugular vein and carotid artery catheters, were fasted for 24 h, followed by intravenous infusions of a mixture containing AA and glucose for 8 h in a 5 × 5 Latin square design. The AA mixtures were formulated according to the profile of casein. The amounts of AA infused were calculated based on supplies of AA when metabolizable protein (MP) was at requirement (MR). Treatments were an infusate containing glucose without AA (NTAA); an infusate containing 3 × the MR of Ile, Leu, Met and Thr (3F0R); and infusates containing 3F0R plus 1, 2, or 3 × MR of RAA (3F1R, 3F2R, and 3F3R, respectively) according to amounts provided when fed to meet MP requirements for maintenance and lactation for each goat. Milk, arterial blood, and mammary tissue samples were collected immediately after halting the infusion. Relative to NTAA, supplementation of ILMT tended to increase milk protein production and plasma glucose concentrations, and increased milk and lactose production, but had no effects on production or content of milk fat. Graded supplementation of RAA tended to quadratically affect production of milk and lactose. Arterial glucose and glucagon concentrations decreased linearly, and plasma insulin concentrations decreased quadratically with increased RAA. Mammary p70-S6K1 phosphorylation was decreased by addition of ILMT compared with NTAA but increased linearly with increased RAA infusion. Furthermore, EIF4EBP1 gene expression was much lower for 3F-treated goats than for the NTAA treatment. Both MTOR and RPS6KB1 gene expressions were decreased quadratically with increased RAA supply. These results suggested that short-term milk protein yield tended to be increased by elevated ILMT availability, and this trend was not explained by variations in mammary mTOR signaling or pancreatic hormone secretions, whereas graded increase of RAA in combination with ILMT appeared to regulate the efficiency of conversion of glucose to lactose in a manner not involving milk protein production.     

曲虫治理效果分析

通过对曲虫治理应用研究效果的分析 ,结果表明 :质量效果提高 7% ,糖化力效果提高 80 % ,综合效果提高 92 7%。