Influence of rumen escape starch on pancreatic exocrine secretion of goats

The objective of the experiment was to evaluate the effect of rumen escape starch (RES), accomplished by altering dietary starch concentrations on pancreatic exocrine secretion of goats. Four goats (36.8 ± 3.2 kg) with common bile duct re‐entrant and duodenal catheters were used in a 4 × 4 Latin square. Goats were fed diets containing 20%, 30%, 40% and 50% starch. Periods consisted of 10 day adaptation followed by 3 day of sample collection. Juice was collected in 1‐h fractions continuously for 72 h. Total juice secreted was recorded, and 3% sub samples were retained to form a composite sample. The remaining fluid was returned to the duodenum. Juice composite samples were analyzed for activities of α‐amylase, trypsin, chymotrypsin and lipase. Secretion of pancreatic α‐amylase was lower (p < 0.05) when comparing lambs fed 20% starch diet with 30%, 40% and 50% starch diets. Lipase secretion was greater (p < 0.05) in lambs fed 40% starch diet compared with the other diets. Total secretion of juice, trypsin and chymotrypin was not affected (p > 0.05) by dietary starch concentration. Rumen escape starch increased with increasing dietary starch concentration (p < 0.05). Regression analysis showed that increasing RES results in a quadratic increase (p < 0.05) in pancreatic α‐amylase and lipase secretion, and the secretion of α‐amylase and lipase is maximum when RES is 113 and 83 g/day respectively. These results suggest that optimal RES for pancreatic secretion of α‐amylase and lipase is 80–110 g/day in adult goats.     

Influence of substrate and/or neurohormonal mimic on in vitro pancreatic enzyme release from calves postruminally infused with partially hydrolyzed starch and/or casein

Our objectives were to determine the effects of neuroendocrine challenge and substrates on in vitro alpha-amylase and trypsin release in pancreatic tissue collected from Holstein calves (n = 24; 88 +/- 3 kg) abomasally infused for 10 d with tap water (control), partially hydrolyzed starch (SH; 4 g/[kg of BW x d]) and/ or casein (0.6 g/[kg of BW x d]). The caudal portion of the pancreas was removed, rinsed with ice-cold saline, cut into approximately 2 x 2-mm segments, and incubated in oxygenated Krebs Ringer bicarbonate buffer containing no substrate (control), glucose, amino acids, or VFA at 39 degrees C. After 60 min of incubation, neurohormonal mimics (none; control), carbachol (acetylcholine analog; 10 microM final), or caerulein (cholecystokinin mimic; 100 nM final) were added to the flasks and tissue was incubated for 60 min. Pancreatic tissue concentrations and in vitro release of alpha-amylase and trypsin decreased (P < 0.001) in calves abomasally infused with SH. Carbachol increased (P < 0.10) alpha-amylase and trypsin release in tissue collected from all calves. An effect of caerulein to increase alpha-amylase release (P < 0.10) was only observed with prior exposure to abomasal casein infusion in vivo or with simultaneous incubation with amino acids in vitro. Caerulein increased (P < 0.10) trypsin release in tissue collected from all calves except for those receiving SH + casein. Glucose decreased (P < 0.10) alpha-amylase release from pancreatic tissue collected from calves receiving abomasal control and casein treatments. Amino acids decreased (P < 0.10) alpha-amylase and trypsin release from pancreatic tissue collected from calves receiving the abomasal control treatment. Glucose, amino acids, and VFA decreased (P < 0.10) trypsin release from tissue collected from calves receiving abomasal SH. These data indicate that carbachol can stimulate pancreatic enzyme release in vitro. Caerulein, however, is only effective in stimulating in vitro pancreatic enzyme release in tissue from calves with an increased postruminal protein supply or in tissue incubated with amino acids. The results indicate that postruminal and local nutrients might be important in altering the responsiveness to a neuroendocrine challenge and could be an important regulatory event involved with dietary adaptation in ruminants.     

Influence of abomasal carbohydrates on small intestinal sodium-dependent glucose cotransporter activity and abundance in steers

Most animals adapt readily to increased supplies of carbohydrate in the intestinal lumen by increasing enzymes for degradation and increasing glucose transporter activity. However, the extent of upregulation of Na+-dependent glucose cotransporter 1 (SGLT1) activity and content in response to increased delivery of carbohydrate to the small intestinal lumen of ruminants is unclear. Therefore, an experiment was conducted to determine the effect of glucose and starch hydrolysate on the activity and abundance of SGLT1 in the small intestine of steers. In a randomized complete block design, 40 crossbred beef steers (243+/-2 kg BW) were fed 0.163 Mcal of ME/(kg BW0.75(d; W), 0.215 Mcal of ME/(kg BW0.75 x d; 2M), or 0.163 Mcal ME/(kg BW0.75 x d) and infused for 35 d into the rumen (R) or abomasum (A) with 12.6 g/(kg BW0.75 x d) of starch hydrolysate (S) or into the abomasum with 14.4 g/(kg BW0.75 x d) of glucose (G). Steers were slaughtered, and brush-border membrane vesicles were prepared from the small intestinal samples obtained from five equidistant sites along the intestine. Maltase activity in vesicles and homogenates differed with intestinal sampling site (quadratic, P < 0.001). Steers on the AG treatment yielded a greater intestinal maltase activity (38 nmol glucose x mg protein(-1) x min(-1)) compared with the AS, RS, W, or 2M treatments (34, 26, 23, and 23 nmol glucose x mg protein(-1) x min(-1) respectively [SEM = 3; P = 0.02]). Sodium-dependent glucose uptake averaged 18.4+/-3.94 pmol glucose/(mg protein x s) and was not affected by treatment, but uptake decreased distally along the intestine (P < 0.001). There was no effect of treatment on SGLT1 protein abundance, but SGLT1 protein abundance increased linearly from the duodenum to the ileum (P = 0.05). The inverse relationship between glucose uptake and SGLT1 abundance suggests that the regulation of brush border Na+-dependent glucose transport capacity is complex, involving factors other than the presence of luminal carbohydrate.     

Effect of dietary chromium-L-methionine on glucose metabolism of beef steers

Thirty-six crossbred steers (288 +/- 3.7 kg initial BW) were used to determine the effect of Cr, as chromium-L-methionine, on glucose tolerance and insulin sensitivity in beef calves. Calves were fed a control diet or the diet supplemented with 400 or 800 microg Cr/kg of diet as chromium-L-methionine. Calves were kept in drylots (six calves/pen; two pens/dietary treatment). Steers were caught twice a day in locking headgates and individually fed their respective diets for a period of 22, 23, or 24 d prior to the metabolic challenges. Calves received a totally mixed diet containing 54% corn, 38% cottonseed hulls, and 5% soybean meal. On d 21, 22, and 23, four calves/dietary treatment were fitted with an indwelling jugular catheter. Approximately 24 h after catheterization, an intravenous glucose tolerance test (500 mg glucose/kg of BW), followed 5 h later by an intravenous insulin challenge test (0.1 IU insulin/kg of BW), was conducted. There was no effect (P > 0.10) of dietary treatment on ADG or ADFI. During the intravenous glucose tolerance test, serum insulin concentrations were increased by supplemental chromium-L-methionine (linear effect of Cr, P < 0.05). There was a time x treatment interaction (P < 0.05) on plasma glucose concentrations after the glucose infusion. Plasma glucose concentrations of calves fed 400 microg Cr/kg of diet were lower than those of controls and calves supplemented with 800 microg Cr/kg of diet (quadratic effect of Cr, P < 0.05) 5 and 10 min after the glucose infusion. Supplemental chromium-L-methionine increased the glucose clearance rate from 5 to 10 min after the insulin challenge test (linear effect of Cr, P < 0.05). Glucose half-life from 5 to 10 min after the insulin infusion was also decreased by supplemental chromium-L-methionine (linear effect of Cr, P < 0.10). These data indicate that supplemental Cr, as chromium-L-methionine, increased glucose clearance rate after an insulin infusion and increased the insulin response to an intravenous glucose challenge in growing calves with functioning rumens.     

Nitrogen metabolism and somatotropin secretion in beef heifers receiving abomasal arginine infusions

Twelve Angus x Hereford heifer calves (233 kg) were fitted with abomasal infusion cannulas and used to study N and endocrine responses to abomasally infused arginine (Arg). Heifers were allotted randomly to three treatment groups and received continuous abomasal infusions (2 liters/d) of water (CON) or Arg solutions providing .33 g Arg.HCl/kg BW (LOW) or .50 g Arg.HCl/kg BW (HIGH) each day. A 12-d dietary adjustment period preceded a 7-d infusion and collection period. Each calf received 4,544 g DM/d of a basal diet in equal portions at 0600, 1200, 1800 and 2400. Calves were housed in individual metabolism crates and fitted with urinary bladder catheters for total excreta collection. On d 1 and 5, blood samples were collected at 15-min intervals for 8 h between 1200 and 2000. Single samples were obtained at 1400 on remaining days. The infusion of Arg increased the quantity of N retained by heifers (P less than .01) and the percentage of total N retained (P less than .10); however, no differences were observed between LOW and HIGH heifers. Increased (P less than .01) urinary N excretion by Arg heifers was associated with greater (P less than .05) quantities of urinary urea N and ammonia N. Blood urea N and serum Arg concentrations were highest (P less than .05) in Arg heifers, whereas total serum AA concentrations were lower (P less than .05) in Arg heifers than in CON heifers. Serum glucose and insulin concentrations were not affected (P greater than .10) by treatment. Characterization of somatotropin (STH) profiles revealed that amplitude and frequency of STH pulses were not affected (P greater than .10) by treatment, whereas mean (P less than .10) and basal (P less than .05) STH concentrations were elevated in HIGH compared to LOW heifers on d 1 and 5. The similar N retention responses of LOW and HIGH heifers and similar STH profiles of CON and LOW heifers suggest that the stimulatory effect of the HIGH dose on STH secretion occurred only after tissue N requirements had been satisfied.     

山楂对鸭胰腺分泌的影响

随中西医结合研究的不断深入 ,关于脾胃学说中的脾的功能 ,众说纷纭 ,李聪甫等指出“中医对脾脏的生理功能认为是助胃消化的”。而帮助消化的主要应为胰腺[1] 。因此胰腺在脾胃学说中的作用越来越受到重视。健脾消食中药山楂具健脾开胃 ,消食化积之作用 ,其对胰腺外分泌的作用却未见报道 ,为此 ,我们以鸭为试验动物 ,选择胰液分泌的 7个指标全面观测其对胰液分泌的影响。1　材料与方法1 .1　试验材料1 .1 .1　试验动物　购自中国农业科学院畜牧所北京鸭 3 0只 ,体重为 1 .5kg左右 ,按王贤等报道的鸭第一胰管胰肠瘘管法进行胰肠瘘管手术 [2 ]…     

The effects of caerulein on exocrine pancreatic secretion in pigs

Caerulein administered to anaesthetized pigs by slow i.v. infusions at doses of 0.5, 1.0 and 2.0 ng kg^–1min^–1 for 30 min, stimulated pancreatic juice production, increased the protein content of the juice and enhanced its amylolytic, lipolytic and proteolytic activities. In a single experiment, an i.v. infusion of secretin (0.001 U kg^–1min^–1) lasting through the whole experimental time, provoked potentiation of the caerulein stimulatory effects on pancreatic juice production, protein content and amylolytic activity.     

Effects of mesenteric vein n-butyrate infusion on liver metabolism by beef steers.

Effects of a 3-d mesenteric vein n-butyrate infusion (25 mmol/h) on net metabolism of nutrients by portal-drained viscera (PDV) and liver were measured in six Hereford x Angus steers. Steers were fed a pelleted 75% concentrate: 25% alfalfa diet at 135 kcal of ME/kg BW.75. Six measurements of blood flow and net metabolism of nutrients were obtained at hourly intervals immediately before beginning and ending n-butyrate infusion. Measurements were obtained during two trials, with three steers (457 kg BW, 28 mo of age in Trial 1; 478 kg BW, 19 mo of age in Trial 2) in each trial. The infusion of n-butyrate increased (P less than .01) net PDV release of n-butyrate. Infusion increased net liver removal of n-butyrate (P less than .01) and L-lactate (P less than .02) and release of beta-hydroxybutyrate (BOHB; P less than .02) and increased (P less than .03) liver extraction ratio for alanine. Net total splanchnic (PDV plus liver) release of n-butyrate (P less than .03) and BOHB (P less than .01) were increased, and net total splanchnic release of L-lactate (P less than .05) and propionate (P less than .07) were decreased by n-butyrate infusion. The infusion of n-butyrate decreased (P less than .01) net PDV release and liver removal of propionate in five of six steers. Infusion had no effect (P greater than .10) on insulin and glucagon concentration or net flux. In a companion in vitro study, L-lactate metabolism to glucose and CO2 by calf hepatocytes was decreased (P less than .08) by n-butyrate addition (2.5 mM). Effects of n-butyrate on liver L-lactate and alanine metabolism suggest that pyruvate carboxylase activity was increased, but our study failed to show a consistent effect of n-butyrate infusion on liver glucose production.     

The effect of stress conditions on exocrine pancreatic secretion in growing pigs

Introduction   Competition and aggression in pigs is known to reduce daily weight gain (DWG) (R und GREN and L& ouml ; fqvist 1989; H yun et al. 1998; L und et al. 1998), and to impair feed conversion ratio (W alker 1991; L und et al. 1998). The exact biological mechanisms behind these effects are not fully understood. Aggression and competition activate a cascade of reactions of biological relevance, such as inhibition of the parasympathetic nervous system, stimulation of the sympathetic nervous system, including the adrenal medulla (A xelrod et al. 1970; D alin et al. 1993a, 1993b), and activation of the hypothalamo-hypophyseal-adrenal (HHA) axis resulting in higher adrenocorticotropic hormone (ACTH) and higher cortisol concentrations in the plasma (D alin et al. 1993b; O lsson and S vendsen 1997). These responses as well as muscular activity increase metabolic losses (S chrama et al. 1993).
Hyper-physiological treatment with glucocorticoids stimulates pancreatic amylase activities in piglets (B aintner and N emeth 1982; C happle et al. 1989a, 1989b, 1989c), but no observations in growing pigs have been published. Inhibition of the parasympathetic nervous system (C hey et al. 1979) and stimulation of the sympathetic nervous system (C hey 1991) reduce exocrine pancreatic secretion. So, there might be some conflicting physiological responses of the exocrine pancreas to stress conditions. In order to increase our understanding of the animal's physiological responses to conditions of stress, we tested the hypothesis that conditions associated with stress (mixing with unfamiliar pigs, frustration and ACTH treatment) reduce exocrine pancreatic secretion. In addition, we tested the effect of treatment with Amperozide (a neurolepticum which reduces aggression and the effects of stress in pigs) on exocrine pancreatic secretion.     

Ileal exposure to pig pancreatic juice and bile inhibit exocrine pancreatic secretion in pigs

The mechanisms involved in the down regulation of the exocrine pancreas are still not fully elucidated. The purpose of the present study was to examine the effect of duodenal and ileal exposure to pancreatic enzymes and bile on pancreatic secretion. Experiments were performed with pigs fitted with pancreatic duct, ileal and jugular vein catheters, and duodenal T-shaped cannula. A negative feedback regulation of pancreatic secretion was found for both duodenal and ileal delivery of pancreatic juice. Pancreatic secretion was unaffected by duodenal delivery of bile and bile salts, while ileal delivery of bile and bile salts lowered it. On the other hand, pancreatic secretion was increased by duodenal loading of commercial non- or activated pancreatic enzyme preparations, thus probably recognised as dietary protein. Plasma cholecystokinin (CCK) level was lowered only by duodenal delivery of pancreatic juice. In conclusion, the results prove the existence of negative feedback mechanism regulating pancreatic secretion dependent on the presence of pure pancreatic juice or bile at the ileal level. The mechanism at the duodenal level is exclusively sensitive to pure pancreatic juice.     

Influence of realimentation diet on recovery of rumen activity and feed intake in beef steers

Two trials were conducted to determine the influence of realimentation diet energy, protein, B-vitamin (BV) and Lactobacillus acidophilus (LAC) content on recovery of rumen activity and feed consumption in beef steers. In trial 1, ruminal-fistulated steers were fasted and refed 1) prairie hay, 2) 10% protein (LCP), 3) 12.5% protein (MCP), 4) LCP + BV or 5) LCP + LAC. In trial 2, calves were fasted and refed 1) 60% cottonseed hulls-40% alfalfa dehy (high roughage), 2) LCP, 3) 15% protein (HCP), 4) LCP + BV or 5) LCP + LAC. Rumen fermentative capacity declined 74% (P less than .05) during feed and water deprivation, but returned to control levels by d 7 of realimentation. On d 3 of realimentation, steers fed the LCP and MCP diets had molar proportions of ruminal butyrate in excess of 35%. Steers fed the hay, LAC and BV diets did not have a high butyrate fermentation. In trial 2, calves lost about 15% of their body weight during feed and water deprivation. Calves fed the high roughage diet appeared to return to prefast feed and energy intakes more slowly than steers fed the medium roughage diets. Results of this study indicate that rumen fermentative capacity is a factor limiting feed intake in fasted calves for 7 to 14 after the reintroduction of feed and water.     

Effect of suckling isotonic or hypertonic solutions of sodium bicarbonate or glucose on abomasal emptying rate in calves

OBJECTIVE: To determine and compare the abomasal emptying rates in calves suckling milk replacer or an isotonic or hypertonic solution of NaHCO(3) or glucose. ANIMALS: 5 male Holstein-Friesian calves that were < 30 days of age. PROCEDURES: Calves were fed 2 L of milk replacer or isotonic (300 mOsm/L) or hypertonic (600 mOsm/L) solutions of NaHCO(3) or glucose containing acetaminophen (50 mg/kg). Venous blood samples and transabdominal ultrasonographic abomasal dimensions were obtained periodically after feeding, and abomasal luminal pH was continuously monitored by placement of a luminal pH electrode through an abomasal cannula. Abomasal emptying rate was assessed by the time to maximal plasma acetaminophen concentration, ultrasonographic determination of the half-time of abomasal emptying, and the time for luminal pH to return to within 1 pH unit of the preprandial value. RESULTS: Hypertonic NaHCO(3) solution was emptied slower than an isotonic NaHCO(3) solution, isotonic glucose solution was emptied slower than an isotonic NaHCO(3) solution, and hypertonic glucose solution emptied slower than an isotonic glucose solution. CONCLUSIONS AND CLINICAL RELEVANCE: An electrolyte solution for oral administration with a high osmolarity and glucose concentration may lead to a slower resuscitation of dehydrated diarrheic calves because such solutions decrease the abomasal emptying rate and therefore the rate of solution delivery to the small intestine. Whether slowing of the abomasal emptying rate in dehydrated diarrheic calves suckling an oral electrolyte solution is clinically important remains to be determined.     

Influence of chlortetracycline and dietary protein level on visceral organ mass of growing beef steers

Thirty-two beef steers (285 +/- 3 kg BW) were used to determine the effects of chlortetracycline and dietary protein level on visceral tissue mass, chemical composition, intestinal morphology, and proliferation rate indices. Steers were allotted randomly by weight to a factorial arrangement of dietary treatments consisting of either 10 or 13% CP diets top-dressed with a corn meal carrier (500 g/d) containing either 0 or 350 mg of chlortetracycline. After 84 d, steers were slaughtered and visceral organs removed and separated. Rinsed wet tissue mass was recorded; total RNA, total DNA, tissue DM, and tissue N content were determined; and tissue sections were prepared for immunohistochemical analysis. Thin tissue sections were evaluated to determine crypt depth and villus height as well as proliferation rate by immunohistochemical detection of the nuclear antigen Ki67. Rumen and abomasum weights and small intestinal length were greater (P < 0.04) in steers fed the 13% CP diet than in those fed the 10% CP diet on both an absolute weight basis and a percentage of empty BW. Chemical composition of the small intestinal and ruminal segments were largely unaffected by increased dietary protein. Increasing the dietary CP also increased the villus height in duodenal (P = 0.02) and the crypt depth of jejunal (P = 0.03) sections. Dietary administration of chlortetracycline decreased (P < 0.01) small intestinal weight both on absolute and empty BW bases. Nitrogen and RNA concentrations of the small intestinal segments were unaffected (P > 0.1) by dietary administration of subtherapeutic levels of chlortetracycline; however, because of increases (P < 0.05), or tendencies for an increase (P < 0.1), in the tissue content of DNA, the ratio of N to DNA was decreased (P < 0.05) or tended to be decreased (P < 0.1) in the small intestinal segments of the chlortetracycline-treated animals. The observed decrease in small intestinal epithelial mass does not appear to be due to alterations in cell proliferation rate but rather cell size. Consistent with this finding, cell proliferation, as determined by Ki67 antigen staining, was not affected by dietary treatment. Chlortetracycline administration decreased small intestinal mass that may be a result of decreased cell size.     

Impact of nutrition on pancreatic exocrine and endocrine secretion in ruminants: a review.

Because of the unique features of the ruminant digestive system, variations in diet composition and intake produce dramatic changes in ruminal fermentation. Optimizing nutritional management requires an understanding of how these variations and changes influence digestion and metabolism. Although the pancreas plays a central role in digestion and subsequent nutrient metabolism, relatively little is known about pancreatic adaptation to nutritional changes in the ruminant. Increasing starch intake has been suggested to increase pancreatic alpha-amylase; however, recent work suggests that dietary energy per se may drive these changes, and interactions with other nutrients, such as protein, may exist. Studies describing the influence of altered protein and lipid intakes on pancreatic adaptation in ruminants are lacking. Pancreatic secretion of both insulin and glucagon respond to the intravenous infusion of VFA in a dramatic fashion; however, feeding studies suggest that the influence of VFA on insulin and glucagon may be more subtle. Interactions exist between stimulatory signals and physiological state, such as lactation. Assessment of pancreatic endocrine secretion is further complicated by a variable removal of insulin and glucagon by hepatic tissues. These studies point out that pancreatic hormone secretion is controlled by integrated and complex mechanisms. Studies of these controlling mechanisms should consider the entire array to more fully understand hormone secretion.     

Performance and meat quality of beef steers fed corn-based or bread by-product-based diets

A feeding trial was conducted with beef breed steers (120) to determine the effects of substituting bread by-product (BBy) for whole shelled corn on performance and meat quality. Chemical analysis of each diet ingredient and in vitro rates of digestion from gas production of BBy and corn were determined to provide accurate information for diet evaluations using the 1996 Beef NRC Model Level 2. Bread by-product contained 16% CP (75.6% degradable) and 75.1% non-structural carbohydrates (70% as starch, which had a digestion rate of 16%/h). The steers were given one estrogenic implant (Synovex-S) and started on the experiment at 15 mo of age and an average weight of 364 kg. The cattle were commercially slaughtered in three groups (40 steers at 101, 60 steers at 126, and 20 steers at 160 d on feed) weighing an average of 553 kg when they reached a small degree of marbling. Carcasses were electrically stimulated to prevent cold shortening of muscles. Warner-Bratzler shear force values were measured in rib steaks at 5, 14, and 21 d after slaughter (n = 76). Rib steaks from 30 steers per treatment were evaluated for palatability traits. Use of BBy at 55% of the diet (substituted for 75% of the corn) significantly improved feed efficiency by 8.1%. There were no statistically significant differences between the two diets for effects on ADG, carcass characteristics, shear force values, or sensory panel ratings of tenderness, juiciness, flavor, or overall acceptability. After adjusting intestinal starch digestibility in Level 2 to 63% for the whole corn and 90% for the BBy, predicted ADG matched that observed. Apparent NE(g) values for BBy and corn were 1.57 and 1.41 Mcal/kg, respectively.     

Effects of rumen-protected methionine supplementation and bacterial lipopolysaccharide infusion on nitrogen metabolism and hormonal responses of growing beef steers

Metabolic demand for sulfur-containing AA increases during inflammation in nonruminants. Therefore, Met supplementation may alleviate the negative effects of infection on N balance. Effects of gram-negative bacterial lipopolysaccharide (LPS) and supplemental dietary Met on N balance, serum hormones and haptoglobin, and plasma urea-N and AA were evaluated in 20 Angus-cross steers (BW = 262 +/- 6.3 kg). Treatments (2 x 2 factorial) were infusion of no LPS (-LPS) or a prolonged low dose of LPS (+LPS) and dietary supplementation of no (-MET) or 14 g/d (+MET) of rumen-protected Met (providing 7.9 g/d of dl-Met). Steers were adapted to a roughage-based diet (DMI = 1.4% of BW daily) and supplemental Met for 14 d, and were then infused (1 mL/min via intravenous catheter) with LPS on d 1 (2 microg/kg of BW) and 3 (1 microg/kg of BW) of a 5-d collection period. Blood was collected on d 1, before LPS infusion, and at 2, 4, 6, 8, 10, 12, and 24 h after LPS challenge. Diet samples, feed refusals, feces, and urine were collected daily for 5 d. Rectal temperature and serum concentrations of cortisol, prolactin, tumor necrosis factor-alpha, and haptoglobin increased, whereas thyroxine and triiodothyronine decreased for +LPS vs. -LPS steers (LPS x h; P < 0.01). Plasma urea-N was greater for +LPS than -LPS steers (LPS; P = 0.03), and serum IGF-1 was not affected (P > or = 0.26) by LPS or Met. Plasma concentrations of Thr, Lys, Leu, Ile, Phe, Trp, Asn, Glu, and Orn decreased, plasma Ala increased, and Gly and Ser initially increased, then declined in +LPS vs. -LPS steers (LPS x h; P < or = 0.04). Plasma Met was greater for +MET than -MET steers before LPS infusion, but declined in +MET steers after LPS infusion (LPS x Met x h; P < 0.01). By design, DMI was not different, but DM digested was less (P = 0.04) for +LPS than -LPS steers. Infusion of LPS did not affect (P > or = 0.24) N intake, fecal N excretion, or N digested, but resulted in greater (P < 0.01) urinary N excretion and less (P < 0.01) N retention. The absence of an LPS x Met interaction (P = 0.26) for N retention indicates that supplemental Met does not improve the N utilization of growing beef steers exposed to a gram-negative bacterial endotoxin. Decreases in plasma concentrations of several essential AA in +LPS steers suggest that metabolic demand for these AA likely increased in steers exposed to endotoxin.     

The effect of abomasal methionine supplementation on nitrogen retention of growing steers postruminally infused with casein or nonsulfur-containing amino acids

An experiment was conducted to develop a system useful for measuring methionine requirements of growing steers. Seven ruminally cannulated steers (312 kg, gaining .91 kg/d) were fed a diet based on ammoniated corn cobs, corn starch, molasses and urea. Quantities of N and sulfur-containing amino acids disappearing from the small intestine were 96.0 and 14.8 g/d, respectively. Postruminal infusions of Na-caseinate (CAS) resulted in linear (P less than .01) increases in N retention with values increasing from 30.1 g/d with no postruminal CAS infusion to 39.3, 50.8 and 59.2 g/d (averaged across methionine supplementation) when 100, 200 and 300 g/d CAS were infused. Postruminal infusions of a mixture of crystalline L-amino acids (simulating the nonsulfur-containing essential amino acid pattern of casein; SIM) at levels of 100, 200 and 300 g/d also led to linear increases (P less than .01) in N retention with steers retaining 30.9, 38.9 and 50.5 g N/d (averaged across methionine supplementation), respectively. Postruminal infusion of 12 g/d L-methionine across CAS and SIM infusions improved (P less than .01) N retention by 7.6 g/d but infusion of SIM, which is devoid of sulfur amino acids, also increased N retention. Responses to methionine supplementation was greatest when 200 or 300 g/d SIM were abomasally infused. The data are interpreted to demonstrate that, for steers fed a diet containing little true protein, postruminal supplementation with nonsulfur-containing amino acids tended to increase the ability of growing steers to respond to methionine supplementation.     

瘤胃保护性蛋氨酸和细菌脂多糖对肉牛的营养代谢和激素水平的影响

<正>1材料和方法1.1试验设计选取初始体重为262±6.3kg的杂交安格斯肉牛20头,牛棚地面铺2.54cm的橡胶,可以用自来水自动冲洗。所有的肉牛在上午7:00和晚上19:00饲喂1.4%单位体重(以DM为基础)的粗日粮(表1),自由饮水,整个试验时间持续19d,在饲喂粗饲料的14d内所有的肉牛基本适应了该种日粮,其余的5d为收集样品期。其中没有添加     

Feed utilization of beef steers fed grass as hay or silage with or without nitrogen supplementation.

Six Hereford steers averaging 256 kg were used in a 2 x 3 factorial arrangement within a 6 x 6 Latin square design to study the effect of forage conservation (silage vs hay) and N supplementation (0, 200 g of fish meal plus 43 g of urea, or 400 g of fish meal) on ruminal characteristics, digestibility, blood urea, and in situ degradability of DM, N, and ADF. Dry matter intake of forage and total DMI did not differ among treatments (P greater than .05) and averaged 5.3 and 5.5 kg, respectively. Steers fed silage had greater (P less than .05) pH and concentrations of ammonia N, isobutyrate, isovalerate, and valerate in the rumen than in the rumen of those fed hay. Nitrogen supplementation increased (P less than .05) concentrations of total VFA and valerate in the rumen. Digestibility of N and ADF was greater (P less than .05) for silage than for hay, and N supplementation increased digestibility of N. Plasma urea concentrations were greater (P less than .05) for steers fed silage than for those fed hay. These data suggest that feed utilization is better with silage than with hay and is increased by N supplementation.     

Effects of cowpea (Vigna Unguiculata) feeding on the pancreatic exocrine secretion of pigs

Introduction   Cowpea (Vigna unguiculata) is a valuable protein source that can contribute towards overcoming a predicted protein deficit equivalent to more than 1 000 000 t oilcake in Southern Africa by the year 2000 (N ell et al. 1992). However, like most other legumes, cowpeas contain antinutritional factors (ANFs) (M akinde et al. 1996). It has also been shown that feeding raw cowpea causes reduced growth and histomorphometric changes in the various segments of the intestine (M akinde et al. 1997) attributable to ANFs. The major ANFs in the cowpea are trypsin inhibitors, tannins and phytates (A letor and A ladetimi 1989). Although the protease inhibitors are found in most legumes, only soybean inhibitors have been thoroughly investigated (L iener and K akade 1980), and trypsin inhibitors in other legumes have received little attention.