Biomedical subjects

D L Harmon

Publications and source records attributed to D L Harmon.

At least 91 records · Page 5Linked to original sources

PubMed1991

Effect of energy source fed to sows during late gestation on neonatal blood metabolite homeostasis, energy stores and composition.

Four experiments utilizing 49 primiparous and 34 multiparous sows were conducted to evaluate the effect of feeding either starch, soybean oil or medium-chain triglyceride (MCT) during late gestation (d 100 to parturition) on neonatal fasting blood glucose homeostasis (Exp. 1 and 2), d-100 maternal circulating insulin, glucagon and glucose concentrations (Exp. 3 and 4), neonatal energy stores (Exp. 3 and 4) and colostrum composition (Exp. 1, 2, 3 and 4). In all cases, sows were fed 7.2 Mcal/d of a diet that supplied 279 g of protein daily. During fasting, pigs from MCT-fed dams had higher blood glucose concentrations (P less than .05) than pigs from starch-fed dams. No differences between treatments were observed for total carcass fat, liver glycogen or carcass glycogen of pigs killed prior to suckling. In general, colostrum fatty acid profiles were influenced by diet; however, the shifts in fatty acids differed for experiments. Starch-fed sows had higher blood insulin and lower blood glucagon (P less than .05) than lipid-supplemented sows; however, sow blood glucose remained constant across treatments. This study indicates that any positive effects of feeding soybean oil to sows during late gestation are most likely mediated by a change in fatty acid composition of colostrum; any beneficial properties of MCT feeding most likely are mediated through improved blood glucose maintenance of the neonate when it is subjected to fasting conditions.

Animal Feed↗

PubMed1991

Influence of source and level of ruminal-escape lipid in supplements on forage intake, digestibility, digesta flow, and fermentation characteristics in beef cattle.

Six ruminally fistulated steers (550 kg) and 24 heifers (315 kg) were used to determine the effect of source and amount of ruminal-escape lipid in a supplement on forage intake and digestion. Steers were used in a 6 x 6 Latin square digestion study to evaluate six supplementation treatments: 1) negative control (NC), no supplement; 2) positive control (PC), soybean meal:grain sorghum supplement; 3) low-Megalac (calcium salts of fatty acids; LM) supplement; 4) high-Megalac (HM) supplement; 5) low-Alifet (crystallized natural animal fat, LA) supplement; and 6) high-Alifet (HA) supplement. Supplements were fed at .30% of BW on a DM basis and were isoenergetic within fat levels (high vs low). Steers were fed mature brome hay (7.2% CP) at 1.5% of BW on a DM basis. In the forage intake trial, heifers were assigned randomly to the same supplement treatments. Prairie hay (4.4% CP) was offered at 130% of ad libitum intake. Dry matter and NDF digestibility, ruminal DM fill, indigestible ADF passage rate, and fluid dilution and flow rates were not different (P greater than .10) among treatments. Total VFA concentrations were greater (P less than .01) and acetate-to-propionate ratio (Ac:Pr) was less (P less than .01) in supplemented groups; however, neither source nor level of escape lipid influenced either total VFA or Ac:Pr. Forage intake was greater (P less than .01) for supplemented groups than for the NC. At the high level of fat inclusion, heifers supplemented with Alifet ate slightly more (P less than .05) forage than those supplemented with Megalac.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1991

Small intestinal starch digestion in steers: effect of various levels of abomasal glucose, corn starch and corn dextrin infusion on small intestinal disappearance and net glucose absorption.

Eight Holstein steers (four at 300 kg, four at 406 kg) fitted with an elevated carotid artery, hepatic portal and mesenteric venous catheters, and abomasal and ileal cannulas were used in several 4 x 4 Latin square experiments to evaluate small intestinal starch digestion. They were fed alfalfa hay at 1.5% of BW and abomasally infused with water or glucose, corn starch or corn dextrin (one carbohydrate per Latin square) at 20, 40 or 60 g/h, with subsequent determination of small intestinal disappearance and net portal glucose absorption. Increasing the amount of all three carbohydrates infused abomasally increased the amount of carbohydrate disappearing in the small intestine. Increased infusion of glucose caused a continual increase (linear, P less than .01) in net glucose absorption, whereas net glucose absorption for starch and dextrin was maximal at the 20 g/h infusion (quadratic, P less than .05). With the 60 g/h infusion, 94% of the glucose but only 38% of starch and 29% of small intestinal dextrin disappearance could be accounted for as net glucose absorption, leaving a large portion of starch and dextrin disappearance unaccounted for. Of the infused starch and dextrin passing the ileum, 5.8 and 7.3%, respectively, was unpolymerized glucose, indicating that, at least in the distal small intestine, complete starch hydrolysis exceeded the capacity for glucose disappearance. It is concluded that only about 35% of the raw corn starch disappearing in the steer's small intestine resulted in net portal glucose absorption.

Animals↗

PubMed1991

Effects of feeding endophyte-infected fescue hay on portal and hepatic nutrient flux in steers.

Six Holstein steers (313 +/- 10 kg BW) surgically fitted with hepatic portal, mesenteric venous, mesenteric arterial, and hepatic venous catheters were used in a replicated crossover design experiment to evaluate the feeding of Acremonium coenophialum-infected fescue hay on portal-drained visceral and hepatic nutrient metabolism. Only four steers had functional hepatic catheters. Infected (INF) and endophyte-free (EF) fescue hays were harvested on the same day in May, at the soft dough stage of maturity, from a similar location in southeast Kansas. The hay was chopped through a 2.5-cm screen and fed in 12 portions daily. Intake was limited to 5.2 kg of DM/d to equalize consumption. Each experimental period lasted 21 d. Dietary CP concentration was greater for INF than for EF (9.9 vs 8.6%); however, apparent digestibilities of DM (52.6%) and N (37%) were not different. Ruminal total VFA concentrations and molar proportions were not different with the exception of butyrate, which was increased (P less than .10) for steers when they were fed INF. Feeding of INF increased (P less than .05) arterial beta-hydroxybutyrate concentration and decreased (P less than .10) arterial butyrate concentration. Steers fed EF showed a greater (P less than .05) portal-arterial concentration difference for acetate and an increased (P less than .05) net portal flux of acetate (500 vs 620 mmol/h). No differences in net flux were noted for any of the other VFA, glucose, lactate, urea N, insulin, glucagon, or prolactin.(ABSTRACT TRUNCATED AT 250 WORDS)

Acremonium↗

PubMed1991

Fat source and calcium level effects on finishing steer performance, digestion, and metabolism.

A 111-d finishing study evaluated animal growth and carcass characteristics using 138 steers (366 kg) in a randomized complete block design with a 2 x 3 factorial arrangement of treatments. The dietary treatments consisted of no supplemental fat or 3.5% tallow or soybean oil soapstock (SS) fed with .6% and .9% dietary Ca. Fat increased DMI (P less than .05) but interacted with Ca level (P less than .05) for gain/feed and ADG. All diets containing fat or .9% Ca were converted more efficiently to gain than the .6% Ca, no supplemental fat diet (P less than .05). The .9% Ca interacted with fat source to decrease gain (P less than .05) and tended to decrease efficiency in the tallow diet but improved efficiency (P less than .05) and tended to improve gain in the no-fat diet. In the SS diet, .9% Ca had no effect on ADG, DMI, or efficiency of gain. Fat addition increased backfat (P less than .10) and interacted with Ca on hot carcass weight, final weight, and dressing percentage (P less than .05). Feeding fat increased the proportion of 18:0 (P less than .02) and decreased the proportion of 16:1 fatty acids (P less than .06) in intermuscular fat. A replicated 3 x 3 Latin square design, using six Holstein steers (349 kg) fed three diets, with no supplemental fat or 3.5% SS or tallow with 1.0% Ca, was used to explore the effects of fat sources when fed with high Ca on digestion and metabolism. Ruminal fluid pH was higher (P less than .10) when steers were fed fat. Adding fat did not affect (P greater than .10) duodenal or ileal pH, VFA proportions or total concentration, or ruminal liquid volume or flow rate. Liquid retention time was shorter and liquid rate of passage was higher (P less than .05) with dietary fat addition. Adding fat did not affect site or extent of starch or DM digestion. There was net synthesis of 16:0, 18:0, and 18:1 fatty acids in the rumen. When steers were fed tallow, synthesis of 16:0 and 18:0 fatty acids in the rumen was lower (P less than .10) than when steers were fed SS. Feeding fat tended to decrease (P = .11) bacterial N flowing at the duodenum but did not affect nonbacterial N or total N. Fat addition seems to affect ruminal kinetics, and the effects may vary with fat source, particularly relative to fatty acid synthesis and digestion.

Adipose Tissue↗

PubMed1991

Influence of protein supplementation on site and extent of digestion, forage intake, and nutrient flow characteristics in steers consuming dormant bluestem-range forage.

Four multicannulated Holstein steers (initial BW 424 +/- 16 kg) were used in a 4 x 4 Latin square to determine the influence of protein supplementation on forage intake, site and extent of digestion, and nutrient flow in steers consuming dormant bluestem-range forage (2.3% CP). Treatments were 1) control, no supplement; 2) 1.8 kg of low-protein supplement, 12.8% CP (Low-CP); 3) 1.8 kg of moderate-protein supplement, 27.1% CP (Mod-CP); and 4) 2.7 kg of dehydrated alfalfa pellets, 17.5% CP (Dehy). The Dehy supplement was fed to provide the same amount of CP/d as Mod-CP, and all supplements provided similar amounts of ME/d. Forage DMI was increased (P less than .05) by feeding Mod-CP and Dehy. Ruminal OM digestibility was 39% greater (P less than .05) for the Mod-CP and Dehy supplementations than for the Low-CP supplementation and control. Ruminal CP digestibility was negative for all treatments, and control (-326%) was less (P less than .05) than supplemented treatments (average -27%). Total tract OM digestibility was greatest (P less than .10) for steers fed Mod-CP and least for control steers; Low-CP and Dehy steers were intermediate. Total tract NDF digestibility tended (P = .15) to be less with Low-CP than with Mod-CP and Dehy. Duodenal N flow was greater (P less than .05) with Mod-CP and Dehy than with Low-CP and control. In summary, supplementation with Mod-CP increased forage intake, digestion, and duodenal N flow compared with Low-CP or control; however, the response was similar when Mod-CP and Dehy supplements were fed to provide equivalent amounts of CP and ME daily.

Ammonia↗

PubMed1991

Mixtures of wheat and high-moisture corn in finishing diets: feedlot performance and in situ rate of starch digestion in steers.

Wheat and high-moisture corn (HMC) were fed singly and in three combinations using dry-rolled wheat (DRW) (ratios of 75:25, 50:50, and 25:75, respectively, Trial 1), or singly and in two combinations using steam-rolled wheat (SRW) (ratios of 67:33 and 33:67, respectively, Trial 2) to finishing beef cattle fed a high-concentrate diet. In situ rate of starch digestion (Trial 3) was measured on grains used in Trial 1 (excluding the 25 HMC: 75 DRW mixture) and ground dry corn. In Trial 1 (132 d), gain/feed did not differ (P greater than .10); however, final weight, hot carcass weight, and ADG decreased linearly (P less than .05) and DMI exhibited a cubic response (P less than .05) as the percentage of wheat in the diet increased. Carcass characteristics were not different. In Trial 2 (113 d), there were no differences attributable to treatment for ADG, DMI, gain/feed, or carcass characteristics. Positive associative responses for gain efficiency (gain/feed) were greatest for the first increment of wheat addition (25% DRW and 33% SRW in Trials 1 and 2, respectively) and for the early portion of the feeding period (57 and 28 d for Trials 1 and 2, respectively), indicating a more rapid diet adaptation and(or) less propensity for subacute acidosis. In Trial 3, the treatment grains or mixtures did not differ in rate of starch digestion. Although the differences were not statistically significant, starch in the 100% wheat diet was digested twice as fast as the 100 or 75% HMC mixtures.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗

PubMed1990

Influence of hydrocortisone acetate on pancreas and mucosal weight, amylase and disaccharidase activities in 14-day-old pigs.

1. One litter of 12 pigs was used to evaluate the effects of hydrocortisone acetate injection on organ weight and carbohydrase activities. 2. Pigs were injected with hydrocortisone acetate or an equal volume of saline at 7 days of age and killed at 14 days, and tissues were collected, weighted, and analyzed for carbohydrase activities. 3. Hydrocortisone had no effect (P greater than 0.40) on daily gain, liver weight, spleen weight, or small intestinal length. 4. Hydrocortisone increased pancreatic weight by 29% and total pancreatic alpha-amylase content by 38%. 5. Hydrocortisone increased duodenal mucosal weight by 23%, duodenal lactase activity by 44%, duodenal maltase activity by 163%, and duodenal sucrase activity by 214%.

Amylases↗

PubMed1990

Effect of fat sources and combinations on starter pig performance, nutrient digestibility and intestinal morphology.

Three growth trials and one digestion trial were conducted to compare the effect of dietary fat sources and combinations on starter pig performance, nutrient digestibility and intestinal morphology. Growth trials 1 and 2, utilizing a total of 324 weanling pigs (21 +/- 3 d), were conducted to determine the influence of addition of soybean oil, coconut oil, choice white grease, 50% soybean oil: 50% coconut oil or 50% choice white grease: 50% coconut oil on starter pig performance. Diets were supplemented with 10% fat for the first 2 wk of the study and with 5% for the final 3 wk. The third growth trial, utilizing a total of 210 weanling pigs, was conducted to evaluate the effects of addition of soybean oil, coconut oil, 50% soybean oil: 50% coconut oil, 75% soybean oil: 25% coconut oil or 25% soybean oil: 75% coconut oil on starter pig performance and nutrient digestibility. Average daily gain and feed/gain were not changed during wk 0 to 2, but they were improved from 3 to 5 wk postweaning when fat was added to the diets. The combination of 50% soybean oil and 50% coconut oil resulted in higher ADG than the other fat combinations. A digestion trial utilizing 24 weanling pigs (21 +/- 3 d) was conducted to evaluate the effects of soybean oil, coconut oil, or combination of soybean oil and coconut oil on morphology of the small intestine and ileal and total tract apparent digestibilities of individual fatty acids, total fatty acids, N, DM and GE from d 5 to 8 postweaning. Pigs fed the combination of soybean oil and coconut oil tended to have increased (P less than .08) villus height compared with pigs fed soybean oil or coconut oil alone. Micrographs revealed intestinal morphology with long, round villi when this combination of oils was fed. These trials demonstrated that a combination of soybean oil and coconut oil improved (P less than .05) pig growth performance over coconut oil alone or with added choice white grease and tended to improve (P less than .12) ileal digestibility of medium-chain fatty acids (less than or equal to 14 C) compared to diets without added fat or containing soybean oil or coconut oil alone.

Animals↗

PubMed1990

Portal-drained visceral flux of nutrients in lambs fed alfalfa or maintained by total intragastric infusion.

An experiment was performed using lambs fitted with chronic indwelling catheters in appropriate blood vessels for portal-drained visceral (PDV) flux measurements. The objective of the experiment was to evaluate PDV nutrient flux in alfalfa-fed and intragastrically infused lambs and to evaluate the effects of amount of energy and N infused on PDV nutrient metabolism. Lambs were fed alfalfa or infused with 1.64 and 10.9; 1.82 and 12.3; or 2.37 and 15.0 Mcal GE and g N/d, respectively. Arterial concentrations and PDV fluxes of glucose, L-lactate, acetate and portal blood flow were not different (P greater than .10) between alfalfa-fed and infused lambs. Net flux of alpha-amino N, ammonia N and branched-chain VFA were lower (P less than .05) and net flux of propionate, butyrate and total VFA were higher for intragastric infusion vs alfalfa. No consistent differences in PDV fluxes were noted among the three levels of energy and N infused, although the energy and N levels tested were near maintenance requirements. Nitrogen retention increased as level of energy and N infusion increased. Approximately 47, 70 and 22% of ruminally infused acetate, propionate and butyrate, respectively, were found on a net basis in portal blood as VFA. Measurements of net nutrient utilization by the PDV that eliminate the influence of ruminal fermentation are possible. How the changes in PDV tissues due to intragastric infusion influence these estimates is unknown.

Animal Feed↗

PubMed1990

Supplementation of dormant tallgrass-prairie forage: I. Influence of varying supplemental protein and(or) energy levels on forage utilization characteristics of beef steers in confinement.

Three experiments were conducted to evaluate effects of supplemental protein vs energy level on dormant forage intake and utilization. In Exp. 1, 16 ruminally cannulated steers were blocked by weight (avg wt = 242 kg) and assigned randomly to a negative control or to one of three isocaloric supplement treatments fed at .4% BW: 1) control, no supplement (NS); 2) 12% CP, low protein (LP); 3) 28% CP, moderate protein (MP); 4) 41% CP, high protein (HP). In Exp. 2 and 3, 16 ruminally cannulated steers were blocked by weight (avg wt = 332 kg, Exp. 2; 401 kg, Exp. 3) and assigned randomly to a 2 x 2 factorial arrangement of treatments. The treatments contrasted low (LP) and high (HP) levels of supplemental protein (.66 g CP/kg BW vs 1.32 g CP/kg BW) with low (LE) and high (HE) levels of supplemental ME (9.2 kcal/kg BW vs 18.4 kcal/kg BW). In Exp. 1, forage DMI as well as ruminal DM and indigestible ADF fill at 4 h postfeeding were greater (P less than .10) with the MP and HP steers than with control and LP steers. Total DM digestibility increased (P less than .10) for supplemented steers (35.5% for control vs 47.3 for supplemented steers); however, LP depressed (P less than .10) NDF digestibility. In Exp. 2, forage DMI, indigestible ADF flow and liquid flow were depressed (P less than .10) in LP-HE supplemented steers. In Exp. 3, HP steers had greater (P less than .10) forage DMI, indigestible ADF fill values (4 h postfeeding), liquid volume and tended (P = .11) to have greater ruminal DM fill (4 h postfeeding). In summary, increased levels of supplemental protein increased intake and utilization of dormant tallgrass-prairie forage (less than 3% CP). Increasing supplemental energy without adequate protein availability was associated with depressed intake and digestibility.

Animal Feed↗

PubMed1990

Steam-rolled wheat diets for finishing cattle: effects of dietary roughage and feed intake on finishing steer performance and ruminal metabolism.

Two experiments were conducted to determine the influence of dietary roughage concentration and feed intake on finishing steer performance and ruminal metabolism. In Exp. 1, 126 steers (334 kg) were used in a completely randomized design and fed (120 d) diets of steam-rolled wheat without roughage or containing 5, 10 or 15% roughage (50% alfalfa hay:50% corn silage). Steers fed 5 or 10% roughage gained faster (quadratic, P less than .05) and were more efficient (quadratic, P less than .05) than steers fed 15% or no roughage. In Exp. 2, six ruminally cannulated steers (447 kg) were used in a 6 x 6 latin square design and fed (twice daily) diets of steam-rolled wheat without roughage or containing 5 or 15% alfalfa hay at twice or three times NE required for maintenance. Increasing dietary roughage increased (linear, P less than .01) ruminal liquid passage 38%, indigestible ADF passage 63%, Yb-labeled wheat passage 75% and fiber fill 31%. The rate of in situ starch digestion tended to increase (linear, P = .16), and ruminal VFA concentration was 40 mM higher (P less than .01) at 4 h after feeding with increased roughage. Increased feed intake increased (P less than .05) ruminal starch fill, fiber fill, liquid fill and liquid passage 23%, Yb-labeled wheat passage 50% and Dry-labeled hay passage 20%. It reduced protozoa five- to sixfold (P less than .01) but doubled total bacterial counts (P less than .01). Ruminal NH3N was lower (P less than .01) and total VFA concentration was 50 mM higher (P less than .01) at 4 h after feeding. The acetate:propionate ratio was reduced from 2.3 to 1.3 (P less than .01) with increased intake. Adding roughage to a steam-rolled wheat diet increased passage and tended to increase rate of starch digestion; increased feed intake with its associated effects on ruminal fill and passage dramatically shifted the microbial population and fermentation end products.

Animal Feed↗

PubMed1990

Effects of isoenergetic infusions of propionate and glucose on portal-drained visceral nutrient flux and concentrations of hormones in lambs maintained by total intragastric infusion.

Three lambs were used in a repeated Latin square design to determine the influence of isoenergetic infusions of propionate or glucose on portal-drained visceral flux (PDV) of nutrients and concentrations of insulin, glucagon, growth hormone and prolactin. Lambs were fitted with appropriate catheters for blood sampling and maintained on total intragastric infusion of nutrients. Basal VFA, casein, mineral and vitamin infusions (isocaloric and isonitrogenous) were supplemented with an additional 22 +/- .5 kcal/h from propionate, glucose or a combination of propionate plus glucose. Ruminal fluid proportion and arterial blood concentration and PDV flux of propionate increased (P less than .10) by 17 mol/100 mol, .02 mM and 40 mmol/h, respectively, with infusion of an additional 61 mmol/h of propionate. Regression equations predicted that, on a net basis, 67% of ruminally infused propionate and 43% of abomasally infused glucose appeared in portal blood. Arterial L-lactate, beta-hydroxybutyrate and acetate concentrations, and beta-hydroxybutyrate flux were increased (P less than .10) by .34 mM, .20 mM, .50 mM and 4.2 mmol/h, respectively, with infusion of 33 mmol/h of added glucose. Net utilization of glucose by the PDV was approximately 4.4 mmol/h when no glucose was infused. Increased infusion of propionate resulted in a 22.2-micrograms/h increase in PDV flux of insulin (P less than .08) but had no effect on arterial insulin, glucagon and prolactin concentrations (P greater than .10). Arterial growth hormone increased by 3.8 ng/ml with increasing glucose infusion (P less than .08).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1990

Influence of dietary forage and feed intake on carbohydrase activities and small intestinal morphology of calves.

Twenty (12 Holstein, 8 Longhorn cross) calves (198 kg and 7 mo old) were used in a randomized complete block design to evaluate the effects of dietary forage concentration and feed intake on carbohydrase activities and small intestinal (SI) morphology. Calves were individually fed 90% forage (alfalfa) or a 90% concentrate (50% sorghum: 50% wheat) diet at either one or two times NEm for 140 d and slaughtered; tissues and small intestinal digesta were collected. Increased feed intake increased (P less than .05) pancreatic weight, alpha-amylase and glucoamylase activities in the pancreas, SI length and SI digesta weight. Forage-fed calves gained faster (P less than .01) and had greater (P less than .05) pancreatic protein concentrations, alpha-amylase and glucoamylase activities in the pancreas and greater SI digesta alpha-amylase activities than grain-fed calves did. Increased feed intake increased (P less than .01) mucosal weight/cm small intestine only in forage-fed calves and increased (P less than .05) SI surface/volume only in grain-fed calves. Mucosal weight was greatest (P less than .05) at the terminal ileum, surface/volume was greatest (P less than .05) in the duodenum, and mucosal protein concentration was highest (P less than .05) in the SI mid-section. Mucosal lactase was higher (P less than .05) in proximal segments, whereas mucosal isomaltase was higher in middle and distal segments of the small intestine. For mucosal maltase activity, there was a feed intake x SI sampling site interaction (P less than .05) and for trehalase, a diet x feed intake x SI sampling site interaction (P less than .05). The SI distribution patterns of maltase and isomaltase were similar, as were those of trehalase and lactase. The alpha-amylase activity in the pancreas and SI morphology were influenced greatly by diet composition and feed intake by calves.

Amylases↗

PubMed1989

Utero-placental transfer of octanoic, palmitic and linoleic acids during late gestation in gilts.

The transfer across the swine uterus and placenta of [1-14C]octanoic acid, [9,10(n)-3H]palmitic acid and [1-14C]linoleic acid was studied in five gilts and their fetuses during late gestation following a single bolus injection. Only trace amounts of labeled fatty acids were found in fetal plasma lipid. The highest fetal plasma lipid values were less than 1.2% of the peak maternal values. The concentration of plasma free fatty acids (FFA) and fatty acid profiles in the umbilical artery (FA) and vein (FV) and uterine artery (UA) and vein (UV) were compared. There were no measurable umbilical arterio-venous differences. Concentrations of FFA in FA and FV were about 40% of the UA and UV values (187, 194, 73, 82 microEq/liter for UA, UV, FA and FV, respectively). Fetal plasma contained larger amounts of 14:0, 16:1, 18:1 and 20:4, whereas maternal plasma contained larger amounts of 18:0 and 18:2. There was difference between fetal and maternal plasma for 16:0 and 18:3; the latter was present only in minute amounts. In conclusion, only trace amounts of FFA cross the swine placental tissues during late gestation; therefore, their contribution to fetal energy supply or lipid storage appears limited.

Animals↗

PubMed1989

Estimating salivary flow and ruminal water balance of intake, diet, feeding pattern, and slaframine.

Three experiments with ruminally fistulated cattle fed 12 times daily were conducted to study the role of saliva secretion in ruminal water balance when intake, diet, and feeding pattern were altered. Water balance data were determined from continuously infused Co-EDTA and pulse-dosed Cr-EDTA with saliva flow estimated by difference between water intake and ruminal outflow. Any net transruminal water flux would be included in the estimate of salivary flow. When the concentration of bluestem hay in the diet was increased from 50 to 90%, ruminal fluid volume, saliva secretion, water intake, dilution rate, and total ruminal outflow increased. At equal intake, the higher forage diet increased ruminal liquid volume, outflow, and saliva secretion but had no effect on dilution rate. Intake, but not forage concentration, affected ruminal pH when 50 and 90% hay diets were fed. Increasing feeding frequency of forage in a 65% bluestem hay diet from 4 to 12 times daily (the grain portion was fed 12 times daily) increased dilution and ruminal outflow; however, the latter was only significant with data from Cr-EDTA. Ruminal volatile fatty acids were not altered by feeding frequency of forage. Nycterohemeral patterns were seen in water intake, ruminal dilution rate, outflow, and salivary flow in both studies. Slaframine increased saliva flow by 29% and was accompanied by increased ruminal liquid volume, dilution rate, and outflow.

Animals↗

PubMed1988

Comparisons of ruminal fermentation characteristics and microbial populations in bison and cattle.

Ruminal microbial populations, fermentation characteristics, digestibility, and liquid flow rates in two ruminally cannulated bison and two ruminally cannulated Hereford steers fed a prairie hay diet were compared. No significant differences in anaerobic bacterial counts, volatile fatty acid concentrations, or ruminal pHs were evident between bison and cattle. Also, no significant differences in neutral detergent fiber digestibility, indigestible fiber retention time, or intake were detected between bison and cattle, although cattle had higher levels (P less than 0.08) of ruminal dry matter and indigestible fiber than bison. Bison had a smaller (P = .02) ruminoreticular volume, faster liquid dilution rates, and faster liquid turnover times than cattle. The average ruminal ammonia nitrogen concentration was higher (P = 0.02) in bison (1.17 mg/dl) than in cattle (0.79 mg/dl). Total ciliate protozoal counts and cell volume were greater (P = 0.07) in bison (32.8 x 10(4)/g and 407.1 x 10(-4) ml/g, respectively) than in cattle (15.7 x 10(4)/g and 162.2 x 10(-4) ml/g, respectively). Bison harbored higher (P less than 0.02) numbers of Dasytricha spp., Eudiplodinium maggii, Eudiplodinium bursa, and Epidinium spp. than cattle and possessed a type B protozoan population. The cattle possessed a mixed type A-type B population that was characterized by Ophryoscolex spp. and Polyplastron spp. in association with low concentrations of Epidinium spp. and Eudiplodinium maggii.

Animal Feed↗

PubMed1988

Net portal nutrient flux in steers fed diets containing wheat and sorghum grain alone or in combination.

Three Holstein steers (280 to 353 kg during the experiment) fitted with hepatic portal, mesenteric venous and arterial catheters were fed 90% concentrate diets containing wheat, dry-rolled sorghum grain or a 50:50 mixture of the two to determine the effect of dietary grain source on net portal nutrient flux. Steers were allotted to a six-period crossover design with treatments lasting 2 wk. Diets were fed in 12 portions daily to equal intakes across treatments. Simultaneous arterial and portal blood samples were taken four times per day for the final 3 d of the treatment period. Portal blood flow was determined by continuous infusion of p-aminohippuric acid, and net portal nutrient absorption was calculated by venous-arterial difference X blood flow. Dry matter intakes averaged 6.2, 6.1 and 6.0 kg/d for wheat, 50:50 mixture and sorghum grain, respectively. Net fluxes of glucose, lactate, NH3, urea-N or alpha-amino-N were not affected by diet. Net fluxes increased for propionate and decreased for 2-methylbutyrate as the level of wheat increased (P less than .10). Overall, acetate and propionate net fluxes contributed 57% to 66% of the absorbed energy on these diets, with glucose contributing a maximum of 4% on the sorghum grain diet.

Animal Feed↗