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Biomedical subjects

G D Adams

Publications and source records attributed to G D Adams.

13 recordsLinked to original sources
PubMed1992

Influence of fiber form in a complete mixed ration on incidence of left displaced abomasum in postpartum dairy cows.

During the fall of 1982, increased incidence of left displaced abomasum (LDA) was seen in a group of cows fed a complete pelleted ration (3/16 inch) at the university's dairy center during the early postpartum period. Of these, 17.4% developed LDA when fed this experimental ration, whereas only 1.6% of the remaining cows in the herd developed LDA. The latter cows (as a control) were fed loose alfalfa hay, sorghum silage, and an 18% crude protein mix. Most of the fiber in the experimental diet or pelleted diet was alfalfa hay (30% as-fed basis) that was ground through a quarter-inch screen for incorporation into the pellet. Another 10% of the dietary fiber was contributed by cottonseed hulls. Thus, increased incidence of LDA may be associated with short length of the dietary fiber in the pelleted form.

Abomasum↗
PubMed1992

The use of a layering technique for enhancing stability of lyophilized reagents.

An enzyme-mediated assay has been developed for the measurement of salicylate using salicylate monooxygenase purified from Pseudomonas cepacia ATCC 29351. Two assay formulations were produced, based on either a multiple-reagent or a single-reagent formulation, to allow sufficient flexibility for automated use. The multiple-reagent formulation was especially suited to diagnostic laboratories performing infrequent manual salicylate estimation where stability of the reconstituted reagent is of paramount importance. This was achieved by preparing the enzyme and color reagents in separate vials, so keeping the enzyme at a stable pH. For more frequent assay use where a reconstituted reagent shelf life was less important, the single-reagent system offers advantages of convenience. However, the working reagent required a pH of 10.0 upon reconstitution. Although the enzyme was sufficiently active at this pH to give a reliable assay, its storage stability was poor at pH 10.0, preventing lyophilization of the reagent at a pH suitable for immediate use on reconstitution. This incompatibility was overcome by use of a layering technique. The enzyme was separated from the buffering solution in the same vial by freezing the buffering solution and then overlayering with the enzyme reagent prior to a second freezing cycle and subsequent freeze drying.

Aspirin↗
PubMed1992

Influence of dietary cation-anion balance during the dry period on the occurrence of parturient paresis in cows fed excess calcium.

Our objective was to evaluate the effectiveness of a low dietary cation-anion balance (DCAB) in preventing milk fever and udder edema in dry cows consuming a high-Ca diet and to evaluate the effect of this diet on calves delivered by these cows. Seventy primiparous or multiparous cows and 50 pregnant heifers were offered alfalfa hay-based diets beginning 4 wk before their projected calving date. Diets contained 1.6% Ca and a DCAB of -3 or +9 mEq/100 g of diet DM. Blood and urine samples were collected weekly from 3 wk prepartum until 3 wk postpartum. Blood samples were collected from calves at parturition and weekly thereafter for 3 wk. Feeding a low vs high DCAB in a high-Ca diet for 3 wk prepartum did not reduce the incidence of milk fever; this lack of response may have been attributable to the relatively low DCAB of each diet and the small difference in DCAB between the two diets. Udder edema seemed to regress more rapidly postpartum for cows that had consumed the low DCAB during the dry period. Test diets fed to prepartum cows did not affect systemic acid-base status or plasma mineral content of their calves, although plasma Ca was somewhat lower for calves from cows consuming a low DCAB and was higher for calves from primigravid cows. Correlations of plasma mineral concentration of the cows with those of their calves were highest for plasma Ca (r = .75; P less than .001). We conclude that the prophylactic effects on the occurrence of milk fever of feeding a low DCAB during the dry period may be absent when diets contain greater than 1.6% Ca and DCAB is greater than or equal to -3. The cation-anion balance of the diet consumed by dry cows did not affect the acid-based status or plasma mineral content of their calves.

Acid-Base Equilibrium↗
PubMed1992

A buffer value index to evaluate effects of buffers on ruminal milieu in cows fed high or low concentrate, silage, or hay diets.

Our objective was to develop a buffer value index that would incorporate alterations in both ruminal fluid pH and buffering capacity as indicators of the influence of dietary buffering and alkalinizing agents on ruminal acid-base status. This index was evaluated using ruminal fluid from four lactating Holstein cows fed either sorghum silage or alfalfa hay in high or low concentrate diets. Ruminal fluid was incubated in vitro for 1, 2, 3, 4, or 5 h with no buffer or with 7.1 g of either NaHCO3, sodium sesquicarbonate, or a multielement buffer added per liter of ruminal fluid. Ruminal fluid pH was lower for diets based on high concentrate or alfalfa; buffering capacity between pH 5 and 7 was greater for high concentrate diets but was not affected by forage type. Ruminal fluid pH was higher for sesquicarbonate than for NaHCO3, the multielement buffer, or the control; however, ruminal fluid H+ concentration was similar between sesquicarbonate and NaHCO3, and both were lower than for the multielement buffer. Hydrogen ion concentration for the multielement buffer was lower than for the control. Buffering capacity was highest for NaHCO3, followed by sesquicarbonate, the multielement buffer, and the control. The buffer value index, which accounted for alterations in both H+ concentration and buffering capacity, was highest for NaCHO3, followed by sesquicarbonate, the multielement buffer, and the control. The poor response to the multielement buffer may be attributable to our relatively short incubation interval (less than 5 h). Dietary buffers increase both ruminal fluid pH and buffering capacity; both of these responses are beneficial.(ABSTRACT TRUNCATED AT 250 WORDS)

Acid-Base Equilibrium↗
PubMed1992

Evaluation of a system for rating edema in dairy cattle.

Our objective was to evaluate a subjective edema rating system to quantitate edema severity. Edema was evaluated with 20 nulliparous Holstein heifers from 3 wk before their expected calving date until 3 wk postpartum. Severity of udder edema was evaluated independently daily by five people throughout the 68-d experiment; a 10-point rating system (0 = no edema, 10 = severe edema) was used. One of the people developing the scoring system served as the official scorer. The accuracy of the rating system, defined as the closeness of test evaluator scores to official scores, was highest for scores 2 to 8. The precision of the system, identified by the standard error of the mean, was similar for each score in the rating system. The largest disagreement between official and test evaluator scores was evident postpartum. The large number of defined points in this rating system and the similarity between official and test scores in this study indicate the usefulness of this tool to evaluate precisely the severity of edema in dairy cattle.

Animals↗
PubMed1992

Influence of calcium chloride fed prepartum on severity of edema and lactational performance of dairy heifers.

Twenty Holstein heifers in a completely randomized design were used to evaluate the effects of prepartum dietary CaCl2 on the development and regression of edema and on subsequent lactational performance. Heifers were assigned to diets containing either 2.17% limestone or 1.5% CaCl2 (DM basis) at 3 wk before expected calving date. Except for the Ca sources, diets were identical. Test diets were only fed prepartum; at calving, all heifers were offered a lactation diet for 3 wk. Severity of edema was evaluated independently by five people daily throughout the experiment; a 10-point rating system was utilized to quantify the severity of edema. Calcium chloride reduced the severity of edema, although this response was most evident during the 1st wk that this salt was fed. The beneficial effects of CaCl2 on edema prepartum disappeared postpartum, when CaCl2 was removed from the diet. Indeed, edema was higher for heifers fed CaCl2 than for those fed limestone at 2 wk postpartum. Calcium chloride reduced DMI prepartum, but, following parturition, a compensatory increase in feed intake occurred. Postpartum daily DMI averaged 1.3 kg higher for heifers fed CaCl2 than for those fed the limestone diet prepartum. Milk yield and composition were somewhat lower for heifers fed CaCl2, although this response was most evident at 1 wk postpartum. Feeding CaCl2 prepartum to prevent milk fever also may reduce the severity of udder edema prepartum and increase feed intake during early lactation.

Animals↗
PubMed1992

Influence of dietary fiber and buffer value index on the ruminal milieu of lactating dairy cows.

The influence of dietary buffer value index and dietary ADF content on ruminal fluid pH, buffering capacity, and buffer value index was measured. Four lactating Holstein cows (two primiparous) averaging 72 +/- 60 DIM were used in a 4 x 4 Latin square with 3-wk experimental periods. Treatments were a 2 x 2 factorial arrangement of TMR containing two ADF concentrations (16 and 21% of DM) and two buffer value indexes (calculated from analysis of individual dietary ingredients to be -200 and 0). Milk fat content and milk fat yield tended to be increased by high ADF, and protein yield tended to increase with low buffer value index and low ADF. Although the high ADF diets increased ruminal fluid pH, they reduced buffering capacity; because the magnitude of the pH increase was greater than the reduction in buffering capacity, ruminal fluid buffer value index was increased by added ADF. The high buffer value index diets reduced ruminal fluid pH and increased ruminal fluid buffering capacity; effects on pH outweighed those on buffering capacity so that the ruminal fluid index paradoxically decreased as the dietary index increased. Ruminal fluid acetate increased and propionate decreased as ADF increased. We conclude that ruminal fluid buffer value index increases with dietary ADF, likely because of reduced ruminal concentrations of fermentation acids. Because diets with the highest index produced the lowest ruminal indexes, dietary buffer value index must be studied further before it can be included in any model purporting to predict the need for supplemental dietary buffers.

Acetates↗
PubMed1992

Sodium bicarbonate or multielement buffer via diet or rumen: effects on performance and acid-base status of lactating cows.

Our objective was to compare the influence of dietary NaHCO3 and a multielement buffer on ruminal acid-base status and lactation performance of dairy cows. Five ruminally fistulated, primiparous and multiparous lactating Holstein cows averaging 123 +/- 21 d postpartum were assigned randomly to treatments in a 5 x 5 Latin square with 3-wk experimental periods. Treatments were a basal diet without supplemental buffers, with 1.5% NaHCO3 or 1.5% multielement buffer, or with NaHCO3 or multielement buffer solutions poured into the rumen via cannula at 2 h postfeeding. Addition of either buffer to the diet reduced ruminal fluid hydrogen ion concentration from 0 to 6 h postfeeding; only NaHCO3 reduced ruminal fluid acidity when dosed via the cannula. Addition of buffers via ruminal cannula appeared to retard the reduction in ruminal fluid acidity that normally occurs from 6 to 12 h postfeeding; this may have been related to a feedback mechanism inhibiting salivary buffer secretion. Buffering capacity of ruminal fluid tended to increase with buffer addition; the increase was greatest during infusion of NaHCO3. The ruminal fluid buffer value index increased by 4 units for control cows from early (0 to 6 h) to late (6 to 12) postfeeding; smaller increases were noted for addition of multielement buffer. This index was not different for NaHCO3 during these two intervals. Milk yield and DMI were not affected by buffer addition. Although milk fat content tended to be higher with the multielement buffer than with NaHCO3, it was not accompanied by the expected alterations in ruminal acid-base status. Therefore, this increase may be related to systemic effects of specific minerals in the multielement buffer rather than to a more stable ruminal environment. Based on the ruminal fluid buffer value index, NaHCO3 tended to maintain the most stable ruminal acid-base status.

Acetates↗
PubMed1991

Controlled ruminal infusion of sodium bicarbonate. 1. Influence of postfeeding infusion interval on ruminal milieu.

Four ruminally cannulated, lactating Holstein cows were assigned to a 4 x 4 Latin square to monitor the effects of intraruminal NaHCO3 infusion on changes in the rumen environment. Sodium bicarbonate (110 g), dissolved in 3.8 L of water, was infused twice daily at a constant rate for 2 h starting at 0, 2, or 4 h postfeeding. All cows had access to their diet containing sorghum silage and concentrate in a 35:65 ration (DM basis) for 45 min twice daily. Ruminal fluid was collected at feeding and every 30 min postfeeding for 12 h on the last day of each 7-d period. Dry matter intake was lower for buffer infusion at 2 to 4 h than for water-infused control but was not affected by the other NaHCO3 infusions. Although total milk yield was not affected, milk fat percentage and fat yield tended to be lower for the NaHCO3 treatments. Compared with the water infusion, the NaHCO3 infusion from 2 to 4 h postfeeding most effectively prevented the postfeeding increase in ruminal free proton concentration. Additionally, volume of ruminal liquid was increased for the NaHCO3 infusions from 0 to 2 h and 4 to 6 h; ruminal liquid turnover time was increased for the NaHCO3 infusion at 4 to 6 h, but ruminal kinetics otherwise were not affected by NaHCO3. Although infusion of NaHCO3 from 2 to 4 h prevented severe alterations in ruminal acid-base status, it did not increase total VFA concentration or the acetate:propionate ratio. Although total VFA concentrations were not affected by NaHCO3 infusion, acetate:propionate ratio was higher for the NaHCO3 infusion from 0 to 2 h than for the control. Based upon alterations in ruminal acid-base status, exogenous buffer ideally should be provided to the rumen from 2 to 4 h postfeeding; however, our results indicate that the effectiveness of this regimen might be improved if buffer is combined with a rapidly released or unprotected dietary buffer.

Acid-Base Equilibrium↗
PubMed1991

Controlled ruminal infusion of sodium bicarbonate. 2. Effects of dietary and infused buffer on ruminal milieu.

Four ruminally cannulated, lactating Holstein cows were assigned to a 4 X 4 Latin square to monitor the effects of NaHCO3 infusion on ruminal environment of cows receiving dietary sodium bicarbonate. Sodium bicarbonate (110 g) was mixed with 3.8 L of water and infused at a constant rate into the rumen from 0 to 2, 2 to 4, or 4 to 6 h postfeeding twice daily. All cows were fed sorghum silage and concentrate in a 35:65 DM ratio for 45 min twice daily. Ruminal fluid was collected at feeding and every 30 min postfeeding for 8 h on the last day of each 1-wk experimental period. Dry matter intake was not affected by NaHCO3 infusion. Yields of milk and its components were reduced with 4- to 6-h NaHCO3 infusion. At certain isolated times, especially during infusion, NaHCO3 infusion increased ruminal fluid buffer. Concentrations of ruminal fluid total VFA were not affected by NaHCO3 infusions, whereas acetate to propionate ratio tended to be reduced. Ruminal liquid volume tended to be increased by 0- to 2-h NaHCO3 infusion, and ruminal outflow rate tended to be reduced by the 2- to 4-h infusion. Intraruminal infusion of NaHCO3 into cows receiving supplemental dietary NaHCO3 altered ruminal acid-base status as typically reported for those receiving dietary NaHCO3; however, these alterations were not accompanied by shifts in ruminal VFA patterns or in milk composition that normally result from such feeding regimens. The effects of NaHCO3 infused directly into the rumen may be different from those of dietary NaHCO3 and are possibly related to the different time of entry into the rumen relative to feeding.

Acid-Base Equilibrium↗
PubMed1975

Oral inhalation system for exposing rabbits to cigarette smoke.

An oral inhalation system for exposing rabbits to cigarette smoke has been developed. The essential components of the system comprise a smoke delivery device that adapts to the oral cavity, a molded face mask, and a sealable body enclosure. The functional capability of the system has been validated by detecting the presence of nicotine in plasma and by measuring the deposition of dotricontane labeled with radioactive carbon (14C) in lungs after exposure to cigarette smoke.

Animals↗
PubMedDate not supplied

Formation and early years of the AAPM.

This vignette recites significant steps leading to the formation of the AAPM and transpiring in the developments of the first decade, approximately. Persons involved, dates, and places are recognized. A table summarizes the progression of events. This recitation ends with the term of Kereiakes, the last President to be elected by the Board of Directors from its own membership, and with the move of the annual meeting time to mid-summer.

Biology↗