Biomedical subjects

D L Palmquist

Publications and source records attributed to D L Palmquist.

At least 37 records · Page 2Linked to original sources

PubMed1994

The role of dietary fats in efficiency of ruminants.

Fat increases energetic efficiency in lactating cows by increasing total energy intake, by generating ATP more efficiently (ATP/unit energy expended) than volatile fatty acids or protein, by direct incorporation into product, and by promoting nutrient partition toward milk production. Factors that limit utilization of large amounts of fat by ruminants include inhibitory effects on ruminal fermentation, lower intestinal absorption at high intake, low contribution to total oxidation of nutrients, and sensitivity to nutrient imbalance, causing reduced energy intake. Research has resolved many problems associated with effects on ruminal fermentation; research in the future may improve fat digestibility and reduce limits of oxidation. Effect of high fat on regulation of feed intake has received little attention.

Animals↗

PubMed1994

Site of mineral absorption in lactating cows fed high-fat diets.

Five lactating Holstein cows with ruminal and duodenal cannulas were used in a 5 x 5 Latin square to determine the site of mineral absorption and effects of sources and amount of dietary fat on apparent absorption. Cows were fed (DM, 17.4 +/- .8 kg/d) chopped alfalfa hay, alfalfa haylage, corn silage, and concentrate at 1:1:1:2 (DM) at 12-h intervals. Calcium salts of palm fatty acid distillate (CS) or animal-vegetable (AV) fat were 0% (control), 2.5% (low, L), or 5.0% (high, H) of the diet DM. After 2 wk of adaptation, duodenal and fecal grab samples were collected at 7-h intervals for 5 d and composited by animal. Calcium intake increased (P < .05) with high-fat diets (195 vs 170 g/d), whereas Mg intake remained unchanged (54.3 +/- 9.0 g/d). Apparent absorption, estimated by Cr2O3, was regressed on Ca or Mg intake (grams/day) and fatty acid (FA) intake (grams/day). Total absorption of Ca (grams/day) = -37.4 + .264 Ca (P = .07, R2 = .14). Ruminal absorption of Mg was independent of FA intake, and magnesium was secreted posterior to the duodenum. Total tract Mg absorption (grams/day) was described by -7.685 + .464 Mg -.0044 FA (P < .0005, R2 = .46). Fat intake decreased (P < .05) total tract Mg absorption, and Ca absorption was decreased by high fat compared with low fat intake (P < .05).(ABSTRACT TRUNCATED AT 250 WORDS)

Absorption↗

PubMed1994

Blood and hydrolyzed feather meals as sources of undegradable protein in high fat diets for cows in early lactation.

Thirty-six cows were in a 2 x 3 factorial study during the first 2 mo of lactation to examine effects on milk yield and composition of added fat (5% of feed DM) and percentage of ruminally undegradable protein (100, 120, or 140% of recommended intake) in the diet. The main source of added undegradable protein was a 1:1 (wt/wt) mixture of blood meal:hydrolyzed feather meal. Diets were low in ADF (ca. 14%) and were highly fermentable in the rumen. The amount of intermediate dietary protein reduced feed intake. Milk yield was high (40 to 44 kg/d), similar among treatment groups, and was sustained for the entire 60-d trail. All cows yielded milk of low fat content (2.1 to 3.2%); supplemental fat decreased proportions of C6 to C14, C18:2, and C18:3 in milk fat and increased C4, C16:0, C18:0, and C18:1. Higher dietary protein had a positive linear effect on milk fat percentage and increased C16:0 and decreased trans-C18:1 and C18:2 contents of milk fat. Added fat did not change total milk N but increased NPN as a percentage of total milk N. Percentage of total N in milk and yield of whey N was reduced when the intermediate protein diet was fed, associated with the lower DMI of this diet. A requirement for ruminally undegradable protein intake higher than recommended by NRC was not demonstrated with the highly fermentable diets fed in this study; however, ruminal acetate: propionate ratio and milk fat percentage were low.

Acetates↗

PubMed1994

Evaluation of chemical and physical properties of feeds that affect protein metabolism in the rumen.

The goal of the NC-185 Cooperative Regional Research Project is to provide the information needed to improve the nutrition and feeding of dairy cattle, a major factor determining composition of milk and cost of milk yield. Emphasis is placed on understanding how energy and protein nutrition of lactating cows can be manipulated to increase the quantity and improve the profile of AA passing to the small intestine and to improve yield of milk and milk protein. To achieve this goal, one of the major objectives of this project has been to evaluate quantitatively the chemical and physical properties of protein and energy sources that determine AA availability to lactating cows. Reliable measurements of microbial protein synthesis and protein degradation in the rumen are critical in the evaluation process. Therefore, one of the ongoing areas of investigation of this research project has been to determine the most appropriate methods for estimating microbial protein synthesis and dietary protein degradation in the rumen. Other areas have been investigated, using continuous culture fermenters and ruminally and duodenally cannulated cows, including factors that alter microbial metabolism of N in the rumen and subsequently protein supply to the small intestine, such as sources of carbohydrate, protein, and fat and interrelationships of protein and carbohydrate. Findings of the NC-185 Cooperative Regional Research Project Committee and other investigators are summarized in this review.

Animal Feed↗

PubMed1993

Diurnal variation of rumen ammonia, serum urea, and milk urea in dairy cows at high and low yields.

Milk urea content as an indicator of nutritional status may be a useful tool if major sources of variation are considered. Blood and milk samples were collected frequently during 16 to 19 h from four Holstein cows to study diurnal variation of urea content. Corn silage, alfalfa hay, and concentrates were fed. Rumen ammonia, VFA, and pH were measured in three of the cows. A clear serum urea peak, 70 to 85% higher than the lowest concentration, was observed in the higher yielding cows. The serum urea peak occurred 1.5 to 2.0 h after the rumen ammonia peak. Urea in milk equilibrated with serum with a time lag of 1 to 2 h when the rate of change in serum was .5 to 1.0 mM/h. At this rate, the average difference between serum and milk urea content was .8 mM. Urea in total milk tended to be more closely correlated to serum than samples from the gland cistern, but deviations were minor. Our results indicate a relatively rapid equilibration between blood serum and milk urea, also in the gland cistern. Equilibration may be explained by diffusion of urea along the mammary ducts and through the mucosa in the alveoli. If urea is to be used as an indicator of nutritional status, diurnal variations of serum and milk urea should be considered; time of sampling versus time of feeding is crucial. A small milk sample from a healthy quarter may give information on urea that is as good as that of a sample from regular milking.

Ammonia↗

PubMed1993

Ruminal, intestinal, and total digestibilities of nutrients in cows fed diets high in fat and undegradable protein.

To study relationships of high undegradable intake protein and dietary fat on intestinal AA supply, the ruminal, intestinal, and total digestibilities of diets with or without added fat (5% of DM) and animal protein (blood meal: hydrolyzed feather meal, 1:1; 8% of DM) were examined with four cows in a 2 x 2 factorial design in a 4 x 4 Latin square experiment. Ruminal degradabilities were 14.9 and 18.6%, and intestinal digestibilities were 98.9 and 68.3%, respectively, for CP in blood meal and feather meal. Treatment effects on ruminal digestibilities were small. Protein supplementation increased total N intake by 29%, duodenal AA N flow by 39%, and AA N absorbed by 37%; absorption of Leu and Lys increased 60 and 33%, and absorption of Ile and Met increased 11 and 7%, respectively. Measured duodenal AA N flow (Cr2O3 marker) was 33% higher in cows cannulated adjacent to the pylorus compared with cows cannulated 100-cm distal to the pylorus, but only when cows were fed protein-supplemented diets; the estimates from those diets caused calculated microbial protein efficiency to exceed theoretical values. We postulated that blood meal and feather meal segregated near the pylorus, yielding high estimates of duodenal AA N flow. Removal of data for protein-supplemented diets obtained from cows cannulated at the pylorus yielded estimates of microbial protein synthetic efficiency consistent with literature values. Microbial synthesis of AA N was related linearly to ruminal digestion of carbohydrate. Location of intestinal cannulas may influence accuracy of nutrient flow estimates.

Amino Acids↗

PubMed1993

Feed and animal factors influencing milk fat composition.

Genetic selection for increased milk fat percentage leads to increased proportions of short-chain fatty acids in milk fat and decreased proportions of long-chain fatty acids. Milk fat composition is strongly influenced by stage of lactation; proportion of short chains (de novo synthesis) is low initially and increases until at least 8 to 10 wk into lactation. Milk fat composition is changed more by the amount and composition of dietary fat than any other dietary component. Seasonal and regional differences in milk fat composition are measurable, most likely because of local differences in feed supplies. Milk fat composition can be modified readily by changing the feeding regimen. The most significant changes in milk fat quality relate to rheological (melting) properties, which influence numerous aspects of character and quality of manufactured dairy products. Dietary fat fed to change milk fat composition may also influence contents of protein, urea, citrate, and soluble calcium in milk and influence oxidative stability and flavor. It is important for both dairy nutritionists and dairy food chemists to understand the consequences of feeding programs on milk quality.

Animal Feed↗

PubMed1992

Glucose and insulin metabolism in ruminating and veal calves fed high and low fat diets.

Holstein male calves were maintained on conventional (milk to 6 wk of age, fed grain and hay after weaning) and veal (milk replacer only) diets to 16 wk of age. Within each of these 2 physiological states (ruminating or non-ruminating), calves were fed low or high fat diets (ruminating: 3 and 10%; veal: 10 and 18%). Glucose tolerance tests were undertaken at 8 and 16 wk of age in each group. Basal concentrations (4 hr postfeeding) and areas under the response curves for plasma glucose and insulin were higher in veal calves (P < .0001). Ruminating calves fed higher fat utilized glucose more readily (smaller areas under the curves for both glucose and insulin, P < .10) than those fed lower fat. Age did not influence basal glucose concentrations (P > .10), but older calves had higher basal insulin (P < .0001) and greater areas under the curves (P < .0005) for both glucose and insulin after a glucose challenge. Rate of clearance (k) was greater in ruminating calves (P < .001). Though rate of clearance in veal calves was slower, larger plasma pool size caused veal calves on average to utilize glucose at a 15% greater rate per kg body weight than ruminating calves. Whereas fat concentration in the diets did not influence glucose metabolism in veal calves, the high lactose content (> 50% of diet dry matter) of veal diets induced severe insulin resistance in these calves.

Animals↗

PubMed1991

Dietary fat composition influences fatty acid composition of milk fat globule membrane in lactating cows.

Milk fat globule membranes are derived directly from the apical plasma membrane of mammary epithelial cells. To evaluate the effect of dietary fat on mammary membranes, we determined the fatty acid composition of the milk fat globule membrane in lactating dairy cows fed diets supplemented with fats of different fatty acid composition, or infused intravenously with soy oil emulsion. A preliminary survey, using an abbreviated preparation procedure (membranes isolated at 48,000 x g-max for 15 min), yielded about 45% of the total membrane fatty acids that could be recovered by centrifuging at the same speed for 120 min, and showed that changes in fatty acid composition of membranes reflected dietary fatty acids to some extent. Dietary palmitic acid increased the content of 16:0 in the membranes. A high corn diet increased ruminal formation of t18:1, and its level increased to 12% of membrane fatty acids. Infusion of soy oil emulsion increased 18:2 membrane content, and decreased the levels of 18:1 and 20:4. All treatments decreased the ratio of unsaturated/saturated fatty acids as compared to controls, whereas the ratio of polyunsaturated/saturated fatty acids was increased by feeding a high corn diet or by infusing soy oil. The ratio of 18:2/c18:1 increased from 0.31 to 1.0 after infusing soy oil for 4 days. The fatty acids of membranes isolated upon 120-min centrifugation were slightly more saturated. The differences were not sufficiently large, however, to affect overall results significantly.

Animals↗

PubMed1991

Evaluation of n-alkanes as digesta markers in dairy cows.

Recovery of hentriacontane (C31 alkane) in feces as influenced by amount consumed and level of dietary fat was examined in a 2 x 2 factorial study in a 4 x 4 Latin square. Treatments were 1) alfalfa hay:concentrate (70:30; AH); 2) AH + calcium soap (500 g/d); 3) grass hay:concentrate (70:30, GH); and 4) GH + calcium soap. Fat did not influence C31 recovery in feces. Fecal recovery (grams/day) decreased quadratically with increasing C31 intake. Compared with AIA, which was 100% recovered in feces, DM digestibility was estimated more accurately (P less than .05) by AIA than by C31. In a second experiment, site of loss of alkane in the intestinal tract was examined by dosing C32 into the rumen or duodenum. Recovery was lower with ruminal dosing, suggesting ruminal loss of the marker. Alkanes are potentially useful markers of particulate matter in the digestive tract; however, documentation of their behavior in a wider range of diets is needed.

Alkanes↗

PubMed1991

Influence of source and amount of dietary fat on digestibility in lactating cows.

Digestibility of commercial fat supplements was determined in two experiments with high (59% of diet DM) forage diets. Experiment 1 was a preliminary trial in which six Jersey cows were in two 3 x 3 Latin squares to evaluate two formulations of calcium soap at two intake levels (500 and 1000 g/d). The two formulations were compared with control (0 supplement) within squares; the squares differed in amount of soap supplemented. Mean apparent digestibilities of fat were not influenced by source or amount of fat supplemented and averaged 82.5, 84.3, and 83.4% for control, 500, and 1000 g/d. In Experiment 2, six Jersey cows were in a 6 x 6 Latin square to compare effects of various commercial fats on digestibility of diet components at 2.85 and 5.7% (DM) added fat. Higher fat decreased digestibility of P and fatty acid. Fatty acid intake affected fatty acid digestibility quadratically, and variability among cows increased at higher fatty acid intake. Endogenous fecal fat was 55.9 g/d; apparent digestibility of fat was relatively constant at 80 to 82% between 2 and 5% of diet DM, whereas marginal true digestibility decreased linearly (4.4% units/100 g fatty acid consumed). There were no differences among fat sources in fatty acid digestibility. Rumen VFA were not influenced by dietary fat.

Animals↗

PubMed1991

Ruminal metabolism, fiber, and protein digestion by lactating cows fed calcium soap or animal-vegetable fat.

Effects of two levels of Ca soap or animal-vegetable fat on digestion of fiber and N and on microbial protein synthesis were studied in five ruminally and duodenally cannulated lactating cows in a 5 x 5 Latin square. Fat was added at 0, 2.5%, or 5% of dietary DM, which consisted of a 60:40 forage:concentrate mix. Treatment did not influence DMI, duodenal OM flow, or digestibility. Fat linearly increased liquid dilution rate (12.1 vs. 11.1 h-1) and reduced liquid (53.6 vs. 62.4 L) and ruminal (61.6 vs. 70.1 L) volumes. Source and amount of fat did not influence mean ruminal pH, ammonia N, or VFA concentrations; however, animal-vegetable fat reduced acetate:propionate ratios compared with Ca soap (3.47 vs. 3.64). Neither source nor amount of fat influenced fiber flow, digestion, or efficiency of microbial protein synthesis. Source and amount of fat did not change ruminal or total digestibilities of DM, OM, ADF, or NDF; however, dietary fat increased total tract apparent digestion of N (70.3 vs. 66.8). Estimates of ruminal DM digestibility were lower (24.2 vs. 39.0) and total tract DM digestibility was higher (63.3 vs. 60.5) with Cr marker compared with C31 hydrocarbon marker. Animal-vegetable fat or Ca soap can be supplemented up to 5% of the dietary DM in high forage diets without adverse effects on ruminal metabolism and digestion.

Ammonia↗

PubMed1991

Ruminal synthesis, biohydrogenation, and digestibility of fatty acids by dairy cows.

Ruminal synthesis and biohydrogenation of fatty acids in dairy cows were determined by sampling duodenal digesta through T-cannulas. Fatty acid digestibility in the total tract also was measured. Five diets (concentrate:alfalfa hay:alfalfa haylage:corn silage, 2:1:1:1, DM) in a 5 x 5 Latin square contained either no added fat; 3 or 6% added calcium soap; or 3 or 6% animal-vegetable blend fat. Seventy percent of dietary fatty acids were recovered at the duodenum, and 106 g/d were synthesized in the rumen regardless of diets. Fatty acids synthesized in greatest amounts were odd or branched chains, whereas more than 90% of the fatty acids shorter than 14 carbons disappeared. Fatty acids in calcium soap were biohydrogenated 57% and in animal-vegetable blend 87%. Fatty acids in calcium soap were more digestible (80.0 vs. 75.7%) than those in the blended fat due to greater unsaturation in the small intestine. Ruminal microorganisms selectively synthesized fatty acids.

Animal Feed↗

PubMed1991

Synthesis and biohydrogenation of fatty acids by ruminal microorganisms in vitro.

Ruminal degradation, synthesis, and biohydrogenation of fatty acids were examined in vitro. Diets were incubated with ruminal contents, and changes of fatty acids were measured. Two fat supplements, a calcium soap and an animal-vegetable blend, were included in diets at various levels. Addition to diets of acetate and isoacids (collective term for certain short-chain acids) also were tested for effects on fatty acid synthesis. Overall, 6.6 mg of fatty acids/g of fat-free diet were synthesized during 24-h incubation regardless of supplementations. Fatty acids synthesized in greatest amounts were odd-numbered or branched chains, whereas chains of 16 and 18 carbons changed little, and chains shorter than 14 carbons decreased. Degradation of [1-14C]palmitic acid was negligible, as determined by recovery of the label in CO2 (.03%) and acetate (1.09%) after 4-h incubation with rumen contents. Biohydrogenation of fatty acids averaged 47% in diets containing calcium soap and 71% with animal-vegetable blend. Synthesis and biohydrogenation were similar to those measured previously in vivo, showing that in vitro measurements reliably predicted metabolism of fatty acids in vivo.

Animal Feed↗

PubMed1990

Effects of calcium soaps of long-chain fatty acids on feedlot performance, carcass characteristics and ruminal metabolism of steers.

Two trials were conducted to determine the effects of calcium soaps of long-chain fatty acids (calcium soap) on feedlot performance, diet digestibility, carcass characteristics and ruminal metabolism of steers fed diets (85% concentrate:15% corn silage) containing 0, 2, 4 or 6% calcium soap. In Trial 1, increasing calcium soap decreased (P less than .05) DM, CP and gross energy intake but increased total fatty acid intake. Feed to gain ratio tended to improve with increased calcium soap; gross energy conversion was not affected (P greater than .05) by diet. Average daily gain and hot carcass weight decreased (P less than .05) with addition of calcium soap; other carcass characteristics were not affected (P greater than .05). Apparent digestibilities of DM, N, energy and ash were not affected (P greater than .05) by calcium soap. Neutral detergent fiber digestibility increased linearly (P less than .08) with increasing calcium soap, whereas digestibility of total fatty acids was affected quadratically (P less than .05); fatty acid digestibility was similar among 0, 2 and 4% calcium soap diets but decreased for the 6% calcium soap diet. In Trial 2, increased calcium soap did not affect (P greater than .05) ruminal VFA concentrations, pH or in sacco NDF disappearance of orchardgrass following 12, 24 and 48 h of incubation. Calcium soap increased (P less than .07) ruminal concentrations of calcium soap fatty acids at 1, 2, 4 and 8 h postfeeding. Calcium soap did not improve performance of feedlot cattle fed high-concentrate diets. Further, calcium soap did not affect ruminal fermentation and did not dissociate significantly even when ruminal pH was below 6 for extended periods of time.

Animal Feed↗

PubMed1990

Dissociation of calcium soaps of long-chain fatty acids in rumen fluid.

Dissociation of 5% solutions of calcium soaps of soya, tallow, stearic acid, and palm fatty acid distillate was studied by titration with 1 N HCl. Release of calcium ions was directly correlated with decrease in pH value. Estimated pKa values were 5.6, 4.6, 4.5, and 4.5 for calcium soaps of soya, palm fatty acid distillate, tallow, and stearic acid, respectively. Dissociation of 5% solutions in acetate buffer at pH values of 5.0, 5.5, 6.0, and 6.5 was measured in terms of release of soluble calcium. Dissociation was maximum at pH 5.0, minimum at pH 6.5, and dependent on unsaturation of fatty acids in the soaps. Soluble calcium in the acetate-buffered rumen fluid was higher than predicted from pKa of calcium soaps, due to formation of soluble calcium acetate; however, the relative patterns were similar to their pKa values. Unsaturated soaps are less satisfactory for maintaining normal rumen function, because dissociation is relatively higher. Calcium soaps of palm fatty acid distillate were satisfactorily stable to pH 5.5.

Animals↗

PubMed1989

Effect on days of lactation and methionine hydroxy analog on incorporation of plasma fatty acids into plasma triglycerides.

Methionine hydroxy analog has been proposed to stimulate hepatic lipoprotein synthesis and incorporation of plasma fatty acids into plasma triglyceride. Seven cows were fed diets containing 0 or 30 g analog/d starting 14 d prepartum. At approximately 30 and 60 d postpartum, cows were continuously infused intravenously with 1-[14C] palmitic acid for 160 min to achieve steady-state labeling of plasma fatty acid and triglyceride. Turnover of fatty acid and transfer quotients for triglyceride and CO2 were 3.3 and 2.7 mmol min-1; 13.0 and 10.0%; and 8.0 and 5.0%, for control and analog, respectively. Proportion of fatty acid turnover incorporated into triglyceride and CO2 were 14.0 and 15.0%; and 21.0 and 18.0, respectively, for control and analog. Analog increased 14C recovered in milk fat (52 vs. 36%). Plasma concentration of fatty acids, percent oxidized to CO2, and percent of CO2 from fatty acids decreased with increasing lactation days. Milk fat percent and yield, fatty acid turnover, and oxidation were positively correlated with concentration of plasma fatty acids, whereas fatty acid incorporated into plasma triglyceride was negatively correlated with fatty acid concentration. The data suggest that hepatic triglyceride secretion is not increased in early lactation; further, no effects of analog on lipid metabolism were detected.

Animals↗

PubMed1988

ATP citrate lyase activity in liver and adipose tissue of veal or ruminating calves (Bos taurus).

1. The activity of ATP citrate lyase in liver and adipose tissue and the concentrations of glucose and insulin in plasma were determined in veal and in ruminating calves. 2. The activity of ATP citrate lyase per g of tissue was substantially higher in liver and adipose tissues of veal calves. 3. Although activity of this enzyme was higher in liver than in adipose tissue on a per g of tissue basis, comparison on a per mg protein basis showed the adipose tissue levels of the enzyme to be higher. 4. Both plasma glucose and insulin levels were also higher in veal calves which agreed well with both the ATP citrate lyase activity and with data from previous studies.

ATP Citrate (pro-S)-Lyase↗