Biomedical subjects

D M Webel

Publications and source records attributed to D M Webel.

24 records · Page 2Linked to original sources

PubMed1998

Limiting order of amino acids in a low-protein corn-soybean meal-whey-based diet for nursery pigs.

Three trials were carried out with pigs between 5 and 8 wk of age to determine the limiting order of amino acids in a 13.5% CP corn-soybean meal-based diet containing 8% dried whey. The positive-control diet was a 19.2% CP corn-soybean meal-based diet (1.15% lysine), also with 8% dried whey. Amino acid additions to the low-protein, negative-control diet were based on levels needed to accomplish 110% of ideal ratios (to lysine, set at 1.15%). In Exp. 1, the addition of an amino acid mixture containing Lys, Trp, Thr, Met, Ile, and Val to the low-protein diet increased (P<.05) gain and gain: feed ratio, and these response traits were not different from those of pigs fed the 19.2% CP positive-control diet. Single deletion of Lys from the supplemental amino acid mixture depressed performance to a greater (P<.05) extent than single deletion of any of the other amino acids. Single deletions of Trp, Thr, Met, or Val decreased (P<.05) performance in a similar but lesser magnitude than the decrease caused by Lys deletion, whereas Ile deletion was without effect. Experiments 2 and 3 were designed to evaluate the limiting order of AA beyond Lys in the low-protein diet. Neither His nor Glu were found to be deficient, and, as in Exp. 1, deletion of Trp, Thr, Met, or Val from the supplemental amino acid mixture resulted in performance depressions (P<.05) that were similar. The results suggest that Lys is first-limiting and Trp, Thr, Met, and Val are equally second-limiting in a reduced protein (13.5% CP) corn-soybean meal-based diet with 8% whey for 10-kg pigs.

Amino Acids↗

PubMed1998

Hepatic and renal betaine-homocysteine methyltransferase activity in pigs as affected by dietary intakes of sulfur amino acids, choline, and betaine.

In Exp. 1, young pigs were fed a basal diet containing .17% methionine (Met) (.14% digestible Met), and .48% cystine (.38% digestible cystine) for 14 d (34 to 48 d of age). Treatment additions were .25% DL-Met, .34% betaine, .30% choline, or .25% DL-Met and .34% betaine. Methionine, but not betaine or choline supplementation, increased (P < .05) weight gain and feed efficiency. Hepatic betaine-homocysteine methyltransferase (BHMT) activity was increased (P < .05) by betaine and choline supplementation but was not affected by Met deficiency. Renal BHMT activity was increased (P < .05) by Met deficiency and was further increased (P < .05) by betaine supplementation. In Exp. 2, 10-kg pigs were fed the basal diet from Exp. 1 supplemented with enough DL-Met to bring the total basal Met to .24% (.20% digestible Met). Treatment additions consisted of .20% DL-Met or .34% betaine, and diets were fed for 16 d (34 to 50 d of age). Feed efficiency increased (P < .05) in response to Met, but not to betaine, supplementation. Hepatic BHMT activity increased (P < .05) in response to betaine and Met, but no changes in renal BHMT activity occurred. Although statistically significant changes in hepatic and renal BHMT activity occurred in both experiments, the magnitude of the responses was probably not physiologically important. Therefore, in contrast to previous findings with rats and chicks, it does not seem that hepatic and renal BHMT activity in pigs is influenced substantially by Met deficiency, or by surfeit levels of choline or betaine.

Amino Acids, Sulfur↗

PubMed1997

Time course of increased plasma cytokines, cortisol, and urea nitrogen in pigs following intraperitoneal injection of lipopolysaccharide.

The emerging view is that reduced feed intake, lean muscle accretion, and growth in immunologically challenged pigs is the result of increased cytokine activity, but this has not been directly tested. To begin addressing this issue, 72 crossbred barrows and gilts (11.55 +/- .19 kg BW) were not fed for 12 h and then injected i.p. with 0, .5, or 5 micrograms/kg of Escherichia coli lipopolysaccharide (LPS). Blood was collected by jugular puncture at 0, 2, 4, 8, 12, and 24 h after injection. Plasma levels of tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), cortisol, plasma urea nitrogen (PUN), NEFA, and triglycerides were determined. Immunological stress was induced by LPS as indicated by increased secretion of TNF-alpha, IL-6, and cortisol. In pigs receiving 5 micrograms/kg of LPS, plasma TNF-alpha was increased 10-fold at 2 h after injection and was still elevated (P < .01) at 4 h. In these same pigs, plasma concentration of IL-6 was increased at 2 h and peaked at 4 h with levels exceeding baseline values by 200-fold (P < .01). Cortisol was elevated at 2, 4, and 8 h after injection (P < .01). The increased secretion of cytokines and cortisol in pigs injected with 5 micrograms/kg of LPS was followed by an increase in protein degradation, as evidenced by PUN values that were increased two- and threefold at 8 and 12 h after injection, respectively. However, unlike previous reports in laboratory animal species, plasma glucose, NEFA, and triglycerides were not altered by LPS. Nonetheless, as the period of feed deprivation progressed from 12 to 36 h, plasma NEFA and triglycerides increased (P < .05) and plasma glucose tended to decrease. We believe that immunological challenge induces cytokine synthesis and secretion in swine which, in turn, may induce protein catabolism.

Animals↗

PubMed1996

Maintenance requirement for valine and efficiency of its use above maintenance for accretion of whole body valine and protein in young chicks.

Experiments were conducted with chicks during the period 10-20 d posthatching to assess valine accretion and protein accretion as a function of incremental valine intakes between 5 and 95% of its ideal level (requirement for maximal growth). Chemically defined crystalline amino acid diets were fed, and amino acids other than valine were maintained at minimized excess levels as valine was increased. With dietary valine concentrations representing 5, 10, 40, 55, 70 and 95% of the ideal level, weight gain (r2 = 0.98), protein accretion (r2 = 0.98) and valine accretion (r2 = 0.99) increased linearly (P < 0.01) as a function of valine intake. Slope of the valine accretion curve was 0.73 +/- 0.02, and there was no indication of decreased valine utilization as valine intake increased to 95% of its required level for maximal growth. Using the linear regression equation, i.e., valine accretion (Y) regressed on valine intake (X), the maintenance valine requirement (X at Y zero) was 18.4 mg/d or 48.8 mg/d per kg body weight3/4. Whole body valine was 4.72 g/100 g whole body protein accreted and was constant at all levels of valine intake. At zero protein accretion, however, valine accretion was negative (-3.8 mg/d). Thus, the valine requirement for zero valine accretion (48.8 mg/d per kg(3/4) was higher than the valine requirement for zero protein accretion (32.4 mg/d per kg3/4). In a subsequent experiment, also involving whole body valine and protein accretion, valine doses of 40, 55 and 70% of ideal were compared using amino acid-balanced diets (amino acids other than valine at 55, 70 and 85% of ideal levels, respectively) or imbalanced diets (amino acids other than valine at a constant 100% of their ideal levels). Straight-line (P < 0.01) valine and protein accretion responses occurred, but slope of the response curves (accretion vs. valine intake) was lower in the imbalanced series than in the balanced series. The results of these studies suggest a constant utilization above maintenance of absorbed valine over a wide range of valine intake.

Analysis of Variance↗

PubMed1996

Sulfur amino acid requirement and cystine replacement value of broiler chicks during the period three to six weeks posthatching.

Three experiments were conducted with commercial broiler chicks to determine the SAA requirement during the growth period 3 to 6 wk posthatching. A 20% CP corn-peanut meal basal diet (3,200 kcal ME(n)/kg) was analyzed to contain 0.23% Met and 0.28% cystine. True digestibility assessment in cecectomized cockerels revealed that Met and cystine in the basal diet were 81 and 75% digestible, respectively. Therefore, the basal diet contained 0.19% digestible Met and 0.21% digestible cystine. When fully fortified with DL-Met, growth rate and feed efficiency of chicks fed the corn-peanut meal diet were equal to that of chicks fed a 20% CP Met-fortified corn-soybean meal diet. In the SAA requirement assay, Ross x Hubbard male chicks were fed graded increments of DL-Met (0.03%) and L-cystine (0.03%) to achieve digestible SAA concentrations of 0.40, 0.46, 0.52, 0.58, 0.64, and 0.70%. Weight gain and feed efficiency responded quadratically (P < 0.01) to increasing doses of SAA. The estimated requirement for maximal feed efficiency was higher than that for maximal weight gain. Both visual appraisal and curve fitting procedures suggested a requirement of close to 0.61% digestible SAA. When extrapolated to a corn-soybean meal diet where SAA true digestibility is 87.5%, the total SAA requirement calculates to be 0.70% of the diet. However, because commercial corn-soybean meal diets typically contain supplemental Met, which is only 81% efficient (wt:wt) in furnishing cystine, the estimated total SAA requirement for chicks fed 20% CP Met-fortified corn-soybean meal diets with 3,200 kcal of ME/kg would probably approximately 0.72% of the diet. A DL-Met vs L-cystine supplementation assay suggested that digestible cystine can supply no more than 52% of the total requirement for digestible SAA of chicks during the 3- to 6-wk growth period.

Amino Acids, Sulfur↗

PubMed1996

Digestible threonine requirement of broiler chickens during the period three to six and six to eight weeks posthatching.

Four experiments were conducted to determine the digestible Thr requirement of commercial broiler chickens (Ross x Hubbard) during the period 3 to 6 and 6 to 8 wk posthatching. Threonine-deficient corn-peanut meal basal diets (3,200 MEn/kg) contained 20% CP and 0.50% Thr for 3- to 6-wk-old birds, and 18.3% CP and 0.50% Thr for 6- to 8-wk-old birds. True digestibility assessment using cecectomized roosters indicated that Thr was 81% digestible in both basal diets. Thus, both diets contained 0.40% digestible Thr. Growth rate and feed efficiency of chicks fed the corn-peanut meal basal diets supplemented with surfeit Thr was equal to that of chicks fed a 20% CP Met-fortified corn-soybean meal diet. Graded doses of Thr produced marked responses (P < 0.05) in weight gain and feed efficiency in birds of both age groups. Maximal feed efficiency was achieved at 0.61% digestible Thr in 3- to 6-wk-old birds and at 0.52% digestible Thr in 6- to 8-wk-old birds. Extrapolating these digestible Thr requirements to total requirements for chicks consuming corn-soybean meal diets (Thr digestibility = 87%) results in estimates of 0.70 and 0.60% for broiler chickens during the growth periods 3 to 6 and 6 to 8 wk posthatching, respectively. These estimates are lower than those of NRC (1994) but are in close agreement with those obtained from ideal protein calculations, i.e., Thr requirements should be 70% of lysine requirements for chicks 3 to 8 wk of age.

Aging↗