True Metabolizable Energy Corrected to Nitrogen Equilibrium

Parsons, C. M.; Pötter, Luciana; Bliss, B. A.

doi:10.3382/ps.0612241

Cited by 77 publications

(34 citation statements)

References 9 publications

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“…77,No.4 where AMCN* and MECN* are apparent assimilable mass and apparent metabolizable energy coefficients (unitless proportions of mass or energy), respectively; Q; and Qe are dry matter intake and output in grams per day; GE; and GEe are the energy contents of food and excreta in kiloJoules per gram; and N; and Ne are nitrogen contents of the food and excreta expressed as proportions (Karasov 1990). The numerical factors 3.0 gig N and 34.5 kJ/g N are the dry matter and energy equivalents of nitrogen lost as uric acid, respectively (Parsons et a!. 1982, Karasov 1990).…”

Section: Discussionmentioning

confidence: 99%

Nutritional Costs of a Plant Secondary Metabolite Explain Selective Foraging by Ruffed Grouse

Guglielmo¹,

Karasov²,

Jakubas³

1996

Ecology

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Plant secondary metabolites (PSMs) are commonly thought to deter vertebrate herbivores by being toxic or by reducing nutrient assimilation. An alternative, complementary hypothesis is that PSMs may influence herbivore forage selection at subtoxic levels by imposing high detoxication costs post absorption. Many studies of insect herbivores have been undertaken to measure the metabolic load of detoxication as it relates to host—plant specialization, but results have been equivocal and the subject of much debate. Some recent studies of vertebrate herbivores indicate that metabolism of PSMs can impose a cost by increasing nutrient losses due to conjugation of PSMs to endogenous materials, and by upsetting pH homeostasis. In this study, we demonstrate that detoxication costs in Ruffed Grouse are substantial, and are reduced by selective foraging. In winter, Ruffed Grouse feed preferentially on quaking aspen with relatively low levels of coniferyl benzoate (CB) in staminate flower buds. We collected aspen buds with low—and high—CB levels and conducted feeding trials with captive Ruffed Grouse that had been acclimated to an aspen bud diet. We measured nutrient utilization efficiencies and excretion of detoxication conjugates. Grouse assimilated 24% less energy from high— vs. low—CB buds. Using a nutritional model, we determined that the reduction of energy utilization efficiency was mainly due to dilution of the diet by CB, and not by digestive inhibition. As CB intake increased, grouse excreted more glucuronic acid and ornithine (two major detoxication conjugates), resulting in an energetic cost of 10% to 14% of metabolizable energy intake for low— and high—CB buds, respectively. Conjugation with the amino acid ornithine increased minimum nitrogen requirement by 68% to 90% for low— and high—CB buds, respectively. Ammonium excretion also increased with CB intake, indicating an upset of pH homeostasis. Thus, detoxication costs were relatively high and increased with higher CB intake. Ruffed Grouse preference for low—CB, high—protein aspen buds in nature appears to be related to lower utilization efficiency and higher detoxication costs associated with high CB concentrations. The importance of detoxication cost to herbivores must be more thoroughly evaluated and integrated into existing models of herbivore foraging behvior.

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Section: Discussionmentioning

confidence: 99%

Nutritional Costs of a Plant Secondary Metabolite Explain Selective Foraging by Ruffed Grouse

Guglielmo¹,

Karasov²,

Jakubas³

1996

Ecology

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“…The excreta and DSBM samples were analyzed for gross energy using a bomb calorimeter and for amino acids by the methods described previously for the DSBM samples. True digestibility of amino acids was calculated by the method of Sibbald (1979) and TME,, by the method of Parsons et al (1982).…”

Section: Methodsmentioning

confidence: 99%

Effect of Overprocessing on Availability of Amino Acids and Energy in Soybean Meal

et al. 1992

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Commercial, dehulled, solvent-extracted soybean meal (DSBM) was overprocessed by autoclaving at 121 C and 105 kPa for 0,20,40, or 60 min. Analyzed concentrations (acid hydrolysis followed by ion-exchange chromatography) of lysine and cystine, and to a lesser extent arginine, in DSBM were reduced by increased autoclaving time. Autoclaving time had little or no effect on levels of other amino acids. Performance of chicks fed 40-min autoclaved DSBM as the sole source of dietary protein was inferior to that of chicks fed unautoclaved DSBM. True digestibilities of several amino acids in DSBM decreased (P<.05) as autoclaving time increased, with the largest decreases being observed for lysine, cystine, histidine, and aspartic acid. The effect of autoclaving on lysine was due both to reduced concentration of analyzed lysine and reduced digestibility of the lysine remaining after autoclaving. True digestibilities of most amino acids determined in conventional cockerels were higher (P<.05) than those determined in cecectomized cockerels. Bioavailabilities determined by chick growth assay of lysine in unautoclaved DSBM and DSBM autoclaved for 40 min were 82 and 70%, respectively. Autoclaving had no significant effect on TMER of DSBM. (

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“…Excreta were collected quantitatively for 48 hr from all cockerels and then lyophilized, ground and analyzed for gross energy and nitrogen (AOAC, 1980). True dry matter digestibility and TME were calculated by the procedure of Parsons et al (1982). The TME values were corrected to zero nitrogen retention (TMEn) using the value of 8.22 kcal/g for any nitrogen retained in the body or voided as products of tissue catabolism (Parsons et al, 1982).…”

Section: In Vitro Enzyme Digestibility Assaymentioning

confidence: 99%

An In Vitro Digestibility Assay for Prediction of the Metabolizable Energy of Low‐Calorie Dextrose Polymeric Bulking Agents

White

Parsons

Baker

1988

Journal of Food Science

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A method was developed to predict in vivo digestibility and metabolizable energy of dextrose polymers from in vitro enzyme digestibility measurements. A high correlation (r = 0.98) was established between in vivo true digestibility (TD) and in vim percent dextrose yield (DY) for polymeric compounds representing a wide range of in vivo digestibility (22-96%). The linear regression equation describing this relationship was TD (%) = 1.11 DY + 10.68. The in vivo nitrogencorrected true metabolizable energy (TMEn) of four test compounds was predicted from in vi&o digestibility data with good accuracy using the linear regression equation TMEn (kcal/g) = 0.038 DY + 0.637 (r = 0.97). The in vitro method is most useful for predicting in vivo digestibility and metabolizable energy of dextrose polymers with in vitro dextrose yields less than 80% and in vivo metabolizable energy values less than 3.6 kcal/gram.

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True Metabolizable Energy Corrected to Nitrogen Equilibrium

Cited by 77 publications

References 9 publications

Nutritional Costs of a Plant Secondary Metabolite Explain Selective Foraging by Ruffed Grouse

Nutritional Costs of a Plant Secondary Metabolite Explain Selective Foraging by Ruffed Grouse

Effect of Overprocessing on Availability of Amino Acids and Energy in Soybean Meal

An In Vitro Digestibility Assay for Prediction of the Metabolizable Energy of Low‐Calorie Dextrose Polymeric Bulking Agents

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