Methods for Determining Amino Acid Availability of Feeds

Bragg, D. B.; Ivy, C. A.; Stephenson, E. L.

doi:10.3382/ps.0482135

Cited by 57 publications

(22 citation statements)

References 4 publications

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“…In a experiment of Yamazaki (1983) Bragg et al (1969) with that of Likuski and Dorrell 0978) showed the latter to give, on average, slightly higher values, which is in agreement with findings of reduced AA excretion by fasted birds .…”

Section: Sibbald -Bioavailable Amino Acid Estimation 251supporting

confidence: 79%

“…Payne et al (1968) found ileal digestibility to be the more sensitive. Varnish and Carpenter (1971) The assays of Bragg et al (1969) and Likuski and Dorrell (1978) were compared by (Likuski and Dorrell 1978;Sibbald l979a,b) yields data more readily than any of the other assays and the tabulations of Likuski (1982) suggest close agreement among laboratories. A collaborative study of the assay produced remarkably good results with the major contributor to variation being the measurement of total AA (Engster et al 1985).…”

Section: Sibbald -Bioavailable Amino Acid Estimation 251mentioning

confidence: 99%

“…Waring (1969) (1969) The correction suggested by Bragg et al (1969) (1978) who appear to have offered the N-F diet to a control group of birds at the time the experimental diets were fed.…”

Section: Sibbald -Bioavailable Amino Acid Estimation 251mentioning

confidence: 99%

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Estimation of Bioavailable Amino Acids in Feedingstuffs for Poultry and Pigs: A Review With Emphasis on Balance Experiments

Sibbald¹

1987

Can. J. Anim. Sci.

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A bioavailable nutrient has the potential to be utilized when ingested. Ideally, the nutrient requirements of animals and the nutrient concentrations of feedingstuffs should be expressed in terms of bioavailable units. Bioavailability is an abstract concept which cannot be measured but it can be estimated. The purpose of this review is to describe, evaluate and compare procedures used to estimate the concentrations of bioavailable amino acids (BAA) in feedingstuffs for pigs and poultry. Accurate and precise measurement of total amino acid (AA) concentrations is of fundamental importance to many assays. Problems are encountered both in making the AA available for measurement (hydrolysis) and in the measurement procedures. There is need for standardization of methodology but until this is achieved caution must be exercised when comparing data obtained by different techniques or even from different laboratories. In vitro assays for BAA are relatively fast and can be made without access to animals. Enzymic digestion has the potential to be a good estimator of BAA but is constrained by a lack of information about the bioavailabilities of the peptides which are liberated. Chemical assays and dye binding produce data which sometimes, but not always, correlate with biological estimates of BAA. The future of such assays seems to be in quality control where comparisons are made among samples within ingredients. Among the indirect biological assays, those based on microbial growth have received the most attention. The major weakness of such assays resides in the difference between animal and microbe in the ability to utilize peptides. Plasma free amino acids are not satisfactory estimators of BAA although they can help to identify limiting AA in feedingstuffs. Nitrogen digestion lacks the sensitivity to be a predictor of BAA. Growth assays are thought by many to be the ultimate measure of bioavailability but in fact they measure utility which is not the same. Nevertheless, growth assays can provide valuable estimates of BAA providing that their limitations are understood. The assays are expensive and slow and the results can be affected by many variables including changes in nutrient concentrations when a test material is added to an assay diet. Much of the review is devoted to balance experiments which require great care and attention to detail if reliable, reproducible data are to be obtained. Procedures have been refined during many years of use and with the advent of new equipment and techniques. Concern is currently focussed on corrections for metabolic and endogenous losses and on the effects of the microflora of the alimentary tract. Recent developments have increased assay efficiency, particularly with poultry. The balance experiment provides BAA estimates, that can be used effectively in diet formulation, at a much faster rate than growth assays. The final section of the review makes comparisons among various methods of estimating BAA. Interspecies comparisons are useful because they provide guidance when attempting to apply data derived with one species to formulate diets for another. The search for a single assay which provides data applicable to several species is a worthwhile objective. In the meantime, there are many assays used to estimate BAA which have specific applications and limitations. Key words: Pigs, poultry, amino acids, assay methodology, feedingstuffs, review

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Section: Sibbald -Bioavailable Amino Acid Estimation 251supporting

confidence: 79%

Section: Sibbald -Bioavailable Amino Acid Estimation 251mentioning

confidence: 99%

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Estimation of Bioavailable Amino Acids in Feedingstuffs for Poultry and Pigs: A Review With Emphasis on Balance Experiments

Sibbald¹

1987

Can. J. Anim. Sci.

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“…Protein efficiency ratio (PER), net protein ratio (NPK) and true digestibility were also estimated. Availability of essential amino acids was estimated by the balance trial method [3]. Amino acid content of diets and feces were determined by amino acid analysis using the Technicon Automatic Amino Acid Analyzer [14].…”

Section: Methodsmentioning

confidence: 99%

“…The availability was calculated by using the equations described by BRAGG et al [3]. Baking of corn does not affect its amino acid availability.…”

Section: Aitdubility Of Nitrogen and Essential Amino Acids By Balancementioning

confidence: 99%

Availability of essential amino acids in corn flour and corn bread

El‐Shafei¹,

Abbassi

Bassily³

et al. 1983

Nahrung

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The availability of nitrogen, lysine and 9 essential amino acids was determined in corn before and after baking. Lysine avdibdbility was determined by the growth response method on weaning rats using regression analysis of body weight gain or moisture gain against lysine consumed from corn flour and corn bread. The results show a high correlation between lysine consumed and weight gain or moisture gain (r = 0.95) for rats fed the standard diets for 3 weeks. A good correlation was also obtained for corn bread. The results of lysine availability show that baking greatly improves availability by both ways of calculation.The availability of nitrogen and essential amino acids were also investigated by the balance trials with rats. Results show that availability values for nitrogen and all amino acids except threonine increased by baking. Data for food intake, weight gain, food efficiency, PER, NPR and true digestibility revealed that baking had little or no effect on nutritive value of corn tested in this investigation.

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The effect of baking on availability of essential amino acids in wheat

El‐Shafei

Kamal

Abbassi

et al. 1983

Nahrung

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Lysine availability in wheat flour and bread was determined by the growth response method on rats using regression analysis relating gain in body weight and/or in body water to lysine consumed at two extractions, 87% and 72%. The availability of nitrogen and of essential amino acids were also determined by the balance trials method (fecal analysis method) with rats. The results of growth method show that baking increases lysine availability on the basis of body water gain. Also extraction levels affect lysine availability on the basis of change in body water. Wheat flour and bread of 72% extraction has more lysine availability values than the 87% extraction on the basis of moisture gain. Results of balance trials show that neither the extraction level nor the baking has a significant effect on essential amino acids availability. A fairly good correlation is obtained for wheat flour and bread for the two extractions. Values of change in weight, food efficiency, PER, NPR and true digestibility showed that baking and level of extraction of wheat has no significant effect on the nutritive value of wheat investigated in the present study.

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Methods for Determining Amino Acid Availability of Feeds

Cited by 57 publications

References 4 publications

Estimation of Bioavailable Amino Acids in Feedingstuffs for Poultry and Pigs: A Review With Emphasis on Balance Experiments

Estimation of Bioavailable Amino Acids in Feedingstuffs for Poultry and Pigs: A Review With Emphasis on Balance Experiments

Availability of essential amino acids in corn flour and corn bread

The effect of baking on availability of essential amino acids in wheat

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