Biomedical subjects

C M Parsons

Publications and source records attributed to C M Parsons.

At least 73 records · Page 4Linked to original sources

PubMed1998

Dietary formulation with meat and bone meal on a total versus a digestible or bioavailable amino acid basis.

The digestibility and bioavailability of amino acids (AA) in meat and bone meals (MBM) may vary greatly due to different processing conditions. In the present study, two experiments were conducted to evaluate formulation of diets containing high or low quality MBM on a total AA basis vs a digestible or bioavailable AA basis compared to a corn-soybean meal control diet. Lysine, methionine, and cystine digestibilities (precision-fed cecectomized rooster assay) were 92, 91, and 71%, respectively, for high quality MBM and were 71, 83, and 31%, respectively, for the low quality MBM. Bioavailability values (slope-ratio chick growth assay) for TSAA in the two MBM were approximately 15 percentage units lower than the digestibility values. Male crossbred chicks were fed a 20% CP corn-SBM diet or corn-SBM diets containing 10 or 20% high or low quality MBM that were formulated to be equal in total, digestible, or bioavailable AA to the corn-SBM diet. All diets contained 3,200 kcal of TMEn/kg, 1.4% Ca, and 0.7% nonphytate P and were fed to chicks from 8 to 22 d posthatching. Growth performance of chicks fed 10 or 20% high or low quality MBM on a total AA basis was lower (P < 0.05) than that of chicks fed the corn-SBM diet. Growth of chicks fed 10% low quality MBM or 10 or 20% high quality MBM on a digestible or bioavailable basis was equivalent to that of chicks fed the corn-SBM diet; however, dietary inclusion of 20% low quality MBM depressed growth (P < 0.05) even on a digestible or bioavailable AA basis. Further supplementation of the latter diet with additional AA yielded growth that was similar to the corn-SBM control diet. The results indicated that formulation of diets containing MBM on a digestible or bioavailable AA basis is superior to formulation on a total AA basis. However, feeding high levels of a low quality MBM may require additional AA supplementation to obtain maximum chick growth.

Amino Acids↗

PubMed1998

Availability of amino acids in high-oil corn.

True digestibility of amino acids, bioavailability of Lys, and TMEn in three types of high-oil corn (HOC) and one conventional corn (CC) were determined. The CC, HOC1, HOC2, and HOC3 contained 4.3, 5.9, 6.6, and 9.5% ether extract, respectively, on a DM basis. True digestibility of amino acids was determined using the precision-fed cecectomized rooster assay in which each corn sample was tube-fed (30 g) to nine roosters and excreta were collected for 48 h. True digestibility of most amino acids in HOC2 and HOC3 were significantly higher (P < or = 0.05) than those in CC and HOC1. Mean digestibility of 15 amino acids in HOC2 and HOC3 was 91% compared to 80% for CC and HOC1. The TMEn values (kilocalories per gram DM) of CC, HOC1, HOC2, and HOC3 were 3.883, 4.024, 4.038, and 4.140, respectively. Lysine bioavailability was assessed using a slope-ratio chick growth assay in which a Lys-deficient crystalline amino acid diet was supplemented with 0, 0.1, or 0.2% L-Lys from L-Lys x HC1 to provide a standard curve. Six additional dietary treatments consisted of supplementing the basal diet with 28 or 56% of CC, HOC2, or HOC3. The nine diets were fed to four replicate groups of six chicks from 8 to 18 d posthatching. Lysine bioavailability was calculated using multiple regression slope-ratio methodology where Y was weight gain and X was intake of Lys from the L-Lys x HC1 or a corn. Supplementation of the basal diet with L-Lys x HC1, CC, HOC2, or HOC3 yielded linear (P < or = 0.001) growth responses. Bioavailability values (percentage) for the Lys in CC, HOC2, and HOC3 relative to the Lys in L-Lys x HC1 were 65 +/- 10, 72 +/- 10, and 91 +/- 8, respectively. The results of this study indicated that digestibility of amino acids and bioavailability of Lys in HOC are equal to or greater than those in CC.

Amino Acids↗

PubMed1998

Effect of acute heat stress on amino acid digestibility in laying hens.

An experiment was conducted to determine the effect of acute heat stress exposure on amino acid digestibility in laying hens. A total of 30 commercial laying hens were singly housed in an environmentally controlled facility, fed a standard laying ration, and exposed to a constant thermoneutral temperature (21 C) for 12 d. The hens were then randomly fed one of three diets (10 hens per diet) and exposed to three consecutive temperature periods (8 d each), which consisted of: 1) a constant 21 C temperature, 2) a cycling temperature of 35 C for 12 h and 29 C for 12 h, and 3) a constant 21 C temperature. The three isonitrogenous (18% CP) diets fed were: 1) a corn-soybean meal diet, 2) a corn-soybean meal diet containing 15% meat and bone meal, and 3) a corn-soybean meal diet containing 5% alfalfa meal and 20% wheat bran. Excreta were collected from all hens during the last 4 d of each temperature period and apparent amino acid digestibility was determined. There was a significant diet effect (P < 0.05) on amino acid digestibility. Digestibility of amino acids in Diet 2 (corn-soybean meal/meat and bone meal) was higher (P < 0.05) than in the other two diets. In addition, digestibility of amino acids in Diet 3 (corn-soybean meal/alfalfa meal/wheat bran) was significantly lower (P < 0.05) than in Diets 1 or 2. Heat stress generally had no significant effect on amino acid digestibility except for His and Lys digestibility. Histidine digestibility was higher during the heat stress period than during the initial and recovery thermoneutral periods, whereas Lys digestibility was higher during the heat stress period than during the initial thermoneutral period. These results indicated that acute heat stress (8 d) had no adverse effects on dietary amino acid digestibility in laying hens.

Amino Acids↗

PubMed1998

Effects of species raw material source, ash content, and processing temperature on amino acid digestibility of animal by-product meals by cecectomized roosters and ileally cannulated dogs.

We conducted experiments to determine amino acid (AA) digestibility of nine animal by-product meals using precision-fed cecectomized roosters and ileally cannulated dogs. The products initially evaluated in roosters were meat and bone meals (MBM) containing 24 or 34% ash, poultry by-product meals (PBP) containing 7 or 16% ash, lamb meals (LM) containing 15 or 24% ash, a LM analog containing a mixture of LM and turkey meal, and two MBM processed at either a low or high temperature. The MBM and PBP differing in ash, low-ash LM, and low-temperature MBM then were incorporated into extruded dry dog foods and evaluated in cecectomized roosters and ileally cannulated dogs. True digestibility of total AA in roosters averaged 76% for the nine meals fed alone, with the low-temperature MBM being highest at 84% and the low-ash LM being lowest at 66% (P < .05). No consistent differences in rooster AA digestibility were observed between pairs of meals differing in ash content. Digestibilities of AA were higher in the low-temperature MBM than in the high-temperature MBM. Differences in rooster AA digestibility values among the six extruded dog foods containing selected animal meals were similar to those observed when the animal meals were fed alone. The ileally cannulated dog assay yielded results for AA digestibilities that were highly correlated (r = .87 to .92) with those of the rooster assay, whereby the high-ash MBM and low-temperature MBM foods had the highest mean AA digestibility at 82% and the low-ash LM food had the lowest mean AA digestibility at 62% (P < .05). Again, no consistent differences in AA digestibilities for dogs were observed between pairs of dog foods containing MBM or PBP differing in ash content. Results of this study indicated that processing temperature influenced AA digestibility of MBM, but species raw material source and ash content had no consistent effect on AA digestibility. Results also indicated that the precision-fed cecectomized rooster assay could be used to predict differences in AA digestibility among animal by-product meals for dogs.

Amino Acids↗

PubMed1997

Maintenance threonine requirement and efficiency of its use for accretion of whole-body threonine and protein in young chicks.

Broiler chicks were fed on chemically-defined crystalline amino acid diets containing graded levels of L-threonine (Thr) during the period 10-20 d post-hatching. Doses of Thr represented 5, 10, 15, 40, 55, 70 and 95% of its ideal level for maximal weight gain and feed efficiency. Other amino acids were maintained at minimized excess levels that were 15% (of ideal) above the various doses of Thr. Following 10 d of feeding and a 24 h fast, chicks were killed for whole-body protein and amino acid analysis. Using pen accretion means, weight gain (r2 0.98), protein accretion (r2 0.99), and Thr accretion (r2 0.99) were linear (P < 0.01) functions of Thr intake. Slope of the Thr accretion regression line indicated that 82% of the Thr intake was recovered in whole-body protein. At zero Thr intake, chicks lost 11.9 mg Thr/d. The Thr maintenance requirement was 45.7 mg/d per kg body weight 0.75. Increasing doses of Thr resulted in increased (P < 0.05) concentrations of methionine, isoleucine, histidine and lysine in whole-body protein. Other indispensable amino acids, including Thr, also tended to increase. Whole-body glycine, proline, serine and cystine concentrations decreased (P < 0.05) as Thr was increased in the diet. The maintenance need for Thr represented 5.5% of the total need for Thr. The data suggest that efficiency of Thr utilization is constant at all levels of Thr intake between 5 and 95% of the level required for maximal weight gain and feed efficiency.

Analysis of Variance↗

PubMed1997

Order of amino acid limitation in meat and bone meal.

Three experiments were conducted to determine the order of amino acid (AA) limitation in meat and bone meal (MBM) using AA addition and deletion assays. In two addition assays, various individual and combined additions of eight AA were made to semipurified basal diets containing 16% protein solely from a MBM. The two MBM had previously been determined to vary greatly in protein quality. In the deletion assay, a semipurified basal diet containing 13.5% CP provided solely by MBM was supplemented with L-Thr, L-Val, DL-Met, L-Leu, L-Ile, L-Phe, L-Tyr, L-Lys-HCl, L-His, and L-Trp to fulfill the Illinois Ideal Protein or AA pattern on a digestible basis. Each AA was then deleted individually from the basal diet, and the effect of its deletion on growth performance was assessed. In both addition assays, supplementation of the MBM basal diet with Trp and Cys together yielded a large increase in growth performance, whereas supplementation with these AA individually had no effect. These results indicated that Trp and sulfur AA (with a primary need for Cys) were equally first limiting in the MBM. The order of limitation for the other AA was unclear. The results of the deletion assay showed that deletion of Trp, Thr, Phe + Tyr, Ile, Met, Lys, Val, or His significantly depressed growth performance. The results of the combined addition and deletion experiments indicated that the order of AA limitation in MBM was 1) Trp and sulfur AA, 2) Thr, 3) Ile and Phe + Tyr, 4) Met, 5) Lys, and 6) Val and His. The deletion assay using diets formulated on an ideal protein basis was more effective than the addition assay for determining the order of AA limitation in MBM.

Amino Acids↗

PubMed1997

Evaluation of protein and energy quality of rendered spent hen meals.

This study evaluated three spent hen meals (SHM) that were produced in commercial rendering plants. The levels (percentage) of selected nutrients (mean and range) in the meals were: CP, 64 (56 to 71); ash, 16 (12 to 18); lysine, 4.0 (3.6 to 4.3); methionine, 1.3 (1.2 to 1.4); cystine, 1.1 (0.8 to 1.5). Protein efficiency ratios (PER; weight gain per unit of protein intake) were determined in chicks fed 10% CP diets containing a SHM as the only source of dietary protein. The PER values for the SHM averaged 1.6 but varied from 1.1 to 2.2. An experiment was conducted using New Hampshire x Columbian chicks during the 7 to 20 d age period to determine the effect of substitution with either 7.5 or 15% of a SHM to a 21.5% CP corn-soybean meal diet. When substituted at 7.5%, growth performance was not affected by two of the SHM but was depressed by the other one. Growth performance was decreased by all SHM when substituted at 15% of the diet. True amino acid digestibility and TMEn of the SHM were determined using the precision-fed cecectomized rooster assay in which four roosters were crop-intubated with 30 g of a SHM and excreta were collected for 48 h. True amino acid digestibility varied among SHM (P < or = 0.05) and digestibility of cystine was substantially lower than digestibility of the other amino acids. Mean TMEn (kilocalories per gram of DM) of the SHM was 3.003 but varied by 44% among samples. The results of this study indicated that SHM has substantial nutritional value for poultry but the nutritional quality may vary greatly among samples.

Aging↗

PubMed1997

Effects of raw material source, ash content, and assay length on protein efficiency ratio and net protein ratio values for animal protein meals.

Experiments were conducted to determine the protein efficiency ratio (PER) and net protein ratio (NPR) of meat and bone meals containing 24 or 34% ash, poultry by-product meals containing 7 or 16% ash, lamb meals containing 15 or 24% ash, a lamb meal analog containing 19% ash (mixture of lamb meal and turkey meal), and two meat and bone meals processed at either a low or a high temperature. The PER values (weight gain per unit of protein intake) and NPR values (PER corrected for maintenance) were determined using a chick growth assay in which chicks were fed a N-free diet or 10% CP diets containing one of the animal meals as the only source of dietary protein for 6, 9, or 13 d. The PER of the lamb meal analog was greater (P < 0.05) than that of the other meals, and the PER values of the poultry by-product meals were generally greater than those for the lamb and meat and bone meals. The PER values for the lamb meals were higher than those for most of the meat and bone meals. The PER of the 34% ash meat and bone meal was lower (P < 0.05) than the PER of the 24% ash meat and bone meal (1.03 vs 1.63, respectively, at 9 d). Further experiments showed that the lower PER of the high ash meat and bone meal was not due to its high Ca and P content. Ash content had no significant effect on PER of the poultry by-product and lamb meals. The PER of the low-temperature meat and bone meal was higher (P < 0.05) than the PER of the high-temperature meat and bone meal. The relative differences in NPR values among the animal meals were similar to those observed for PER values. Decreasing the length of the assay from 13 to 6 d increased the PER and NPR of all meals but had little or no effect on the ranking of values among meals. The results of this study indicated that PER and NPR values of animal meals were influenced by raw material source, and that ash content and processing temperature affected the PER and NPR of meat and bone meal. The results also indicated that PER and NPR assays could be reduced to 6 d without reducing sensitivity.

Analysis of Variance↗

PubMed1997

Protein and amino acid quality of meat and bone meal.

The in vivo protein quality of 14 meat and bone meals (MBM) was evaluated in three chick growth assays and a 48-h excreta collection assay using conventional and cecectomized roosters. In addition, in vitro evaluation of protein quality was assessed using pepsin N digestibility (0.2, 0.002, or 0.0002% pepsin), KOH protein solubility, and multi-enzyme pH change. Crude protein, lysine, and SAA in the MBM varied from 48 to 56, 2.32 to 3.01, and 1.0 to 2.13%, respectively. Protein efficiency ratio (weight gain:protein intake) estimated from feeding chicks diets containing 9% protein from a MBM ranged from 0.61 to 2.89 and averaged 1.78. Lysine bioavailability determined by slope-ratio chick assay ranged from 43 to 89%. True amino acid digestibility and TMEn values determined in cecectomized roosters were generally lower (P < 0.05) than those determined in conventional roosters. True digestibility of amino acids (percentage) also varied among MBM, with the mean (and range) for lysine, methionine, and cystine in cecectomized birds being 81 (73 to 88), 85 (77 to 91), and 58% (37 to 72%), respectively. Pepsin N digestibility values determined using 0.002 or 0.0002% pepsin were positively correlated (P < 0.05) with lysine digestibility. Pepsin N digestibility determined using 0.2% pepsin, KOH protein solubility, and multi-enzyme pH change were not significantly correlated with in vivo protein quality. Ash content was negatively correlated (-0.80, P < 0.05) with protein efficiency ratio. These results indicated that there is substantial variation in protein quality among commercial MBM and that pepsin N digestibility and ash content are correlated with some in vivo protein quality measurements.

Amino Acids↗

PubMed1997

Effect of processing systems on protein quality of feather meals and hog hair meals.

Experiments were conducted to evaluate the effects of five commercial processing systems and to a lesser extent, processing temperature within system, on protein quality of feather meals (FM). Two hog hair meals (HH) were also evaluated. True digestibilities of AA were determined with a 48-h excreta collection assay using cecectomized cockerels. Protein efficiency ratio (PER; grams of gain:grams of CP consumed) was determined with chicks by feeding Met-fortified 15% CP diets containing a FM or HH as the sole source of dietary protein. The six FM samples averaged 88.7% CP, 1.99% Lys, 4.83% Cys, and 0.71% Met on a DM basis. For HH, these values were 92.6, 2.78, 3.76, and 0.85%, respectively. True digestibilities of amino acids and PER of the FM varied among processing systems (e.g., lysine digestibility range was 58 to 72%, PER range was 0.71 to 1.13). Increasing the temperature during processing had no significant effect on protein quality of one FM and one HH. Digestibilities of AA in the FM water-soluble fraction collected after cooking were higher than those in the insoluble fraction. True amino acid digestibility coefficients for FM were higher than those for HH, whereas the PER of several FM were lower than those of HH. The latter response was probably due to the higher Lys content in the HH. The results of this study suggested that type of commercial processing system or conditions can affect the protein quality of FM.

Amino Acids↗

PubMed1997

Assessment of postruminal amino acid digestibility of roasted and extruded whole soybeans with the precision-fed rooster assay.

The objectives of these studies were to predict the effects of roasting and extrusion temperatures of whole soybeans (SB) on intestinal protein digestibility in cattle. Intestinal digestibility was assessed with a two-stage in vitro or in situ ruminal incubation/precision-fed cecectomized rooster bioassay. In Exp. 1, whole SB (raw SB or SB roasted to 141, 149, or 157 degrees C exit temperature from a commercial roaster and steeped for 30 min) were incubated in strained ruminal fluid and McDougall's buffer (50:50) at 39 degrees C for 16 h. In Exp. 2, SB (ground raw SB or SB extruded at 116, 138, or 160 degrees C) were placed in polyester bags (20 x 30 cm) and suspended in the ventral rumen of steers for 16 h. Lyophilized residue of the in vitro or in situ incubations and samples of raw SB and most extensively heated SB (roasted SB at 157 degrees C or extruded SB at 160 degrees C) for each respective experiment were crop-intubated to cecectomized roosters. Total excreta were collected for 48 h after intubation and lyophilized, and amino acid (AA) concentrations were determined. In Exp. 1, total AA digestibility was 61.6 and 84.5% for unincubated whole raw SB and 157 degrees C roasted SB, respectively, and 66.2, 88.9, 91.3, and 91.6% for in vitro residues of whole raw SB and SB roasted at 141, 149, and 157 degrees C, respectively. Trypsin inhibitor (TI) activity was 20.09, 1.69, 1.54, and 1.84 mg/g fat-free DM for unincubated whole raw SB and 141, 149, and 157 degrees C roasted SB, respectively, and 30.84, 1.01, .90, and .26 mg/g fat-free DM for in vitro residues of whole raw SB, 141, 149, and 157 degrees C roasted SB, respectively. In Exp. 2, total AA digestibility was 68.5 and 87.7% for unincubated ground raw SB and 160 degrees C extruded SB, respectively, and 81.9, 91.3, 89.7, and 89.4% for in situ residues of ground raw SB and 116, 138, and 160 degrees C extruded SB, respectively. Trypsin inhibitor activity was 17.61, 4.89, 4.08, and 1.56 mg/g fat-free DM for unincubated ground raw SB, 116, 138, and 160 degrees C extruded SB, respectively, and 3.62, .59, .55, and .21 mg/g fat-free DM for incubated ground raw SB, 116, 138, and 160 degrees C extruded SB, respectively. Heat treatment by roasting and extrusion improved AA digestibilities of SB, but there were no differences detected among the roasting or extrusion temperatures. Ruminal fermentation did not eliminate the negative effects of TI activity on intestinal digestibility of AA in whole SB but did reduce TI activity in ground SB.

Amino Acids↗

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

Efficacy of a lysine-tryptophan blend for growth of chicks.

Two chick experiments were conducted to compare the growth-promoting efficacy as well as the toxicity of a new source of L-tryptophan and L-lysine, Tryptosine (16.1% tryptophan, 56.3% lysine). A corn-feather meal-soybean meal basal diet was made singly deficient in either lysine or tryptophan, and graded doses of lysine or tryptophan from either Tryptosine or feed-grade sources of lysine and tryptophan were supplemented. Linear (P < .01) weight gain responses occurred, and responses to lysine or tryptophan in Tryptosine were similar to those obtained with equal doses of lysine or tryptophan provided by feed-grade sources of L-lysine.HCI or L-tryptophan. The toxicity trial involved additions of 1, 2, or 4% lysine with .29, .58, or 1.16% tryptophan to a lysine- and tryptophan-adequate corn-soybean meal diet. Both amino acids were provided as either Tryptosine or as feed-grade sources of lysine and tryptophan. Weight gain and feed intake were reduced in a linear fashion (P < .01) as levels of the two excess amino acids increased. The decreases caused by Tryptosine were similar to those caused by equivalent levels of excess feed-grade lysine and tryptophan.

Animals↗

PubMed1996

Bioavailability of the digestible lysine and vilaine in cottonseed and soybean minerals.

Previous research showed that formulation of chick diets containing cottonseed meal (CSM) using true digestible amino acid (AA) values was superior to formulation based on total AA; however, optimum growth performance could not be obtained from high CSM diets even when formulated on a digestible AA basis. Therefore, two experiments were conducted to determine whether the digestible AA in CSM were totally bioavailable or utilizable for protein synthesis. Soybean meal (SBM) was also evaluated for comparison. True digestibility of Lys and Val in CSM and SBM were determined using the precision-fed cecectomized rooster assay. Bioavailability was then assessed by chick growth assay using purified crystalline AA diets deficient in Lys or Val that were supplemented with varying levels of the test AA, CSM,SBM, or AA mixtures simulating the digestible AA composition of CSM and SBM. Multiple regression slope-ratio methodology indicated that bioavailability of the digestible Lys in CSM and the digestible Lys and Val in SBM did not differ (P > 0.05) from 100% for most response parameters. Bioavailability of the digestible Val in CSM ranged from 78 to 96% depending on response parameter. Bioavailabilities of crystalline Lys and Val in the AA mixtures simulating CSM and SBM were generally lower than the bioavailabililties of the digestible Lys and Val in CSM and SBM. The results of this study indicated that the digestible Lys and Val in SBM and CSM as measured by the precision-fed cecectomized rooster assay are totally or almost totally bioavailable for protein synthesis.

Amino Acids↗

PubMed1996

Bioavailability of digestible lysine in heat-damaged soybean meal for chick growth.

Previous experiments indicated that true digestible Lys values for soybean and cottonseed meals obtained with the precision-fed cecectomized rooster assay were accurate estimators of Lys bioavailability for chick growth. This study was conducted to determine whether the digestible Lys in overheated soybean meal (SBM) was totally bioavailable for protein synthesis. Soybean meal alone or mixed with dextrose (SBM:dextrose ratio = 3:1) was autoclaved at 114 C and 97 kPa for 0 to 60 min. True digestibility of Lys in SBM was determined using the precision-fed cecectomized rooster assay. Bioavailability was then assessed by chick growth assay using purified crystalline amino acid diets deficient in Lys that were supplemented with varying levels of crystalline L-Lys.Cl or a SBM. Multiple regression slope-ratio methodology indicated that the digestible Lys in unautoclaved SBM was 100% bioavailable. For SBM autoclaved for 40 or 60 min and SBM-dextrose autoclaved for 20 min, bioavailability of digestible Lys based on weight gain or carcass Lys gain was 81 to 87% and significantly less (P < 0.05) than 100%, whereas bioavailability values based on feed efficiency and carcass N gain did not differ (P > 0.05) from 100%. Bioavailability values for digestible Lys in SBM:dextrose autoclaved for 30 min ranged from 55 to 73% for all performance criteria. Partitioning the response criteria, so that only the response to the supplemental Lys source (not the basal diet) was being evaluated, increased the bioavailability values for all treatments except SBM:dextrose autoclaved for 30 min. The results of this study indicated that digestible Lys in severely heat-damaged SBM measured by the precision-fed cecectomized rooster assay was not totally bioavailable for protein synthesis.

Animal Feed↗

PubMed1996

Effects of overprocessing on the nutritional quality of peanut meal.

Two experiments were conducted to evaluate the effects of overprocessing by autoclaving on the in vivo protein quality and in vitro protein solubility in 0.2% KOH of solvent-extracted peanut meal containing 48% protein. The peanut meal was autoclaved at 120 C and 105 kPa for 0, 20, 30, 40, 50, 60, or 90 min. In vivo protein quality of the autoclaved peanut meal was evaluated in chicks fed corn-peanut meal diets (22.5% protein) from 8 to 22 d of age and in adult cecectomized roosters using a precision-fed amino acid digestibility assay. Chick performance was significantly decreased when peanut meal had been autoclaved (P < 0.05) 60 min or more in one experiment and by 40 min or more in the other experiment. True digestibility of amino acids in peanut meal also decreased as autoclaving time increased. The effect of autoclaving was greatest for lysine, wherein digestibility was 87, 72, 68, and 57% for peanut meal autoclaved for 0, 30, 60, or 90 min, respectively. Protein solubility of peanut meal in 0.2% KOH decreased from 78 to 56% as autoclaving time increased from 0 to 90 min. Protein solubility values of 70% or lower were indicative of decreased in vivo peanut meal quality. The results of this study indicated that overprocessing by autoclaving reduces the protein quality of peanut meal and that protein solubility in KOH is a useful in vitro index of overprocessing.

Amino Acids↗

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↗