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The aim of this study was to evaluate the chemical composition, energy and amino acid profile of dried salmon silage (DSS) for broilers. The DSS was obtained by acid digestion of salmon mortalities and subsequently co-dried with wheat bran in a 70:30 ratio (70 parts silage and 30 parts wheat bran). Samples of DSS were evaluated for chemical composition, gross energy, nitrogen-corrected true metabolizable energy (TMEn ), mineral content, total and digestible amino acids for broilers, and amino acid score. The chemical composition of DSS was (mean ± SD): moisture (12.3 ± 0.8%), crude protein (44.0 ± 1.1%), ether extract (5.0 ± 2.4%), crude fiber (3.3 ± 0.4%) and ash (9.4 ± 0.6%). The gross energy and TMEn for broilers were 4 069 kcal/kg and 2 613 kcal/kg, respectively. The DSS mineral composition showed a high content of calcium (1.01%) and phosphorus (1.08%). The DSS had high levels of digestible methionine (0.74%), lysine (2.27%), and threonine (1.16%), and did not present limiting amino acids for broilers. Nutritional composition of DSS showed high protein content with an amino acid profile considered to be suitable as a protein source for broiler feeding.

Manufacturers of distillers dried grains with solubles (DDGS) are changing practices to extract corn oil from DDGS in the process of ethanol production. The resulting product is called low-oil DDGS (LO-DDGS) and may be included in broiler diets. Two LO-DDGS and one unextracted DDGS were used in a broiler performance trial to determine maximum levels of inclusion without detrimental effects. Corn- and soybean meal-based mash diets were used with different DDGS samples included at 10 or 20%. Six hundred thirty Cobb 500 male by-product chicks were randomly assigned to 6 replicate pens containing 15 chicks each and fed diets from 0 to 18 d of age. There was a significant interaction between source and level on BW at d 11 and 18 when 10 and 20% of LO-DDGS was included compared with the control group. There was also a significant effect of source and level interaction on BW at d 18 (P < 0.05). Feed efficiency from d 0 to 18 was improved when 10% LO-DDGS was used compared with 20% inclusion. Abdominal fat pad weights were higher when LO-DDGS samples were included at 10 or 20% compared with the control group. There was a significant effect of DDGS source and level on fat pad weights (P < 0.05). Producers may achieve an increase in performance when including 10% LO-DDGS in broiler diets. Up to 20% inclusion levels may have no detrimental effects on performance parameters compared with a standard corn-soybean diet.

Six battery experiments determined the effect of feeding raw soybeans (RSB) in corn-soybean diets on coccidiosis in broiler chickens. The experimental design represents a 2 × 3 factorial arrangement of treatments with three dietary levels of incorporation of RSB (0, 50, and 100%), and chickens either infected or uninfected. The coccidial species tested singularly were Eimeria acervulina, Eimeria maxima, Eimeria necatrix, Eimeria brunetti, and Eimeria tenella. With all species of Eimeria a significant diet by infection interaction demonstrated with a stepwise increase in weight gain and reduction in lesion scores with increasing levels of raw soybeans. To cause the pancreas to become hypertrophied and hyperfunctional, the 100% RSB diet was fed for an extended period. The experimental design represents a 2 × 3 factorial arrangement of treatments with three feeding regimens [Treatment A: 0% RSB (0 d to termination), Treatment B: (0% RSB: 0 12 d then 100% RSB 12 d to termination), and Treatment C: (100% 0 d to termination)] and chickens either infected (E. tenella) or uninfected. There was significant difference for weight gain between uninfected and infected chicks of Treatments A and C but this difference was absent for Treatment B. Coccidiosis was not reduced by continuously feeding 100% RSB (Treatment C).

Three experiments were conducted to compare urease activity (UA), orange G-binding capacity (OGBC), and protein solubility (PS) in a potassium-hydroxide solution of soybean meal (SBM) as indicators of overprocessing. In two additional experiments, amino-acid supplementation was employed in an attempt to overcome the growth depression associated with overheating SBM. Subsamples of commercially prepared lots of dehulled SBM were heated for varying periods of time in an autoclave at 121 C. In Experiments 1, 2, and 3, UA dropped to zero (pH change) after approximately 10 min of cooking. The assay was unable to differentiate between meals that were heated for longer periods. The OGBC of SBM was decreased by autoclaving. However, the narrow range of the orange G values that corresponded to degrees of heat treatment indicated that this test may be of limited value in identifying overprocessed SBM. By contrast, PS values decreased with each increase of autoclaving time, and did not approach zero even with 80 min of heating. Adding .2 % lysine either singly or in combination with .2% arginine or. 1% methionine, or both, totally overcame the growth depression due to overprocessing. The weight gains and feed conversions of broiler chicks were negatively correlated with autoclaving times in excess of 10 minutes. In all experiments, PS values more closely reflected the impaired chick performance from overheated SBM than UA or OGBC. The PS values below 70% suggested overprocessed SBM.

Twenty-six samples of dried bakery product (DBP) were obtained from commercial sources and were evaluated for their proximate composition and TMEn content. Among the samples, marked variations were noted in ash, fiber, ether extract, and TMEn content. An equation to predict the TMEn content from the proximate composition was developed: TMEn (kcal/kg) = 3.9 + .02 × ether extract – .09 × crude fiber .03 × ash (R2 = .80). Ten additional samples of DBP were evaluated for proximate composition and TMEn in order to test the prediction equation. The error obtained when estimating the TMEn content from the prediction equation (4.1%) was substantially less than that obtained when assuming an average value based on Samples 1 to 36 (6.8%). The final prediction equation, derived from Samples 1 to 36, was: TMEn (kcal/g) = 4.34 –.10 × crude fiber – .04 × ash – .03 × protein + .01 × ether extract (R2 = .78). The mean errors based on the initial and final equations were 2.91 and 2.65%, respectively. Both compare favorably with the residual error of 5.78% obtained when using the average value of 3.63 kcal/g. All values given are expressed on the basis of 90% dry matter.

Two experiments were conducted to compare standardized ileal amino acid (AA) digestibility in 7- and 21-d-old chicks and true AA digestibility as determined by the precision-fed cecectomized rooster assay for several ingredients used in poultry feeds. Diets were formulated to contain soybean meal, cottonseed meal, poultry by-product meal, and fish meal in experiment 1 and corn, wheat, soybean meal, poultry by-product meal, feather meal, and fish meal in experiment 2 as the sole sources of protein. Celite, used as an indigestible marker, was added at 1.5% of the diet. The test diets were fed ad libitum to broiler chicks from 0 to 7 d of age in experiment 1 and from 4 to 7 and 17 to 21 d of age in experiment 2. Ileal digesta samples were collected after euthanizing the birds at 7 d of age in experiment 1 and at 7 and 21 d of age in experiment 2. Additionally, cecectomized, Single-Comb White Leghorn roosters were used for crop intubation of the test diets for determination of true AA digestibility. In experiment 1, AA digestibility of all ingredients tested was significantly lower at 7 d of age than when determined by the rooster assay. In experiment 2, no differences were detected between AA digestibility at 7 or 21 d of age in the chick assay for the majority of the indispensable AA. However, the AA digestibility coefficients obtained by the chick assay at 7 d and, in some cases, at 21 d of age, were significantly lower than those obtained by the rooster assay. In conclusion, there were differences in the AA digestibility coefficients obtained through the chick and the rooster assays. Such discrepancies could be associated with an age effect or the methodological differences between both methods.

Two experiments were conducted to evaluate the use of distillers dried grains with solubles (DDGS) from modern ethanol plants in broiler diets. Experiment 1 was a 2 x 2 factorial experiment with diets containing 2 levels of DDGS (0 and 15%) and 2 diet densities (high and low). The high- and low-density diets were formulated to contain 22% CP and 3,050 kcal MEn/kg and 20% CP and 3,000 kcal MEn/kg, respectively. Eight pens of 6 chicks were fed an experimental diet from 0 to 18 d of age. Weight gain and feed efficiency (gain:feed ratio) of the chicks receiving the high-density diets were (P0.05) better than those of chicks fed the low-density diets. However, within the 2 density levels there was no difference in performance of chicks fed diets with 0 or 15% DDGS. In experiment 2, 6 replications of 50 chicks were fed 1 of 4 dietary treatments for 42 d. The diets were formulated to be isocaloric and isonitrogenous and contained 0, 6, 12, or 18% DDGS. There was no significant difference in performance or carcass yield throughout the 42 d experiment except for a depression in BW gain and feed conversion when chicks were fed diets with 18% DDGS in the starter period. These studies indicate that DDGS from modern ethanol plants is an acceptable feed ingredient for broiler diets and can be safely used at 6% in the starter period and 12 to 15% in the grower and finisher periods.

Tuna meal is distinct from many other types of fish meal in that fillets have previously been removed for human consumption. Three samples of tuna meal were found to have less protein but a proportionately higher mineral content than reference values for meals made from whole fish. The metabolizable energy content of tuna meal was lower than values reported for most common types of fish meal.

In five experiments an attempt was made to reduce the effects of heat stress on broiler chicks by lowering the heat increment of the diet. Percent of energy derived from fat was increased by replacing corn starch with fat, calorie for calorie, which reduced formula weight and increased diet density. In one treatment total protein level was reduced also while maintaining adequate essential amino acid levels. The effect of caloric and nutrient density was separated from that of “percent fat calories” by the use of a non-nutrient filler in one diet. Experimental rations were fed to male broiler chicks from 4 to 7 weeks of age in hot (31.1 ± 2 C) vs. cool (20.0 ± 2 C) controlled temperature chambers. In all experiments, metabolizable energy (ME) intake was increased when fat calories replaced carbohydrate (CHO) calories. In the high fat treatments, chicks gained significantly more body weight than did the high CHO control groups. This increase, however, was similar at both temperatures, indicating that the beneficial effect of dietary fat was independent of temperature. A portion of the improvement in ME intake and weight gains resulting from increased ratio of fat to non-fat calories was retained when diet density was equalized. Heat production measured by energy balance studies was numerically lower in chicks fed diets with the high ratio of fat to non-fat calories.

Three experiments were conducted to test the preference of broiler chicks for a high fat as opposed to a high carbohydrate (CHO) diet, and to determine whether environmental temperature would influence the choice. In one experiment conducted in controlled environment chambers in finishing batteries, chicks maintained in a comfortable environment (20.5 C) as well as those exposed to heat stress (32.5 C) demonstrated a highly significant (P≤.01) preference for the high fat diet. In two experiments conducted in floor pens in uninsulated broiler houses in midsummer, a clear-cut preference for the high fat diet was also demonstrated. Preference for the high fat diet was less pronounced when feeder space was reduced. The effect of feeder location was tested in control pens receiving a single diet and was found not to be a factor in determining preference. When chicks were offered only the high fat or the high CHO diet, body weight gains were greatest in pens receiving the high fat diet (P≤.05) in three of four comparisons.

When assayed at a 2.5% level of inclusion in a corn-soybean meal basal diet with 40 replications per treatment, no significant differences could be demonstrated between the true metabolizable energies (TME) of corn oil and two samples of tallow varying in stearic acid (18:0) content. All values were in excess of the gross energy of fat, suggesting an improvement in the absorption of other dietary constituents. When assayed at a 15% level in a purified basal diet, the TME of corn oil was significantly higher than that of the tallows; all values were below the gross energy of fat. Use of the practical corn-soybean meal basal improved the TME of the fats by 22.4% (corn oil), 34.9% (low 18:0 tallow), and 43.0% (high 18:0 tallow). A portion of the improvement in the TME of the tallows is presumed to be accounted for by an interaction with fatty acids in the practical basal ingredients that may be obscured at higher levels of inclusion. It is concluded that with adequate replication it is feasible to assay the TME of fats at low levels of dietary inclusion. A comparison of fatty acid absorption in Single Comb White Leghorn roosters during a TME study and in 8 to 9 week broilers on a full-feed regimen suggests that the conditions imposed during a TME assay provide a satisfactory model for evaluating the fat absorption of chickens reared under normal conditions.

Broiler chicks 5 to 7 weeks of age were subjected to a constant cool (14 ± 1 C) or hot (31 ± 1 C) environment and fed diets varying in fat level and energy and nutrient density. Chicks gained significantly (P≤.01) more body weight in the cool than in the hot environment. In both environments chicks fed high fat or high fat-high density diets gained more weight than those fed diets low in fat, and there was no diet × temperature interaction. When temperatures were cycled diurnally (cool, 14 to 22 C; hot, 22 to 33 C), as would occur under natural conditions, the growth depression due to heat stress was less in chicks fed the diets high in fat. The special benefit of fat at high temperature was probably the result of reduced heat increment. Under constant temperature conditions, chicks in the cool environment, pair-fed at the same level of feed intake as those in the hot environment, gained significantly (P≤.05) more weight than the latter. These data indicated that factors other than reduced feed intake contributed to the growth depression associated with high temperature. Thyroid size was significantly (P≤.05) reduced in chicks held at constant high temperature and slightly but not significantly reduced in chicks subjected to cyclic heat stress. This decrease in thyroid size suggested there is a practical limit on overcoming by nutritional means the deleterious effects of heat stress in broilers.

A series of experiments was conducted to determine the influence of energy intake on the endogenous energy excretion of Single Comb White Leghorn (SCWL) roosters. In the first study, 0, 12.5, and 25.0 g of a 50% glucose-corn starch mixture were each fed to 32 roosters previously fasted for 24 hr. Energy and nitrogen excretion for the 24 hr postfeeding decreased significantly as energy intake was increased. In the second study, eight SCWL roosters were assigned to each of six feeding regimens: fasted, 20 g glucose, 20 g yellow corn, 20 g yellow corn plus 20 g glucose, 20 g soybean meal, and 20 g soybean meal plus 20 g glucose. Energy and nitrogen excretion for the 24-hr postfeeding period were determined. Roosters receiving glucose voided less energy and nitrogen than did those in corresponding treatments without glucose. This reduction was significant (P These results suggest that endogenous energy loss is inversely related to level of energy intake, presumably due to a sparing effect on the catabolism of body tissue. Possible implications of this effect on true metabolizable energy assays are discussed.

Metabolizable energy values of a feather meal sample were compared using four different assay techniques. One variation of the classical chick assay (substitution for basal diet, full-fed chicks, 0 to 14 days of age, chromic oxide indicator) gave 2.34 ± .08 kcal MEn/g dry matter when substituted into the reference diet at 400 g/kg, and 2.83 ± .12 kcal/g at 200 g/kg. A second MEn variation (substitution for basal diet, full-fed chicks, 7 to 14 days of age, total excreta collection) gave a value of 2.77 ± .04 kcal/g when substituted into the reference diet at 400 g/kg. Values from Sibbald’s (1986) TMEn and Farrell’s (1978) AMEn assays using adult cockerels were 3.34 ± .09 and 3.42 ± .10 kcal/g, respectively. Values derived from the two rapid cockerel assays were essentially the same but higher than those from the classical type of assay with ad libitum-fed chicks.

Two experiments were conducted to investigate whether values obtained using the true metabolizable energy (TME) assay are applicable in the formulation of practical diets for poultry. In the first study, five diets of increasing energy and nutrient density were assayed for TME and nitrogen corrected, apparent metabolizable energy. (AMEn). Chick response to each diet was evaluated in a 3-week growth trial. The determined TME of three practical diets exceeded the respective determined AMEn by 13 to 14%. A comparison between feed efficiency of chicks and the TME and AMEn content of the test diets indicated that TME values more closely reflected observed chick performance than did AMEn. In the second study, seven feed ingredients were assayed for TME and crude protein content. On the basis of these analyses, four isocaloric, isonitrogenous diets were prepared using the assayed lots of ingredients in varying proportions. In all diets, critical nutrients were included in excess of requirements, energy thus being limiting for optimal chick performance. In a 3-week growth study, chicks receiving each of the test diets exhibited virtually identical body weight gains and feed conversion ratios. Assays of the mixed diets indicated TME values of individual ingredients to be additive to within 1.6% of calculated totals. It was concluded that the TME system provided an accurate measure of metabolizable energy.

Metabolizable energy values from assays with fasted roosters are often calculated: 1) without regard to variability in data from control roosters, 2) with chemical determination on pooled and not individual data, and 3) from data sets with statistically aberrant points removed. Data from determinations of the ME of a feather meal sample were used to examine the influence of these practices on the reported mean and variance values. Ignoring the variability of the fasted controls or pooling excreta samples did not have large effects on the means or variances of these samples. Eliminating data from roosters whose excreta weights are more than one standard deviation from the mean had little effect on the mean value but made the variance appear much smaller than it actually was. As a result of these practices, researchers may place too much confidence in their data and fail to use enough replicates (roosters) to justify that confidence.

Two experiments were conducted to study the utilization of nonprotein nitrogen sources (urea and diammonium citrate), sugar beet molasses, and their combinations by laying hens and growing chicks. Basal diets containing 12 and 20% protein and all essential amino acids according to NRC recommendation (1977) were formulated for laying hens and growing chicks, respectively. Basal diets were supplemented with 3% protein equivalent from soybean meal, urea, or diammonium citrate (DAC) both with and without 10% molasses. In the laying hen experiment, molasses was used also at 15 and 20% in the diet containing 3% supplemental protein from soybean meal. Egg production was increased significantly when the basal diet was supplemented with soybean protein or urea; however, the response to soybean meal supplementation was significantly greater than to that of urea. Diammonium citrate significantly decreased egg production and it had an adverse effect on feed consumption, egg weight, and nitrogen retention. Molasses failed to increase utilization of urea for egg production, but it reduced the adverse effect of DAC on egg production. In the chick studies a growth response was obtained when the basal diet was supplemented with soybean meal, but no response was obtained from urea or DAC. Molasses did not improve the performance of chicks with or without protein supplementation. Molasses per se can be used effectively as an energy source as it had no adverse effects on performance of laying hens and growing chicks up to the maximum levels which were used in these experiments.

The true metabolizable energy (TME) of corn oil was determined using both practical and purified carriers. When assayed with “high-fat” practical carriers (corn or mixed feed), the TME of corn oil averaged 9.21 kcal/g compared with a significantly (P≤.05) higher value of 9.66 kcal/g when assayed with “low-fat” carriers (soybean meal or ether-extracted feed). As the latter value exceeded the gross energy of fats, it was concluded that the addition of corn oil to the low fat carriers enhanced the absorption of these substances, and this was reflected in the TME of the corn oil by extrapolation. It was found that neither glucose nor corn starch alone was satisfactory as a carrier for determining the TME of corn oil. Combinations of glucose and corn starch had TME values equal to their gross energies, indicating virtually complete absorption. The TME of corn oil determined using these carriers was 8.90 kcal/g, which was not significantly different (P≤.05) than when high fat practical carriers were used. Glucose-corn starch carriers may find application in evaluating the interactions between supplemental fats and basal diets in energy determinations.

Experiments were conducted to determine the metabolizable energy (MEn) of eight poultry by-product meal (PBPM) samples. Samples averaged 5.44% moisture, 4.84 kcal gross energy (GE)/g dry matter (DM), 61.2% crude protein, 13.38% ether extract, 16.1% ash, 5.14% calcium, and 2.36% phosphorus. Samples of PBPM were substituted in the diet at levels of 20 and 40%. Values of ME were calculated with substitution for the diet (Matterson’s method) and for glucose (Hill’s method) and by the fasted cockerel method. Values of PBPM MEn were 7.9% greater when substitution was for diet as compared with substitution for glucose; values were 2.95 and 2.74 kcal/g DM, respectively. Using Matterson’s method with three samples, MEn values were determined to be 12.1% greater when PBPM was substituted at the rate of 20% than at 40%; values were 3.33 and 2.97 kcal/g DM, respectively. Differences in MEn between the best and poorest samples (3.79 and 2.77 kcal/g DM) could be attributed to differences in gross energy (5.00 and 4.49 kcal/g DM) and percentage of gross energy metabolized (75.7 and 61.7%). Metabolizable energy was more closely related to body weight gains than the amount of feed consumed. When a modification of Sibbald’s fasted cockerel technique was used, true MEn of the eight samples averaged 3.35 kcal/g DM and 69% of GE metabolized. For the three samples assayed by both methods, Matterson’s method gave values averaging .97% higher than Sibbald’s (+4.3, +.8, and −2.2%). Differences in MEn were mostly highly correlated with ash (−.89), calcium (−.85), and GE (.78) contents of the diets. Projections from relationships found between ME and nutrient compositions of these samples to the average sample used by the poultry industry in the Southeast indicate an average of 3.57 kcal ME/g DM of PBPM (3.39 kcal/g as is).

Experiments were conducted to evaluate the influence of basal dietary fat on the true metabolizable energy (TME) of test fats differing in composition and physical properties. Two samples of blended fats and one sample of tallow were tested using a simplified corn-soy basal diet with all of the fat extracted and with the extracted fat added back in increasing increments up to 10% of the diet. The test fats were added at levels of 5 to 15%, resulting in ratios of basal fat to test fat of 0:15 to 10:5. The TME of tallow and one of the blends was improved as the ratio of basal fat:test fat was increased from 1:4.5 up to 7.5:7.5, at which point there were no significant differences in TME among the fats. Even at a more narrow ratio (5:10), the TME of the tallow was equal to or higher than that of either blend. Fatty acid absorption was determined using the fat-free diet to determine endogenous fat excretion. Absorption of 18:0 and, to a lesser extent, 16:0 was improved as the ratio of basal fat:test fat was increased from 0:15 to 7.5:7.5. The TME of the tallow was the same when fed with extracted (fat-free) basal as with the unextracted basal suggesting involvement of two separate mechanisms.

Two samples of corn differing substantially in bushel weight were obtained from a commercial feed mill. The light weight sample (606 g/L; 47 lb/bu) was higher in protein (9.3%) and lower in ether extract (2.95%) than the normal weight corn (696 g/L; 54 lb/bu), which contained 8.1% protein and 3.43% ether extract. The determined TME of the corn samples on a dry matter basis did not differ significantly (3.81 vs. 3.83 kcal/kg). The normal corn had increased levels of lysine, methionine, and methionine plus cystine when the amino acid levels were compared as a percentage of total amino acids. No differences were observed when comparisons were made as a percentage of the total sample. In the light corn sample, the analyzed lysine and sulfur amino acid concentrations (percentage amino acids/percentage CP) were 13 to 16% lower than calculated values derived from published prediction equations. In the normal corn, the differences were only 8 and 3%, respectively.

The effect of excreta drying procedure on resulting true amino acid availability (TAAA), true metabolizable energy (TME), and nitrogen-corrected TME (TMEn) values was investigated using two high-protein feedstuffs. The TAAA and TME assays were based on those of Likuski and Dorrell (1978) and Sibbald (1976), respectively. Twenty-five grams of either dehulled soybean meal (SBM) or poultry offal meal (POM) was administered to White Leghorn roosters. Excreta samples were divided, one portion being freeze dried and the other dried in a forced air oven at 60 C. The TAAA, TME, and TMEn values, based on the excreta samples from the different drying procedures, were compared. No significant differences (P≤.05) in the TME or TMEn of either ingredient could be attributed to drying technique. It is concluded that the capability to freeze dry excreta is not a prerequisite to the successful use of the TME and TMEn bioassays. The availability of the total of amino acids in the test ingredient was similarly unaffected by drying technique; however, for several individual amino acids, including lysine and arginine in both ingredients, methionine in SBM and valine in POM, values were significantly higher when excreta were oven dried. This suggests either a limited destruction or irreversible binding of these amino acids during oven drying.

Comparisons were made between the repeatability of true metabolizable energy (TME) and nitrogen corrected TME (TMEn) values for yellow corn and dehulled soybean meal (SBM). Seven samples of each ingredient were evaluated twice for TME and TMEn content. The mean differences between the two determined TME and TMEn values (i.e., repeatability) were 1.2 and .5%, respectively, for corn and 2.6 and 2.7% for SBM. It is concluded that both TME and TMEn values are highly reproducible.

Two experiments were conducted to determine whether a previously observed preference of broiler chicks for high fat vs. low fat rations would also be noted: 1) under cold conditions, 2) when energy and nutrient density are increased, and 3) when the physical texture of test rations is equalized by pelleting. In the first experiment conducted in unheated houses under winter conditions, diets compared were A) low-fat low density, B) high fat-high density, and C) high fat-low density. These were offered in pairs (A vs. B, A vs. C, B vs. C) to broiler chicks 4 to 7 weeks of age. A highly significant preference was shown for the high fat-high density diet over both low density diets and for the high fat-low density over the low fat-low density diet. In the second experiment high fat and low fat rations were presented in either mash or pelleted form. Regardless of physical texture, the high fat diet was again preferred by a highly significant (P≤ .01) margin. The relative position of feeders had no apparent influence on the pattern of feed consumption.

An alfalfa protein concentrate (Pro-Xan) was assayed for proximate composition, true metabolizable energy (TME), nitrogen-corrected TME (TMEn), and true available amino acid (TAAA) content. The sample had a crude protein content of 52.7%, ether extract of 8.4%, crude fiber of 2.9%, ash of 9.2%, moisture of 7.8%, and nitrogen-free extract of 19.0%. Determined TME and TMEn values were 3.28 and 2.97 kcal/g, respectively, on a dry matter basis. With one exception, the true availabilities of 16 amino acids were between 83.6 and 92.3% with an overall average of 86.1%.

Brewers’ condensed solubles (BCS) is a by-product of the brewing industry. It contains about 50% solids, consisting mainly of residual sugars recovered from the mashing vessels after wort production. Several experiments were conducted to determine its value as a feed ingredient for chickens. The BCS was incorporated into both broiler and layer diets at levels of 0, 1, 2.5, and 5%, isocalorically, based on a predetermined true metabolizable energy (TME) value. Four replicate groups of 10 chicks received each of the experimental rations to 4 weeks of age. No significant differences in growth rate or feed efficiency were observed on any of the treatments. In the laying hen trial three replicate groups of 10 hens each received each of the experimental rations for four 28-day periods. No significant differences among treatments occurred in egg production, egg weights, Haugh units, or feed efficiency. Two samples of BCS were assayed for TME on a corn carrier and found to contain 4.25 ± .12 and 4.58 ± .14 kcal/g DM, respectively. The second sample was also found to contain 4.32 ± .16 kcal/g DM apparent metabolizable energy (AME). These results indicate that BCS can serve as a satisfactory feed ingredient in broiler and layer rations at least up to 5%.

True metabolizable energy (TME) values were determined for five feed ingredients (yellow corn, dehulled soybean meal, corn gluten meal, menhaden fish meal, and poultry byproduct meal), and three combinations of these ingredients, using Single Comb White Leghorn roosters, 6-week-old broiler males (Cobb), and 6-week-old male turkey poults (Large White). There was generally good agreement in the TME values between roosters, broilers, and poults although the values for broilers tended to be slightly lower than for roosters or poults. Values for the ingredient combinations as assayed with the three classes of birds showed differences of 3% or less between “predicted” and “determined” in seven of nine comparisons, indicating a satisfactory degree of additivity of TME values for these ingredients.

The relationship between the protein content of feedstuffs and the magnitude of difference between corresponding true metabolizable energy (TME) and nitrogen-corrected TME (TMEn) was investigated. Fifty-two samples of feed ingredients, mixtures of ingredients, and mixed feeds were assayed for TME and TMEn. A positive relationship was observed between the protein content of the feed samples and the magnitude of difference between determined TME and TMEn values. The regression equation describing this relationship is Y = .122X + 3.724, where X equals percent protein and Y the percent difference between TME and TMEn. The corresponding r2 was .60.

In two experiments graded levels of either aflatoxin and tannic acid (experiment 1) or aflatoxin and a high-tannin variety of grain sorghum (BR-64) (experiment 2) were incorporated into broiler chick starting diets in a factorial design. When present singly, aflatoxin and both tannic acid and high tannin sorghum significantly depressed chick growth. When present in combination, and deleterious effects of aflatoxin and either tannic acid or high tannin sorghum on chick growth and feed conversion ratios were found to be additive.

Gossypol, a natural component of cottonseed meal, exists in positive (+) or negative (-) enantiomeric forms, and their levels and ratio could be altered by developing new genetic strains of cotton. Two experiments were conducted to determine the relative toxicity of the individual gossypol enantiomers in laying and broiler breeder hens. In the first experiment, 25 individually caged Hy-Line W-36 forty-three-week-old laying hens were fed a standard corn-soy diet supplemented with either no gossypol or the individual enantiomers at 200 and 400 mg/kg of diet for 20 d (5 hens/treatment). In the second experiment, 15 individually caged Cobb 500 fast-feathering 44-wk-old broiler breeder hens were fed a standard corn-soy-wheat middlings diet supplemented with either no gossypol or the individual enantiomers at 400 mg/kg of diet for 18 d (5 hens/treatment). In both experiments, feed intake, egg production, and egg weight were determined daily. All eggs were individually opened and scored for yolk discoloration. At the end of both experiments, several organ and tissue samples were collected for gossypol analyses. In both experiments, the addition of (+)-gossypol to the diet reduced egg production. Only laying and broiler breeder hens fed (+)-gossypol produced eggs with severe yolk discoloration (score > or = 4). Total feed intake was lower (P < 0.05) in laying hens fed the 400 mg/kg level of (+)-gossypol compared with laying hens fed the other dietary treatments. In contrast, broiler breeder hens consumed less of the diet supplemented with (-)-gossypol. In both experiments, tissue accumulation of (+)-gossypol was higher than (-)-gossypol, with the exception of bile and excreta. The results suggest that in hens the ingestion of (+)-gossypol has a greater effect on egg yolk discoloration than the consumption of (-)-gossypol.

Use of cottonseed meal in poultry diets has been avoided in large part because of fear of gossypol toxicity. Gossypol exists naturally as a mixture of 2 enantiomers that exhibit different biological activities. Two experiments were conducted to determine the relative toxicity of gossypol enantiomers on broilers. In the first experiment, 3-d-old broilers were fed a standard diet containing 0, 100, 200, 300, or 400 mg of gossypol from gossypol acetic acid per kilogram of diet from 3 to 42 d of age. This form of gossypol contains both enantiomers in an equimolar ratio. Each dietary treatment consisted of 6 replicate pens of 4 birds. In the second experiment, 3-dold broilers were divided into 15 pens of 4 birds each and fed a standard diet supplemented with either no gossypol or one of the gossypol enantiomers at 200 or 400 mg/kg of diet from 3 to 21 d of age. In both experiments, feed intake and BW gain were measured. In addi- (Key words: cottonseed meal, gossypol, gossypol enantiomer, broiler) 2005 Poultry Science 84:1376–1382 INTRODUCTION Cottonseed meal (CSM) could be an attractive alternative protein source for poultry diets, but concern over the presence of the potentially toxic agent, gossypol, has limited its use. Gossypol [1,1′,6,6′,7,7′-hexahydroxy-5,5′- diisopropyl-3, 3′-dimethyl-(2, 2′- binaphthalene)-8, 8′-dicarboxaldehyde] is a polyphenolic compound located in pigment glands that are distributed throughout the cotton plant. Gossypol is composed of 2 naphthalene rings with restricted rotation around the bond connecting the rings. As a result of this restricted rotation, gossypol occurs naturally as a mixture of 2 enantiomers [(+)- and (−)- 2005 Poultry Science Association, Inc. Received for publication February 7, 2005. Accepted for publication May 5, 2005. 1This research was supported in part by grant 2631RE683-118 from the Georgia Cotton Commission, Perry, GA. 2Mention of trade names or commercial products in this article is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the US Department of Agriculture. 3To whom correspondence should be addressed: ajdavis@uga.edu. 1376 tion, several organ and tissue samples were collected at 21 d (experiments 1 and 2) and 42 d (experiment 1) of age and analyzed for gossypol. In experiment 1, feed consumption and BW gain were reduced (P < 0.05) at 21 and 42 d for the birds fed the highest level of gossypol. The concentration of gossypol in the heart, kidney, and plasma were equivalent at 21 and 42 d of age. In experiment 2, total feed consumption was reduced only in birds consuming (−)-gossypol, but BW gains were lower for birds fed either enantiomer. However, (−)-gossypol was more detrimental to growth than (+)-gossypol. The liver had the highest tissue concentration of both enantiomers, and accumulation of (+)-gossypol was higher than (−)- gossypol in all tissues examined. No racemization of the enantiomers was apparent in the tissues analyzed. Our results indicated that both gossypol enantiomers were toxic to broilers but that (−)-gossypol was more harmful to efficient broiler production than (+)-gossypol.