Male White Pekin Ducks Research Articles

Effects of pyridoxine on growth performance and plasma aminotransferases and homocysteine of white pekin ducks.

A dose-response experiment with seven supplemental pyridoxine levels (0, 0.66, 1.32, 1.98, 2.64, 3.30, and 3.96 mg/kg) was conducted to investigate the effects of pyridoxine on growth performance and plasma aminotransferases and homocysteine of White Pekin ducks and to estimate pyridoxine requirement for these birds. A total of 336 one-day-old male White Pekin ducks were divided to 7 experimental treatments and each treatment contained 8 replicate pens with 6 birds per pen. Ducks were reared in raised wire-floor pens from hatch to 28 d of age. At 28 d of age, the weight gain, feed intake, feed/gain, and the aspartate aminotransferase, alanine aminotransferase, and homocysteine in plasma of ducks from each pen were all measured. In our study, the pyridoxine deficiency of ducks was characterized by growth depression, decreasing plasma aspartate aminotransferase activity and increasing plasma homocysteine. The ducks fed vitamin B6-deficient basal diets had the worst weight gain and feed/gain among all birds and this growth depression was alleviated (p<0.05) when pyridoxine was supplemented to basal diets. On the other hand, plasma aspartate aminotransferase and homocysteine may be the sensitive indicators for vitamin B6 status of ducks. The ducks fed basal diets had much lower aspartate aminotransferase activity and higher homocysteine level in plasma compared with other birds fed pyridoxine-supplemented diets (p<0.05). According to quadratic regression, the supplemental pyridoxine requirements of Pekin ducks from hatch to 28 days of age was 2.44 mg/kg for feed/gain and 2.08 mg/kg for plasma aspartate aminotransferase and the corresponding total requirements of this vitamin for these two criteria were 4.37 and 4.01 mg/kg when the pyridoxine concentration of basal diets was included, respectively. All data suggested that pyridoxine deficiency could cause growth retardation in ducks and the deficiency of this vitamin could be indicated by decreasing plasma aspartate aminotransferase activity and increasing plasma homocysteine.

Choline requirements of male White Pekin ducks from 21 to 42 d of age

1. A dose–response experiment with 6 dietary choline concentrations (0, 342, 779, 1285, 1662 and 1962 mg/kg) was conducted with male White Pekin ducks to estimate the choline requirement from 21 to 42 d of age.2. Ninety 21-d-old male White Pekin ducks were allotted to 6 dietary treatments, each containing 5 replicate pens with three birds per pen. At 42 d of age, final weight, weight gain, feed intake and feed/gain were measured. Liver was collected to determine total liver lipid, triglyceride and phospholipids.3. Significant positive effects of dietary choline on final weight, weight gain and feed intake were observed. In addition, dietary choline supplementation significantly decreased liver lipid and triglyceride content and increased liver phospholipids of Pekin ducks.4. According to broken-line regression analysis, the choline requirements of male White Pekin ducks from 21 to 42 d of age for weight gain, feed intake and total liver lipid were 980, 950 and 1130 mg/kg. Pekin ducks needed more choline to prevent excess liver lipid deposition than to maintain growth.

Threonine requirement of White Pekin ducks from hatch to 21 d of age

1. A dose-response experiment with 5 dietary threonine concentrations (5.0, 5.8, 6.6, 7.4 and 8.2 g/kg) was conducted to estimate the threonine requirement of White Pekin ducks from hatch to 21 d of age.2. A total of 240 one-d-old male White Pekin ducks were allotted to 5 experimental treatments and each treatment contained 6 replicate pens with 8 ducks per pen. Ducks were reared in raised wire-floor pens from hatch to 21 d of age. At 21 d of age, growth performance and intestinal morphology were determined.3. The weight gain and feed intake of Pekin ducks increased and feed/gain of these birds decreased linearly or quadratically as dietary threonine increased from 5.0 to 8.2 g threonine/kg. Compared to ducks fed on diets containing 5.0 g threonine/kg, ducks given diets containing 7.4 g threonine/kg had higher villus height in duodenum, jejunum and ileum.4. The threonine requirements for weight gain of White Pekin ducks from hatch to 21 d of age was estimated to be 6.72 g/kg when dietary crude protein concentration was 189.8 g/kg and threonine supply was critical for maintaining intestinal structure of these birds.

Hypothalamic protein profiles associated with inhibited feed intake of ducks fed with insufficient dietary arginine

An experiment was conducted to investigate the effect of arginine on feed intake regulation. One hundred and twenty six 1-day-old male White Pekin ducks (Anas platyrhynchos domestica) were randomly were allotted to one of two dietary treatments. The birds were fed diets containing 0.71% (deficient) or 1.27% (sufficient) arginine for 3 weeks. At 21 days of age, feed intake was determined and hypothalamic protein profiles were analyzed using isobaric tags for relative and absolute quantification technique. The birds fed with arginine-deficient diet had a lower final live BW and cumulative feed intake (P<0.01) than those fed with arginine-sufficient diet. A total of 16 proteins were identified in the hypothalamus with >1.5-fold expressional changes between arginine-deficient and -sufficient dietary treatments. Nine of these proteins were upregulated and seven of them were downregulated. The identified proteins could be regrouped into six categories: protein processing, carbohydrate metabolism and energy production, transporter, cytoskeleton, immunity and neuronal development. Dietary arginine deficiency decreased expression of proteins involved in energy production (glycine amidinotransferase, aldolase B fructose-bisphosphate, aconitase, transaldolase, 6-phosphofructokinase type C-like) and oxygen transportation (haemoglobin subunit α expression). The proteomic alterations described here provides valuable insights into the interactions of arginine with appetite.

Effects of niacin status on tryptophan requirements of starter white Pekin ducks

A 4×5 factorial experiment, using 4 supplemental nicotinamide levels (0, 40, 80, and 120mg/kg) and 5 dietary Trp levels (1.32, 1.67, 2.02, 2.37, and 2.72g/kg), was conducted to study the effects of niacin status on Trp requirements for growth of starter white Pekin ducks from hatch to 3wk of age. Eight hundred and forty 1-d-old male white Pekin ducks were assigned to 20 treatments with 6 replicate pens and 7 ducks per pen. All ducks were reared in raised wire-floor pens from hatch to 21d of age. No supplementation of nicotinamide in diets caused bowed leg deformity regardless of dietary Trp levels and the 40mg and greater supplemental nicotinamide/kg completely prevented bowed leg deformity at all Trp levels. The interaction between nicotinamide and Trp influenced weight gain and feed intake of ducks (P<0.001). Supplementation of Trp in diets alleviated the depression of weight gain and feed intake caused by niacin deficiency at 0mg supplemental nicotinamide/kg, but supplementation of nicotinamide in diets did not alleviate the depression of weight gain and feed intake caused by dietary Trp deficiency (1.32gTrp/kg). According to the broken-line regression, the Trp requirements of starter Pekin ducks for weight gain from hatch to 3wk of age at 0, 40, 80, and 120mg/kg of supplemental nicotinamide were 2.42, 1.68, 1.69, and 1.69g/kg, respectively, and the Trp requirement was much greater at 0mg/kg of supplemental nicotinamide than at other 3 supplemental nicotinamide levels (P<0.05). In conclusion, the interaction between niacin and Trp in duck diets was supported by the effects of niacin status on Trp requirements of starter white Pekin ducks and niacin deficiency markedly increased the Trp requirements of white Pekin ducks.

Comparative amino acid digestibility for broiler chickens and White Pekin ducks

A total of 608 three-week-old male broiler chickens and White Pekin ducks were used in a 5-d trial to compare ileal amino acid (AA) digestibility of soybean meal (SBM) and canola meal (CM) using the regression method. A corn-casein-cornstarch-based diet was mixed to contain 15% CP. Cornstarch was replaced with test ingredient (SBM or CM) to contain 18 or 21% of CP in 4 other diets. A nitrogen-free diet (NFD) was used for standardization of apparent digestibility. Birds received a standard starter diet (23% CP) from d 0 to 14 posthatch and then 6 experimental diets for 5 d. On d 19 posthatch, birds were asphyxiated with CO2, and digesta from the distal section of ileum was collected. The ileal digestibility of AA from the test ingredients was assessed by multiple linear regression analysis using data on daily apparent ileal digestible AA and total AA intakes. The basal endogenous losses of N and all AA for ducks were significantly higher than those for broilers. For ileal AA digestibility by regression of apparent digestible AA intake against AA intake, there was a higher (P < 0.05) digestibility for Cys and Pro in ducks compared with broilers (P < 0.05). Within species, digestibility was not different between SBM and CM except for Lys of ducks, and Lys and Pro of broilers (P < 0.05). The results of this study showed that ducks have higher basal endogenous AA losses compared with broiler chickens as well as higher ileal Cys and Pro digestibility estimates derived from regression approach, indicating that data obtained from broilers should not be used to formulate diets for ducks.

Arginine requirements of White Pekin ducks from 1 to 21 days of age

An experiment was conducted to estimate optimal dietary arginine requirement in White Pekin ducks from 1 to 21 d of age. Six hundred thirty 1-d-old male White Pekin ducks were randomly allotted to 10 dietary treatments with 7 replicate pens of 9 birds per pen. Birds in each group were fed corn-corn gluten meals diet containing 0.71, 0.84, 0.95, 1.03, 1.17, 1.27, 1.39, 1.47, 1.62, and 1.72% arginine, respectively. At 21 d of age, weight gain, feed intake, feed/gain ratio, and breast meat yield from each treatment were measured. Dietary supplementation of arginine significantly improved weight gain, feed intake, feed/gain, and breast meat yield (P < 0.01). Based on quadratic broken-line regression analysis, the arginine requirement of male White Pekin ducks from 1 to 21 d of age was 0.95, 1.16, and 0.99% for weight gain, feed/gain, and breast meat yield, respectively.

Effect of dietary amounts of inorganic and organic zinc on productive and physiological traits of White Pekin ducks

The effects of different dietary amounts of organic and inorganic Zn were studied in male White Pekin ducks (WPD) from 1 to 56 days of age. The control diet (26 ppm of Zn from raw ingredients) was supplemented with 30, 60 and 120 ppm of Zn from both inorganic and organic sources, for a total of seven treatment groups, each containing five replicates of nine 1-day-old ducklings each. BW, feed intake and feed conversion ratio (FCR) were recorded at 1, 28 and 56 days of age. At 56 days of age, five birds per group were used in a digestibility trial to measure Zn retention and excretion. At the end of the trial, five birds per treatment were slaughtered and carcass traits as well as Zn content in tibia and liver were measured. Samples of blood from five birds per treatment were used to measure plasma concentration of Zn and Cu. BW gain during the entire period of the trial increased (P < 0.001) by 30 and 60 ppm of Zn. Increasing Zn contents progressively increased (P < 0.001) the tibia and the liver Zn contents as well as the plasma Zn and Cu contents. The concentration of 120 ppm of Zn increased (P < 0.001) tibia ash and decreased (P < 0.001) abdominal fat in the carcasses. In the period 1 to 56 days, Zn oxide increased (P < 0.001) growth rate and improved (P < 0.03) FCR compared with organic Zn, whereas organic Zn increased (P < 0.003) the dressed carcass percentage. Organic Zinc increased (P < 0.001) Zn and Cu concentration in the plasma. A level of 30 ppm of Zn from an inorganic source was adequate for male WPD during 1 to 56 days of age, based on positive effects of growth rate and Zn excretion.

Effect of diet dilution ratio at early age on growth performance, carcass characteristics and hepatic lipogenesis of Pekin ducks

This study was conducted to test the hypothesis that proper diet dilution ratio at early age might improve feed conversion ratio (FCR) and reduce body fat deposition of meat-type ducks. One hundred and fifty 1-day-old male and female White Pekin ducks (44.5±1.0 g) were randomly assigned into three treatments with five replicates (pens) of 10 birds each, respectively representing the experimental diets with 0 (control), 40 or 60% rice hulls inclusion in the basal diet between 8 and 14 d of age. The basal diet was fed before and after this period. The results showed that diluting the diet with 40% rice hulls increased (p 0.05) as the controls at 42 d of age. The diet diluted with 60% rice hulls resulted in lower (p < 0.05) body weight at market age than the other treatments. The diet with 40% rice hulls reduced (p < 0.05) skin with fat and abdominal fat pad, crude fat content in the carcass and in breast meat, and increased (p < 0.05) carcass crude protein at 42 d of age. These changes may be explained by the lower (p < 0.05) activities of hepatic malic dehydrogenase (MDH), glucose-6-phosphate dehydrogenase (G-6-PDH) and fatty acid synthetase (FAS) enzymes both at 14 and 42 d of age in birds fed the diluted diets relative to the control birds. The results of this study indicate that feeding diets diluted with 40% rice hulls to Pekin ducks between 8 to 14 d of age may induce compensatory growth during the following recovery period, and may be used to improve FCR and to reduce body fat deposition at market age.

Effect of different dietary concentrations of inorganic and organic copper on growth performance and lipid metabolism of White Pekin male ducks

1. The effect of different dietary concentrations of inorganic and organic copper on performance and lipid metabolism of White Pekin ducks (WPD) was investigated from 1-49 d of age. A common basal diet was supplemented with 4, 8, 12 and 150 mg/kg of copper (Cu) from inorganic and organic sources to obtain 9 treatments, including 4 concentrations of Cu x two sources, and the unsupplemented control group. Each treatment contained 5 replicates of 9 male ducks each. 2. Supplementation of Cu at 8 mg/kg in inorganic form was adequate for growth of male WPD from 1-56 d of age. Inorganic Cu significantly decreased feed intake and improved feed conversion ratio, compared with the organic form. 3. Plasma Cu significantly increased, while plasma Zn significantly decreased, due to Cu supplementation. Organic Cu showed better efficacy than inorganic for improving liver Cu concentration, Cu excretion and apparent Cu retention. 4. Dietary Cu concentration significantly affected percentage blood and Hgb and abdominal fat deposition. In addition, inorganic Cu increased percentage blood and abdominal fat deposition compared with the organic source. 5. Supplementation of 150 mg/kg of Cu significantly decreased liver and meat lipids, cholesterol, and colour and tenderness of meat; while liver protein and moisture was increased. In addition, dietary 150 mg/kg of Cu supplementation significantly decreased plasma lipids, triglycerides and cholesterol, while increasing plasma AST and ALT. 6. Organic Cu was more potent for decreasing plasma triglycerides than the inorganic source. However, plasma cholesterol was only significantly decreased with the inorganic source of Cu, compared with the unsupplemented control. 7. The organic Cu was safer as a feed additive for WPD, especially at the lower concentrations up to 12 mg; while some mild to moderate changes may be developed at the higher doses, when fed at pharmacological concentrations as a growth promoter.

Dietary L-arginine supplementation beneficially regulates body fat deposition of meat-type ducks

1. Unlike mammals, uricotelic species, such as the duck, cannot synthesise endogenous arginine (Arg). This study was conducted to test the hypothesis that dietary L-Arg supplementation might regulate body fat deposition in ducks without affecting their fast growth rate. 2. A total of 160 21-d-old male and female White Pekin ducks were assigned randomly to two treatments: a non-supplemented control and supplementation at 10 g/kg L-Arg of a maize and soybean meal-based diet. 3. The 3-week feeding trial showed that the addition of L-Arg had no significant effect on feed intake, but significantly increased body weight gain by 5·2 %, breast muscle weight relative to live body weight by 9·9%, carcase crude protein content by 9·2%, ether extract content in breast muscle by 11·9%. Arg supplementation significantly decreased skin with fat and abdominal fat pad contents by 7·6% and 4·9% respectively and the ether extract content of carcase by 7·2%. 4. The results of this study indicate that a diet with 10 g/kg supplemental L-Arg could reduce the fat deposition of carcase and abdominal adipose cell size (diameter and volume), enhance intramuscular fat in breast muscles, as well as increase muscle and protein gain. The decreased fat depot in the carcase may be attributed to a reduction of hepatic lipogenic enzyme activity.

Phosphorus equivalency value of an Escherichia coli phytase in the diets of White Pekin ducks

Male White Pekin ducks at 7 d posthatch were used in a 10-d experiment to determine the equivalency value of an Escherichia coli phytase (Phyzyme XP) in corn-soybean meal-based mash diets. Two hundred fifty-six ducks were grouped by weight into 8 blocks of 8 cages with 4 ducks per cage. The 8 diets consisted of a P-adequate positive control corn-soybean meal formulated to contain CP, Ca, total P, and nonphytate P at 220, 8, 6.6, and 4 g/kg, respectively; a low-P negative control (NC) corn-soybean meal basal diet formulated to contain CP, Ca, total P, and nonphytate P at 220, 6.5, 3.9, and 1.3 g/kg, respectively; NC diet plus 0.5, 1.0, or 1.5 g of inorganic P from monosodium phosphate/kg; and NC diet plus E. coli phytase at 500, 1,000, or 1,500 units/kg. Ducks were provided ad libitum access to water and experimental diets. Feeding the low-P NC diet to ducks reduced (P<0.01) BW gain, feed intake, G:F, tibia ash, ileal digestibility, and utilization of P. Supplementation of the NC diet with inorganic P or phytase linearly improved (P<0.01) final weight, BW gain, feed intake, G:F, tibia ash, and ileal P digestibility. There were linear increases (P<0.01) in the utilization of P from 33.8 to 42% or from 33.8 to 46.6% as dietary added inorganic P or phytase increased from 0 to 1.5 g/kg or 0 to 1,500 units/kg, respectively. Linear regression equations for the tibia ash as the dependent variable and supplemental intake of inorganic P and phytase or supplemental level of inorganic P and phytase as independent variables were used to generate P equivalency values of phytase. The mean P equivalency values of phytase from linear regression equations derived from ducks fed a low-P NC diet supplemented with graded levels of inorganic P or phytase from d 7 to 17 posthatch for 500, 1,000, and 1,500 phytase units/kg of diet were 0.453, 0.847, and 1.242 g/kg of diet, respectively. The results of this study showed that this phytase was efficacious in hydrolyzing phytate P for bone mineralization and growth of ducks.

Metabolisable energy and amino acid digestibility of high-oil maize, low-phytate maize and low-phytate soybean meal for White Pekin ducks

1. Two experiments were conducted to determine the metabolisable energy and amino acid digestibilities of high-oil maize (HOM), low-phytate maize (LPM) and low-phytate soybean meal (LPSBM) as compared with normal maize (NM) and normal soybean meal (NSBM) using male White Pekin ducks. 2. In the first experiment, the TMEN (kJ/g) value of HOM (16·58) was higher than that of NM (16·05), but that of LPM (16·11) did not differ from those of HOM or NM. The true digestibility coefficients for methionine (0·874, 0·871 or 0·876), lysine (0·805, 0·816 or 0·813) and tryptophan (0·946, 0·959 or 0·960) did not differ among NM, LPM and HOM, respectively. The average true digestibility coefficients for all amino acids in NM, LPM or HOM (0·886, 0·890 or 0·900, respectively) did not differ among the three ingredients. 3. In the second experiment, the TMEN value of LPSBM (12·39) was approximately 8% higher than that of NSBM (11·46). The true digestibility coefficients for most amino acids were higher for LPSBM than for NSBM, except in the case of histidine, cysteine and tyrosine, which were not different. The average true digestibility coefficient for all amino acids in LPSBM (0·945) was higher than in NSBM (0·924). 4. Results of the two experiments indicate that the energy and amino acids in the feed ingredients evaluated were well utilised by ducks and that LPSBM has a higher energy value as well as digestible essential amino acid concentration than NSBM for ducks.

Investigations on the availability of inorganic phosphate from different sources with growing White Pekin ducks

Methodological aspects of determination of P availability in ducks were addressed in this study. Three balance experiments with quantitative excreta collection were performed with growing male White Pekin ducks that were 3 wk of age. When P from monobasic calcium phosphate (MCP) was added in graded levels below the requirement to a low-P basal diet, ducks responded nonlinearly in P accretion. With increases in dietary Ca:P ratio from 1.2:1 to 1.6:1 to 2.0:1, ymax in P accretion increased from 0.91 to 0.97 to 1.03 g/duck during the 5-d period of measurement, and marginal efficiency of utilization (δy/δx) of P from MCP increased from 75 to 85 to 91%. The overall utilization of plant P from the low-P basal diet was adversely affected by increasing dietary Ca:P ratio and decreased from 49 to 45 to 40%. Seven inorganic P sources were supplemented to a low-P basal diet to increase P content by 0.9 or 1.9 g/kg. Utilization of P from the sources was lower at 1.9 g/kg compared with at 0.9 g/kg, although supply was still below requirement, indicating that ducks fed 1.9 g/ kg were in the diminishing part of the response curve. Thus, only the values determined at the low level of supplementation were considered as a measure of availability. P availabilities were 100% for monosodium phosphate, 96% for anhydrous dibasic calcium phosphate, 92% for calcium sodium magnesium phosphate, 91% for monodibasic calcium phosphate, 86% for 2 batches of dihydrated dibasic calcium phosphate, and 77% for calcium sodium phosphate. It was concluded that availability studies aiming to characterize the capacity of an ingredient require standardization with regard to the level of P supply and the dietary Ca:P ratio. Similar to results from other species, the availability of inorganic feed phosphates for ducks is on an overall high level, but differences between P sources should be considered in diet formulation.

Nutritional evaluation of peas for ducks

AbstractThe nutritive value of four pea cultivars (AC Advantage, Carneval, CDC Mozart and Keoma) and soybean meal (SBM) was evaluated in a 102 h study with 48 male White Pekin ducks. All birds were tube‐fed 25 g of dextrose at 24 and 30 h after feed withdrawal, then 25 g of each feedstuff was tube‐fed to eight ducks at 48 and 54 h after feed withdrawal. Excreta were quantitatively collected during the next 54 h. Endogenous nitrogen, amino acids and energy per bird in the 54 h collection period were 1.06 ± 0.58 g, 0.047 ± 0.025 g and 0.098 ± 0.049 MJ respectively. There were differences (P &lt; 0.05) in apparent amino acid digestibilities (AAAD) and true amino acid digestibilities (TAAD). On average, AAAD were 82.8, 82.0, 70.3, 82.4 and 77.7% and TAAD were 89.4, 89.2, 82.3, 89.5 and 85.3% for SBM, AC Advantage, Carneval, CDC Mozart and Keoma respectively. The nitrogen‐corrected apparent and true metabolisable energy values did not differ among the pea diets and were 13.36 ± 0.071 and 14.59 ± 0.071 MJ kg−1 respectively. Respective values for SBM were 12.16 ± 0.16 and 13.39 ± 0.16 MJ kg−1 and both were lower (P &lt; 0.05) than in peas. Copyright © 2004 Society of Chemical Industry

Energy Values of Feed Ingredients for White Pekin Ducks

A modified true metabolizable energy bioassay was used to determine the nitrogen-corrected apparent (AMEn) and true (TMEn) metabolizable energy of various feed ingredients for ducks. In each of two experiments, which lasted 102 h with a 54-h excreta collection period following a 48-h period of fee d withdrawal, six male White Pekin ducks were assigned to each of three test feed ingredients and dextrose. Dextrose-fed ducks were used for estimation of endogenous losses of energy and nitrogen. The test ingredients consisted of corn, bakery byproduct and wheat red dog in experiment 1 and corn, corn gluten meal and soybean meal in experiment 2. The AMEn and TMEn values of corn were similar in the first and second experiments at 3.322 and 3.358 and 3.289 and 3.528 kcal/g, respectively. The AMEn and TMEn values of corn were higher (P < 0.05) than those of wheat red dog (2.519 and 2.662 kcal/g), but lower (P < 0.05) than those of bakery byproduct (3.75 and 3.896 kcal/g). Corn gluten meal had the highest (P < 0.05) AMEn and TMEn values (3.695 and 3.934 kcal/g) among three feed ingredients. The AMEn and TMEn value of soybean meal (2.562 and 2.799 kcal/g) were lower (P < 0.05) than those of corn. The study provide new information on AMEn and TMEn values for bakery byproduct, corn, corn gluten meal, soybean meal and wheat red dog; and demonstrated that the energy values, for White Pekin ducks, of bakery byproduct and corn gluten meal are greater than those of corn or soybean meal.

Nutritional evaluation of two agroindustrial by-products for ducks and pigs.

Forty-eight male White Pekin ducks and 24 crossbred barrows (Landrace or Yorkshire sows; PIC Line 355 boars) were used in three experiments to evaluate the nutritional value of two by-products generated from agricultural industries. In each experiment, test ingredients consisted of a dried meat solubles product (DMS) from swine processing facilities and a yeast fermentation product (YFP) from a commercial source. Soybean meal (SBM) with a CP content of 48% served as the control ingredient in the three experiments. Different batches of each by-product were evaluated in the three experiments utilizing an apparent ME (AME) assay for poultry (Exp. 1 and 2) and a digestibility assay for barrows (Exp. 3). The nitrogen-corrected AME (AMEn) for SBM, DMS, and YFP in Exp. 1 were 2.909, 2.801, and 3.292 kcal, respectively. The AMEn for SBM, DMS and YFP in Exp 2 were 2.809, 3.207, and 3.565 kcal, respectively. In Exp. 3, diets were formulated such that the test ingredients provided the sole source of amino acids in each experimental diet. The AME of SBM, DMS, and YFP in Exp. 3 were 3.844, 2.208, and 3.552 kcal, respectively. Based on the results of the ME assay for poultry, the DMS product compares well to SBM and seems to be suitable for feeding to ducks. The YFP does not seem to be suitable for feeding nonruminant species based on poor ability to support nitrogen retention in both species (-36% and -20% in Exp. 1 and 2, and 20% in Exp. 3).

Comparative Fate of the Tritiated Trichothecene Mycotoxin, T-2 Toxin, in Chickens and Ducks

A tritiated preparation of the trichothecene mycotoxin, T-2 toxin, was administered as a single oral dose to 21-day-old male broiler (Hubbard × Hubbard) chickens and White Pekin ducks. There were few significant differences between the two species in metabolism, tissue retention, and excretion of T-2 toxin and its metabolites. On the basis of the data obtained, the differences in toxicological sensitivity to T-2 toxin known to exist between these two species cannot likely be attributed to differences in the metabolism or elimination of T-2 toxin from the body.

The Effect of Dietary Lysine Levels on Performance and Meat Yields of White Pekin Ducks

Four trials were conducted to determine the effects of dietary lysine levels ranging from .70 to 1.00% on performance and yield of different carcass components of male and female White Pekin ducks. Dietary lysine had no significant effect on weights or feed efficiencies at market age of 48 or 49 days; however, significant differences were obtained with yields of component parts for the males in Trial 2 and the females in Trial 3. In these trials, overall meat yields were significantly better for males fed levels of lysine between .80 and .95% and for females fed a lysine level of .90%.

Feed/Gain Ratios of White Pekin Ducks as Affected by Age and Environmental Temperature

Feed/gain ratios of male and female White Pekin ducks were ascertained on a daily basis during the latter stage of grow-out in order to determine at what age poor feed efficiencies occur. Two temperature regimens were utilized in Trial 1 with the temperature of the control and heated environmental chambers being 18.3 and 29.4 C, respectively. In Trial 2, the ducks were subjected to varying environmental conditions since they were raised in a windowed poultry house during March, April, and May. Body weights and feed consumption were determined weekly up to 35 days of age and then daily from 39 to 52 and 36 to 61 days of age for Trials 1 and 2, respectively.The results of both trials indicate that male and female ducks exposed to environmental temperatures within their comfort zone should be marketed between 48 and 51 days of age when considering feed efficiency only. The earlier age of 48 days would be preferable to 51 days in order to increase the probability of avoiding poor feed efficiencies. If ducks reared during the summer season are exposed to high ambient temperatures, then feed/gain ratios may peak earlier than 48 days of age with losses in weight gains.