Dietary AME Research Articles

Xylanase supplementation of pelleted wheat-based diets increases growth efficiency and apparent metabolizable energy and decreases viscosity of intestinal contents in broilers

This study was designed to test graded supplementation of a thermostable xylanase in pelleted, wheat-based diets fed to broiler chickens over a 28-d period. A total of 600 Ross 708 male broilers were allotted to 1 of 5 dietary treatments: positive control (PC), negative control (NC; 125 kcal of AME/kg diet reduction relative to PC), and NC supplemented with 10, 15, or 30 g/ton of xylanase. Wheat-soybean meal-based diets were pelleted and fed in 2 feeding phases (14-d each). Study outcomes included growth performance, AME, and ileal digesta viscosity with 20 battery cages of 6 birds per treatment. Data were analyzed by 1-way ANOVA along with estimation of Pearson correlation coefficients. Whereas no difference between NC and PC was observed for BW gain, NC birds exhibited increased (P < 0.05) feed intake during each feeding phase and overall, which caused improvements (P < 0.05) in feed conversion ratio (FCR) for PC vs. NC birds. The analyzed AME of PC birds was 112 kcal/kg of diet greater (P < 0.05) than for NC birds, though no differences in digesta viscosity were observed. Xylanase supplementation of the NC diet at 15 or 30 g/ton elicited overall improvements (P < 0.05) in BW gain beyond the PC, while the 30 g/ton level equalized feed intake with the PC. Regardless of level, xylanase supplementation improved (P < 0.05) the FCR relative to the NC, thereby equalizing the response with the PC. Similarly, supplementation with any xylanase level increased (P < 0.05) AME over the NC, making all treatments synonymous with the PC. Digesta viscosity of all xylanase-supplemented treatments was decreased relative to both the NC and PC treatments. Overall, this study provided clear evidence that addition of a thermostable xylanase to pelleted wheat-based diets elicited improvements in growth performance of broilers concomitant with a reduction in digesta viscosity and elevation of analyzed dietary AME content.

The effect of gradually decreasing the dietary energy content, at constant or increased lysine:energy ratio on broiler performance, carcass yield, and body composition

Formulating diets with high AME, especially in the grower and finisher phases, hinders the inclusion of alternative ingredients that are usually cheaper and have lower AME. Moreover, as the chicken grows the feed intake capacity is greater and may be able to maintain BW over a wide range of AME. The objective of this study was to evaluate the performance of chickens fed diets with progressive AME reductions, at constant or increased standardized ileal digestible (SID) lysine:AME ratio (Lys:AME). Treatment 1 (control) was formulated following the SID lysine and AME recommendations for a 4-phase feeding program. Treatment 5 was formulated with −4, −8, and −12% AME in the grower-1, grower-2, and finisher phases, respectively, and with the same Lys:AME compared with the control. Treatment 9 had the same AME as treatment 5 but higher SID lysine, increasing the Lys:AME by 1.5, 3.5, and 5.0% compared with treatment 5. In the grower-1, grower-2, and finisher phases, the final 9 dietary treatments were prepared by mixing the control diet with either treatment 5 or 9 at different proportions (75:25, 50:50, or 25:75). All birds were fed the same starter control diet. Treatments were replicated in 10 pens with 31 male chickens each, and the growth performance of birds was monitored for 42 d. Final BW linearly decreased (P < 0.05) when lowering dietary AME, but it followed a positive quadratic response with higher Lys:AME (P < 0.05). Feed intake increased (P < 0.05) with low AME, independently of the Lys:AME; but the linear regression in the feed conversion ratio (FCR) had a lower slope when the Lys:AME increased. At the end of the study, there were no differences in carcass or breast meat yield (P > 0.10). Progressively reducing AME in the last feeding phases may be a viable nutritional strategy to increase the inclusion of alternative ingredients and potentially reduce feeding costs, despite increments in feed intake and FCR. Adjusting the Lys:AME in low AME diets may help maintain the final BW of birds.

Effects of dietary energy level and guanidino acetic acid supplementation on growth performance, carcass quality and intestinal architecture of broilers

Energy, known as the most expensive nutrient in broiler feed, is what strongly adjusts and affects the growth of broilers. Creatine has a key role in cellular energy metabolism and could be synthesised from guanidinoacetic acid (GAA) in the liver; however, its de novo synthesis is not able to adequately fulfil the demand of energy metabolism, especially in fast-growing modern broilers. So the aim of the study was to evaluate the efficiency of commercial GAA in energy-reduced broiler diets on performance and intestinal development. Overall, 11 400 day-old Ross 308 chicks were randomly allocated to six dietary treatments with ten replicates in each. Dietary treatments were designed as a 3 × 2 factorial arrangement with three levels of dietary metabolisable energy (AME&lt;sub&gt;n&lt;/sub&gt;) recommended by Aviagen for Ross 308 broilers (12.55 MJ/kg, 12.97 MJ/kg and 13.38 MJ/kg for starter, grower and finisher, respectively), 0.209 MJ/kg and 0.418 MJ/kg reduced and two levels of GAA (0.00% and 0.06%). There was no significant GAA × AME&lt;sub&gt;n&lt;/sub&gt; interaction for all performance parameters, carcass traits and jejunal morphological parameters (except for the villus width). Reduction of dietary AME&lt;sub&gt;n&lt;/sub&gt; (0.209 MJ/kg and/or 0.418 MJ/kg) caused a significant depression in body weight (BW) gain (P &amp;lt; 0.001) and feed conversion ratio (FCR) (P &amp;lt; 0.001). However, a decreasing AME&lt;sub&gt;n&lt;/sub&gt; level increased villus height (P &amp;lt; 0.003) and villus surface area (P &amp;lt; 0.03), while crypt depth and villus width were similar. The GAA improved final BW and FCR by 1.77% and 1.66%, respectively (P &amp;lt; 0.001). Birds fed low energy diets supplemented with GAA showed a significant improvement in the performance so that BW and FCR were the same as in the control birds; however, no such positive effects were obtained in jejunal villus development. Hence, it might be concluded that 0.06% GAA supplementation improves BW and FCR and can save at least 0.209 MJ/kg dietary AME&lt;sub&gt;n&lt;/sub&gt; in broiler diets.

Exogenous α-amylase improves the digestibility of corn and corn–soybean meal diets for broilers

Starch is the main energy source in broiler diets. However, endogenous amylase secretion in young broilers is suboptimal to completely digest dietary starch, so exogenous α-amylase supplementation may help increase starch digestibility. The objective of this study was to assess the supplementation of increasing doses of an exogenous α-amylase (0, 40, 80, 120, and 160 kilo-novo α-amylase units (KNU)/kg) on corn and on a complete corn–soybean meal diet for 25-day-old broilers. Jejunal and ileal apparent digestibility coefficients of available starch, resistant starch, total starch, and DM, DM total tract retention, as well as dietary AME levels were evaluated. Interactions (P < 0.05) between diets and α-amylase showed that the enzyme had a more evident effect on increasing DM jejunal digestibility and AME on corn compared with the complete diet. Corn DM digestibility increased to a maximum of 67.84% with up to 47 KNU/kg, whereas 89 KNU/kg led to a maximum of 53.92% in the complete diet A maximum increase of 64 kcal AME/kg was obtained with 80 KNU/kg on the complete diet, whereas 109 KNU/kg generated 327 kcal AME/kg on corn (P < 0.05). Increasing the α-amylase dose linearly increased ileal digestibility of resistant starch (P < 0.05), and the effect on DM total tract retention was quadratic (P < 0.05). Corn showed a higher digestibility for DM, resistant and total starch, as well as DM total tract retention and AME, compared with the complete diet (P < 0.05). Treatments had no influence on available starch. The inclusion of exogenous α-amylase improves starch, DM, and energy utilization of corn-based and corn–soybean meal–based diets for broilers.

Dietary resistant potato starch improves growth performance and feather development in Pekin ducks fed a low phosphorus diet

This study investigated whether dietary resistant potato starch (RPS) inclusion could ameliorate the negative impact of a low nonphytate phosphorus (nPP) diet on growth performance, feather growth, feather follicles (FF) development, and carcass traits by improving nutrient utilization and cecal microbiome fermentation capacity in Pekin ducks. The experiment was performed with a 2 × 2 randomized block design with 2 levels of RPS (0 or 12%) and 2 levels of nPP (low or normal, low: 0.22% at 1–14 d and 0.18% at 15–35 d of age; normal: 0.40% at 1–14 d and 0.35% at 15–35 d of age) for a total of 4 treatments, each with 8 replicate pens per treatment of 12 birds per pen. As regards growth performance and carcass traits, RPS inclusion markedly increased (P < 0.05) BW of 14 and 35 d, BWG and FI of 1–14 d, 15–35 d, and 1–35 d as well as abdominal fat and breast meat percentage of 35 d in ducks fed low nPP diets; moreover, RSP inclusion significantly reduced (P < 0.05) mortality in ducks fed low nPP diets. As regards feather growth and follicles development of 35 d, RPS inclusion significantly increased (P < 0.05) the fourth primary feather length, absolute feather weight, and the density of primary FF in the back skin in ducks fed low nPP diets. In regard to nutrition utilization, RPS supplementation significantly increased (P < 0.05) the availability of DM, CP, and energy, as well as dietary AME at 35 d of age in ducks fed low nPP diets. However, RPS supplementation had no effect (P > 0.05) on the concentration of cecal short-chain fatty acids and the activities of cecal phytase and cellulase in ducks fed low nPP diets. These results indicate that RPS can improve nutrient availability to ameliorate the negative effects on performance and feather development caused by a low nPP diet in Pekin ducks.

Impact of varying starter amino acid density and energy on 42 d male Cobb MV × Cobb 500 broiler performance and processing

Summary Previous research has shown that feeding high amino acid density (AAD) diets or increased AME improved broiler performance, though the relationship between AAD and AME on performance needs to be further explored. Therefore, the objective of this study was to evaluate the impact of feeding 2 AAD and 4 AME levels from day 0 to 14 on performance and yield of 42-day-old Cobb MV × Cobb 500 males. Starter diets were formulated to medium or high AAD (HAA), and very low (VLE), low (LE), medium (ME), or high (HE) AME. Common diets were provided from day 15 to 41. A 2 × 4 factorial arrangement of treatments was used, with day 0 BW considered as a covariant. On day 0 to 14, birds receiving HAA had the lowest feed conversion ratio (FCR) corrected and uncorrected for mortality (uFCR). Birds receiving VLE diets had the highest day 0 to 14 FCR when compared to birds fed other AME levels. Feeding LE diets resulted in higher day 0 to 14 FCR when compared to ME and HE diets. An AAD × AME interaction for day 0 to 14 total Lys intake/bird found that Lys intake/bird decreased when increasing dietary AME for HAA diets. An AAD × AME interaction was observed for day 0 to 28 uFCR whereas increasing starter AAD in diets formulated to ME and HE increased day 0 to 28 uFCR; no change was observed for VLE and LE diets. However, overall performance and processing was not affected by varying starter AAD and AME levels. Further research should investigate similar feeding strategies, but in other feeding phases.

Effects of Curcuma longa rhizome powder on egg quality, performance and some physiological indices of laying hens fed different levels of metabolizable energy.

High-energy diets of laying hens may improve roductive performance, although some negative effects may also appear with respect to egg quality and physiological parameters. Curcuma longa rhizome powder (CRP) has beneficial effects on health indices of the birds through antioxidant and antimicrobial properties, especially when the birds experience nutritional stress. Increasing dietary CRP enhanced egg quality by improving eggshell thickness and hardness but decreasing yolk cholesterol content (P < 0.05). The best feed conversion ratio was obtained in birds fed high-apparent metabolizable energy (AME) diets supplemented with 2.0 g kg-1 CRP (P < 0.05). Although increasing dietary AME elevated the serum concentration of triglycerides (P < 0.05) and enzymatic activities of alanine aminotransferase and aspartate aminotransferase (P < 0.05), dietary inclusion of CRP alleviates the blood levels of these enzymes (P < 0.01). Low level of dietary CRP boosted the immune responses to Newcastle virus (P < 0.01) and sheep red blood cells (P < 0.05) antigens but decreased the heterophil to lymphocyte ratio (P < 0.05). Inclusion of at least 2.0 g kg-1 CRP in the diet of laying decreased Escherichia coli enumerations in the ileal content (P < 0.01) and improved villus height, crypt depth and goblet cell numbers (P < 0.05). An improvement in the productive performance of laying hens fed high-energy diets might be associated with decreasing health indices and product quality, which could potentially be amended by nutritional modifications such as incorporating medicinal herbs in the feed. © 2016 Society of Chemical Industry.

Metabolizable energy content of wheat distillers’ dried grains with solubles supplemented with or without a mixture of carbohydrases and protease for broilers and turkeys

In this study, 2 experiments were conducted to determine the AME and AMEn of wheat distillers’ dried grains with solubles (DDGS) without or with supplementation of an enzyme mixture containing xylanase, amylase, and protease (XAP) in broilers and turkeys. One hundred twenty-six male Ross 308 broilers (Experiment 1) or 126 male BUT 10 turkeys (Experiment 2) were offered a nutrient-adequate diet from d 1 to 14. On d 14, birds in each experiment were allocated to 6 treatments consisting of 3 levels of wheat-DDGS (0, 300, or 600 g/kg) and 2 levels of XAP (0 or 250 mg/kg diet) in a randomized complete block design. The AME or AMEn content of wheat-DDGS was determined from the slope of regression of wheat-DDGS-associated energy intake (kilocalories) against wheat-DDGS intake (kilograms). In Experiment 1, wheat-DDGS inclusion in the diets linearly decreased (P < 0.05) DM retention, AME, and AMEn, irrespective of XAP supplementation. The AME of wheat-DDGS without or with XAP for broilers was 3,587 or 3,700 kcal/kg DM, respectively, and AMEn was 3,356 and 3,459 kcal/kg DM for wheat-DDGS without and with XAP, respectively. In Experiment 2, wheat-DDGS inclusion in the diet linearly decreased (P < 0.05) DM retention irrespective of XAP supplementation. Diet AME and AMEn linearly decreased (P < 0.05) as the level of wheat-DDGS increased in the diets without added XAP, whereas there was no effect of increasing wheat-DDGS level on dietary AME or AMEn in the XAP-supplemented diets. The AME of wheat-DDGS without and with supplemental XAP for turkeys were 3,355 and 3,558 kcal/kg DM, respectively, and AMEn was 3,109 and 3,294 kcal/kg DM, respectively, for wheat-DDGS without and with XAP. Supplemental XAP increased (P > 0.05) the AME and AMEn of wheat-DDGS for broilers and turkeys by up to 6%. It was concluded that wheat-DDGS is a valuable source of AME for broilers and turkeys.

Effects of dietary amino acid density and metabolizable energy level on the growth and meat yield of summer-reared broilers

The effects of dietary amino acid (AA) density and AME on the growth and meat yield of summer-reared Cobb × Cobb 700 (CCB-700) broilers were evaluated. In addition, the responses of CCB-700 and Cobb × Cobb 500 (CCB-500) broilers to dietary AME levels (with low AA) were compared. All chicks were fed through a starter, grower, finisher, and withdrawal phase program. Grow-out performance, carcass traits, meat yield, and feed cost efficiency were evaluated using 2 separate 2-way ANOVA based on 2 separate 2 × 2 factorial arrangements of treatments. Each group includes 14 replicate pens with 14 chicks/replicate. Mortality was not affected by treatment; however, as compared with birds fed other diets, feeding CCB-700 broilers a low-AME and high-AA density diet decreased feed intake and BW on d 35, 42, and 54, and decreased carcass, breast, wing, front half, and back half weights on d 55. The CCB-500 broilers consumed more feed and gained more weight as compared with CCB-700 broilers at 14, 28, and 35 d of age. However, at 55 d of age, breast weight and wing yield were observed to be higher in the CCB-700 than in the CCB-500 broilers. However, the back half (drumstick and thigh) weights were lower in the CCB-700 than in the CCB-500 broilers. In conclusion, without affecting feed costs, broiler performance and carcass yield were affected by diet in both strains. More specifically, a higher AME diet and lower AA density increased the yield of all cut-up parts, except for legs, in summer-reared CCB-700 chicks.

The effect of lipid saturation on nutrient digestibility of layer diets

A study was conducted to investigate the effect of dietary lipid saturation on nutrient digestibility of layer diets. Five isoenergetic (12.6 MJ AME/kg DM) and isonitrogenous (170 g CP/kg DM) diets were formulated using different lipid sources at a constant 30 g/kg inclusion level. The control n-3 diet was formulated using a blend (50 : 50) of linseed- and fish oil, while fish oil (polyunsaturated n-3), sunflower oil (polyunsaturated n-6), high oleic acid (HO) sunflower oil (monounsaturated n-9) and tallow (saturated fatty acid) were used as other supplementary lipid sources. The five dietary treatments were randomly allocated to the two hundred (200) individually caged Hy-Line Silver-Brown laying hens (20 weeks of age) (n = 40/treatment). Experimental diets were provided to the birds on an ad libitum basis for a 22 week period (from 20 to 42 weeks of age). At 42 weeks of age, six hens per treatment (n = 6 replicates/treatment), were randomly selected to partake in a digestibility study over a 7 day period using the total collection technique. The polyunsaturated n-6 treatment resulted in the lowest crude protein digestibility, whereas the saturated fatty acid treatment resulted in the lowest fat digestibility. Furthermore, the polyunsaturated n-3 diet resulted in the highest dietary AME (13.29 MJ/kg DM) and AMEn (12.74 MJ/kg DM) content.

Effects of exogenous enzymes and dietary energy on performance and digestive physiology of broilers

The study was conducted to compare the effects of XG with AG and BM at different metabolizable energy diets on growth performance, digestive physiology and energy utilization of broilers fed with corn-SBM diet. A 2 × 4 factorial design was used with two basal diets (the positive control group, PC; negative control with ME reduction 100 kcal/kg, NC) and with or without the addition of three exogenous enzymes (0.02% BM; 0.01% AG; 0.05% XG) respectively. 1,200 one-day-old broilers were randomly allocated to 8 treatments with 10 pens of 15 broilers. There was no significant difference on BW, BWG, and FI at 0-21d, 21-42d or 0-42d for diet, enzymes or their interactions, but FI at 22-42d and 0-42d were tend to be decreased with the addition of enzymes. The F/G was significantly improved by the addition of enzymes especially in NC diet. The dietary AME and TME in PC or NC diet were significantly increased by XG or AG in NC diet. The villus length and V/C of ileum were significantly increased by the addition of BM or XG. XG improved the activities of trypsin, chymotrypsin and amylase, BM improved the activity of trypsin at 21d, and AG improved the activity of chymotrypsin at 21d. Comparing to PC diet, the addition of enzymes in PC or NC diet decreased feed cost per kg body weight gain especially in NC diet (except AG in PC diet) with the highest profits for XG in NC diet. In conclusion, supplementation of 0.02% BM or 0.01% AG or 0.05% XG could improve feed conversion of broilers in corn-soybean meal diet by improving energy utilization and digestive physiology, and also supplementation of 0.05% XG had a preferable efficacy in low energy diet.

Effects of a mono-component endo-xylanase supplementation on the nutritive value of wheat-based broiler diets

1. Two trials were conducted to evaluate the effects of a mono-component thermostable endo-1,4-β-xylanase derived from Thermomyces lanuginosus on the nutritive value of wheat-based broiler diets. In a 5-week growth trial, the efficacy of xylanase supplementation at 0, 100, 150, 200, 400 and 4000 FXU/kg diet was evaluated. A short-term balance trial was carried out according to a 4 × 2 factorial arrangement of treatments, involving 4 wheat cultivars and endo-xylanase at 0 or 200 FXU/kg. 2. In the growth trial, enzyme supplementation from 0 to 400 FXU/kg reduced feed intake and improved feed conversion linearly. Digesta viscosity was significantly reduced by all enzyme inclusion levels by 49·6–56·9%, in a quadratic manner. 3. In the balance trial, xylanase supplementation resulted in a significant improvement of protein, lipid and dry matter apparent digestibility coefficients of diets, accompanied by improved dietary AME N values. There was a significant wheat × enzyme interaction on AME N and lipid digestibility. There was a significant effect of wheat cultivar on dry matter digestibility.

Effects of xylanase supplementation on performance, total volatile fatty acids and selected bacterial population in caeca, metabolic indices and peptide YY concentrations in serum of broiler chickens fed energy restricted maize–soybean based diets

The effects of xylanase supplementation on production performance, carcass traits, caecal volatile fatty acid and peptide YY concentration in serum of broiler chickens fed maize–soybean based diets were tested in a 42d experiment. Dietary metabolizable energy (AME, N uncorrected) was decreased in the experimental diets by 0 (E1), 230 (E2) and 420kJ/kg (E3). Each of these diets was supplemented with 0 (X1) or 16,000units/kg (X2) of a commercial xylanase. The objective was to ascertain if the xylanase could spare dietary energy for growth through its effects on peptide YY concentration in blood. Reduction of dietary AME depressed body weight gain (P=0.014), deteriorated feed conversion ratio (P=0.018) and decreased carcass yield (P=0.0001) over 42d. Irrespective of the level of supplemental xylanase, breast meat yield was the poorest in the E2 groups (P=0.003). Supplementation of xylanase had no effect on body weight gain, feed consumption, feed conversion ratio (feed consumption: body weight gain) and carcass traits (P>0.05). Low energy diets increased total volatile fatty acids (VFA) in caeca (P=0.0001). Xylanase supplementation tended to decrease caecal VFA irrespective of dietary AME (P=0.07). Increasing dietary AME reduced Salmonella (P=0.018) and Escherichia coli (P=0.019) and increased Enterobacteriaceae (P=0.012) populations in caeca. Reduction in dietary AME decreased glucose (P=0.0001) and cholesterol (P=0.012) in serum, particularly in the E3 groups. Serum glucose increased due to xylanase supplementation in the E1 and E3 groups but not in the E2 group (energy×xylanase P=0.0001). Supplementation of xylanase to the E2 groups decreased serum cholesterol as compared with the E1 and E3 groups (energy×xylanase P=0.002). On the other hand, xylanase supplementation decreased serum concentrations of protein in the E1 and E2 groups (energy×xylanase P=0.0001) and uric acid in the E2 and E3 groups (energy×xylanase P=0.006). Serum insulin reached a maximum (P=0.0001) in the E2 group irrespective of xylanase supplementation and added xylanase increased serum insulin (P=0.0001) at all dietary AME levels. There was an interaction between dietary AME and supplemental xylanase on serum peptide YY concentration (P=0.0001) which suggested that the xylanase induced increase in the serum peptide YY concentration was dependent on dietary energy density. It was concluded from the present investigation that supplementation of xylanase to a maize–soybean based diet of broiler chickens may consistently increase serum peptide YY concentration and improve metabolic indices like serum insulin levels. However, the results also indicated that with maize–soybean based diet, such positive effects on metabolic indices may not translate into performance if the diet is compromised with energy by 230kJ/kg or more.

Effects of nonantibiotic feed additives on performance, nutrient retention, gut pH, and intestinal morphology of broilers fed different levels of energy

SUMMARY An experiment was conducted to determine the effects of different feed additives on performance, nutrient retention, gut pH, and intestinal morphology of broilers fed different levels of energy. This study was a 4 × 2 factorial arrangement of 4 feed additive programs (a basal diet without any feed additive as the control, the basal diet with added organic acid, the basal diet with added prebiotic, and the basal diet with added probiotic) with recommended levels (3,150 and 3,200 kcal of ME/kg of diet for the starter and finisher diets, respectively) or low levels (90% of recommended) of energy. A total of 640 one-day-old male and female broiler chicks were randomly assigned to 8 treatments. Each treatment consisted of 4 replicate floor pens of 20 birds each. Starter and finisher diets were fed from 1 to 21 d and 21 to 42 d of age, respectively. Dietary levels of other nutrients, housing, and general management practices were similar for all treatments. Dietary inclusion of additives had no significant effects on broiler performance, intestinal villus height, crypt depth, gut pH, and dietary AME. Birds fed the low-energy diets were heavier but had inferior FCR compared with those fed the recommended-energy diets. Prebiotic and organic acid significantly (P < 0.05) improved protein digestibility. The recommended-energy diets significantly (P < 0.05) increased AME and protein digestibility. No interactions were observed for the measured parameters.

Effects of Dietary Energy on Growth Performance and Carcass Quality of White Growing Pekin Ducks from Two to Six Weeks of Age

A dose-response experiment with 6 dietary energy levels (2,600, 2,700, 2,800, 2,900, 3,000, 3,100 kcal of AME /kg) was conducted to study the effects of dietary energy on growth performance and carcass quality of White Pekin ducks from 2 to 6 wk of age. Six hundred 14-d-old White Pekin ducks were randomly divided to 6 dietary treatments, each containing 5 replicate pens with 10 males and 10 females per pen, and these birds were raised until 6 wk of age. At 42 d of age, weight gain, feed intake, and feed:gain of ducks from each pen were measured, and 2 ducks (1 male and 1 female) selected randomly from each pen were slaughtered to evaluate the yields of abdominal fat, breast meat (including pectoralis major and pectoralis minor), and leg meat (including thigh and drumstick). As dietary energy increased from 2,600 to 3,100 kcal of AME/kg, the weight gain of ducks increased significantly, and the feed intake and feed:gain decreased significantly. According to the broken-line regression analysis, the AME requirements of White Pekin ducks from 2 to 6 wk of age for optimal weight gain and feed:gain were 3,008 and 3,030 kcal/kg, respectively, when dietary protein was 18%. On the other hand, high dietary energy did not affect breast and leg meat (P> 0.05), but abdominal fat increased (P< 0.05) when dietary AME was above 2,700 kcal/kg.

Dietary Apparent Metabolizable Energy and Amino Acid Density Effects on Growth and Carcass Traits of Heavy Broilers

Two experiments (EXP) were conducted to evaluate the interactive effects of dietary AME and amino acid (AA) density (total basis) on broiler chickens from 42 to 56 d of age. In EXP 1, diets were formulated to contain low AME (3,140 kcal/kg) and moderate AME (3,240 kcal/kg) in combination with moderate AA (16.2% CP, 0.88% Lys, and 0.75% TSAA) and high AA (18.0% CP, 0.98% Lys, and 0.83% TSAA) and fed to male broilers. Dietary treatments in EXP 2 were diets formulated to contain moderate AME (3,220 kcal/kg) and high AME (3,310 kcal/kg) combined with moderate and high AA concentrations used in EXP 1 and fed to male and female broilers. In general, dietary AME and AA did not interact to influence growth and meat yield responses. Broilers provided the low AME diet in EXP 1 consumed more feed and had poorer feed conversion but had higher total breast meat yield than birds fed the moderate AME diet. In EXP 2, broilers fed the high AME diet from 42 to 56 d had increased BW gain, decreased feed consumption, and improved feed conversion. Feeding the high AA diets in both EXP decreased feed consumption, improved feed conversion, and increased total breast meat yield. Nutritionists establishing nutritional programs for heavy broilers late in development from 2.5 to 3.6 kg may need to consider increasing AA density to optimize breast meat yield. Increasing the AME content of the diet improves feed conversion but not breast meat yield.

Apparent Metabolizable Energy Needs of Broilers from Two to Four Kilograms as Influenced by Ambient Temperature

During winter production, the optimum temperature set points for heavy broilers (>3.4 kg) approaching market weight are subject to debate in commercial practice. Apparent ME needed to optimize nutrient utilization may be influenced by ambient temperature. This experiment examined potential interactive effects of AME × ambient temperature from 36 to 60 d of age. A 4 × 2 factorial arrangement of treatments was used. Dietary treatments were diets formulated to 3,175, 3,220, 3,265, and 3,310 kcal of AME/kg. Two temperature regimens were provided consisting of variable temperature regimen (VTR) or constant temperature regimen (CTR) set points. The VRT was 21.1°C from 36 to 38 d of age, 20.2°C from 39 to 42 d of age, 18.9°C from 43 to 46 d of age, 17.8°C from 47 to 50 d of age, 15.6°C from 51 to 54 d of age, and 12.8°C from 55 to 60 d of age. The CTR was 21.1°C from 36 to 60 d of age. Significant AME × temperature interactions were observed for cumulative BW, BW gain, feed consumption, feed conversion, and mortality. In the CTR, increasing AME led to increased BW gain but not in the VTR. As dietary AME increased, the improvement in feed conversion was more pronounced in the CTR than the VTR. With the VTR, decreasing AME increased feed consumption. The experimental treatments did not influence abdominal fat percentage or total breast meat yield. These data provide evidence that broilers exposed to CTR respond to increased AME.

Diets Containing Escherichia coli-Derived Phytase on Young Chickens and Turkeys: Effects on Performance, Metabolizable Energy, Endogenous Secretions, and Intestinal Morphology

The aim of this experiment was to compare the responses of young broiler chickens directly with the responses of turkeys to different dietary phytase concentrations. Nine hundred sixty birds (480 female Ross 308 broilers, and 480 female BUT6 turkeys) were reared in 64 floor pens from 0 to 21 d of age. Each species was fed a nutritionally complete (12.79 MJ/kg of AME, 231 g/kg of CP vs. 11.75 MJ/kg of AME, 285 g/kg of CP for chickens and turkeys, respectively), low-P (28 and 37 g/kg available P for chickens and turkeys, respectively) corn (maize)-soy feed supplemented with either 0, 250, 500, or 2,500 phytase units (phytase/kg of feed) to give a total of 4 diets per species. The study was conducted in a split-plot design and each dietary treatment was replicated 8 times. Performance, AME, sialic acid (SA) excretions, and ileal villus morphology of 21-d-old broiler chickens and turkeys were determined. Overall, chickens grew faster and consumed more than turkeys throughout the study period. Dietary enzyme concentrations linearly increased the feed intake and weight gain of birds. The results were improved, on average, as follows: feed intake by 11.2 and 6.5%, gain by 10.2 and 13.2%, feed efficiency by 0 and 7.6%, AME by 1.4 and 5.7%, and AME intake by 13.1 and 9.8% for chickens and turkeys, respectively. The AME data were subject to a species × phytase interaction, whereby increasing the phytase dosage led to significant increments in parameters for turkeys but not broilers; broilers recovered significantly more energy from the ration than did turkeys. A quadratic relationship existed between dietary AME and phytase concentrations. Turkeys excreted more SA than did chickens in the absence of phytase, whereas supplementation with phytase (250 and 500 phytase units) reduced the excretion of SA in turkeys. Enzyme supplementation did not affect the ileal villus morphometry of the 2 species. We concluded that both species can tolerate phytase concentrations much higher than 1,000 phytase units and that these concentrations have further beneficial effects compared with lower phytase concentrations. The work reported here supports the hypothesis that supplementing turkey diets with phytase will need to be considered independently of chicken diets, considering the components in the diets, such that optimal responses can be obtained.

The Effect of a Commercial Enzyme Preparation on Apparent Metabolizable Energy, the True Ileal Amino Acid Digestibility, and Endogenous Ileal Lysine Losses in Broiler Chickens

The effect of a commercial enzyme preparation containing xylanase, α-amylase, and β-glucanase on dietary AME content and the apparent and true ileal amino acid digestibility of a corn-soy broiler diet and endogenous ileal lysine flow was determined. Two predominantly corn-soy diets also containing wheat bran and canola meal were formulated; one diet contained no added enzymes, whereas the other was supplemented with α-amylase, β-glucanase, and xylanase. Titanium dioxide was included as an indigestible marker. The diets were given to broiler chickens, and AME and true ileal amino acid digestibility were determined. Portions of the 2 test diets were guanidinated and fed to similar aged broiler chickens and endogenous lysine flows determined. The chickens appeared healthy throughout the study, and the mean bird weights at the time of slaughter were not significantly different (P < 0.05) among any of the treatment groups. Dietary AME content was significantly (P < 0.05) higher for the enzyme-supplemented corn-soy diet (2,829 kcal/kg) compared with its unsupplemented control diet (2,766 kcal/kg). True ileal amino acid digestibility was significantly (P < 0.05) higher for all amino acids investigated. The increase ranged from 4% for arginine and glutamic acid to 12% for cystine. There was no significant difference in endogenous ileal lysine flow between broilers fed the unsupplemented diet and those fed the enzyme-supplemented diet. Overall, enzyme supplementation with an enzyme blend containing α-amylase, β-glucanase, and xylanase increased the AME content of a corn-soy broiler diet as well as apparent and true ileal amino acid digestibility for all amino acids, but had no effect on endogenous ileal lysine flow.

Growth Performance, Meat Yield, and Economic Responses of Broilers Fed Diets Varying in Metabolizable Energy from Thirty to Fifty-Nine Days of Age

Two studies examined responses of broilers to diets varying in AME from 30 to 59 d of age. A 59-d termination allows for evaluation of energy needs applicable to “big bird” programs, because research on nutritional needs for such programs is warranted. Two experiments were conducted: experiment (exp.) 1 having low temperatures whereas exp. 2 used moderate temperatures. The treatments in exp. 1 and 2 were AME concentrations ranging from 3,175 to 3,310 kcal/kg with CP, TSAA, and Lys being identical across all treatments. In exp. 2, an additional treatment consisted of a diet containing 3,310 kcal of AME/kg with CP, TSAA, and Lys being increased by 4% of those specifications used in the other treatments so as to minimize differences in energy:CP ratio.In both experiments, feed consumption and conversion decreased linearly as dietary AME increased, but breast meat yield was reduced with the high AME diet and only increasing amino acids in exp. 2 ameliorated the negative effect. Live production costs and gross feeding margin (bird return over feed costs) were optimized in exp. 1 with 3,220 kcal of AME/kg of diet, but 3,310 kcal of AME/kg of diet and increased amino acids were needed in exp. 2 for improved monetary returns. In both experiments, broilers had similar caloric consumption indicating that these broilers can compensate to varying dietary AME concentrations within practical limits. These results demonstrated that the response to dietary AME was more pronounced under moderate ambient temperatures.