Effects of dietary phytase on performance and nutrient metabolism in chickens

1. A broiler growth study was conducted to compare the effect of different concentrations of an Escherichia coli-derived phytase on performance, apparent metabolisable energy (AME), nitrogen (N), amino acid and mineral metabolisability, sialic acid excretion and villus morphology when fed to broiler chickens. 2. Female Ross 308 broilers (480) were reared in floor pens from 0 to 28 d of age. All birds were fed on nutritionally complete starter (0 to 21 d of age) and grower diets (21 to 28 d of age) with the exception that they were low in P (28 and 23 g/kg available P, respectively). These maize-soy diets were supplemented with 0, 250, 500 or 2500 phytase units (FTU)/kg feed. 3. Between 21 and 28 d of age, two birds from each floor pen were selected, and each pair placed in one of 32 metabolism cages (two birds per cage). Feed intake was recorded and excreta collected for the last 2 d of the feeding period, and AME, N, amino acid and mineral metabolisability coefficients and endogenous losses were determined following a total collection procedure. 4. Feed intake and weight gain increased in a linear manner in response to phytase dose, with an average increase of approximately 11.7 and 13.5%, respectively, compared with chickens fed on the low-P diet. Birds given diets with 2500 FTU weighed 6.6% more and had a 2.4% higher feed conversion efficiency (FCE) than those fed on diets containing 500 FTU. 5. Enzyme supplementation increased the intake of AME and metabolisable N by 10.3 and 3.9%, respectively, principally through increases in feed intake. Birds given enzyme-supplemented diets also improved their intake of metabolisable amino acids and P by approximately 14 and 12.4%, respectively, compared with birds fed on the control diet. Enzyme supplementation did not affect ileal villus morphometry of the birds.     

The effects of supplementary bacterial phytase on dietary energy and total tract amino acid digestibility when fed to young chickens

1. Four diets were offered to broiler chickens from 7 to 17 d of age; these included a phosphorus-adequate positive control (PC) (4·7 g/kg available P), a sub-optimal P negative control (NC, 2·5 g/kg available P) with (500 and 12500 FTU/kg) and without phytase. Dietary apparent metabolisable energy (AME), dietary net energy for production (NEp), the efficiency of AME retention (Kre), heat production and total tract amino acid digestibility coefficients were determined. The determination of NEp involved a comparative slaughter technique in which growing chickens were fed the experimental diets ad libitum. 2. Feed intake, weight gain and feed conversion efficiency increased significantly in a dose dependent manner in response to dietary phytase activity. Overall, the NEp of the phytase supplemented diets significantly improved by approximately 15·6% compared with the negative control, while dietary AME was unaffected. Although phytase did not affect AME, the large increase in the NEp demonstrated that dietary phytases improves energy utilisation, i.e. diverting more energy, not accounted for in the AME procedure, for production. This is largely a result of the stimulatory effect that phytase has on feed intake rather than on digestibility of the diet. 3. Overall, the diet supplemented with 12500 FTU had 6·4% significant improvement in total tract digestibility coefficients of the total amino acids compared with the negative control. With regard to individual amino acids, the impact of phytase was far more pronounced for threonine, an important component of the gastrointestinal mucin, than for other amino acids. 4. Dietary NEp was more highly correlated with performance criteria than dietary AME and seems to be a more sensitive way to evaluate broiler response to phytase supplementation.     

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.     

Organic acids in diets for entire male pigs

The aim of this study was to investigate the effect of organic acids in diets for entire male pigs on growth performance, composition of microbiota in the gastrointestinal tract (GIT), on concentration of skatole and indole in digesta, plasma and adipose tissue, and concentration of volatile fatty acids (VFA) in digesta. Restrictively-fed pigs (n = 60) (28 and 113 kg initial and final BW, respectively) were used. The dietary treatments consisted of a basal diet and the basal diet added either 1.0% formic acid, 0.85% benzoic acid, 0.85% sorbic acid, 1.2% fat coated Ca-butyrate or 1.5% fat and inulin coated Ca-butyrate. All levels of organic acids corresponded to 0.85% of pure acid. Digesta samples for microbiological examinations were taken from the proximal jejunum, colon descendens, and rectum. Digesta samples for skatole, indole and VFA analyses were taken from colon descendens. The results showed that the addition of organic acids to diets had no effect on daily weight gain or feed intake, but formic, benzoic and sorbic acid tended to improve FCR of pigs compared with the control pigs. Organic acid supplementation did not affect levels of skatole, indole, or VFA in the digesta or levels of skatole or indole in adipose tissue compared with the control. Plasma skatole levels were reduced in pigs fed diets containing formic and benzoic acid compared with the control pigs. Pigs fed organic acids had lower levels of coliforms, enterococci and lactic acid producing bacteria in all three sampling sites of the GIT. Supplementing diets with organic acids did not affect levels of skatole in digesta or adipose tissue of entire male pigs.     

The effect of organic acids on the control of porcine post-weaning diarrhoea

Post-weaning diarrhoea syndrome (PWDS) of piglets is caused mainly by Enterotoxigenic Escherichia coli (ETEC) strains. Six organic acids were tested for their efficacy in the control of PWDS, using a total of 384 weaned piglets, in eight groups, during a 28-day period. One group (negative control) was offered a diet free of antimicrobials, one group (positive control) was offered the same diet medicated with 44 p.p.m. of lincomycin and 44 p.p.m. spectinomycin (Lincospectin 22 premix, Upjohn), and six groups were offered feed supplemented with either 1.0 per cent propionic acid, 1.6 per cent lactic acid, 1.2 per cent formic acid, 1.2 per cent malic acid, 1.5 per cent citric acid or 1.5 per cent fumaric acid. Groups were compared with regard to the appearance of clinical signs, mortality, weight gain and feed conversion. All groups supplemented with organic acids had reduced incidence and severity of diarrhoea, and performed significantly better than the negative control group (P<0.05). At the end of the trial, ETEC strains were detected in the control group not receiving antibiotics but not in the treated group. Organic acids and especially lactic acid are a useful tool in controlling PWDS.     

The effect of herbs and their associated essential oils on performance, dietary digestibility and gut microflora in chickens from 7 to 28 days of age

1. The effect of the dietary inclusion of 5 culinary herbs or their essential oils on the growth, digestibility and intestinal microflora status in female broiler chicks was assessed. From 7 to 28 d of age, either a basal control diet without supplement was given or one of 10 others, consisting of the basal diet with either 10 g/kg herb (thyme, oregano, marjoram, rosemary or yarrow) or 1 g/kg of essential oil. 2. Body mass (BM) and feed consumption (AFC) were measured on a weekly basis and used to calculate chick performance. Total viable counts of lactic acid bacteria, coliforms, anaerobes and Clostridium perfringens were determined at 25 d. Apparent nutrient digestibilities were calculated from the measured values for gross energy, nitrogen (N), dry matter (DM) and organic matter, and sialic acid concentration was also measured. 3. Generally, dietary thyme oil or yarrow herb inclusion had the most positive effects on chick performance, while oregano herb and yarrow oil were the poorest supplements. Only thyme and yarrow in these diets had a different effect when used as a herb or oil on weight gain and BM. 4. Dietary treatment had no effect on the intestinal microflora populations, apparent metabolisable energy (AME) or the calculated coefficients of digestibility. Sialic acid concentration was greatest in the birds given dietary thyme oil, compared with all other treatments except those birds receiving marjoram oil, rosemary herb and the controls. However, less sialic acid was excreted in those birds given diets with oregano or rosemary oils, or oregano herb, than in the controls. 5. Plant extracts in diets may therefore affect chick performance, gut health and endogenous secretions, although the chemical composition of the extract appears to be important in obtaining the optimal effects.     

Effects of dietary supplementation with vitamin C or vitamin E on cardiac lipid peroxidation and growth performance in broilers at risk of developing ascites syndrome

OBJECTIVE: To assess effects of high dietary amounts of vitamin C or vitamin E and oxidative stress on the heart and growth performance of broilers maintained at an altitude of 2,200 m above sea level. ANIMALS: 360 chicks (1-day-old broilers). PROCEDURE: Birds were randomly assigned to 3 groups (120 chicks/group). Each group of birds was fed a specific diet (control group, basal diet containing 12 mg of vitamin E (DL-alpha-tocopherol acetate)/kg of feed without additional ascorbic acid; vitamin E group, basal diet supplemented with 75 mg of vitamin E/kg of feed; and vitamin C group, basal diet supplemented with 400 mg of ascorbic acid/kg of feed) throughout the entire 7 weeks of the study. Feed consumption and body weight of chicks were recorded on a weekly basis. Nine randomly selected birds from each group were euthanatized each week. Remaining birds were euthanatized at the end of the study. Samples of cardiac tissues were obtained to measure thiobarbituric acid reactive substances (TBARS), an indicator of oxidative stress. RESULTS: Vitamin E-supplemented diets resulted in better growth performance, lower rates of feed conversion, and lower TBARS content. Vitamin C-supplemented diets resulted in lower feed consumption and lower rates of feed conversion. When used separately, neither of the vitamins had any effect on mortality attributable to ascites syndrome. CONCLUSION AND CLINICAL RELEVANCE: It is recommended that diets supplemented with vitamin C, vitamin E, or both be fed to broilers maintained at an altitude of 2,200 m above sea level to improve growth performance.     

Organic acids in diets for entire male pigs: Effect on skatole level, microbiota in digesta, and growth performance

The effect of different organic acids in diets of entire male pigs on the concentration of skatole in colon, plasma, and adipose tissue and on the composition of the microbiota in the gastrointestinal tract was evaluated. Entire male pigs (n = 60) of sows inseminated with boars disposition for high skatole levels (31.7 and 113.2 kg initial and final body weight, respectively) were fed either control, 1.0% formic acid, 0.85 % benzoic acid, 0.85% sorbic acid, 1.2% fat coated Ca-butyrate, or 1.5% fat and inulin coated Ca-butyrate diets. All levels of organic acids corresponded to 0.85% of pure acid. Digesta samples from colon descendens were analyzed for skatole, indole, and organic acids. Digesta samples for microbiological examinations were taken from proximal jejunum, colon descendens, and rectum. There were no differences in levels of skatole, indole, or organic acid levels in colon descendens among pigs fed organic acid supplemented diets and control diet. Plasma skatole levels were significantly reduced in pigs fed diets containing formic acid or benzoic acid compared with the control, but supplementing diets with organic acids did not affect skatole levels in adipose tissue. Pigs fed organic acids had significantly lower levels of coliforms, enterococci, and lactic acid producing bacteria (LAB) in all sampling sites of the gastro-intestinal tract. Pigs fed 1.5% fat and inulin coated Ca-butyrate had less reduction in the number of coliforms and LAB in the small intestine compared with pigs fed formic, benzoic and sorbic acid. Formic acid had a stronger antibacterial effect on coliforms than benzoic or sorbic acids in the small intestine. Pigs fed diets containing formic acid, benzoic acid, or sorbic acid had significantly higher average daily gain and better feed conversion ratio (FCR) than the control pigs during the grower phase, and tended to improve FCR during the overall period. The inclusion of fat coated Ca-butyrate or fat and inulin coated Ca-butyrate had no effect on growth performance of the pigs. In conclusion, supplementing diets with different organic acids reduced number of coliforms, enterococci, and LAB in the gastrointestinal tract, but did not affect skatole levels in colon or adipose tissue of entire male pigs.     

The effect of supplementary bacterial phytase on dietary metabolisable energy, nutrient retention and endogenous losses in precision fed broiler chickens

Thirty-two Ross 308 male broiler chickens were used in a precision feeding assay to investigate the effect of exogenous phytase (EC 3.1.3.26) on dietary apparent metabolisable energy (AME), dry matter digestibility (DMD) coefficient, nitrogen (NR), amino acid and mineral retentions. The excretion of endogenous losses measured as sialic acid (SA) was also determined. Four dietary treatments (control (C), C + 250 FTU (phytase units per kg feed), C + 500 FTU, and C + 2500 FTU) were studied with each treatment replicated eight times in randomised complete block design. Diets were formulated to be nutritionally adequate with the exception of available P content (2.3 g/kg non-phytate P). Over the 48-h collection period, the phytase fed birds retained 29.3 mg more Na and 2.3 mg more Zn (p < 0.05) than the control fed birds, with the relationship between phytase dose and Na and Zn retention being best described by a linear function (p < 0.05 and p < 0.001, for Na and Zn, respectively). Phytase supplementation did not have an effect on dietary AME, DMD and NR. However, increasing the dose of phytase led to a linear increase in dietary amino acid retention (p < 0.05). Dietary phytase decreased total sialic acid excretion in a linear fashion (p < 0.05). It can be concluded that supplementary phytase increases the retention (reduces the excretion) of dietary Zn and Na in broiler chickens. The beneficial effects of the addition of exogenous phytases to poultry diets seems to be mediated through improved dietary nutrients absorption and reduced endogenous losses.     

The influence of phytase,pre-pellet cracked maize and dietary crude protein level on broiler performance via response surface methodology

Background: The reduction of crude protein levels in diets for broiler chickens may generate economic,environmental and flock welfare and health benefits; however, performance is usually compromised. Whole grain feeding and phytase may improve the utilization of reduced crude protein diets.Results: The effects of pre-pellet cracked maize(0, 15% and 30%) and phytase(0, 750 and 1500 FTU/kg) in isoenergetic maize-soy diets with three levels of crude protein(22%, 19.5% and 17%) were evaluated via a BoxBehnken response surface design. Each of 13 dietary treatments were offered to 6 replicate cages(6 birds/cage) of male Ross 308 broiler chicks from 7 to 28 d post-hatch. Model prediction and response surface plots were generated from experimental data via polynomial regression in R and only significant coefficients were included and discussed in the predicted models. Weight gain, feed intake and FCR were all influenced by pre-pellet cracked maize, phytase and crude protein level, where crude protein level had the greatest influence. Consequently, the reduction from 22% to 17% dietary crude protein in non-supplemented diets reduced weight gain, feed intake,relative gizzard weight, relative gizzard content and relative pancreas weight but improved FCR. However, the inclusion of 30% cracked maize to 17% crude protein diets restored gizzard weight and 1500 FTU phytase inclusion to 17% crude protein diets increased relative gizzard contents and pancreas weights. Cracked maize and phytase inclusion in tandem to 17% crude protein diets increased weight gain, feed intake and FCR; however, this FCR was still more efficient than broilers offered the non-supplemented 22% crude protein diet. Broilers offered the prepellet cracked maize and phytase inclusions reduced AME in 22% crude protein diets but improved AME by 2.92 MJ(14.16 versus 11.24 MJ; P 0.001) in diets containing 17% crude protein. Ileal N digestibility was greater in broilers offered diets with 17% crude protein than those offered the 22% crude protein diet; irrespective of phytase and pre-pellet cracked maize.Conclusion: Pre-pellet cracked maize and phytase inclusions will improve the performance of broilers offered reduced crude protein diets.     

Production and carcase traits in broiler chickens given diets supplemented with inorganic trivalent chromium and an organic acid blend

1. The study was conducted to ascertain the effects of supplemental organic acids and chromium (Cr) on production and carcase traits of broiler chickens. 2. A total of 120 1-d-old broiler chicks were divided into 4 treatment groups in a 2 x 2 factorial design (each treatment group contained 6 replicates with 5 birds per replicate). 3. The diets were supplemented with an organic acid blend containing ortho-phosphoric, formic and propionic acid and calcium propionate (1 g/kg diet) and inorganic trivalent chromium (Cr(3+)) as chromic chloride hexahydrate (0.5 mg/kg diet) either independently or together as a combination for 35 d. 4. Individual supplementation of organic acids and Cr(3+) and their combination significantly improved the food conversion ratio, hot and dressed carcase weight and weight of the wholesale cuts compared to the control group of birds. 5. Organic acids, either independently or along with Cr(3+), increased total accretion of ash in carcase. Protein accretion was improved by dietary Cr(3+) and organic acid supplementation compared to the control group and a further improvement in this regard was observed when Cr(3+) and organic acid were supplemented together. Across the treatment groups meat fat content and fat accretion were lower in birds receiving dietary Cr(3+) supplementation. 6. Circulatory Cr(3+) and meat Cr(3+) concentration increased compared to the other treatment groups when Cr(3+) was supplemented to the birds. 7. It was concluded that, instead of individual supplementation, a combination of Cr(3+) and organic acids may improve the production and carcase traits of broilers more effectively presumably because of an additive effect.     

Effect of feeding different sources of selenium on growth performance and antioxidant status of broilers

ABSTRACT

1. This study was conducted to determine the effect of different sources of selenium (Se) on breast and liver tissue deposition, apparent metabolisable energy (AME), growth performance and antioxidant status of broilers, measured as Se content in liver and breast tissues and glutathione peroxidase (GSH-Px) in blood, when used in 0–35 d broiler chicken diets.

2. A total of 200 male Ross 308 broilers were used in the feeding trial, which comprised two dietary phases, a starter from 0 to 21 d and finisher from 21 to 35 d of age. Four treatments with 10 replications each were used. A control diet (C) was formulated that was sufficient in protein and energy (230 and 215 g/kg of crude protein and 12.67 and 13.11 MJ/kg of metabolisable energy, respectively), for both phases, but contained background Se only from the feed ingredients. Diet 2 (IS) was supplemented with 10.35 g/t inorganic, elemental source of Se. Diet 3 (SY) was supplemented with 136.36 g/t selenised yeast, an organic source derived from Saccharomyces cerevisiae. Diet 4 (SS) was supplemented with 0.666 g/t sodium selenite, an inorganic source.

3. Birds fed the SY diet consumed less and weighed less than those fed IS or C (P < 0.05; 0–35 d of age), but there was no difference compared to birds fed SS diets. There were no differences in FCR or dietary AME between broilers fed different Se sources. All diets containing supplementary Se increased concentrations in the liver and breast muscle, and for GSH-Px levels in blood compared to birds fed the C diet (P < 0.001). Birds fed SY diets had greater Se levels in liver and breast tissues compared to birds fed any of the other diets (P < 0.001).

4. Diets supplemented with Se had variable effects on broiler growth performances and antioxidant status. Feeding Se from a yeast source has higher transfer into breast tissues. Feeding different sources and levels of Se to birds in a more challenging situation to induce oxidative stress may bring more conclusive results.     

Net energy,energy utilization,and nitrogen and energy balance affected by dietary pea supplementation in broilers

Pea starch consists predominantly of C-type of amylopectin chain which is more resistant to digestive enzymes than A-type of starch thus slowly digested in poultry. It was hypothesized that the presence of slowly digested pea starch in broiler diets will increase net energy and the efficiency of energy utilization in broilers. Two experiments were performed to investigate starch digestibility of pea at different incubation times (in vitro study) and the effect of dietary pea on heat increment and net energy in broilers using an open-circuit respiratory calorimetry system (in vivo study). One-day-old Ross 308 male broilers were fed a common starter crumble from d 1 to 10 and standard grower diets thereafter. At d 21, birds were transferred to the chambers each housing 2 birds. Each treatment was replicated 6 times with 2 identical runs of 3 replicates per treatment. A wheat-soybean meal-based diet was used as a control and the treatment diet contained 500 g of pea/kg pea. In vitro study showed that pellet processing increased (P < 0.001) starch digestibility, particularly at shorter times for wheat and a much larger response for pea. Birds offered the pea-based diet had lower (P = 0.002) feed intake, lower (P = 0.020) body weight gain, but a similar (P > 0.05) FCR compared to those offered the wheat-based diet. Net energy (NE) and apparent metabolizable energy (AME) values were higher in the pea-based diet than in the wheat-based diet (P = 0.037 for NE and P = 0.018 for AME). Heat production, respiratory quotient, heat increment of feed, efficiency of utilization of gross energy for AME, and efficiency of utilization of AME for NE did not differ (P > 0.05) between the 2 treatments. There was no effect (P > 0.05) of pea on the total tract digestibilities of dry matter, crude protein and ash, but the total tract digestibility of starch was higher (P = 0.022) in the pea-based diet compared to the wheat-based diet. This study provides insight into the energy metabolism of broilers offered a pea-based diet and indicates that dietary pea supplementation increases dietary AME and NE but has no effect on heat increment of feed and the efficiency of energy utilization in broilers.     

Effect of Phytase Supplementation in Diets on Nutrient Digestibility and Performance in Broiler Chicks

A performance trial was conducted with broiler chicks to study the effect of phytase (PHY) supplementation in diets formulated with reduced AME, Ca, and P. The nutrient digestibility was determined during the 14- to 21-d and 28- to 35-d periods. The treatments consisted of 3 diets (NC1, NC2, NC3) differing in nutrient content and each diet with or without supplemental PHY (NC1, 0 or 500; NC2, 0 or 750; NC3, 0 or 1,000 U of PHY/kg feed) and 1 positive control diet (PC). Compared with the PC diet, negative control diets (NC) resulted in lower AME and apparent ileal amino acid digestibility for some amino acids. Phytase supplementation of the NC diets increased AME, apparent ileal amino acid digestibility, and apparent ileal crude protein digestibility. Phytase addition also increased mineral absorption in 21- and 35-d-old broilers fed NC diets. Reduced nutrient digestibility appears to be a factor in the weight gain and feed intake results. Reducing Ca and P content reduced feed intake in a stepwise fashion in the NC diets. Phytase increased feed intake and generally improved nutrient digestibility, which resulted in an increase in digestible nutrient intake. Averaged across NC diets, PHY improved body weight. Bone-breaking strength was the most consistent predictor of Ca and P reduction. All NC diets had significantly lower bone-breaking strength than the PC. Phytase supplementation of the NC diets gave bone-breaking strengths that were comparable to the PC. Diets with PHY had the highest bioeconomic index.     

Effects of star anise (Illicium verum Hook.f.) essential oil on nutrient and energy utilization of laying hens

An experiment using 96 Hy‐Line brown laying hens at 29 weeks of age that were randomly allocated to four treatments with eight replicates was conducted to assess the effects of star anise (Illicium verum Hook.f.) oil (SAO) on nutrient and energy utilization. Dietary treatments were corn–soybean meal‐based diets supplemented with 0, 200, 400, and 600 mg/kg SAO. The birds were fed the diets for 14 days. The conventional nutrients and amino acids of feed and excreta samples were measured for calculating apparent metabolic efficiency, and gross energy (GE) was analyzed for computation of apparent metabolic energy (AME) and true metabolic energy (TME). Endogenous losses were obtained from another 16 birds for calculating true metabolic efficiency. Birds supplemented with SAO had higher (p < 0.05) metabolic efficiency of crude protein (CP), organic matter (OM), Lys, Met, Arg, and Thr than those of control group. Quadratic effects on utilization of Lys, Met, and Thr were observed (p < 0.05). Inclusion of SAO to diet improved nutrient utilization, and the efficacy is best at 400 mg/kg.     

Effect of dietary xylanase on energy, amino acid and mineral metabolism, and egg production and quality in laying hens

1. The aim was to examine the effect of dietary xylanase on the availability of nutrients for laying hens when fed on wheat-rye-soy-based diets. The basal diet was formulated to contain 11.03 MJ/kg apparent metabolisable energy (AME), and the experimental diets were formulated by supplementing the basal diet with four different activities of xylanase (400, 800, 1200 and 1600 xylanase units (XU)/kg). 2. The AME and nitrogen metabolisability coefficients of xylanase-supplemented diets were 1.2% and 7.1%, respectively, greater than in the control diet. 3. Supplementary xylanase significantly improved the coefficients of metabolisability of indispensable, dispensable and total amino acids by 8.2%, 6.9% and 7.8%, respectively, and led to a significantly linear response of total amino acid metabolisability coefficient to xylanase. There was a range of effects within the indispensable amino acids with xylanase supplementation (1600 XU/kg) significantly improving the metabolisability of threonine by 4.9%, but having no have effect on lysine. The response of total amino acid retention to added xylanase was a significant quadratic function and suggests that 800 XU/kg is the optimum supplementary dosage. 4. Supplementary xylanase significantly improved sulphur metabolisability in a linear fashion to a maximum of 2.3% higher than that of the control diet. In terms of daily retention, most of the minerals responded in a quadratic manner to dietary xylanase, as the suggested optimal supplementary level was between 800 and 1200 XU/kg. 5. The yolk colour of the birds receiving 1200 and 1600 XU/kg was 0.33 and 0.28 units (Roche score); these were 4.1% and 3.5%, respectively, darker than the yolk of the birds given the control diet. 6. Birds receiving xylanase had a significantly higher weight gain than those fed on the unsupplemented diet. Feed intake, the number of eggs per hen per d, dirty and cracked eggs, and feed conversion ratio for egg production were not affected by xylanase. These data suggest that use of a xylanase may improve the metabolisability of many nutrients, but that such effects may not always benefit production parameters.     

Effect of exogenous enzymes in maize-based diets varying in nutrient density for young broilers: growth performance and digestibility of energy, minerals and amino acids

1. A total of 192 male broilers (Cobb 500) were used in a growth and digestibility assay, involving a 2 x 2 factorial arrangement of treatments, to assess the effects of an enzyme cocktail of xylanase, amylase and protease in maize-based diets. 2. The following two diets were formulated: a positive control diet containing adequate nutrient concentrations for broiler starters as per breeder recommendations and a negative control diet to contain approximately 0.63 MJ/kg apparent metabolisable energy (AME) and 3% amino acids less than the positive control. 3. A further two dietary treatments were developed by supplementing each control diet with an enzyme product containing xylanase, amylase and protease. 4. Birds fed on the negative control diet had poorer weight gain and feed efficiency than those given the positive control diet. There was no effect of diet or enzyme on feed intake. The digestibility of nitrogen, calcium, phosphorus and most amino acids were unaffected by dietary nutrient density. 5. Supplementation of both the positive and negative control diets with the enzyme improved weight gain and feed efficiency compared with the unsupplemented diets. In the case of the negative control, supplemental enzyme improved performance to that of the unsupplemented positive control diet. There was no interaction between diet and enzyme for either weight gain or FCR, suggesting similar beneficial responses regardless of the nutrient density of the diet. 6. In both diets, enzyme supplementation improved AME by an average of 3% (0.35 MJ/kg DM) and nitrogen retention by an average of 11.7% (26 g/kg DM intake vs 29 g/kg DM intake). There was no interaction between diet and enzyme for AME or nitrogen retention. 7. Ileal digestibilities of calcium and phosphorus were not influenced by supplemental enzyme, whereas the digestibility of nitrogen and most amino acids was improved by enzyme addition compared with the unsupplemented control diets. There was no interaction between diet and enzyme for the ileal digestibility of nitrogen and amino acids. 8. These data demonstrate that it is possible to improve the nutritional value of a maize/soy-based diet for broiler starters through the use of exogenous enzymes. The nutrient density of the diet does not appear markedly to influence the response to enzyme, offering flexibility in the use of enzymes for maize-based diets. 9. It is concluded that the energy and amino acid values of maize-based diets for broilers can be enhanced by supplementation with an enzyme cocktail of xylanase, amylase and protease, offering potential economic benefits to producers.     

Effects of a multi-enzyme complex on growth performance,nutrient utilization and bone mineralization of meat duck

Background:Previous studies with broiler have shown dietary supplementation with multi-enzyme complex containing non-starch polysaccharides(NSP) degrading enzymes and phytase is efficient in releasing phosphorus(P),calcium(Ca),energy and amino acids from corn-soybean meal diets or corn-sorghum diets,hence compensating considerable levels of nutrients in formulation.Notwithstanding,such potentials have not been well defined in duck nutrition.Giving China being the largest duck producing country,we conducted this study to establish adequate specifications of major nutrients along with multi-enzyme complex to meat duck from day-old to slaughter,focusing on performance,utilization of nutrients and bone mineralization.Five dietary treatments were:Positive control(PC,T1):the nutrients concentration of diet for 1 to 14 d of age were apparent metabolizable energy(AME) 2,800 kcal/kg,crude protein(CP)19.39%,Ca 0.85%,available phosphorus(avP) 0.42%;for 15 to 35 d of age these parameters were AME2,900 kcal/kg,CP 16.47%,Ca 0.76%,avP 0.38%;Negative control 1(NC1,T2),the AME and digestible amino acids(DAA)were reduced by 70 kcal/kg and 2.0%,avP and Ca by 1.0 g/kg from PC diet;Negative control 2(NC2T4),the downspec from PC diet was AME 100 kcal/kg,DAA 2.5%,avP 1.5 g/kg and Ca 1.2 g/kg;The enzyme complex was added at the same dosage(200 ml7 1,000 kg) on NCI(T3) and NC2(T5) diets.Results:Comparing with the ducks fed on T1,T3 and T5 diets,the birds fed on NC2 diet showed the lowest(P 0.05)body weight(d 14 and 35),feed intake(d 35),tibia ash,Ca and P contents(d 14 and 35),and the utilization of nutrients(P 0.05).The supplementation with the enzyme complex to the NC diets restored growth rate,utilization of nutrients and bone mineralization to the level of the PC diet,and increased AME by 60 kcal/kg and117 kcal/kg,respectively for the NCI and NC2 diets.Conclusion:These results suggest that down-spec AME by 100 kcal/kg,DAA by 2.5%,avP by 1.5 g/kg and Ca by1.2 g/kg caused detrimental effects on duck performance compared with those fed on the PC diet,and these performance losses can be compensated by the addition of the multiple-enzyme complex.     

Effect of L-carnitine supplementation on utilisation of energy and protein in broiler chicken fed different dietary fat levels.

Effects of a supplementation of 80 mg L-carnitine per kg diet were studied in broiler chicken at two dietary levels of fat (4 and 8%) and different feeding levels (ad libitum in a growth trial, 95 and 85% of ad libitum in a balance trial). A low-carnitine basal diet adequate in amino acid concentration was used. In the growth trial, each diet was fed to 9 groups of 10 birds each for 16 days from day 5 of live onwards. Growth and feed intake were determined. At the end of the trial, birds were killed and homogenised for subsequent empty body analysis. Accretion of protein and energy was determined using a representative blank group killed at the beginning of the trial. In the balance trial, 8 individual birds were used per treatment. Birds were offered the feed at approximately 85 and 95% of ad libitum intake, which was determined with separate birds for both fat levels. Excreta were quantitatively collected three times daily for 8 consecutive days beginning on day 17 individually for each bird. Supplemented L-carnitine did not significantly affect any response criterion. However, growth and feed conversion tended to be improved by about 5% in the carnitine supplemented diets when fed ad libitum. An interaction between carnitine and fat level occurred with regard to feed conversion, indicating that carnitine had a positive effect at the high fat level, but not at the low fat level. L-carnitine did not positively affect the metabolisability of energy (ME/GE) and the efficiency of energy utilisation (RE/GE or RE/ME). Similarly, no significant carnitine effect was determined with regard to N accretion and the efficiency of utilisation of dietary protein in both trials. It is concluded that endogenous carnitine synthesis is not the limiting factor for energy utilisation in broiler chicken, even at high dietary fat concentration. Occasionally reported positive effects of supplemental carnitine were likewise caused by reasons other than improved energy or protein utilisation. Further studies on amino acid utilisation and catabolism should consider marginal amino acid supply.     

Response of starter pigs to supplementation of corn-soybean meal diets with organic acids

Four growth experiments were conducted to assess the effects of organic acid supplementation on performance of starter and finisher pigs. Three 4-wk starter experiments utilized 392 pigs fed simple corn-soybean meal diets. A fourth experiment employed 135 finisher pigs in a 6-wk study. Each of the starter experiments was initiated immediately after weaning; piglets were 30 +/- 3 d of age. In Exp. 1, weanling pigs fed a 19% crude protein, simple corn-soybean meal diet were compared with pigs fed similar diets supplemented with 2% propionic, fumaric, or citric acid. Addition of each acid improved (P less than .07) efficiency of gain, while propionate depressed (P less than .05) feed intake. Additions of 1, 2, 3 or 4% fumarate were made in Exp. 2, resulting in linear daily gain and feed efficiency improvements (P less than .05). In Exp. 3, a possible protein-sparing effect of fumaric acid was investigated. Increasing protein levels from 16 to 20% improved daily gain (P less than .01) and feed efficiency (P less than .0001); fumarate supplementation (2%) increased (P less than .01) gain:feed. However, there was no protein X fumaric acid interaction. In Exp. 4, no treatment effects were noted with performance of finisher pigs fed a 14% crude protein, corn-soybean meal diet was compared with that of pigs fed similar diets supplemented with 1.5 or 3% fumaric acid.