Search

1. An experiment was conducted to determine the effect of the source of fat (soybean oil or tallow) on the ileal endogenous amino acid (EAA) losses in broilers. 2. Three nitrogen (N)-free diets; a control diet with no added fat and test diets with 60 g/kg of either soybean oil or tallow were formulated. Titanium dioxide (5 g/kg) was added to all diets as an indigestible marker. Each diet was assigned to six replicate cages (eight birds per cage) from d 18 to 21 post-hatch. On d 21, the digesta were collected from the lower half of the ileum. 3. The endogenous losses of nitrogen and amino acids (AA) were lower (p = 0.08; p = 0.001) in broilers fed diets with soybean oil or tallow, respectively, compared to those fed the diet with no fat. Source of fat had no influence (p > 0.05) on EAA losses. 4. The most abundant AA in the ileal endogenous protein was glutamic acid, followed by aspartic acid, threonine, leucine, serine, valine and proline. In general, the concentrations of AA in the endogenous protein were lower (p < 0.05) with added fat. The exceptions were methionine, cysteine, proline and serine, which were unaffected. The effect of fat source on the AA contents of endogenous protein were inconsistent and differed depending on the AA. 5. The inclusion of fats decreased EAA losses which implied they have beneficial effects beyond direct energy contribution. It can be proposed that the reduction of EAA flow may be an additional mechanism contributing to the extra-caloric effect of dietary fats. [ABSTRACT FROM AUTHOR]

1. The proximate composition and, amino acid, fatty acid and mineral profiles of gallbladder bile of 35 d old broiler chickens were determined. 2. The dry matter (DM) content of the bile was determined to be 19.8 g/100 g. Fat, protein and ash contents in the bile were 24.9, 23.0 and 6.6 g/100 g DM, respectively. 3. The content of total fatty acids (FA) in the bile was determined to be 17.68 g/100 g DM. Unsaturated FA dominated the profile in the bile, with an unsaturated: saturated FA ratio of 1.36. Oleic, linoleic, and arachidonic acids were the main unsaturated FA, whereas palmitic and stearic acids were the major saturated FA. 4. A major finding was that the data established taurine as the primary amino acid in chicken bile and not glycine, as previously assumed. Taurine was the dominant amino acid, constituting 62% of bile protein. 5. Among the major minerals, sodium (2.56 g/100 g DM) was in the greatest concentration. The concentrations of other major minerals were relatively low. 6. The present work provided, for the first time, preliminary data on reference values for nutrients in the chicken gallbladder bile. [ABSTRACT FROM AUTHOR]

Two experiments were conducted to examine the effects of conditioning temperature (CT) and the interactive influence of feed acidification (FA) and CT on the performance, coefficient of apparent ileal digestibility (CAID) of nitrogen (N), starch, fat calcium (Ca) and phosphorus (P), and AME in broilers. In both experiments, each treatment was randomly allocated to 6 cages (8 birds per cage) and fed from 1 to 21 D posthatch. In experiment 1, the effect of CT was evaluated using a wheat-based diet at 3 CT: unconditioned, conditioned at 60)C or 90)C. All the diets by-passed the pellet press and collected in mash form. Birds fed the diet conditioned at 90)C consumed more (P, 0.05) feed and tended (P 5 0.087) to have higher feed per gain (F:G) than those fed the unconditioned diet but similar to those fed the diet conditioned at 60)C. A tendency was noted for CT to affect the CAID of N (P 5 0.071) and starch (P 5 0.093), with reduced digestibility values in the diet conditioned at 90)C. Conditioning at 90)C resulted in lower (P, 0.05) AME. In experiment 2, three inclusions of an acidifier (0.0, 7.0, and 10 g/kg) and 2 CT of 60)C and 90)C were evaluated in a 3 ! 2 factorial arrangement of treatments using pelleted diets. Neither the main effects nor the interaction between acidifier addition and CT was significant for weight gain, feed intake, and F:G. The FA increased (P,0.05) the CAID of N, fat, and P at both inclusion levels and of starch at 10 g/kg. Conditioning at 90)C reduced (P, 0.05) the CAID of starch, fat, and Ca, regardless of FA level. Overall, the present data showed that the application of high CT for broiler feed manufacture can impair nutrient utilization and, consequently the feed efficiency in broilers. Feed acidification imparts some benefits to nutrient digestibility in broilers fed pelleted wheat-based diets. [ABSTRACT FROM AUTHOR]

1. A 21-d experiment was conducted to investigate the effect of graded inclusions of waxy starch hull-less (WSHL) barley and a multi-component exogenous carbohydrase on the growth performance, nutrient digestibility and intestinal morphometry of broiler chickens. Five levels of WSHL barley inclusion (0, 65, 130, 195 and 260 g/kg) in a wheat-based diet, and two levels of enzyme supplementation (0 and 150 g/tonne of feed) were evaluated in a 5 × 2 factorial arrangement of 10 dietary treatments. All diets were equivalent in metabolisable energy and digestible amino acid content. A total of 400, one-d-old male broilers (five cages/treatment; eight birds/cage) were used in the experiment. 2. Regardless of enzyme supplementation, feed intake declined (P < 0.001) with increasing inclusion of WSHL barley. Increasing levels of WSHL barley (P < 0.001) and supplemental enzyme (P < 0.01) increased gain to feed ratio. 3. Birds fed diets with 0 g/kg WSHL barley showed the lowest (P < 0.001 to 0.01) digestibility for all nutrients except starch. Only starch digestibility was improved (P < 0.05) by enzyme supplementation. The nitrogen-corrected apparent metabolisable energy improved with increasing inclusion of WSHL barley (P < 0.001) and supplemental enzyme (P < 0.001). Increasing inclusion of WSHL barley increased the relative weight of gizzard (P < 0.001) and reduced jejunal digesta viscosity (P < 0.01). Supplemental enzyme (P < 0.001) reduced digesta viscosity. 4. All levels of WSHL barley inclusion improved digestibility of dry matter, nitrogen and fat, whilst energy utilisation improved at inclusions of 130 g/kg WSHL and above, probably due to lowered digesta viscosity and better development of the gizzard. Gain to feed ratio, starch digestibility, energy utilisation and jejunal digesta viscosity can benefit from carbohydrase supplementation in wheat-based diets, regardless of barley inclusion level. [ABSTRACT FROM AUTHOR]

The present study investigates the interactions between dietary nutrient density and feed form on the growth performance, coefficient of apparent ileal digestibility (CAID) of dry matter (DM), nitrogen (N), starch, fat, calcium (Ca) and phosphorus (P), and N-corrected apparent metabolisable energy (AMEn) in broiler chickens to 21d post-hatch. Maize-soybean meal diets with five tiers of nutrient density were formulated and mixed. The diets were then divided into two equal batches; the first batch was offered as unprocessed mash and the second batch was steam-pelleted at a conditioning temperature of 75 °C. A 5 × 2 factorial array of ten dietary treatments were offered to a total of 480, day-old male broiler (Ross 308) chicks accommodated in 60 cages (eight birds per cage). Significant (P < 0.001) interactions between nutrient density and feed form were observed for weight gain, feed intake and feed per unit gain. While birds fed pelleted diets outperformed those fed mash diets at each nutrient density level, the pellet-associated benefits were more pronounced at the lowest nutrient density. Increasing nutrient density increased (P < 0.001) N digestibility from 0.772 to 0.811, but decreased (P < 0.001) that of starch from 0.969 in very low density diets to 0.943 in very high density diets. No significant (P > 0.05) effect of nutrient density on the CAID of DM and fat was found. Feeding pelleted diets, regardless of nutrient density, reduced (P < 0.001) the CAID of DM, N, starch and fat. Significant nutrient density × feed form interactions were observed for the CAID of Ca (P < 0.001) and P (P < 0.01). Pelleting enhanced (P < 0.05) the CAID of Ca and P in the diet with lowest nutrient density but reduced (P < 0.05) the digestibility of these minerals in all other nutrient density diets. Increasing dietary nutrient density progressively increased the AMEn, but feeding of pelleted diets, regardless of nutrient density, reduced (P < 0.001) the AMEn. Overall, the present data showed that the magnitude of pelleting-induced benefits on broiler performance varied depending on dietary nutrient density, with responses to pelleting decreasing with increasing dietary nutrient density. The present study highlights that dietary nutrient density must be taken into consideration if the full benefits associated with feeding pelleted diets are to be achieved. [ABSTRACT FROM AUTHOR]

Feed intake (FI) is the primary factor driving the growth rate of broilers. Amongst a broad spectrum of the factors affecting the FI, less attention has been paid to the impact of feed processing variables, such as particle size, feed form and whole grain feeding on the FI of the bird. Current poultry feed production involves various processing practices (or at least particle size reduction in the case of mash feed). To achieve the genetic potential of modern broilers that are more than ever susceptible to FI stressors, it is vital to recognise, minimise or even eliminate feed processing-related factors inducing FI suppression. Feed intake in broilers can be affected by feed particle size and, the effects vary with age of birds and the grain type being fed. Fine grinding of wheat should be avoided in broiler mash diets because of beak pasting caused by wheat gluten and possible increase in digesta viscosity with subsequent depressions in FI. The FI response of broilers fed mash diets varying in particle size cannot be extrapolated to pelleted or crumbled diets, because the differences in particle size are evened out during the pelleting process. Macro-structural characteristics of pellets such as proportion of intact pellets, durability, hardness, length and diameter have the ability to influence feed consumption and should also be considered. A wide diversity in experimental methodology used in broiler studies with whole grain feeding complicates drawing definite conclusions of the impact of this feeding strategy on FI. However, to prevent the suppression of FI and achieve the beneficial effects of whole grain feeding on feed efficiency, age of birds, proportion of whole grain in the diet and an adaptation period should be considered before any transition to this feeding strategy. [ABSTRACT FROM AUTHOR]

A total of 640 male Ross 308 broiler chickens were used to explore the interactive effects of diet nutrient density, exogenous protease and ascorbic acid on performance, nutrient digestibility and various gut health metrics. A total of eight dietary treatments were arranged as a 2 x 2 x 2 factorial with the factors being adequate or reduced (~4%) crude protein and amino acids, without or with exogenous protease and without or with supplemental ascorbic acid. Over the 35-day experimental period, birds that received the adequate diet had higher (P < 0.01) bodyweight gain and lower (P < 0.001) feed conversion ratio (FCR) than birds that received the diet with reduced protein and amino acid density. Supplemental protease reduced (P < 0.001) FCR and this influence was more apparent in birds fed the diet with reduced protein concentration. Gut tensile strength tended to be increased by protease (P = 0.09) and ascorbic acid (P = 0.06) supplementation. Supplemental protease reduced (P < 0.001) jejunal goblet cell numbers and epithelial thickness and increased (P < 0.05) villus height compared with unsupplemented diets. Ascorbic acid tended (P = 0.05) to increase sialic acid concentration in ileal digesta. Protease increased (P < 0.01) the coefficients of apparent ileal digestibility for all amino acids other than methionine and this effect tended (P = 0.07 to 0.09) to be more pronounced in the low protein diet for aspartic acid, histidine and arginine. The concentration of taurine in ileal digesta was reduced (P < 0.01) by protease whereas hydroxyproline concentrations tended (P = 0.09) to increase by ascorbic acid addition. These results confirm previous reports on the effectiveness of exogenous protease in diets reduced in crude protein and digestible amino acids. Furthermore, both protease and ascorbic acid may influence gut health through promotion of tensile strength, epithelial morphology and endogenous protein flow. The interaction between exogenous protease and ascorbic acid on gut health with an emphasis on collagen structure and tight junction integrity is an area for future study. [ABSTRACT FROM AUTHOR]

The influence of feed form and particle size on the performance, coefficient of apparent ileal digestibility (CAID) of nutrients, apparent metabolisable energy (AME) and intestinal morphology in broiler starters fed maize-based diets was examined in this study. Two feed forms (mash and pellet) and three particle sizes (fine, medium and coarse) were evaluated in a 2 × 3 factorial arrangement of treatments. Birds fed pelleted diets had higher ( P < 0.05) weight gain and feed intake than those fed mash diets. In mash diets, fine grinding resulted in lower ( P < 0.05) feed per unit gain compared to medium and coarse grinding, whereas, in pelleted diets, there was no effect ( P > 0.05) of particle size. Gizzard pH was not influenced ( P > 0.05) by particle size in mash diets, but fine grinding increased ( P < 0.05) gizzard pH compared to medium and coarse grinding in pelleted diets. Pelleting reduced ( P < 0.05) the CAID of nitrogen but increased ( P < 0.05) the ileal fat digestibility. Particle size had no effect ( P > 0.05) on CAID of starch and AME in mash diets, but in pelleted diets, pellets made from medium and coarsely ground maize showed higher ( P < 0.05) starch digestibility. Coarse grinding resulted in higher ( P < 0.05) AME in pelleted diets. Feeding pelleted diets reduced ( P < 0.05) the CAID of calcium and phosphorus, but increased ( P < 0.05) that of sodium. Medium and coarse grindings resulted in higher ( P < 0.05) calcium digestibility than fine grinding. Feeding pelleted diets reduced ( P < 0.05 to 0.001) the relative length of all small intestinal segments and the relative weight of pancreas, proventriculus, and gizzard. Medium and coarse grinding increased ( P < 0.05) the gizzard weight compared to fine grinding. In both the duodenum and jejunum, birds fed pelleted diets had greater ( P < 0.05) villus height than those fed mash diets. Goblet cell number in duodenum was higher ( P < 0.05) in birds fed diets containing fine particles compared to those fed medium and coarse particle sizes. The crypt depth in jejunum was greater ( P < 0.05) in birds fed pelleted diets. Overall, the present data showed that coarse grinding of maize, through enhanced gizzard development and functionality, is beneficial to nutrient and energy utilisation and growth performance in broilers fed pelleted diets. [ABSTRACT FROM AUTHOR]

Starch, comprising up to 70–80% of most cereal grains, is the primary source of energy in poultry diets. Although it is generally believed that starch is well digested by poultry, low total tract and ileal starch digestibility has been reported in some studies. The structure and composition of starch granules, their interaction with protein matrix, and their availability after feed processing play important roles in the digestion of starch. There is clear evidence that starch digestion is highly correlated with its structural location within feedstuffs and components associated with starch granule. Viscous non-starch polysaccharides and feed technology practices such as pelleting, whole grain feeding and inclusion of fibrous materials also have significant influence on starch digestibility. The aim of this review is to focus on factors affecting the digestion and absorption processes of starch in poultry. The effects of components associated with starch granule, soluble and insoluble dietary fibre, anti-nutrients and feed processing on starch digestion are also reviewed. [ABSTRACT FROM AUTHOR]

The effects of high dose of microbial phytase and an emulsifier on the performance, apparent metabolisable energy (AME) and nitrogen (N) retention in broilers fed on diets containing different fat sources were examined in a 5-week trial. Two fat sources (soy oil and tallow), two inclusion levels of E. coli phytase (500 or 1000 phytase units (FTU)/kg diet) and two inclusion levels of lysolecithin emulsifier (0 or 3.5 g/kg of diet) were evaluated in a 2 × 2 × 2 factorial arrangement of treatments.Throughout the 5-week trial, soy oil supplementation improved weight gain and feed per gain compared with tallow, but had no effect on feed intake.The high dose of phytase increased the weight gain and feed intake and lowered the feed per gain during d 1–21, but had no effect on performance parameters over the whole trial period.An effect of emulsifier was observed for feed intake during d 1–21 and over the whole trial period. Addition of emulsifier increased feed intake compared with diets without emulsifier.During weeks 1, 2, 3 and 5, birds fed on soy oil–based diets had higher nitrogen-corrected AME (AMEN) compared with those fed on tallow-based diets. During weeks 2, 3 and 5, the effect of phytase was significant for AMEN, with the high dose increasing the AMEN. During week 2, AMEN was increased with emulsifier addition.During weeks 1, 2, 3 and 5, birds fed on soy oil–based diets had higher fat retention compared with those fed on tallow-based diets. The high dose of phytase improved the retention of fat during week 5 and the addition of emulsifier resulted in higher fat retention during week 1.During weeks 2, 3 and 5, an interaction between fat source × phytase × emulsifier was observed for N retention. In soy oil–based diets, emulsifier plus 1000 FTU/kg phytase increased N retention compared with other groups, while in tallow-based diets, emulsifier addition increased N retention in diets with 500 FTU/kg, but not in 1000 FTU/kg diet.Overall, the present data suggest that the dietary fat source influenced performance, AMEN and fat retention in broiler chickens. There is opportunity to improve bird performance during d 1–21, AMEN and fat retention with higher doses of microbial phytase. Addition of the emulsifier increased the AMEN during week 2 and tract retention of fat during week 1, but this effect was not translated into improvements in performance. [ABSTRACT FROM PUBLISHER]

1. The effects of microbial phytase on the performance and nutrient utilisation in broilers fed on phosphorus-adequate starter diets were examined in this study. The effect of phytase on the apparent ileal digestibility of fatty acids was of particular interest. Two grain types (maize and wheat) and two inclusion concentrations of a phytase enzyme fromEscherichia coliexpressed inSchizosaccaromyces pombe(0 or 500 phytase units (FTU)/kg of feed) were evaluated in a 2 × 2 factorial arrangement of treatments. 2. Supplemental phytase improved the weight gain and feed per gain, but had no effect on the feed intake of young broilers receiving phosphorus-adequate diets. 3. Phytase supplementation improved the apparent ileal digestibility of nitrogen and phosphorus in both diet types. Phytase supplementation tended to improve the apparent ileal digestible energy in wheat-based diets, but had no effect on the apparent metabolisable energy in both diet types. 4. Supplementation of phytase increased the apparent ileal digestibility of fat, with similar effects for the different fatty acids measured. Increments on ileal fat digestibility due to phytase were not dependent on the type of diet. 5. Dietary supplementation of microbial phytase enhanced not only the digestibility of phosphorus, but also that of nitrogen and fat, exhibiting increased ileal digestibility for all fatty acids in P-adequate maize- and wheat-based diets. [ABSTRACT FROM AUTHOR]

1. The aim of the present experiment was to examine the influence of whole wheat inclusion and a blend of essential oils (EO; cinnamaldehyde and thymol) supplementation on the performance, nutrient utilisation, digestive tract development and ileal microbiota profile of broiler chickens. 2. The experimental design was a 2 × 2 factorial arrangement of treatments evaluating two wheat forms (ground wheat [GW] and whole wheat [WW]; 100 and 200 g/kg WW replacing GW during starter [1 to 21 d] and finisher [22 to 35 d] diets respectively) and two levels of EO inclusion (0 or 100 g/tonne diet). All dietary treatments were supplemented with 2000 xylanase units/kg feed. Broiler starter and finisher diets based on wheat and soybean meal were formulated and each diet fed ad libitum to 6 pens of 8 male broilers. 3. During the trial period (1-35 d), wheat form had no significant effect on weight gain or feed intake. However, WW inclusion tended (P = 0.06) to improve feed per gain. Essential oil supplementation significantly improved weight gain in both diets, but the improvements were greater in the GW diet as indicated by a significant wheat form × EO interaction. 4. Main effects of wheat form and EO on the relative weight, length and digesta content of various segments of the digestive tract were not significant. Significant interactions, however, were found for relative gizzard and caecal weights. Essential oil supplementation significantly increased the relative gizzard weight and lowered relative caecal weight in birds fed on the GW based diet, but had no effect in those fed on the WW based diet. 5. Whole wheat inclusion and EO supplementation significantly improved apparent ileal nitrogen digestibility. Apparent ileal digestible energy was not significantly influenced by the dietary treatments. 6. Ileal microbiota profiling, using denaturing gradient gel electrophoresis, showed that the ileal microbiota composition was influenced by feed form. The mean numbers of bacterial species in the ileal contents of birds fed on the GW diet supplemented with EO tended (P = 0.07) to be higher than those of the ileal contents of birds fed on unsupplemented GW based diet. 7. The present data suggested that dietary addition of EO improves broiler weight gain and ileal nitrogen digestibility both in GW and WW based diets, but that the magnitude of the response to EO for weight gain was greater in GW based diet. Whole wheat feeding was found to be beneficial in terms of feed efficiency. [ABSTRACT FROM AUTHOR]

A total of 640 male Ross 308 broilers were used in a growth performance and digestibility study to explore the interactive effects of a mono-component exogenous protease and ascorbic acid. A total of 7 dietary treatments were generated by formulation of a nutritionally-marginal wheat/soy-based ‘negative control’ diet and supplementation of the same with three concentrations of ascorbic acid, without or with exogenous protease addition. A further ‘positive control’ diet was fed as a reference and was formulated to be nutritionally adequate. Diets were fed ad libitum from d1-35 post-hatch and water and environmental controls were as per breeder recommendations. At the termination of the experiment ileal digesta was collected for assessment of digestibility and the ileum and jejunum were excised for morphological measurements. There were no interactions (P > 0.05) between ascorbic acid and exogenous protease for any of the measurements taken during the study. Overall (d1-35) addition of protease resulted in a significantly lower FCR compared with birds fed the negative control diet. There was no effect of ascorbic acid on performance of the birds with the exception of a small reduction in FCR at the highest inclusion concentration only. Ascorbic acid addition significantly increased gut integrity and exogenous protease reduced (P < 0.05) the presence of sialic acid in ileal digesta. Exogenous protease significantly increased the ileal digestibility of nitrogen and all amino acids but had no effect (P > 0.05) on dry matter digestibility. Ascorbic acid addition had only modest effects on ileal nutrient digestibility but this was confirmed as significant for several amino acids including threonine and cysteine. Finally, addition of ascorbic acid linearly decreased crypt depth in the jejunum and exogenous protease increased villus height, reduced epithelial thickness and goblet cell number in the jejunum. It can be concluded that ascorbic acid and exogenous protease improve intestinal integrity in growing broiler chickens and offer potential as a strategic dietary intervention to enhance performance, intestinal resilience and nutrient recovery. [ABSTRACT FROM AUTHOR]

Two experiments were conducted to investigate the influence of age and dietary cellulose levels on the ileal endogenous energy losses (IEEL) in broiler chickens. In experiment 1, a glucose-based purified diet was used to determine the IEEL. Titanium dioxide (5.0 g/kg) was added to the diet as an indigestible marker. Six groups of broiler chickens aged 1 to 7, 8 to 14, 15 to 21, 22 to 28, 29 to 35 or 36 to 42 d posthatch, were utilized. With the exception of 1-7 d, the birds were fed a starter (d 1–21) and/or a finisher (d 22–35) diet before the experimental diet was introduced. The diet was randomly allocated to 6 replicate cages, and the number of birds per cage was 12 (d 1–7), 10 (d 8–14), and 8 (d 15–42). The ileal digesta were collected at the last day of each week (d 7, 14, 21, 28, 35, and 42). Bird age had no effect (P > 0.05) on the IEEL estimates. The IEEL estimates ranged from 263 to 316 kcal/kg dry matter intake (DMI) during weeks 1 to 6. In Experiment 2, 4 glucose-based purified diets were developed using 0, 25, 50 and 75 g/kg cellulose. Titanium dioxide (5.0 g/kg) was added to the diets as an indigestible marker. The diets were randomly allocated to 6 replicate cages (8 birds per cage) and fed from 18 to 21 d posthatch and, ileal digesta were collected on d 21. The IEEL estimates of broiler chickens at 21 d of age showed a quadratic response (P < 0.05) to increasing cellulose contents. The lowest IEEL (88 kcal/kg DMI) was recorded for the diet without cellulose and the highest IEEL (430 kcal/kg DMI) was observed for the diet with 75 g/kg cellulose. Overall, the present findings confirmed that the IEEL in broiler chickens can be quantified by feeding a glucose-based purified diet. Broiler age had no influence on the IEEL estimates. The IEEL increased with increasing dietary cellulose contents and the IEEL determined using a purified diet without cellulose represents a better estimate of IEEL. [ABSTRACT FROM AUTHOR]

Two experiments were conducted. The first experiment investigated the digestion of fat and fatty acids (FA) from soybean oil and tallow along the gastrointestinal tract of broiler chickens. The second experiment was conducted to determine endogenous fat and FA losses and the FA profile of chicken bile. In experiment 1, 2-wk-old broilers were fed corn-soy diets supplemented with 50 g/kg of soybean oil or tallow for 7 d and digesta were collected from the duodenum, upper jejunum, upper ileum, and lower ileum. Apparent digestibility coefficients were calculated using the titanium marker ratio in diets, and digesta. Digestibility of fat was determined to be negative in the duodenum, indicating marked net secretion of fat into this segment. Fat was rapidly digested in the jejunum, with digestibility coefficients of 0.60 to 0.64 being determined at the end of the jejunum. The digestion of fat continued in the upper ileum. The apparent digestibility coefficient of fat determined at lower ileum in soybean oil diets was higher (P < 0.05) than that in tallow diets (0.82 vs. 0.74). Linoleic acid was digested throughout the intestinal tract, whereas the digestion of palmitic, stearic, and oleic acids started only in the jejunum. Measurements at the lower ileal level showed that the unsaturated FA (linoleic and oleic acids) were well digested (0.90 to 0.94), irrespective of the source of fat. In contrast, the digestibility of saturated FA (palmitic and stearic acids) was influenced (P < 0.05) by the fat source. Digestibility coefficients of palmitic and stearic acids at lower ileum were markedly higher (P < 0.05) in the diet containing soybean oil (0.77 to 0.85) compared with that containing tallow (0.58 to 0.68). In experiment 2, ileal endogenous fat loss was determined to be 1,714 mg/kg of DM intake. Endogenous fat was composed mainly of palmitic (75 g/kg), stearic (131 g/kg), oleic (73 g/kg), linoleic (133 g/kg), and arachidonic (60 g/kg) acids. Fatty acid profile of endogenous fat was found to be remarkably similar to that of the bile, suggesting that the reabsorption of fat and FA from the bile was incomplete in growing broiler chickens. [ABSTRACT FROM AUTHOR]

Abstract: The influence of age of broilers on the apparent metabolisable energy (AME) and total tract digestibility of fat in five fat sources (tallow, soybean oil, poultry fat, palm oil and a 50:50 blend of tallow and soybean oil) was investigated. The assay diets were developed by substituting the different fats for 40g/kg (w/w) of a maize-soy basal diet and the measurements were made during weeks 1, 2, 3 and 5 posthatch. The AME of fats was influenced (P<0.001) by the age of broilers. The AME was markedly lower (P<0.05) during week 1, but improved during week 2. There were no further improvements (P>0.05) in the AME after week 2. There was no interaction (P>0.05) between fat source and age of broilers for the AME, indicating that the effect of age on the AME was similar for all fat sources. The effect of age on the apparent total tract digestibility of fat generally followed the same trend as that on the AME. The AME of palm oil, soybean oil and poultry fat were determined to be similar (P>0.05), but higher (P<0.05) than that of tallow. The AME of the 50:50 blend of tallow and soybean oil was determined to be 9% higher than the arithmetic averages of tallow and soybean oil, suggesting a synergistic effect. Overall, the present data highlight the physiological limitation in newly hatched chicks to effectively digest and utilise fats. [Copyright &y& Elsevier]

• Feed form affects the nutrient digestibility in different grains. • The digestibility responses to pelleting depends on the grain type. • Pelleting reduces starch digestibility in viscous grains. • Effect of feed form should be taken into account in feed evaluation assays. The present experiment was carried out to determine the influence of feed form (FF) on the apparent ileal digestibility coefficients (AIDC) of dry matter (DM), starch and, standardised ileal digestibility coefficients (SIDC) of nitrogen (N) and amino acids (AA) in different grain types (GT). Eight experimental diets were developed in a 4 × 2 factorial arrangement of treatments that included four GT (maize, sorghum, wheat and barley) and two FF (mash vs. pellet). A N-free diet was also used to determine the endogenous N and AA losses for the calculation of SIDC values. Titanium dioxide was incorporated in all diets as an indigestible marker. Ileal nutrient digestibility was determined using the direct method. The four assay diets were formulated to contain 938 g/kg grain as the sole source of AA and starch in the diet. The assay diets and N-free diet were randomly allotted to six replicate cages (eight birds per cage) and fed from 19 to 23 d post-hatch and the ileal digesta was collected on d 23. Pelleting reduced (P < 0.05) the AIDC of DM in all test grains. A significant (P < 0.001) GT × FF interaction was observed for AIDC of starch. Starch digestibility was unaffected by FF in maize- and sorghum-based diets but was reduced in pelleted wheat- and barley-based diets. The GT had a significant (P < 0.05 to 0.001) effect on the SIDC of N and AA. In general, the average values for SIDC of AA were higher in maize followed by sorghum or wheat and barley. The FF showed no significant (P> 0.05) effect on the SIDC of N and AA except cysteine and proline, in which the SIDC values were higher (P < 0.05) in mash than the pelleted diets. Overall, the present data suggest that the physical form of the feed can impact the digestibility of DM, starch and AA in broilers. Because the FF effect on nutrient digestibility can vary depending on the grain type and nutrient, the FF effect should be taken into account in feed evaluation assays to achieve the optimum use of nutrients especially AA. [ABSTRACT FROM AUTHOR]

• Feed form influences metabolisable energy of ingredients for broiler chickens. • Pelleting increased apparent metabolisable energy of cereal grains. • Pelleting effect on metabolisable energy of protein sources depends on the ingredient. • Pelleted diets should be used in energy evaluation assays. The influence of feed form (FF) on the apparent metabolisable energy (AME) of seven feed ingredients for broiler chickens was examined in two experiments. The first experiment was conducted to investigate the interaction between four cereal grains (maize, sorghum, wheat and barley) and two FF (mash vs. pellet) on the nitrogen-corrected AME (AMEn) contents using the direct method. The test diets contained 962 g/kg of each grain. Each diet was randomly allocated to six replicate cages (six birds per cage) and fed for 7 d from 21 to 28 d post-hatch. The feed intake and total excreta output for each replicate cage were measured over the last 4 d of the assay. No interaction (P > 0.05) between grain type and FF was found for the AMEn. Maize and sorghum showed the highest AMEn, barley the lowest and wheat being intermediate. Regardless of the grain type, pelleting increased (P < 0.05) the AMEn of the grains by 0.22 MJ/kg, compared with mash diets. The second experiment was conducted to examine the effect of FF on the AMEn of three protein sources (meat and bone meal [MBM], soybean meal [SBM], and canola meal [CM]) using the difference method. A maize-soybean meal basal diet was formulated, and the test diets were developed by replacing (w/w) 30 % of the basal diet with MBM, SBM or CM. Each diet was randomly allocated to six replicate cages (six birds per cage) and fed for 7 d (d 21–28) and, feed intake and total excreta output were measured over the last 4 d. There was a significant (P < 0.05) interaction between the protein source and FF. Pelleting reduced the AMEn of MBM, had no effect on that of SBM, but increased the AMEn of CM. Overall, pelleting process increased the AMEn of all cereal grains and influenced those of protein sources with the effect varied depending on the ingredient. The current findings suggest that the application of AMEn values determined based on assays using mash diets might result in over- or under-estimation of available energy content of ingredients in commercial pelleted broiler diets and highlights the need for the use of pelleted diets in energy evaluation assays. [ABSTRACT FROM AUTHOR]