Basal ileal endogenous amino acid flow in broiler chickens as influenced by age

Effect of age on the standardized ileal amino acid digestibility of soybean meal and canola meal in broilers

Standardized ileal digestibility coefficients (SIDC) of nitrogen (N) and amino acids (AA) in two protein sources (soybean meal [SBM] and canola meal [CM]) were investigated at six broiler ages (d 7, 14, 21, 28, 35, and 42). Two assay diets were formulated to contain either SBM (413 g/kg) or CM (553 g/kg) as the sole dietary AA source. Titanium dioxide (5 g/kg) was added as an indigestible marker. A total of 696 male broilers at 1 d old were allotted to 12 replicate cages per age group. Each assay diet was offered to birds for 4 d prior to the ileal digesta collection on d 7 (14 birds/cage), 14 (12 birds/cage), 21 (10 birds/cage), 28 (8 birds/cage), 35 (8 birds/cage) and 42 (6 birds/cage), respectively. The apparent digestibility coefficients were standardized using age-specific basal endogenous AA flows. In the SBM group, though the SIDC of N tended to be influenced (quadratic; P = 0.075) by age, no linear or quadratic response of age effect was observed on the average SIDC of indispensable (IAA) and total AA (TAA). An age effect (quadratic; P < 0.05) was observed on the average SIDC of dispensable AA (DAA) in SBM with the highest value recorded at d 7, followed by a decrease from d 14 to 28, which increased beyond d 35. The SIDC of some individual AA (Arg, Thr, Trp, Cys, Pro) were affected (P < 0.05 or P < 0.001) in a quadratic manner by age. In the CM, the SIDC of N, average SIDC of IAA, DAA and TAA were influenced (quadratic; P < 0.05 or P < 0.001) by age. The SIDC of N and average SIDC of DAA and TAA were higher from d 7 to 14, declined at d 21, and then increased beyond d 28. The average SIDC of IAA was low between d 7 and 28 and increased thereafter. The SIDC of individual AA were affected (linear or quadratic; P < 0.05 or P < 0.001) by different magnitudes by age. The age influence on the SIDC AA was variable, depending on the protein source and AA. The results demonstrate that age-specific SIDC AA data might need consideration in broiler feed formulations.

Comparison of methods for estimating basal endogenous losses of amino acids and additivity of digestibility of amino acids in corn and soybean meal for broilers

This study was to compare the estimates of basal endogenous losses (BEL) of amino acids (AA) determined by 3 methods including feeding a nitrogen-free diet (NFD) or a low-casein diet (LCD, containing casein at 30 g/kg diet) or using the regression method. Another objective was to investigate whether the ileal AA digestibility of corn calculated from a casein-supplemented corn diet is additive for a corn-soybean meal (SBM) mixed diet in broilers. On d 31 of age, 168 Ross 308 male broilers were assigned to 8 dietary treatments with 6 replicates in a randomized complete block design. An NFD and 3 diets containing 30, 60, or 90 g/kg of casein were formulated to determine the BEL of AA and ileal AA digestibility of casein. The other 4 diets consisted of a corn diet, SBM diet, casein-supplemented corn diet, and corn-SBM mixed diet. On d 35 of age, digesta from the distal section of the ileum were collected. The BEL of AA in birds fed the LCD were greater (P < 0.05) than those of the NFD and the regression method. There were no differences in the BEL of AA determined between the NFD and the regression method. Apparent ileal digestibility (AID) and standardized ileal digestibility (SID) of AA for corn calculated from the casein-supplemented corn diet were greater (P < 0.05) than those of the corn diet. The predicted AID of Thr in the corn-SBM mixed diet based on the AID of AA for corn in the corn diet was lower (P < 0.05) than the measured AID. However, the predicted AID of AA in the mixed diet based on the AID of AA for corn in the casein-supplemented corn diet did not differ from the measured AID. The predicted SID of AA in the mixed diet did not differ from the measured SID irrespective of casein supplementation. In conclusion, feeding an NFD or using the regression method yields similar BEL of AA, but not feeding an LCD. Casein supplementation in the corn diet increases the ileal AA digestibility for corn, which is additive for the corn-SBM mixed diet.

The fermented product of high-yield surfactin strain Bacillus subtilis LYS1 improves the growth performance and intestinal villi morphology in broilers

This study aimed to select Bacillus spp. for surfactin production by solid-state fermentation and to investigate the physiochemical characterizations of the fermented product (FP) and its effect on growth performance, carcass trait, intestinal morphology, and clinical blood biochemistry of broilers. Accordingly, the correlations between the functional components of FP and the growth performance of broilers are elucidated. Four hundred eighty 1-day-old Ross 308 broiler chicks were randomly assigned to dietary supplementation of 2.5% fish meal, 2.5% unfermented product, or 2.5% FP produced by Bacillus subtilis LYS1 (LYS1), Bacillus amyloliquefaciens Da16, B. subtilis Lo6 (Lo6), B. subtilis NSN7, B. subtilis subsp. natto N21, or B. subtilis N12. Each treatment had 6 replicates. The experimental period was 5 wk. Results showed that the Lo6 showed the highest protease activity among all fermented groups. The LYS1 showed the highest surfactin yields (10.69 mg/g) among all fermented groups (P < 0.05). The weight gain (WG), feed conversion ratio (FCR), and production efficiency factor (PEF) of LYS1 group were significantly better than unfermented group at 0 to 3 and 0 to 5-wk-old (P < 0.05). The Bacillus-like counts and surfactin content of FP were moderately correlated to WG (0.7 > r > 0.3), FCR (-0.3 > r > -0.7), and PEF (0.7 > r > 0.3) at 0 to 3 and 0 to 5-wk-old (P < 0.05). The protease activity of FP was moderately correlated to WG (0.7 > r > 0.3), FCR (-0.3 > r > -0.7), and PEF (0.7 > r > 0.3) at 0 to 3-wk-old (P < 0.05). The villus height to crypt depth ratio in duodenum and jejunum of fish meal group and LYS1 group were higher than unfermented group (P < 0.05). In conclusion, LYS1 shows the highest surfactin yields. Diets supplemented with 2.5% LYS1 FP can improve the growth performance and the development of intestinal villi in broilers. Moreover, this study proves that the surfactin content, Bacillus-like counts, and protease activity of FP show a correlation to the growth performance of broilers.

Calcium Nutrition of Broilers: Current Perspectives and Challenges

Calcium (Ca) plays an essential role in poultry nutrition as 99% of Ca is located in birds' skeletal system. However, oversupply of Ca rather than deficiency of Ca is the current concern in commercial broiler diets. Calcium is an inexpensive dietary nutrient due to the cheap and abundant availability of limestone, the major Ca source; therefore, little attention was given to the oversupply of Ca in the past. The recent shift in the use of digestible P in broiler feed formulations has necessitated a closer look at digestible Ca, as Ca and P are interrelated in their absorption and postabsorptive utilisation. In this context, data on ileal digestibility of Ca and P in ingredients has been determined. Preliminary data on the digestible Ca and digestible P requirements for the different growth stages of broilers have also recently become available. The present review focusses on these recent advances in Ca nutrition. In addition, aspects of homeostatic control mechanisms, different Ca sources and factors influencing Ca digestibility in poultry are covered.

Effects of Solid-State Fermentation on the Standardized Ileal Digestibility of Amino Acids and Apparent Metabolizable Energy in Peanut Meal Fed to Broiler Chickens

Peanut meal (PNM) is a byproduct of the peanut oil extraction process, but its application is seriously limited by the presence of anti-nutritional factors, imbalance in amino acid profiles, and susceptibility to mycotoxin contamination. This study was conducted to investigate the effects of solid-state fermentation on the nutritional quality of PNM, as well as the effects of PNM and fermented peanut meal (FPNM) on the ileal digestibility of amino acids and apparent metabolizable energy (AME) of broiler chickens. The results indicated that the fermentation improved the quality of PNM by increasing the crude protein, TCA-soluble protein, and L-lactic acid concentration (p < 0.05), and decreasing the crude fiber, phytic acid, and aflatoxin B1 concentration (p < 0.05). Solid-state fermentation also increased the free amino acids level and improved the balance of hydrolyzed amino acids of PNM. A nitrogen-free diet was used to determine the loss of endogenous amino acid in birds, and the PNM or FPNM as the only protein source to formulate semi-purified diets. The result showed that feeding on FPNM resulted in higher apparent ileal digestibility (AID) and standardized ileal digestibility (SID) values of the essential amino acids of methionine, lysine, leucine, and phenylalanine (p < 0.05). Moreover, the AID and SID values of the non-essential amino acids of FPNM were both higher than those of PNM, except for proline (p < 0.05). The AME was determined by the classic substitution method, and the results showed that fermentation had no effect on the AME value (p > 0.05). In conclusion, solid-state fermentation improved the nutritional value of PNM, and FPNM was a potential ingredient as an alternative protein source for broilers.

Influence of dietary crude protein on growth performance and apparent and standardized ileal digestibility of amino acids in corn-soybean meal-based diets fed to broilers

This study aimed to examine the influence of dietary CP on the apparent ileal digestibility (AID) and standardized ileal digestibility (SID) of amino acids (AA) and test the additivity of AA digestibility in corn-soybean meal-based diets fed to broilers. Six experimental diets comprising a nitrogen-free diet and five corn-soybean meal-based diets containing 6.0%, 9.5%, 13.0%, 16.5%, and 20.0% CP were prepared. Increments in CP and AA concentrations were achieved by increasing the inclusion rate of corn and soybean meal at the expense of cornstarch. All diets contained 0.5% chromic oxide, which was included as an indigestible index. A total of 960 Ross 308 male broilers 19-day-old male broilers (Ross 308), with a mean BW of 628 g (SD = 58.0), were allocated to six dietary treatment groups in a randomized complete block design, with each treatment group have eight replicate cages and 20 birds per cage. All birds were fed the experimental diets for 4 days. On d 23, individual BW and feed intake were recorded, followed by collection of ileal digesta samples from the distal ileum. Regarding growth, the final BW, weight gain, feed intake, and gain to feed ratio increased linearly (P < 0.001) as dietary CP concentrations increased. With the increase in dietary CP concentrations from 6.0% to 20.0%, the AID of all AA, except Arg, increased linearly (P < 0.05). However, the SID of all AA, except Arg, Cys, and Pro, remained unaffected by CP concentrations in the diets. This study indicated that dietary CP concentrations from 6.0% to 20.0% have an effect on the growth performance of birds and the AID of most AA; however, the SID of most AA was not affected by dietary CP concentrations in the corn-soybean meal-based diets. In conclusion, the SID of AA is more additive than the AID of AA in poultry diets containing CP in the range of 6.0% to 20.0%.

The age-related metabolizable energy of cereal grains, oilseed meals, corn gluten meals, and feather meals for broilers

A 2 × 3 factorial arrangement of treatments with two ages of broilers (11 to 14 or 25 to 28 d of age) and three samples of feed ingredients was utilized to compare metabolizable energy (ME) and ratio of ME to gross energy (GE) in each group of three cereal grains (CG, including one corn, two wheat flour), three oilseed meals (OM, including one soybean meal, one peanut meal, and one cottonseed meal), three corn gluten meals (CGM A, B, and C), and three feather meals (FM A, B, and C). Each treatment contained six replicates of four Arbor Acre male broilers in energy balance experiments. Trends toward interactions between age and source of CG were observed on the ME and ME/GE of CG (0.05

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Key Words

• age
• broiler
• feed ingredient
• metabolizable energy

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MESH Headings

• Male
• Animals
• Digestion
• Edible Grain
• Chickens
• Flour
• Feathers
• Glutens
• Animal Feed/analysis
• Triticum
• Diet/veterinary
• Energy Metabolism
• Zea mays
• Animal Nutritional Physiological Phenomena

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Grants

• BAIC06-2022 Poultry Research Team of Beijing Innovation Consortium of Agriculture Research System
• 2020-YF-03 Cooperative Project between IASCAAS-Newhope Liuhe Co. Ltd

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Affiliation(s)

Mingqiang Song The State Key Laboratory of Animal Nutrition, Institute of Animal Sciences of Chinese Academy of Agricultural Sciences, Beijing 100193, China
Yuming Wang The State Key Laboratory of Animal Nutrition, Institute of Animal Sciences of Chinese Academy of Agricultural Sciences, Beijing 100193, China
Youyou Liu The State Key Laboratory of Animal Nutrition, Institute of Animal Sciences of Chinese Academy of Agricultural Sciences, Beijing 100193, China
Cong Ren The State Key Laboratory of Animal Nutrition, Institute of Animal Sciences of Chinese Academy of Agricultural Sciences, Beijing 100193, China
Lei Yan Newhope Liuhe Co. Ltd., Beijing 100102, China Shandong New Hope Liuhe Group, Qingdao, Shandong 266000, China
Jingjing Xie The State Key Laboratory of Animal Nutrition, Institute of Animal Sciences of Chinese Academy of Agricultural Sciences, Beijing 100193, China
Jinliang Lai Newhope Liuhe Co. Ltd., Beijing 100102, China
Guilian Zhou Newhope Liuhe Co. Ltd., Beijing 100102, China
Yong Li Newhope Liuhe Co. Ltd., Beijing 100102, China
Feng Zhao The State Key Laboratory of Animal Nutrition, Institute of Animal Sciences of Chinese Academy of Agricultural Sciences, Beijing 100193, China

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Effects of Fermentation on the Apparent Metabolizable Energy and Standardized Ileal Digestibility of Amino Acids in Soybean Meal Fed to Broiler Chickens

Two experiments were conducted to test the hypothesis that the apparent metabolizable energy (AME) and standardized ileal digestibility (SID) of amino acids (AA) in fermented soybean meal (FSBM) are greater than those in soybean meal (SBM). FSBM was produced by fermenting SBM with a mixture of Bacillus amyloliquefaciens, Lactobacillus acidophilus, and Saccharomyces cerevisiae. The fermentation process decreased trypsin inhibitor and crude fiber levels by 67.80% and 7.56%, while it increased the total amino acid content by 2.56%. In the first experiment, a substitution method was used to determine the AME and nitrogen-corrected AME (AMEn) of SBM and FSBM. A corn-SBM basal diet and two test diets consisting of 70% of the basal diet plus 30% SBM or FSBM were formulated. The results show that fermentation did not have an effect on the AME and AMEn concentrations of SBM (p > 0.05); the respective AME and AMEn values were 10.29 and 10.62 MJ/kg (DM basis) and 9.09 and 9.23 MJ/kg for SBM and FSBM. In the second experiment, a nitrogen-free diet was formulated to measure the endogenous AA flow, and the other two semi-purified diets containing SBM or FSBM as the sole source of AA were formulated. The results show that the AID and SID of isoleucine, leucine, phenylalanine, valine, cysteine, tyrosine, and aspartic acid were greater in FSBM than in SBM (p < 0.05). In conclusion, the fermentation of SBM by a mixture of B. amyloliquefaciens, L. acidophilus, and S. cerevisiae can improve its nutritional values and is a promising protein resource for broiler production.

Comparison of amino acid digestibility and its additivity determined with slaughter or cecectomy method for yellow-feather chicken

The objective of this experiment was to compare the slaughter and cecectomy methods to determine amino acid (AA) digestibility of corn and soybean meal and their additivity in a corn-soybean meal diet. A completely randomized design was adopted to determine endogenous AA losses (EAAL) and AA digestibility in each of corn, soybean meal, and a corn-soybean meal diet using either slaughter or cecectomy methods. Each treatment contained 6 replicates with 3 chickens per replicate. The endogenous loss (EL) of histidine and glycine was lower and the EL of methionine and phenylalanine was greater when determined by slaughter vs. cecectomy (P < 0.05). The EL of arginine, isoleucine, leucine, lysine, methionine, phenylalanine, valine, alanine, aspartic acid, glutamic acid, and serine determined by slaughter were 1.2 to 3.2 times of those from cecectomy. The standard error (SE) of EL of 14 AA (excluding histidine and glycine) obtained by slaughter method was 2.1 to 9.6 times of those by cecectomy method. The apparent and standardized digestibility was not affected by methods for most AA except apparent digestibility of methionine, phenylalanine and glycine, and standardized digestibility of glycine in corn. The apparent and standardized digestibility of most AA except apparent digestibility of glycine and standardized digestibility of lysine, cysteine and glycine were less for slaughter versus cecectomy methods in soybean meal (P < 0.05). Using slaughter method resulted in reduced apparent digestibility of 15 AA (except glycine) and reduced standardized digestibility of 7 AA (arginine, isoleucine, leucine, valine, aspartic acid, glutamic acid, and proline) relative to cecectomy method (P < 0.05), but the standardized digestibility of glycine was greater when determined by slaughter vs. cecectomy methods in corn-soybean meal diet (P < 0.05). The mean value of SE of 16 AA digestibility in slaughter method was 2.9 times of that by cecectomy method. The apparent digestibility of 2 and 9 of 16 AA and the standardized digestibility of 15 and 7 of 16 AA were additive when using slaughter and cecectomy determinations, respectively. In conclusion, compared to the slaughter method, cecectomy method had less SE and EAAL but greater apparent digestibility of methionine and phenylalanine in corn, and the apparent digestibility of 15 AA (except glycine) in soybean meal and corn-soybean meal diet. Additivity in apparent and standardized AA digestibility was more inconsistent when determined with slaughter vs. cecectomy methods. These findings suggest that the cecectomy method is more suitable than the slaughter method to determine the digestibility of AA.

Effects of broiler chicken age and dietary protease on the standardised ileal digestibility of amino acids in seeds from two lupin species

The extent to which lupin seeds can replace soybean meal in diets for broiler chickens is limited, and one of the reasons for this may be a lack of careful consideration given to the age-related amino acid availability differences in the feed formulation process. This study aimed to determine and compare standardised ileal digestibility (SID) coefficients of amino acids (AA) in raw seeds of the Lupinus luteus (YL) and the Lupinus angustifolius (NLL) cultivars as sole sources of AA in the diet of broiler chickens aged 14 or 28 days. An additional purpose was to check the influence of exogenous mono-component protease added to lupin-based assay diets on AA SID in birds at both ages. Each assay diet was offered to six replicatecages. On both sampling days, the contents from the lower half of the ileum were collected for determination of the apparent digestibility values. The SID coefficients were calculated using the age-appropriate basal ileal endogenous AA losses determined from birds fed a N-free diet. Results indicated a substantial advantage of YL over the NLL in SID of Met, Cys, His, Leu, Gly, Asp, Glu, Pro, Tyr and the average of total AA for 14-d-old chickens. With the exception of Cys and Tyr, there was no significant difference between these Lupinus species in the SID of AA in 28-d-old birds. The significant age-related differences within species were found only for the seeds of NLL, where the higher SID for Met, His, Ala, Pro, and the averages of total and indispensable AA were noted in birds aged 28 d. The protease increased SID of most AA from L. luteus in older broilers, whereas for L. angustifolius its efficacy was more pronounced in younger birds, giving the SID values similar to those determined at 28 d on an enzyme-unsupplemented diet. In conclusion, the SID coefficients of indispensable AA determined at 14 or 28 days of age for yellow lupin should not be applied to the precise formulation of starter-type feeds containing seeds of NLL.

Carcass Characteristics, Digestive System Traits of Spent Broiler Breeder and Dual-Purpose Hens

Raising dual-purpose hens for meat is believed to bring more economic benefits to farmers selling products directly to consumers. The aim of the study was to determine the differences between the carcass features and the digestive system of multipurpose hens and spent broiler breeders. In the experiment, 20 carcasses of 70-week-old Rosa 1 dual-purpose hens and 20 carcasses of 62-week-old Ross 308 broiler breeders were used. Measurements of the length of various sections of the intestine and the diameter of individual intestinal segments were made. During the gutting, proventriculus, gizzard, liver, heart, and spleen were separated and then weighed. Dual-purpose hens differed significantly (p < 0.05) from broiler breeders in weight and carcass dimensions. Multipurpose hens were characterized by significantly lower (p < 0.05) percentages of breast muscles, leg muscles, skin with subcutaneous fat, wings, and carcass remainders. Broiler breeders were characterized by significantly longer (p > 0.05) total intestinal length, duodenum, jejunum, ileum, and terminal intestine. Significant differences were confirmed in terms of the diameter of some segments of the intestine. Broiler breeder hens also had a greater mass of internal organs compared to the dual-purpose layer hens.

Effects of a novel consensus bacterial 6-phytase variant on the apparent ileal digestibility of amino acids, total tract phosphorus retention and tibia ash in young broilers

The effect of a novel consensus bacterial 6-phytase variant (PhyG) on apparent ileal digestibility (AID) of amino acids (AA) and phosphorus (P) utilization in young broilers when added to diets with high phytate-P (PP) content without added inorganic phosphate (Pi) and deficient in digestible (dig) AA and metabolizable energy (ME) was investigated. A total of 256 Ross 308 male broilers were assigned to 4 treatments (8 birds/cage, 8 cages/treatment) in a completely randomized design. Treatments comprised a positive control (PC, 2,975 kcal/kg ME, 3.7 g/kg dig P, 2.83 g/kg PP, 8.4 g/kg Ca, 10.6 g/kg dig lysine), a negative control (NC) without added Pi (ME −68 kcal/kg, crude protein −10 g/kg, dig AA −0.1 to −0.4 g/kg, Ca −2.0 g/kg, dig P −2.2 g/kg, Na −0.4 g/kg vs. PC), and NC plus 500 or 1,000 FTU/kg of PhyG. Test diets were corn/soy/rapeseed-meal/rice-bran-based and fed from 5 to 15 d of age. Ileal digesta and tibias were collected on day 15. Excreta was collected during days 12 to 15 to determine P retention. The NC (vs. PC) reduced (P < 0.05) P retention (−10.4% units), tibia ash (−14.3% units), weight gain (−109 g), feed intake (−82 g) and increased FCR (from 1.199 to 1.504), confirming that the NC was extremely deficient in nutrients and energy. Phytase addition to the NC linearly (P < 0.001) improved performance, but did not fully recover it to the level of the PC due to the severe nutrients/energy reduction in NC. Phytase linearly increased P retention (P < 0.001), tibia ash (P < 0.001), AID of dry matter (P < 0.05), nitrogen (P < 0.01), gross energy (P < 0.05), and all 17 individual AA (P < 0.01). At 1,000 FTU/kg, phytase increased (P < 0.05) P retention vs. PC and NC (+14.5 and +24.9% units, respectively) and increased tibia ash vs. NC (+13.8% units), equivalent to PC. The NC decreased AID of Cys, Gly, Thr, and Met vs. PC (P < 0.05). At 1,000 FTU/kg, phytase increased AID of all 17 AA vs. NC (P < 0.01), equivalent to PC. At 1,000 FTU/kg, AID AA responses (above NC) ranged from +4.5% (Met) to +15.0% (Cys), being maximal for essential Thr (+10.4%) and Val (+8.2%) and non-essential Cys (+15.0%) and Gly (+10.4%). The results highlight the efficacy of PhyG at a dose level of 500 to 1,000 FTU/kg in young broilers for improving the ileal digestibility of nitrogen, AA, and energy alongside P retention and tibia ash. The performance data emphasize the need to consider digestible nutrient intake as a response variable in exogenous enzyme studies.

Microbial phytase is widely used in commercial broiler diets to improve digestion of phosphorus (P) and reduce its excretion into the environment. Phytase improves the digestion of phosphorus and other nutrients including amino acids (AA). This study evaluated the effect of a novel consensus bacterial 6-phytase variant (PhyG) added to a nutrient-reduced diet without any added inorganic P on the digestibility of nutrients including P and AA in the ileum of young broilers. Effects on P retention and bone mineralization were also assessed. Compared to an unsupplemented negative control diet, PhyG improved growth performance, P retention, bone mineralization (tibia ash), digestibility of dry matter, nitrogen, gross energy, and all 17 individual AA during 5 to 15 d post-hatch, in a dose-dependent manner (dose range 0 to 1,000 phytase units [FTU] per kilogram of feed). For some AA, the increases in digestibility with PhyG at 1,000 FTU/kg were substantial (cysteine: +15.0%, threonine:+10.4%), and for all AA were equivalent to the responses produced by a nutritionally adequate positive control (unsupplemented) diet. The results demonstrate the efficacy of PhyG to improve AA digestibility alongside growth performance, P retention, and bone mineralization in young broilers.

Influence of Age on the Standardized Ileal Amino Acid Digestibility of Corn and Barley in Broilers

The aim of this study was to determine the standardized ileal digestibility coefficients (SIDCs) of nitrogen (N) and amino acids (AAs) in corn and barley at six different ages (days 7, 14, 21, 28, 35 and 42) of broilers using the direct method. The apparent AA digestibility coefficients were corrected using age-appropriate basal endogenous AA losses. No age effect (p > 0.05) was noted for the SIDC of N in corn. The average SIDC of indispensable AAs (IAAs) and total AAs (TAAs) was influenced in a quadratic manner (p < 0.05) with the values being higher at day 7 that decreased at day 14, increased and plateaued between days 21 and 35 and dropped again at day 42. The average SIDC of dispensable AAs (DAAs) was influenced linearly (p < 0.05). In barley, the SIDC of N and average IAAs, DAAs and TAAs was affected (quadratic; p < 0.001) by age. The digestibility increased from day 7 to 21 and then plateaued up to day 42. The present findings confirm that the SIDC of AA in corn and barley are influenced by broiler age and that the age effect on AA digestibility may need to be considered for precise feed formulation.

An investigation into the influence of age on the standardized amino acid digestibility of wheat and sorghum in broilers

Standardized ileal digestibility coefficients (SIDC) of nitrogen (N) and amino acids (AA) in wheat and sorghum at 6 different ages (d 7, 14, 21, 28, 35, and 42) of broilers were determined. Two assay diets were formulated to contain 93.8% of each grain as the sole source of AA in the diet. Titanium dioxide (0.5%) was added as an indigestible marker. Each assay diet was fed to 6 replicate cages housing 14 (d 7), 12 (d 14), 10 (d 21), 8 (d 28), 8 (d 35), and 6 (d 42) birds per cage for 4 d prior to ileal digesta collection. The apparent ileal digestibility coefficients (AIDC) were standardized by using the age-appropriate basal endogenous AA losses. In the case of wheat, AIDC of N and all AA increased (linear or quadratic, P < 0.05 to 0.001) with advancing age. No age effect was noticed on the SIDC of N, average of indispensable (IAA) and dispensable AA (DAA), though the average of total AA (TAA) tended (linear, P = 0.09) to increase as birds grew older. In sorghum, the AIDC of N, average of IAA and DAA were unaffected (P > 0.05) by age. The SIDC of N, average SIDC of IAA, DAA and TAA were higher at d 7, reduced at d 14 and then plateaued. Among the IAA, the SIDC of Arg, His, Ile, Leu, Lys, Thr, Val, and the SIDC of all individual DAA (except Cys) decreased with age (linear or quadratic, P < 0.05 to 0.001) with higher values at d 7. The higher SIDC values determined at d 7 were due to higher EAA losses during wk 1. The results showed that broiler age influences AA digestibility and this may need be considered in practical feed formulations. The age effect is variable depending on the grain type and specific AA.

Nutrition and Digestive Physiology of the Broiler Chick: State of the Art and Outlook

Simple Summary

The first week after hatch is the most challenging period in the life of broilers. The digestive tract of the newly hatched chick is immature and must undergo dramatic changes before it can efficiently digest and absorb nutrients. The gut is the vital organ where nutrient digestion and absorption take place. Ontogenic changes that accompany improved digestion and absorption include increased secretion of digestive enzymes, increase in the gut absorptive surface area, and enhanced nutrient transporters. The obvious limiting factors are the secretion and activities of digestive enzymes, and the surface area for absorption. These limitations are overcome as the birds grow older, with concurrent improvements in nutrient utilization. In addition, substantial changes also take place in the physical and functional development of the immune system and intestinal microbial ecology. However, the focus of the current review was on nutrition-related challenges and nutritional approaches to assist the chick during this highly demanding period.

Abstract

Because the intestine is the primary nutrient supply organ, early development of digestive function in newly hatched chick will enable it to better utilize nutrients, grow efficiently, and achieve the genetic potential of contemporary broilers. Published data on the growth and digestive function of the gastrointestinal tract in neonatal poultry were reviewed. Several potential strategies to improve digestive tract growth and function in newly hatched chick are available and the options include breeder nutrition, in ovo feeding, early access to feed and water, special pre-starter diets, judicious use of feed additives, and early programming.