S. A. Adedokun

Standardized Ileal Amino Acid Digestibility of Plant Feedstuffs in Broiler Chickens and Turkey Poults Using a Nitrogen-Free or Casein Diet

The standardized ileal amino acid digestibility (SIAAD) of 5 plant-based ingredients was determined in 5- and 21-d-old broiler chicks and turkey poults. Two diets (N-free diet, NFD, and a highly digestible protein diet 10% casein, HDP) were fed to determine ileal endogenous amino acid flow, and each was used for endogenous amino acid correction for the plant-based ingredients. The plant-based ingredients evaluated were 2 samples of corn distillers dried grains with solubles (light and dark DDGS), canola meal, corn, and soybean meal. Each diet was fed for 5 d to 6 replicate cages containing 30 or 8 birds, which were sampled on d 5 or 21, respectively. For chicks, apparent ileal amino acid digestibility increased with age for all the feed ingredients. After standardization, SIAAD increased with age when chicks were fed DDGS and corn, but not soybean meal or canola meal. For all the feed ingredients evaluated, SIAAD values for both methods of standardization were not different at d 5. However, the HDP method resulted in greater SIAAD values for most of the amino acids in light DDGS, canola meal, and corn (d 21). In poults, the apparent ileal amino acid digestibility values increased with age for all the feed ingredients except the dark DDGS and canola meal. After standardization, there was no effect of age on amino acid digestibility in all the feed ingredients evaluated, with the exception of corn. Within a particular age (d 5 or 21), both methods of standardization resulted in similar amino acid digestibility values except for corn, for which the SIAAD values were greater (NFD method) in 11 amino acids. Results from this study showed that age-appropriate endogenous amino acid standardization is necessary and, in some cases, results in no age-associated differences in amino acid digestibility. With the exception of corn, standardization of amino acid digestibility with ileal endogenous amino acid flow from birds fed an NFD or HDP did not differ for most plant feedstuffs.

Factors affecting endogenous amino acid flow in chickens and the need for consistency in methodology

Accurate estimation of ileal endogenous amino acid (EAA) losses is important when formulating diets on a standardized ileal digestible amino acid basis. In addition to the undigested and unabsorbed amino acids of dietary origin, amino acids of endogenous origin, which can be basal or diet specific, are found in digesta. The improvement in the techniques used in amino acid analysis as well as a shift from sampling excreta to ileal digesta has resulted in more accurate amino acid digestibility coefficients. Despite this, however, it is important to determine the amino acids in the digesta that are of endogenous origin. Although the need for standardization and its associated advantages is still subject to debate, it is important to evaluate how values from various methodologies compare. Several methods have been used to estimate ileal EAA flow. The classical methods, including the regression method, the use of nitrogen-free diet (NFD), and the fasted cecectomized rooster method, are the most widely used. The criticisms with the last 2 methods are that birds are not in a normal physiological state and the ileal EAA flow is, therefore, underestimated. Different methods have resulted in different endogenous flow estimates, with the NFD method having the lowest values when compared with flows from the regression and highly digestible protein methods. In addition to the influence of methods on ileal EAA flows, the influence of the age of the birds on flow is important. Data on EAA losses are copious in the literature; however, variation in data across and within laboratories calls for investigation of factors contributing to the variation. This review compares results from different methods and examines the issue of repeatability and consistency of EAA losses data from different laboratories. Finally, composition of an NFD for estimating EAA losses is proposed.

Comparison of amino acid digestibility of feed ingredients in broilers, laying hens and caecectomised roosters

1. This study determined the effect of bird type (broilers, laying hens, or caecectomised roosters) on amino acid digestibility of feedstuffs from 5 plant sources and one animal source. 2. The standardised amino acid digestibility (SAAD) were obtained by correcting apparent ileal amino acid digestibility (AIAAD) values for basal ileal endogenous amino acid (EAA) flow obtained by feeding a N-free diet (NFD) to broilers and laying hens or from fasted EAA flow from caecectomised roosters. 3. The apparent total amino acid (TAA) digestibilities did not differ between broilers and roosters for three of the 6 feed ingredients. 4. Broilers had higher apparent total amino acid (TAA) digestibility than laying hens and roosters when fed on the maize diet (canola meal, maize, and soybean meal). 5. The apparent TAA digestibilities were similar across bird types for the dark distillers’ dried grain with solubles, but the apparent lysine digestibility was much lower in the caecectomised roosters (15%) than the broilers (49%) and laying hens (43%). 6. The standardised TAA digestibility values in roosters were higher than in broilers for three of the 6 feed ingredients (canola meal, soybean meal, or meat and bone meal). 7. There were no differences between broilers and roosters, however, in the standardised TAA digestibility values for maize, dark and light DDGS. 8. The standardised TAA digestibility values for laying hens were lower for maize, higher for meat and bone meal, but no different for the remaining ingredients when compared with broilers. 9. The results from this study showed that both the apparent and standardised amino acid digestibility values in caecectomised roosters, laying hens, and broilers ingredients are similar for some, but not all, feed ingredients. 10. Nutritionists should, therefore, be cautious about using digestibility coefficients obtained by different methodologies as values may differ.

Determining the equivalent phosphorus released by an Escherichia coli-derived phytase in broiler chicks

Seven-day-old male Ross 308 broiler chicks were used in a 14-d experiment to determine the equivalency value of a new phytase using corn-soybean meal based diets. The experimental diets consisted of positive control (PC) or negative control (NC) diets which were formulated to contain 5.0 or 1.2 g kg-1 non-phytate P, respectively, with a total P of 7.7 or 3.9 g kg-1, respectively; and respective calcium levels of 10.0 or 7.6 g kg-1. The test diets were formulated by the addition of monosodium phosphate (MSP; analyzed to contain 224.0 g kg-1 P) to the NC diet to supply 0.5, 1.0, or 1.5 g of P kg-1 diet, and phytase was added to the NC diet at 500 FTU or 1000 FTU kg-1 at the expense of corn starch. Each diet was randomly assigned to eight cages of four birds each. Body weight gain (BWG) showed both linear and quadratic increase (P < 0.05) with increasing level of dietary P or phytase supplementation (450 to 656 or 603 g, respectively). Feed efficiency (g BWG/g feed intake) increased linearly (P < 0.05) with ...

Ileal endogenous amino acid losses: Response of broiler chickens to fiber and mild coccidial vaccine challenge

The effects of mild coccidial vaccine (5× dose) challenge and fiber levels on ileal endogenous amino acid (EAA) losses was determined in 26-d-old broiler chickens using the regression method. Birds were fed semipurified diets containing 3 levels of casein (40, 80, or 120 g/kg of diet) as the only source of dietary protein at 2 levels of fiber (purified cellulose at 25 or 75 g/kg of diet). One half of the experimental birds were gavaged with coccidial vaccine on d 20. The 3 levels of casein were used to determine EAA losses for each replicate cage of birds. The design of the study was a randomized complete block employing a factorial arrangement of treatments with 2 levels of coccidial challenge (control or unchallenged, and challenged) and 2 levels of fiber, with 6 replicate cages per treatment and 8 birds per cage. Birds were killed on d 26 and contents from the entire ileum were flushed with distilled water and stored at -20°C until processed. Ileal EAA losses were determined from the ordinate intercept, at zero amino acid (AA) intake, of the regression of ileal digesta AA concentration in milligrams per kilogram of DM intake against dietary AA intake in milligrams per kilogram of DM. The effect of fiber level on EAA losses, expressed in milligrams per kilogram of DM intake, were higher (P < 0.05) for most of the AA in birds fed 25 g of fiber/kg of diet. Coccidial vaccine challenge decreased (P < 0.05) EAA losses for 8 of the 18 AA. A significant interaction between fiber level and coccidial vaccine challenge was obtained for all AA except His and Lys. Coccidial vaccine challenge resulted in increased (P < 0.05) NaPi-IIb expression. The results suggest that ileal EAA loss is higher in challenged birds fed the diet containing 25 g of fiber/kg of diet. Changes in EAA losses as a result of dietary fiber level and coccidial infection are important in amino acid nutrition of the broiler chicken.

Standardized ileal amino acid digestibility of meat and bone meal and soybean meal in laying hens and broilers.

The objective of this study was to determine the standardized ileal amino acid digestibility (SIAAD) of 7 meat and bone meal (MBM) and 3 soybean meal (SBM) samples in broilers (Ross 708) and laying hens (Hy-line W36). All 10 feed ingredients were evaluated in 21-d-old broiler chickens and 30- or 50-wk-old laying hens. Standardization was accomplished by correcting for basal ileal endogenous amino acid losses using a nitrogen-free diet. Broilers were reared in cages from d 0 to 16 on a standard broiler starter diet adequate in all nutrients and energy; thereafter, they were allotted to treatments using a randomized complete design with 6 replicate cages of 8 birds each. For the laying hens, 6 replicate cages of 6 birds each (542 cm(2)/bird) were used. Each treatment diet, which was fed for 5 d, was semipurified, with MBM or SBM being the sole source of amino acids in each diet. Ileal endogenous amino acid losses were not different between broilers and the 2 groups of laying hens. Meat and bone meal from different locations varied widely in digestibility. Broilers had higher (P < 0.05) SIAAD in 4 of the 7 MBM samples. In 2 of the 3 SBM samples, broilers had higher (P < 0.05) SIAAD for most of the nonessential amino acids. Generally, hens had 6.4 and 7.7% units less Met and Lys digestibility of all MBM samples after standardization. Dry matter digestibility values of the SBM samples were higher (P < 0.05) in broilers. Likewise, broilers had 4.1 and 1.5% units more Met and Lys digestibility of all the SBM samples evaluated compared with those from laying hens. The results of these experiments suggest that differences exist in the digestive capabilities of laying hens and broilers, which indicates that species-specific nutrient digestibility values or adjustments may be needed.

Comparison of endogenous amino acid flow in broilers, laying hens and caecectomised roosters

1. This study was conducted to determine and compare endogenous amino acid (EAA) flow in broilers, laying hens, and caecectomised roosters fed on either a nitrogen-free diet (NFD) or a highly digestible protein diet (HDP). 2. Also, the EAA flows using three methods (fasted, NFD, or HDP) in precision-fed caecectomised roosters were compared. 3. EAA flow did not differ between broilers and laying hens on either the NFD or HDP diets. 4. Endogenous amino acid flow in caecectomised roosters was 3·5–12-fold higher than for broilers and laying hens for both methods (NFD and HDP) of estimation. 5. When caecectomised roosters were fasted or precision-fed (NFD or HDP), there was no difference in EAA flow between the NFD- or HDP-fed birds. 6. However, flows from fasted roosters were lower than from roosters receiving either the NFD or HDP diet. 7. Results from this study showed that EAA flow is method-dependent. Total amino acid flow from fasted birds was 31% less than when a NFD was fed to caecectomised roosters.

Acute inflammation plays a limited role in the regulation of adipose tissue COL1A1 protein abundance

Obesity is an inflammatory condition that is also associated with increased extracellular matrix (ECM) gene expression. However, a direct link between adipose tissue inflammation and ECM gene expression has not been established. Therefore, we determined the effect of chronic inflammation induced by obesity and acute inflammation by lipopolysaccharide (LPS) challenge on ECM genes including biglycan (BGN), collagen 1A1 (COL1A1) and COL6A1, major ECM genes in adipose tissue. Male C57BL/6J mice fed either a control diet (10% fat calories) or a high-fat diet (HFD) (60% fat calories) for 6 weeks were treated with LPS or saline 24 h before sacrifice. Expression of ECM genes in the epididymal (EWAT) and subcutaneous adipose tissue (SWAT) was determined by RT-PCR and protein abundance by Western blotting. Human SWAT from lean and obese subjects was also analyzed. Increased messenger RNA (mRNA) expression of ECM genes BGN and COL1A1 was observed in the mouse EWAT after HFD (P<.05). However, reduced amount of COL1A1 protein was observed in EWAT of mice on HFD and in SWAT from obese human subjects. Acute inflammation induced BGN mRNA in EWAT, enhanced the gene expression of matrix metalloproteases (MMPs) 3 and 9. Acute inflammation also resulted in higher MMP9 gelatinolytic activity; however, this showed no association with COL1A1 protein abundance. Higher MMP2 expression in mice on HFD suggests its involvement in the reduction of COL1A1 protein abundance with HFD. Elevated MMP9 gelatinolytic activity in SWAT from obese humans indicates a prominent role for MMP9 in SWAT COL1A1 protein turnover in humans.

Dietary electrolyte balance influences ileal endogenous amino acid losses in broiler chickens

The objective of the current study was to determine the effect of nitrogen-free diets formulated with 2 ratios of corn starch and dextrose and 2 levels of dietary electrolyte balance (DEB; calculated as Na + K - Cl(-), in mEq/kg of diet) on ileal endogenous amino acid (EAA) losses in 48-d-old broiler chickens. On d 43, 240 broiler chickens were allotted to 4 dietary treatments with 6 replicate cages per diet in a completely randomized design. Each experimental diet was fed for 5 d (d 43-48). All diets were free of nitrogen with 2 ratios of corn starch-to-dextrose (0.31 and 1.04) and 2 levels of DEB (108 and 219 mEq/kg of diet). Final BW and BW loss between birds fed the 2 corn starch-to-dextrose ratios and between birds fed 2 levels of DEB were not different (P > 0.05). Birds fed the diet containing a high level of DEB consumed less (P < 0.05) feed than birds on the low-DEB diet. Birds on the high-corn starch-to-dextrose (1.04) diet showed a tendency for higher (P = 0.08) feed intake. High dietary dextrose level (corn starch-to-dextrose ratio of 0.31) resulted in higher (P < 0.05) ileal DM and energy digestibility. A high level of DEB resulted in higher (P < 0.05) ileal endogenous nitrogen loss. Arginine, Ile, Leu, Phe, Val, Ala, Glu, Gly, Pro, and Tyr secretion into the gut increased (P ≤ 0.05) with an increasing level of DEB. Endogenous His, Lys, Thr, Asp, Cys, and Ser showed a tendency for increased (P ≤ 0.1) losses with a high level of DEB. Mean ileal EAA losses for the indispensable and dispensable amino acids for the low-DEB diet were 81 and 82%, respectively, that of the birds fed the high-DEB diet. The 4 amino acids with the lowest endogenous flow were Met, His, Tyr, and Cys, whereas the highest endogenous flow was found in Glu, Asp, Val, and Leu. Data from the current study showed that EAA losses in the ileum of broiler chickens are significantly affected by DEB, but not by the ratio of corn starch to dextrose.

Determination of Nutrient Mass Balance in Turkeys

Retention and excretion of phosphorus and nitrogen were determined for turkeys fed 2 diets at 3 ages, via mass balance based on the nutrient content of consumed feed, carcasses, and litter. The 2 diets consisted of an industry diet (IND) and a low phosphorus + 600 U of phytase/kg (LP) diet. A subsample of birds was weighed and killed at 12, 15, and 18 wk of age for nutrient retention (via whole carcasses) and excretion (via litter). Diet did not affect BW or feed intake from 12 to 18 wk of age. The mass of phosphorus excreted from 0 to 12, 0 to 15, and 0 to 18 wk of age was 37, 46, and 40% greater for birds fed the IND diets compared with birds fed the LP diets. Phosphorus retained as the percentage of phosphorus consumed was greater at 12, 15, and 18 wk for birds fed the LP diets (67.0, 63.8, and 53.8%) than for birds fed the IND diets (47.3, 44.0, and 32.8%). The difference between the mass of phosphorus excreted, as calculated from litter, compared with feed intake minus carcass retention was less than 5% at 18 wk. The nitrogen retained averaged 90.7, 136.7, and 184.2 g/bird, whereas nitrogen excreted averaged 377.6, 620.7, and 921.8 g/bird at 12, 15, and 18 wk of age, respectively. Additionally, with an 18-wk average litter DM of 78.0%, the unaccounted for nitrogen at 18 wk was 427 and 405 g/bird for birds fed the IND and LP diets, respectively (40 and 37% of excreted nitrogen).