Amino Acid Digestibility Coefficients Research Articles

Metabolizable energy and amino acid digestibility of soybean cake subjected to different dry extrusion temperatures for broilers

ABSTRACT Two experiments were conducted to evaluate the apparent metabolizable energy (AME), nitrogen-corrected apparent metabolizable energy (AMEn), and standardized ileal amino acid digestibility coefficient (SIDC) of extruded soybean cake (ESC) at four different extrusion temperatures: 90, 100, 110, and 120 °C. In experiment 1, 300 male broilers were randomly distributed into four treatments (600 g kg−1 reference diet + 400 g kg−1 of SBC at different extrusion temperatures) + reference diet, with six replicates of 10 birds. A metabolic assay [...]

Apparent metabolisable energy and amino acid digestibility of microalgae Spirulina platensis as an ingredient in broiler chicken diets

ABSTRACT1. This work investigates the apparent metabolisable energy (AME), its nitrogen-corrected form (AMEn) and amino acid (AA) digestibility coefficients of the microalgae Spirulina platensis as an ingredient in broiler chicken diets.2. One group of birds was fed with a basal control diet (BD), and another was fed with a test diet composed of the BD with the addition of the microalgae at a proportion of 200 g/kg. AME and AMEn were assessed by total excreta collection and indigestibility analysis using acid-insoluble ash (AIA) as a marker.3. The microalgae comprised 888.0 g/kg dry matter (DM), 18.42 MJ/kg gross energy, 514.7 g/kg crude protein, 9.9 g/kg ether extract, 10.6 g/kg crude fibre, 94.4 g/kg ash, 3.1 g/kg Ca and 11.0 g/kg P.4. The values obtained for AME (13.48 MJ/kg DM) and AMEn (11.72 MJ/kg DM) were higher (p < 0.01) than those obtained using the AIA method (9.39–8.29 MJ/kg DM). The microalgae ileal digestibility coefficients were 0.80 ± 0.04 and 0.78 ± 0.04 for essential and non-essential AA, respectively.5. Overall, the metabolisable energy content and digestibility of AA for S. platensis indicated that the microalgae are potentially an alternative nutrient source for broilers. The AIA method underestimated AME and AMEn in comparison to the total excreta collection method.

Dietary replacement of fishmeal by corn distillers dried grains with solubles (DDGS) in diets for turbot (Scophthalmus maximus, Linneaus, 1758) Juveniles

The aim of this study was to determine the potential of corn distillers dried grain with solubles (DDGS) to partially replace fishmeal (FM) in practical diets for turbot. For that purpose, a control diet was formulated to include 40% FM and a mixture of plant protein ingredients (soybean meal, corn gluten, and wheat gluten). Three other diets were formulated based on the control but with 10, 17.5, or 25% of DDGS replacing FM. Diets were tested in triplicate, in an 84-days growth trial with juveniles of 29 g initial body weight. Feed intake was not affected by diet composition, but growth and feed efficiency linearly decreased with the increase of dietary DDGS level. Whole-body dry matter and protein contents were not affected by diet composition, but lipid and energy content were higher in fish fed the control diet than the 17.5DDGS and 25DDGS diets and the 25DDGS diet, respectively. The apparent digestibility coefficients (ADCs) of protein and amino acids were similar among diets, while the ADCs of energy decreased with the increase of dietary DDGS level. Digestive amylase and lipase activities in posterior intestine were lower in fish fed the 17.5DDGS and 25DDGS diets than the control diet, while proteases activity was not affected by diet. No differences among dietary treatments were observed on plasma glucose, but plasma total protein, albumin, triglycerides, and cholesterol were lower in fish fed the DDGS diets. Activity of key enzymes of glycolysis, gluconeogenesis, and lipogenesis was not affected by diet composition, but activity of alanine aminotransferase increased with the increase of dietary DDGS. Moreover, oxidative status of liver and intestine was not affected by dietary treatments, but susceptibility to oxidative stress was higher in the intestine than in the liver. Overall, it is concluded that replacing FM by DDGS in practical diets for turbot juvenile reduced growth performance and impaired overall nitrogen and energy metabolism.

Amino acid digestibility of larval meal (Musca domestica) for broiler chickens

Work was undertaken to investigate the potential use of housefly (Musca domestica) larvae reared on broiler manure as a source of nutrition for poultry production in the United Kingdom. Nutritional analysis showed that larvae have a high (>45% dry wt.) protein content and a favorable amino acid profile that is rich in key amino acids, such as lysine and methionine. A broiler digestibility trial was carried out to determine the apparent ileal digestibility coefficients (AIDC) and true ileal digestibility coefficients (TIDC) of amino acids (AA) from insect larval meal (ILM) from M. domestica and fishmeal (FM) in broiler chickens. This was calculated using multiple linear regression technique based upon 3 inclusions of each protein source in a semisynthetic diet. One-hundred-forty-four day-old male (Ross 308) broilers were fed from hatch on a commercial starter diet for 20 days. Experimental diets were fed from d 21 to 28, and feed intakes were measured daily. On d 28, the trial was terminated, ileal digesta were collected for the determination of AIDC and TIDC of AA, and inflammatory responses (gizzard erosion and eye discharge) were measured. No significant differences were observed in digestibilities between protein sources for any AA. Furthermore, ILM feeding did not induce gizzard erosion or eye discharge at any inclusion. These results provide strong evidence to suggest that ILM of the common housefly can provide a successful alternative protein source to FM in broiler diets.

Responses in digestibilities of macro-minerals, trace minerals and amino acids generated by exogenous phytase and xylanase in canola meal diets offered to broiler chickens

Atypical diets based on canola meal (584 g/kg) and dextrose, supplemented with phytase and xylanase individually and in combination, were offered to 120 male Ross 308 broiler chicks with six replicates for each of the four treatments. The objective was to determine the effects of phytase and xylanase on the apparent digestibility coefficients of macro-minerals, trace minerals and amino acids along the small intestine of broiler chickens. The combination increased phosphorus digestibility by a two-fold factor (0.694 versus 0.324), calcium digestibility by a three-fold factor (0.527 versus 0.178), increased zinc from -0.141 to 0.324 and increased sodium digestibility coefficients from -1.402 to -0.359 in comparison to the control diet. Similarly, phytase and xylanase in tandem generated better responses in the apparent ileal digestibility coefficients of amino acids. The enzyme combination significantly increased the digestibility of nine essential amino acids by from 5.47% (methionine) to 35.4% (threonine), and seven non-essential amino acids by from 13.9% (glutamic acid) to 32.9% (proline). The better responses in apparent ileal digestibilities of phosphorus, calcium, sodium, zinc and five other trace minerals in broiler chickens offered the combination diet was confounded by its higher enzyme recovery activities in comparison to the individual supplemented diets and the study may suggest that the inclusions of phytase and xylanase in tandem should be considered in diets containing canola meal for broiler chickens.

Partial and total replacement of fishmeal by a blend of animal and plant proteins in diets forSeriola dumerili: Effects on performance and nutrient efficiency

A 154‐day trial was performed to assess the use of an alternative protein blend (corn gluten, krill and meat meal) as a substitute for fishmeal in diets for juvenile yellowtail, using four isolipidic (140 g/kg) and isoenergetic diets (24 MJ/kg) with the same digestible protein content (50%). The control diet was FM100, without replacement, and in FM66, FM33 and FM0, fishmeal was replaced at 33 g/kg, 66 g/kg and 100 g/kg, respectively. At the end of the experiment, no differences in growth parameters were observed. Fish fed the FM0 diet exhibited the lowest survival (23%). This high mortality may be due to different factors, such as a dietary amino acid imbalance or some antinutrient factors contained in the alternative ingredients. Feed intake, feed conversion ratio, digestible protein intake and protein efficiency ratio were similar in all diets. However, digestible energy intake and protein efficiency retention were lowest in fish fed the FM0 diet. Apparent digestibility coefficients for protein, energy and amino acids diminished as a substitution for fishmeal increased. Significant differences were observed in the diet whole‐fish body profile amino acid retention (AAR) ratio for the seven essential amino acids. In summary, total fishmeal replacement by the blend assayed was not feasible for yellowtail. The FM66 diet resulted in good growth, high survival and good nutrient efficiency.

Dietary starch influences growth performance, nutrient utilisation and digestive dynamics of protein and amino acids in broiler chickens offered low-protein diets

A total of 288 day-old, male Ross 308 chicks were offered six dietary treatments from 7 to 28 days post-hatch. A standard maize-soy diet was compared with five low protein diets containing high inclusions of maize starch and various combinations of supplemental amino acids. The assessed parameters included growth performance, nutrient utilisation, digestibility coefficients and disappearance rates of starch, protein and amino acids in four small intestinal segments. Also, the effects of three dietary treatments on free plasma amino acid concentrations in the anterior mesenteric vein or portal circulation were determined. The transition from standard to low protein diets elevated feed intakes and compromised FCR. Overall, tangible differences in responses were not observed in birds offered the five low protein diets which effectively precluded meaningful comparisons between the various combinations of crystalline amino acids. Maize starch inclusions in low protein diets enhanced starch digestibility coefficients and disappearance rates and parameters of nutrient utilisation. However, maize starch also depressed protein digestibility coefficients and disappearance rates. Moreover, amino acid digestibility coefficients were depressed in the three posterior segments of the small intestine. Instructively, proximal ileal starch digestibility coefficients were negatively correlated with digestibility coefficients of twelve amino acids in the proximal ileum to significant extents. Significant differences in concentrations of free amino acids in plasma from the anterior mesenteric vein were observed for histidine, lysine, methionine, threonine and valine in birds offered the standard and two low protein diets. The possibility that glucose and amino acids were effectively competing for intestinal uptakes, especially from the ileum, is discussed. Also, it appears that the metabolic fates of amino acids in enterocytes of the gut mucosa can be manipulated by dietary strategies and that crystalline amino acids may be less prone to undergo catabolism in the gut mucosa.

Progress in comprehending the phytate–phytase axis in chicken-meat production

After an extended delay, the level of acceptance of exogenous phytases by the global chicken-meat industry is now almost complete. Contemporary bacterial phytases degrade phytate primarily in the gizzard. The extent of phytate degradation determines the extent to which phytate-bound phosphorus (P) is liberated; however, studies designed to investigate phytate degradation along the digestive tract have generated some confusing outcomes. This may be related to the reactivity of the phytate moiety, coupled with problems with inert dietary markers and perhaps a lack of complete and uniform extractions of phytate from digesta due to variations in digesta pH and phytate solubility. Quite recently, phytase was shown to have profound impacts on sodium (Na) digestibility coefficients in four segments of the small intestine. This has obvious implications for intestinal uptakes of glucose and amino acids via their respective Na+-dependent transport systems and it is possible that phytate and phytase have reciprocal impacts on ‘sodium pump’ (Na+, K+-ATPase) activity. It has been recently demonstrated unequivocally that phytase has the capacity to increase amino acid digestibility coefficients to the extent that phytase may generate a ‘proximal shift’ in the sites of amino acid absorption. The impact of phytase on starch digestibility is more equivocal and phytase responses may stem more from enhanced glucose absorption rather than starch digestion. The acceptance of phytase is hardly surprising, given its capacity to increase P utilisation coupled with numerous other positive influences that are still being properly realised.

Metabolizable energy and amino acid digestibility of mash and pelleted diets for broilers determined under different methodologies

The objective of this study was to determine the interaction between feed processing and different methodologies for assessing apparent metabolizable energy corrected by nitrogen (AMEn) and standardized ileal digestibility coefficients (SIDC) of amino acids (AA) in broiler diets. A completely randomized design in a 4×2 factorial was used to evaluate AMEn by four methodologies and two physical forms of diet (mash and pelleted). The methodologies were total excreta collection and use of the markers: acid insoluble ash (AIA), titanium dioxide (TiO2) and chromium oxide (Cr2O3). After 5days of total excreta collection, all the birds were slaughtered and ileal content was assessed for AA. There was significant interaction (P<0.05) between the methodologies and physical form of the diets on AMEn values. Regardless of the physical form of the diet, the AIA marker provided similar AMEn values for total excreta collection on a DM basis. Pelleted diets had higher values (P<0.05) of AMEn (MJ/kg) on DM, except for Cr2O3. For AA, there was no interaction (P>0.05) between the markers and the physical form of the diets. There was no difference in SIDC between mash and pelleted diets (P>0.05). The AIA marker provided a higher SIDC compared to the TiO2 and Cr2O3 markers, except as regards methionine and lysine. Overall, pelleting increases dietary AMEn, but does not affect amino acid digestibility. Total collection and AIA lead to similar AMEn values, and AIA provides higher SIDC of the amino acids.

Standardized ileal digestibility of amino acids in European soya bean and rapeseed products fed to growing pigs.

This study was conducted to determine the chemical composition and standardized ileal digestibility coefficients (SID) of crude protein (CP) and amino acids (AA) of European soya bean and rapeseed products in pigs. Six soya bean and two rapeseed products were used as the sole dietary source of CP and AA, including raw (FFSB) and roasted full-fat soya beans (FFSBRoasted ), soya bean (SBC) and rapeseed cake (RSC), and rapeseed meal (RSM) from Bavaria (Germany), soya bean meal (SBM) from the Danube region (Austria; SBMAustria ), a commercially available standard SBM (SBMStd ) and an imported genetically modified organism-free SBM (SBMGMO-free ). Eight ileal- cannulated pigs with an initial body weight of 32±2kg were allotted to a row-column design with eight diets and six periods of seven days each. Trypsin inhibitor activity (TIA) ranged from 1.8 in SBMStd to 24.5mg/g DM in FFSB. The SID of CP and all AA in FFSBRoasted were greater than in FFSB, but lower when compared to SBC and SBMAustria (p<.05). The SID of CP and all AA (except glutamic acid) were not different between SBC and SBMAustria , but the SID of CP and all AA (except methionine) were greater (p<.05) in SBC than in SBMGMO-free . Furthermore, the SID of CP and most AA showed a quadratic response with decreasing TIA, and there exists a quadratic response in SID of CP and all AA with increasing lysine to CP ratio and neutral detergent insoluble nitrogen (p<.05). In conclusion, variation in chemical composition and SID of CP and AA was observed in different European soya bean and rapeseed products as influenced by differences in processing conditions. European SBC and SBMAustria can be used as alternative to imported SBMGMO-free and SBMStd in diets for growing pigs.

Apparent digestibility of animal, plant and microbial ingredients for Pacific white shrimpLitopenaeus vannamei

A digestibility trial was conducted to determine apparent digestibility coefficients of dry matter, protein, energy and amino acids of animal, plant and microbial ingredients for Pacific white shrimp, Litopenaeus vannamei. The tested ingredients included traditional soybean meal (TSBM), PepsoyGen soybean meal (PSBM), NutriVance soybean meal (NSBM), fish meal (FM), poultry meal (PM), squid hydrolysis (SQH), scallop hydrolysis (SCH), flash dried yeast (FDY), two batches of Ulva meal (UMF and UMS) and bacteria biomass (BB). A basal diet was formulated and produced along with the experimental diets which included 300 g/kg of each ingredient and 700 g/kg of the basal diet. Juvenile shrimp (initial mean weight: 12 g, six shrimp/tank, n = 3) were stocked in a recirculation system. Apparent dry matter, protein and energy digestibility coefficients ranged from −40.11% to 78.51%, 15.17% to 97.03% and 13.33% to 82.56% among different protein sources, respectively. In general, protein and energy digestibilities in soy sources (77.6% to 97.03% and 62.77% to 82.56%, respectively) are higher than the tested animal protein (51.39% to 71.41% and 45.29% to 69.77%, respectively) and single-cell protein sources (15.17% to 53.47% and 13.33% to 40.39%, respectively). Among the three soybean sources, TSBM showed highest protein and energy digestibility. Apparent individual amino acid digestibility coefficients were also variable among different types of ingredients, and there was a reasonable correspondence to protein digestibility. The most digestible feed ingredients for Pacific white shrimp in this study were conventional soybean meal (SBM) and NutriVance soybean meal (NSBM), which indicated that these ingredients are good protein and amino acid sources for Pacific white shrimp. Resultant digestibility data may provide useful information to commercial shrimp feed industry.

Evaluation of a fish meal analogue as a replacement for fish meal in practical diets for Pacific white shrimp Litopenaeus vannamei

Three six-week growth trials and a digestibility trial were conducted to evaluate a fish meal analogue (FMA) as a replacement for fish meal (FM) in shrimp feeds. Trials 1 and 2 evaluated and confirmed the potential of FMA supplementation (0, 48.5, 97, 145.5 and 194 g/kg) as a replacement for FM up to 200 g/kg without balancing for phosphorus (P) in practical diets for juvenile Pacific white shrimp L. vannamei. At the end of trial 1, shrimp offered diets containing 48.5 g/kg FMA exhibited significantly higher weight gain (WG) than those fed with the diet containing 145.5 g/kg FMA. At the end of trial 2, dietary FMA inclusion at 48.5 and 97 g/kg significantly improved WG and protein retention (PR), while reducing FCR and protein content of shrimp body compared to the diet containing 194 g/kg FMA. To determine whether P deficiency is the cause of reduced growth, the third trial was conducted utilizing equivalent diet but balanced for P. At the end of trial 3, shrimp fed diet containing 48.5 g/kg FMA+P showed significantly higher WG and PR than those fed diet containing 145.5 g/kg FMA+P. No decreasing trend of growth was detected in the diets containing FMA compared to the FM-based diet. Apparent digestibility coefficients of dry matter, energy, protein and amino acids of FMA were determined using chromic oxide as an inert maker and the 70:30 replacement technique. The energy, protein and individual amino acid digestibility of FMA were significantly lower than those of soybean meal and FM which were run at the same time. Results of this work indicate that FMA can replace up to 200 g/kg FM in shrimp diets with supplemental inorganic P. Given the good growth across the range of inclusion without any indication of a growth depression, the low nutrient digestibility of FMA may be due to an atypical response or the product simply does not work with the testing technique.

Evaluation of green seaweed Ulva sp. as a replacement of fish meal in plant-based practical diets for Pacific white shrimp, Litopenaeus vannamei

A growth trial and a digestibility trial were conducted to evaluate seaweed Ulva sp. as a substitution for fish meal (FM) in commercial-type feed formulation for Pacific white shrimp, Litopenaeus vannamei. Towards this goal, the 6-week growth trial utilized increasing levels (0, 6.35, 12.7, 19.05, and 25.4%) of the first batch of Ulva meal (UM1) to replace up to 8% FM in a plant-based feed formulation. At the end of the growth trial, shrimp offered diets containing 12.7, 19.05, and 25.4% UM1 exhibited significantly reduced weight gain. Apparent net protein retention (ANPR) was significantly decreased, while feed conversion ratio (FCR) was significantly increased when shrimps were fed with diets containing 19.05 and 25.4% UM1. Crude lipid content of whole shrimp samples were significantly decreased when UM1 was supplemented in the diets. Apparent digestibility coefficients of dry matter, energy, protein, and amino acids of two batches of Ulva meal (UM1 and UM2) were determined using chromic oxide as an inert maker and the 70:30 replacement technique. Energy and protein digestibility of UM1 and UM2 were significantly lower than FM and soybean meal (SBM) which were run at the same time. As a result of relatively low protein availability, individual amino acids digestibility of UM1 and UM2 are also significantly lower than those of FM and SBM. Results of the present study indicate that UM1 can be included in the shrimp diet up to 6.35% to replace 2% fish meal without resulting in growth depression. The low nutrients availability and high mineral contents of Ulva meal may explain a portion of the observed reduction in shrimp growth.

Evaluation of a novel bacterial biomass as a substitution for soybean meal in plant‐based practical diets for Pacific white shrimp Litopenaeus vannamei

Three growth trials and a digestibility trial were designed to evaluate the efficacy of a novel bacterial biomass (BB) in commercial-type feed formulation for Pacific white shrimp, Litopenaeus vannamei. In trial 1, the basal diet was supplemented with 0, 60 and 120 g/kg BB to replace soybean meal (SBM). Significant improvement was observed in the survival when BB was incorporated in the diets. However, shrimp fed diets containing 120 g/kg BB exhibited significantly lower weight gain (WG) and higher feed conversion ratio (FCR). To confirm the results from trial 1 and explore the effects of BB supplementation at low levels, the basal diet was incorporated with 0, 10, 20, 40, 60 and 120 g/kg BB to replace SBM in trial 2. Significant reductions in WG, FCR, lipid content of whole body, protein retention efficiency and most amino acids retention efficiency were detected in shrimp fed with diet containing 120 g/kg BB. Trial 3 was designed to elucidate whether the digestible protein is the cause of reduced growth. No improvements in terms of growth performance and FCR were detected in the treatments balanced for digestible protein. Apparent digestibility coefficients of energy, protein and amino acid (AA) for BB were determined using chromic oxide as an inert marker and the 70:30 replacement technique. The energy, protein and individual amino acid digestibility coefficients of BB were significantly lower than those of fish meal (FM) and SBM that were given at the same time. Results of this study indicated that BB can be utilized up to 40 g/kg in shrimp feed without causing a decrease in growth. However, supplementations (≥60 g/kg) of BB can result in negative effects on growth response, FCR and protein as well as amino acids retention efficiency. At the lower levels of inclusion, shrimp performance was improved when BB was supplemented on a digestibility basis; however, at the higher level of inclusion, there was no improvement, indicating there may be other nutrients limiting. Based on enhanced survival in the treatment with BB supplementation in trial 1, further research regarding the immune effects of BB in practical shrimp feed will be necessary.

Effects of processing, particle size and moisturizing of sorghum-based feeds on pellet quality and broiler production.

ObjectiveThis study aimed to assess the effect of pelleted and expanded sorghum-based feeds prepared with different moisture levels and particle size of ingredients on metabolizable energy, ileal digestibility of amino acids and broiler performance.MethodsThe experiment was performed with 720 male broiler chicks of the Cobb strain, with treatments of six replications, with 15 birds each; they were arranged in a completely randomized design and 2×2×2 factorial scheme (pelleted or expanded feed processing, 0.8% or 1.6% moisture addition in the mixer, and particle size of 650 or 850 microns).ResultsHigher pellet quality (pellets, % and pellet durability index [PDI]) was obtained in expanded diets and inclusion of 1.6% moisture. The particle size of 850 microns increased the PDI of final diet. All studied treatments had no significant effect on weight gain and broiler carcass and cut yields. Lower feed conversion occurred for birds fed pelleted feed at 42 d. The highest apparent metabolizable energy (AME) and apparent metabolizable energy corrected to zero nitrogen balance (AMEn) values of feed in the initial rearing phase (10 to 13 days) were observed in birds fed pelleted feed or for feed prepared with 1.6% moisture. The highest ileal digestibility coefficients of amino acids were obtained with the consumption of pelleted feed prepared with a particle size of 650 microns and 1.6% moisture.ConclusionPelleted feed prepared with a milling particle size of 650 microns and 1.6% moisture provided increased ileal digestibility of amino acids and AMEn in the starter period. However, the expanded feed improved pellet quality and feed conversion of broilers at 42 days of age. We conclude that factors such as moisture, particle size and processing affect the pellet quality, and therefore should be considered when attempting to optimize broiler performance.

Evaluation of a high protein distiller's dried grains product as a protein source in practical diets for Pacific white shrimp Litopenaeus vannamei

A series of trials were conducted to evaluate the efficacy of a high protein distiller's dried grains (HPDDG) product in practical shrimp feed formulation. In the three growth trials, the basal diet (35% crude protein, 8% lipid) consisted primarily of fish meal (FM), soybean meal (SBM), whole wheat, and corn starch. In trial 1 and trial 2, test diets were produced by supplementing the basal diet with 10, 20, and 30% HPDDG as a replacement for SBM or a combination of FM and SBM, respectively. In trial 1, shrimp (0.18 initial mean weight, 10 shrimp/tank, n=5) were offered diets for six weeks. No significant differences were detected in the growth and feed conversion ratio (FCR). In trial 2, shrimp (1.24 initial mean weight, 30 shrimp/tank, n=4) were offered diets over seven weeks. Significant reductions in growth and FCR were observed when shrimp were fed with diets containing >20% HPDDG. To explore the upper inclusion limit of this product a third trial was conducted for which the basal diet was modified to contain 6, 12, 18, and 24% HPDDG. Shrimp (0.25 initial mean weight, 10 shrimp/tank, n=4) were offered diets over six weeks. Significant reduced growth and increased FCR as well as enhanced iron and copper contents of whole body were detected in treatment containing 24% HPDDG. Apparent net sulfur, calcium, iron, copper, and zinc retention were also significantly affected by different HPDDG inclusions levels. Apparent digestibility coefficients of energy, protein, and amino acid (AA) for the meal were determined using chromic oxide as an inert marker and the 70:30 replacement technique. Generally, nutrients availability of HPDDG were similar to that of FM, while significantly lower than SBM that were evaluated at the same time. Result of this study indicate that HPDDG is a good plant based ingredient and can be included up to 30% as a replacement of SBM without compromising growth of shrimp. When HPDDG was utilized to replace a combination of SBM and FM, an upper limit of 18% of the diet should be recommended in shrimp feed formulation. The growth depression observed at high levels of inclusion is not likely due to digestibility but a limitation of some nutrients (e.g. marginal amino acids). Palatability shifts or unidentified factors could also be factors influencing the negative effects at high levels (≥18% of the diet).

Potential impact of the digestible indispensable amino acid score as a measure of protein quality on dietary regulations and health.

Regulatory frameworks for protein content claims in Canada and the United States are underpinned by the protein efficiency ratio and protein digestibility-corrected amino acid score (PDCAAS), respectively, which are used to assess the protein quality of a given food. The digestible indispensable amino acid score (DIAAS) is a novel approach to measuring the protein quality of foods and is supported by the Food and Agriculture Organization of the United Nations. Methodological concerns about the PDCAAS are addressed by the DIAAS through introduction of the use of ileal amino acid digestibility coefficients and untruncated protein scores. However, before the DIAAS is widely adopted within regulatory frameworks, a comprehensive assessment is required. Accordingly, this review addresses the potential impact of the DIAAS on regulation, communication, and public health, as well as knowledge gaps, analytical challenges, and cost of implementation. A pragmatic approach to addressing protein quality is advocated by suggesting the use of conservative coefficients of digestibility that are derived from in vitro methods. Before adopting the DIAAS as a framework for supporting protein content claims, updated food-related regulations and policies should also be evaluated through a lens that anticipates the impact on consumer-facing nutrition communication, the adoption of dietary patterns that are nutritionally adequate, and a food value chain that fosters a spirit of food and nutritional innovation.

Effect of gelatin supplementation on growth performance and blood metabolites of broiler chickens fed diets varying in crude protein

An experiment was conducted to investigate the effects of gelatin inclusion on growth performance, blood metabolites and carcass characteristics of broiler chickens fed diets varying in crude protein (CP) concentration in a 42-d study. Four concentrations of gelatin (0, 30, 60, and 90g/kg) and 2 concentrations of CP in the starter (220 and 200g/kg) and grower (195 and 182g/kg) periods were evaluated in a 2×4 factorial arrangement of treatments. Each diet was fed to 5 replicate pens of 15 male broiler chickens (Ross 308) from d 0 to 42. Digestibility coefficients of amino acid (AA) of gelatin were in the range of 0.90–0.95. Gly, Pro, Ala, and Glu were the major AA in gelatin. There were interactions between dietary CP content and gelatin concentration for feed intake (FI; P=0.016), body weight gain (BWG; P<0.001) and feed conversion ratio (FCR; P<0.001) during the starter (d 0–21), grower (d 21–42), and the overall experiment period (d 0–42). In the low CP diets, gelatin inclusion had a greater negative effect on BWG and FCR compared with those fed the normal CP diets over the course of the experiment (gelatin×CP, P<0.001). The contrasts showed that the increase in dietary gelatin content decreased BWG and FI, whereas FCR increased with higher dietary gelatin content from d 0 to 42. The CP×gelatin interactions showed that gelatin addition to the low CP diets increased plasma concentrations of glucose (gelatin×CP, P<0.01) and uric acid (gelatin×CP, P<0.001), and decreased N retention (gelatin×CP, P<0.001) to a greater extent than was the case for the normal CP diets at d 42. The CP×gelatin interactions indicated that gelatin inclusion in the low CP diets decreased carcass yield (gelatin×CP, P<0.01) and abdominal fat (gelatin×CP, P<0.001), and increased heart weight (gelatin×CP, P<0.01) to a greater extent than was the case for the normal CP diets. The present findings showed that gelatin inclusion had a greater negative effect on growth performance and carcass yield in broiler chickens that received the low CP diets compared with those fed the normal CP diet over the course of the study. Also, increasing dietary gelatin content depressed growth rate and N retention.

Amino acid digestibility of animal protein ingredients for bullfrogs in different phases of post-metamorphic development

The development of diets that economically and ecologically meet the requirements of bullfrogs (Lithobates catesbeianus) is important for frog farming. Therefore, the objective of this study was to determine the apparent digestibility coefficients for essential amino acids of eight animal feed ingredients (poultry byproduct meal, meat and bone meal, salmon byproduct meal, tilapia byproduct meal, spray-dried blood meal, powered red blood cells, feather meal and sardine meal) used in the diets of bullfrogs. Additionally, the limiting digestible amino acids were determined for each ingredient. Bullfrogs in different phases of post-metamorphic development were used: 810 animals in the early phase (mean weight: 40 ± 10 g), 405 animals in the growing phase (95 ± 15 g) and 243 animals in the finishing phase (175 ± 25 g). Poultry byproduct meal, salmon byproduct meal and blood meal exhibited the largest number of high apparent digestibility coefficients for essential amino acids (>70%) in the early, growing and finishing phases, respectively. The animal protein ingredients were well digested by the bullfrogs and could be used in practical diets for this species, respecting the limits of inclusion and digestibility values for each developmental phase.

Evaluation of flash dried yeast as a nutritional supplement in plant-based practical diets for Pacific white shrimp Litopenaeus vannamei

Growth and digestibility trials were conducted to evaluate the use of flash dried yeast (FDY) as a supplement in practical shrimp feeds. The six-week growth trial evaluated the effects of FDY supplementation (0, 10, 20, 40 and 60 g kg–1) in the plant-based practical diet on the performances and proximate compositions of juvenile Pacific white shrimp, Litopenaeus vannamei. Final biomass, final mean weight, per cent weight gain (WG), feed conversion (FCR) and protein retention efficiency (PRE) of Pacific white shrimp were not significantly influenced when FDY was added up to 40 g kg–1 of the diet. However, 60 g kg–1 FDY supplementation significantly reduced growth, feed utilization and protein retention. Supplementation of FDY in the practical diets of Pacific white shrimp did not affect protein, moisture, lipid, crude fibre, and ash content of whole shrimp body. Apparent digestibility coefficients of energy, protein, and amino acid (AA) for FDY were determined using chromic oxide as an inert marker and the 70:30 replacement technique. The energy and protein digestibility of FDY were 38.20% and 53.47%, respectively, which were significantly lower than fishmeal (FM) and soybean meal (SBM) that were run at the same time. Most amino acid digestibility of FDY was lowest among the three ingredients tested. Results of this work indicated that energy, protein and amino acid digestibility of FDY are lower compared to SBM and FM, and high levels supplementation (≥60 g kg–1) of FDY can cause negative effects to the growth response of Pacific white shrimp. Based on these results, further research regarding the effects of the low level inclusion of FDY in practical diets on immune responses of Pacific white shrimp is warranted.