Optimisation of distillery co-products for poultry feed

EU legislation has led to an almost ten-fold increase in bioethanol production between 2003 and 2011. The current distillery co-product, distiller’s dried grains with solubles (DDGS), is fed primarily to cattle due to the high fibre content but differentiation of the co-product stream would allow penetration of the large monogastric feed sector. The aim of this project was to evaluate a novel separation process producing a high protein yeast protein concentrate (YPC) from DDGS, and assess the potential of this product as a feed ingredient for poultry. A pilot plant study modelling the process confirmed the variability of the stillage, but highlighted the viability of the process for ameliorating some of these differences. Inter-batch variability was reduced from 10% to 1.2% in terms of protein content but dry matter content still varied by more than 8%, due to fibre contamination. The batches of yeast cream with increased fibre content had significantly reduced drying rates, from 37.3mg/min to 23.6mg/min, due to the larger particle sizes included. Additionally, the increased range of particle size introduced by fibre contamination would lead to product separation with detrimental implications for transport and handling of the dried product. It is vital to have measurements of amino acid content and digestibility for any new feed ingredient to ensure accurate feed formulation. Amino acid digestibility was measured in vivo in broiler chicks for five YPCs from potable and bioethanol sources produced using three drying technologies. Amino acid digestibility coefficients (COD) were significantly better for bioethanol produced YPC than potable (bioethanol 0.73 and 0.63 compared with 0.58 and 0.52 for potable). This is likely to be due to the addition of exogenous enzymes during the bioethanol process resulting in reduction of some of the detrimental effects of non-starch polysaccharides. Drying methodology affected both total amino acid content and digestible amino acid content, with spray drying being the least damaging method (COD 0.73 and 0.58) and ring drying the most damaging (COD 0.39). Lysine was particularly damaged during the heating process; reducing in total content from approximately 5% of protein to 2.3% of protein for ring dried material. Freeze dried YPC samples (COD 0.63 and 0.52) may have been negatively affected by the presence of fibre in the YPC due to processing inconsistencies. In terms of bird performance, bioethanol freeze dried YPC inclusion improved weight gain (p=0.003) and feed intake (p=0.006) compared with potable, again likely due to the enzyme addition during the bioethanol process. This was confirmed by the measured digesta viscosity increase in birds fed diets with increasing potable YPC inclusion (p=0.073). Spray dried YPC did not significantly affect FCR up to 20% inclusion, but both intake and bodyweight gain reduced with rate of inclusion. This may be attributed to spray drying producing a small particle size which increases feeding time and can increase viscosity, as was shown in this project (viscosity of spray dried YPC increased with RoI p=0.031). Ring dried YPC was incorporated into pelleted diets and therefore gave the best performance results. FCR for bioethanol YPC was improved from 1.68 for freeze dried material included at 9% of total diet to 1.4 for ring dried material at a higher rate of 12.5% of total diet. Finally the potential of YPC as a source of available phosphorus was considered, by assessing foot ash content of birds fed diets containing varying YPC levels. Increasing rate of YPC inclusion increased foot ash from 17.3% to 18.5% at 20% inclusion (p=0.031). YPC replaced 35% of supplemental phosphorus in chick diets with no significant effects on bone mineralization. The novel YPC from bioethanol distilleries appears to be a viable protein source for chicks at low inclusion levels (less than 6%). In pelleted diets the inclusion level could rise to 17.5% with no detrimental effects on bird performance. Additionally, YPC provides a source of available phosphorus, reducing the need for supplemental phosphorus in chick diets. The most appropriate drying method appears to be ring drying if care is taken to reduce residence time and heat damage. However there is substantial scope for further improvement of both the process and product as a feed ingredient for poultry

A comparison of two methods for determining titanium dioxide marker content in broiler digestibility studies

The use of inert markers in broiler diets eliminates the need to quantitatively evaluate feed intake and excreta output to determine diet digestibility, and enables nutrient uptake at specific points along the gastrointestinal tract to be examined. Titanium dioxide (TiO2) is commonly used for this purpose and measured using a UV spectrophotometric assay. Two experiments were conducted to observe whether an inductively coupled plasma optical emission spectrophotometer (ICP-OES) assay is able to replace the UV-spectroscopy assay for rapid analysis of TiO2 in broiler feed and ileal digesta samples. In the first experiment, TiO2 was added at 5g/kg to 19 broiler diets. Ross 308, male broilers (n=452) fed these diets were involved in a series of digestion studies to determine ileal digesta recovery of TiO2. In the second experiment, defined amounts of TiO2 were added to ileal digesta samples from Ross 308, male broilers (n=176) and TiO2 recoveries were determined

Use of Zn concentration in the gastrointestinal tract as a measure of phytate susceptibility to the effect of phytase supplementation in broilers

Zinc (Zn) is the most vulnerable cation to complexation with phytate. An experiment was conducted to evaluate the potential of measurements of Zn concentration in the gastrointestinal tract as a marker to assess the anti-nutritional impact of phytate and susceptibility of phytate to phytase in broilers. Ross 308 broilers (n = 180) were fed one of 5 experimental diets with differing phytase activity levels, analyzed at 605, 1150, 1804, 3954 and 5925 U/kg. Broiler performance and Zn concentration, pH and amount of phytate hydrolyzed in the gizzard, duodenum and ileum were analyzed at d21 post hatch. Phytate susceptibility to phytase degradation was determined in vivo and in vitro by measuring total phytate-P hydrolyzed in the tract or in conditions that mimicked the tract, respectively. Phytase activity level had a significant (P < 0.05) impact on Zn concentration and phytate hydrolyzed in the gizzard and ileum, but not in the duodenum. Strong relationships were observed between the amount of phytate hydrolyzed and Zn concentration in the gizzard in birds fed the diets with 1804 U/kg or higher levels of phytase. Phytate and phytase effects could therefore potentially be evaluated by measuring Zn concentration in the gizzard. Susceptible phytate levels measured in vivo and in vitro were almost identical in the diet with phytase activity of 5925 U/kg, but in the diets with lower phytase activity levels the in vitro assay overestimated the amount of P released. There were strong relationships between in vivo susceptible phytate level and pH and amount of phytate hydrolyzed in the gizzard, duodenum and ileum and Zn concentration in the gizzard and ileum. This illustrates that phytate susceptibility directly effects mineral availability in the gastrointestinal tract. Measurements of Zn concentration in the gastrointestinal tract, particularly in the gizzard, can potentially be used as a marker to assess the anti-nutritional impact of phytate and susceptibility of phytate to phytase in broilers

Understanding the direct and indirect mechanisms of xylanase action on starch digestion in broilers

The objective of the current study was to investigate the mechanisms of xylanase action in a maize-soya diet and its effect on starch digestion. A total of 60 broilers were divided into 6 treatment groups; a control group without xylanase, and five other groups supplemented with xylanase (Econase XT 25; 100 g/t) from 1, 2, 3, 4 or 5 weeks before slaughter. At the end of the experiment, digesta was collected from the gizzard, upper and lower small intestine, and both caeca. Digesta pH ranged from pH 2.2-4.4, 5.9-6.6, 6.7-7.8 and 5.7-7.3 in the gizzard, upper small intestine, lower small intestine, and both caeca, respectively, with no effect of xylanase (P > 0.05). Scanning Electron Microscope (SEM) images along with total starch measurements showed the progression of starch digestion through the tract. The SEM did not show any greater disruption to cell wall material with xylanase supplementation. This suggests that xylanase was not working directly on the cell wall and provides evidence for the hypothesis that xylanase works through an indirect mechanism. Peptide YY (PYY) concentration in the blood was higher during the first few weeks of supplementation, with longer periods of supplementation nulling this effect, implying that xylanase may be acting through a prebiotic mechanism. The RT-q PCR results revealed a numerical increase in glucose transporter (GLUT2 and SGLT1) expression at 2 and 3 weeks of xylanase supplementation, respectively, which might suggest a greater absorption capacity of birds. From these results, a potential mechanism of xylanase action in maize-based diets has been proposed

Bioavailability of a novel form of silicon supplement

In this study, we assessed uptake and potential efficacy of a novel, pH neutral form of silicon supplement in vitro and using broiler chickens as a model species. In vitro bioavailability of this supplement was significantly higher than other commercial supplements tested, all of which claim available silica content. To confirm bioavailability of the new supplement in vivo, a broiler chick feeding trial reported blood uptake that was significantly higher than a Bamboo-derived silicon supplement. We assessed dose response of the novel supplement in a further study with increased dose related levels of silicon being detected in the blood and tibia. We found tibia and foot ash residue as a percentage of dry mass was higher with inclusion of the novel supplement in the diet, particularly in young birds and that this was followed by significant increase in tibia breaking strength. This novel supplement may therefore have applications in the improvement of bone integrity, with implications for the reduction of lameness in broilers. These results indicate the novel silica supplement is readily absorbed in chicks, and transported in the blood supply to sites such as the skeleton due to it being present in a non-condensed, monomeric form. There is potential for wider application of this silica supplement in other species where bone breakages are a problem, including high performance sport

Evaluation of oats with varying hull inclusion in broiler diets up to 35 days

Use of local feed ingredients in poultry feed, such as oats, can be limited by their perceived less than ideal nutritional content. Dehulling oats is expensive and it may be that removing hull is detrimental to the bird in terms of gastrointestinal (GI) development, therefore maintaining some of the high fiber oat hull might reduce costs and improve potential for inclusion in poultry diets. Male broilers were fed diets with oats replacing 30% of wheat in diets, either dehulled or with graded inclusions of oat hull from day of hatch until day 35. Each diet was fed to 8 pens of 8 birds and performance recorded weekly. Samples were collected at day 21 and 35, for analysis of ileal amino acid digestibility, apparent metabolizable energy (AME) and gross gut development measures. No detrimental effect was seen on bird weight with hull inclusion, though higher inclusion levels did deleteriously effect feed intake due to increased gut fill from the fiber. AMEn was also adversely effected in the highest hull inclusion diets. However, amino acid digestibility was improved with hull addition, which may be due to an increase in GI tract length, improving nutrient absorption. Gizzard development was also significantly improved and thereby more efficient grinding of diet may also have improved digestibility. At a lower level of hull inclusion (3% total diet) where digestibility is improved without any detrimental effects on gut fill and intake. Oat hull is well known to improve gut development, especially of the gizzard, with resultant increases in digestibility. This is usually attributed to the mechanical effect of fiber in the gizzard having a grinding effect. However in this study, all fiber was finely ground, so the improvements seen cannot be attributed to a physical cause. Oat including diets with some hull remaining are a cost effective way of utilizing oats as a raw material while maximizing bird performance