The first 'Metabolism and Nutrition' session at the International Poultry Scientific Forum (IPSF), held in Atlanta, US in January 2013, included papers on a number of topics that are the focus of new research on poultry. In addition to well-researched areas of distillers dried grain with solubles (DDGS), feed enzymes and amino acid requirements, important work on calcium sources, feed particle size and mycotoxins was also reported.

Calcium Sources

An in-vitro evaluation of calcium sources and particle sizes on calcium and phosphorus solubility was reported by Hannah Wladecki of Virginia Polytechnic Institute and State University (1).

She concluded that particle size affected the solubility of both calcium and phosphorus. However, the response was dependent upon calcium source and location. The fine and medium particle sizes and highly soluble marine calcium source diets had the highest calcium solubilities overall.

Also from Virginia Polytechnic Institute and State University and including authors from AB Vista, Diego Paiva described his investigation into the effects of calcium levels and source as well as phytase supplementation on disease, focusing on the effects during a natural outbreak of necrotic enteritis (2).

He concluded that the lower calcium level (0.60 per cent) resulted in better broiler performance and there were indications that dietary calcium can induce mortality from necrotic enteritis.

The 21-day trial had a 2×2×2 factorial design, which included two dietary levels of calcium (0.60 per cent and 0.90 per cent), two calcium sources (limestone and calcified seaweed) and and two levels of an E.coli phytase (0 and 1,000FTU per kg).

Birds began exhibiting clinical signs of necrotic enteritis (NE) on day 9 and elevated NE-associated mortality persisted until the end of the trial. Mortality was significantly affected by an interaction between calcium source and level; significantly higher mortality was observed when birds were fed diets formulated with 0.90 per cent calcified seaweed than 0.60 per cent calcium, regardless of calcium source, and 0.90 per cent calcium diets formulated with limestone.

Mycotoxin Predisposes Birds to Necrotic Enteritis

* "DON altered intestinal barrier function but not the in-vitro growth of C. perfringens strains"

Continuing on the theme of the feed-related causes of necrotic enteritis, Gunther Antonissen of the University of Ghent in Belgium reported that the mycotoxin, deoxynivalenol (DON), predisposes broilers to necrotic enteritis by affecting the intestinal barrier (3).

He and his colleagues at Ghent as well as from the Institute for Agricultural and Fisheries Research in Melle, Belgium, and Biomin Research Center explained that Clostridium perfringens-induced subclinical necrotic enteritis and mycotoxins both cause important economic losses in the broiler industry. The Fusarium mycotoxin, DON, is a common feed contaminant that can affect the intestinal epithelial barrier function, and may as a result increase the availability of free amino acids in the intestine. This, Gunther Antonissen explained, can promote the massive intestinal proliferation of C.perfringens.

Their study aimed to evaluate and explain the predisposing effect of DON on necrotic enteritis, using an in-vivo infection trial mimicking subclinical necrotic enteritis and comparing intestinal lesions in broilers after feeding DON at a contamination level below the European maximum guidance level of 5,000µg kg feed, with broilers receiving non-contaminated feed.

The researchers found significantly more chickens showed necrotic enteritis lesions in the in-vivo study when their diet was contaminated with DON. It appeared that DON altered intestinal barrier function but not the in-vitro growth of C.perfringens strains.

Feed Manufacturing and Particle Size

* "The higher dietary ME from added fat and coarse maize treatments improved adjusted feed conversion ratio independently"

A study investigating the effect of calcium lignosulphonate and mixer-added fat on feed manufacture and the performance of broilers aged 23 to 42 days was reported by Alina Corey of West Virginia University (4).

The results demonstrate both of the additions affect feed manufacturing variables, and combined with feed form, they can affect broiler performance. The mechanism of interaction remains unclear.

Pelleting technique can affect feed form and nutrient availability, reported Ms Corey. Past research demonstrates that increased mixer-added fat (MAF) decreases frictional heat and pressure within the pellet die. The increased lubrication can maintain digestibility of heat-sensitive nutrients but may also decrease pellet quality. The use of pellet binders, such as calcium lignosulphonate, could enable high inclusions of the fat without causing detriment to pellet quality, they hypothesised.

The use of the pellet binder increased broiler feed intake and live weight gain. In addition, a three-way interaction of main effects occurred for feed conversion ratio. The interaction demonstrated that three per cent mixer-added fat was most beneficial to feed conversion for ground pellets and that the benefit was dependent on the interaction of the fat and binder for pellets.

Satid Auttawong of North Carolina State University reported a litter floor pen experiment evaluating the effects of maize (corn) particle size, dietary metabolisable energy (ME) level, mixer or post-pellet liquid fat application and time-limited feeding on broiler live performance to 28 days of age (5).

Although coarsely ground maize had a negative effect on feed intake during the starter phase, this was accompanied by improved adjusted feed conversion ratio, he reported. Both the higher dietary ME from added fat and coarse maize treatments improved adjusted feed conversion ratio independently.

In the experiment, chicks were assigned to a factorial arrangement of treatments consisting of two dietary inclusions of coarse maize (0 and 20 per cent or 0 and 35 per cent of total maize in starter and grower diets, respectively), two dietary metabolisable energy (ME) levels in grower diets (2.95kcal or 3.05kcal ME per g), two liquid fat application methods (all fat in mixer or 0.75 per cent in mixer plus the remainder added post-pellet) and two feeding programmes (ad libitum or time-limited). The fine maize was ground with a hammermill to 262 microns (2.4mm) while the coarse maize was ground with a roller mill to 1,082 microns. The two were blended to create the coarse maize inclusion levels.

In a related experiment, also from North Carolina State University, Yi Xu reported an evaluation of the effect of coarse maize inclusion on broiler growth performance, digesta retention time and gastrointestinal characteristics (6).

There were no differences in feed intake or bodyweight at 42 days of age. There was an improvement in adjusted feed conversion at 35 days (1.82 versus 1.74 and 1.69) and 42 days (1.94 versus 1.86 and 1.82) of age for the birds fed the 25 per cent and 50 per cent coarse maize diets as compared to 100 per cent fine maize, respectively.

Differences were observed between treatments in gizzard weight at 42 days of age, gizzard pH at 28 days of age, tensile strength of the ileum and digesta retention time.

In further work on coarse maize from North Carolina State University, the effects were investigated of phytase enzyme in broiler diets containing low phytate versus normal phytate soybean meal on male broiler live performance, development of the gizzard and proventriculus and total phosphorus digestibility (7).

Basheer Nusairat concluded from the results that the digestive environment created by both soybean meal phytate level and coarse maize affect phytase function and that these effects may involve changes in gizzard and proventriculus weight and function.

Feed intake and live performance to 21 days of age were not affected.

Feed Enzymes

An experiment conducted with Enzyvia LLC and Foster Farms to evaluate the inclusion of a cocktail NSPase (Enspira) in low energy maize-soybean meal diets on broiler growth performance and carcass yield was reported by Joseph Klein of Texas A&M University (8).

The data confirm that NSPase inclusion in low-energy diets improves growth performance and processing yields in maize-soybean meal diets.

The experimental design included three dietary treatments including a positive control, negative control with a reduction of 130kcal per kg throughout the experiment compared to the positive control and the negative control diet supplemented with the enzyme.

The addition of a novel, heat-stable xylanase decreased digesta viscosity and increased apparent metabolisable energy (AME) of broilers when included in both mash and pelleted wheat-based diets, according to I.B. Barasch of North Carolina State University following three experiments with BioResource International, Inc. (9).

There was a linear increase in AME with increasing xylanase enzyme concentration in two of the trials; in one, the AME was increased 140kcal per kg with 640 units per kg of the enzyme versus the controls fed no enzyme, while in the other, supplementation at 1,920 units per kg provided a 200-kcal per kg increase in AME over broilers fed an unsupplemented diet.

Beta-mannanase enzyme was hypothesised to improve the nutritional value of soybean meal-containing diets for turkeys by enhancing dietary energy utilisation and gut health by Ayuub Ayool of North Carolina State University (10).

Turkey poults were fed experimental diets consisting of a 2×2 factorial arrangement of two levels of dietary energy differing by around 150kcal ME per kg (high versus low fat) and two dietary inclusion levels of endo-beta-mannanase (0 versus 0.05 per cent CTCzyme® from CTCBIO, Inc. of Korea).

The results showed that, although dietary enzyme supplementation had minimal effect on growth performance and nitrogen-corrected AME, it appeared to improve intestinal mucosa health, nitrogen retention and fat digestibility, especially when fed high-fat diets.

Amino Acid Requirements

* "Increased dietary amino acid density from one to 42 days of age optimises profitability in male broilers"

In a trial with Poultry Technical Nutrition Services LLC, Kate Meloche and colleagues from Auburn University investigated the growth of male broilers fed diets varying in digestible threonine from one to to 14 days of age (11).

Using the linear broken line method, she reported optimal threonine to lysine ratios for bodyweight gain and feed conversion to be 70 and 68, respectively. These data support a minimum digestible threonine ratio of at least 68 for Hubbard × Cobb 500 male broilers to 14 days of age, she said.

Also from Auburn University and working with Poultry Technical Nutrition Services LLC, Kurt Perryman concluded from his experiment that increased dietary amino acid density from one to 42 days of age optimises profitability in Ross × Ross 708 male broilers (12).

They used a total of five experimental diets differing in digestible lysine content: basal, industry low, industry high, requirement and summit, which had weighted (based on feed intake) digestible lysine concentrations of 0.86, 0.93, 1.00, 1.07 and 1.14 per cent, respectively.

The birds grew faster and more efficiently when they consumed higher concentrations of digestible lysine. Economic return was maximised (at $3.89 versus $3.56 per bird) for broilers fed diets formulated to their amino acid requirements (1.07 per cent weighted digestible lysine.

Working with Adisseo of France, Kevin Bolek of Iowa State University reported his experiment looking at the effect of chick methionine status and methionine source on broiler performance and physiological response to acute and chronic heat stress (13).

Results indicate that heat treatment had significant adverse effects on bird performance but did not impact hepatic glutathione concentrations. The researchers observed that birds were able to adapt quickly to changes in blood parameters as differences in blood chemistry noted over the acute exposure were not seen after six days of heat exposure.

Neither methionine source nor concentration affected the parameters in this experiment, an observation that was attributed to the adequate dietary concentrations even under high environmental temperatures.

DDGS

* "Each one per cent decrease in the oil content leads to a 45.6kcal reduction in AMEn of DDGS"

The recent trend of removing oil from the thin stillage before mixing with residual grains has resulted in new dried distillers grains with solubles (DDGS) products with reduced oil content, according to Raj Murugesan (14).

He and colleagues at Iowa State Univeristy conducted a chick metabolisable energy experiment to determine the effects of oil removal from DDGS on the nitrogen-corrected AME in broiler chicks.

Their results indicate that in broilers at 27 to 28 days of age, each one per cent decrease in the oil content leads to a 45.6kcal reduction in AMEn of DDGS.

Megan van Benschoten of the Alltech-University of Kentucky Nutrition Research Alliance tested a strategy to increase the level of DDGS fed to brown laying hens (15).

They found that inclusion of up to 35 per cent DDGS in the diet can reduce feed intake in early lay and overall egg production. Including Alltech PN Broiler Grower Premix appeared to lessen these negative effects and increase Haugh units.

References

All papers were presented at the International Poultry Scientific Forum 2013. Atlanta, Georgia, US. 28 to 29 January 2013.

(1) Wladecki H. and A. McElroy. In vitro evaluation of calcium sources and particle sizes on calcium and phosphorus solubility.

(2) Paiva D., C. Walk and A. McElroy. Calcium, calcium source and phytase impact on bird performance during a natural necrotic enteritis outbreak.

(3) Antonissen G., F. Van Immerseel, F. Pasmans, R. Ducatelle, F. Haesebrouck, L. Timbermont, M. Verlinden, G. Janssens, M. Eeckhout, S. De Saeger, P. Boeckx, E. Delezie, S. Hessenberger, A. Martel and S. Croubels. Deoxynivalenol predisposes for necrotic enteritis by affecting the intestinal barrier in broilers.

(4) Corey A., K. Wamsley, T. Winowiski and J. Moritz. The effect of calcium lignosulfonate and mixer-added fat on feed manufacture and 23-42d broiler performance.

(5) Auttawong S., J.T. Brake, P.R. Ferket, C.R. Stark and S. Yahav. The effect of maize particle size, dietary energy level, post pellet liquid fat application, and time-limited feeding on broiler live performance to 28 days of age.

(6) Xu Y., C. Stark, P. Ferket and J. Brake. Evaluation of roller mill ground maize inclusions on broiler growth performance, digesta retention time, and gastrointestinal tract characteristics.

(7) Nusairat B., J. Brake, C. Stark and S. Yahav. Effects of phytase enzyme in combination with 50 per cent coarse maize in broiler diets containing low phytate versus normal phytate soybean meal on male broiler live performance, development of the gizzard and proventriculus, and total phosphorus digestibility.

(8) Klein J., M. Williams, B. Brown, S. Rao and J. Lee. Effects of dietary NSPase inclusion in low energy maize-soybean meal diets on broiler performance and carcass yield.

(9) Barasch I.B., J.L. Grimes, P.E. Biggs, J.D. Garlich and J.J. Wang. The effect of a novel, heat-stable xylanase on digesta viscosity and apparent metabolizable energy when fed to broiler chickens.

(10) Ayoola A., P. Ferket, R. Malheiros and J. Grimes. Effect of Β-mannanase supplementation of high and low fat diets on energy and protein utilization, gut morphology and mucin secretion of turkey poults.

(11) Meloche K., P. Tillman and W. Dozier III. Growth performance of male broilers fed diets varying in digestible threonine from 1 to 14 days of age.

(12) Perryman K., P. Tillman, W. Dozier III. Increased dietary amino acid density from 1 to 42 d of age optimizes profitability in Ross × Ross 708 male broilers.

(13) Bolek K., Y. Mercier and M. Persia. The effect of chick methionine status and methionine source on broiler performance and physiological response to acute and chronic heat stress.

(14) Murugesan G.R., B. Kerr, T. Weber and M. Persia. Energy utilization of reduced oil-dried distillers grains with solubles (RO-DDGS) in chicks.

(15) van Benschoten M., A. Pescatore, A. Cantor, T. Ao, R. Samuel, M. Ford, W.D. King and J. Pierce. Program Nutrition strategy on the productive performance and egg quality of brown laying hens fed distillers dried grains with solubles (DDGS) diets.

April 2013