If the papers presented at the IPSF earlier this year are anything to go by, escalating feed costs are leading researchers to focus on ways to get the most nutrients from conventional feed ingredients such as maize and soybean meal – for example, by adjusting particle size or using additives such as enzymes – or using less commonly used feed ingredients. Interactions between nutrition and health were also reported at the Forum, including the role of glutamine in the immune response of broilers chicks vaccinated against coccidiosis and how necrotic enteritis is impacted by dietary calcium and phosphorus.

Impacts of Feed Ingredients and Form

Soybean Phytate and Corn Particle Size for Broilers

B. Nusairat¹ of North Carolina State University presented the results of a 2×2 factorial experiment to compare normal (NP) and low–phytate (LP) varieties of soybean meal with corn either 50 per cent coarse or 100 per cent fine particle size in terms of the performance of male broilers to 21 days of age in battery cages.

Although bodyweight and feed conversion were improved with the fine diets at nine days of age, the difference did not persist to 21 days. There were no main effects of LP versus NP that persisted to 21 days of age. However, upon necropsy at 21 days of age, the LP diets produced a lower proventriculus weight while the coarse diets produced larger gizzards and smaller proventriculus weights.

The LP diets produced less ileal but more faecal total phosphorus as well as less phytate phosphorus. The LP diets also produced less faecal nitrogen. The coarse diets produced less ileal but more faecal moisture, less ileal nitrogen, and less ileal and faecal phytate phosphorus.

The greatest proventriculus weight was with the NP–fine combination, which could suggest a difference in digesta pH or digestive function affecting endogenous phytate hydrolysis, according to the researchers. This was supported by the finding that ileal and faecal phytate phosphorus was less in the NP–fine than NP–coarse diets and both were greater than the LP diets.

Feeding the 50 per cent coarse particle size corn reduced digestion of phytate phosphorus in NP diets but had no effect in LP diets in the presence of similar live performance in cages, concluded Nusairat.

Coarse– versus Fine–Ground Maize and Litter for Broilers

The results of a 49–day broiler floor pen study to evaluate the effect of coarse–ground corn and litter type on broiler performance and faecal characteristics of broilers were reported by Yi Xu² of North Carolina State University.

The experimental design was a factorial arrangement of two dietary levels of coarse corn (0 or 50 per cent) and two litter forms (finely ground old litter or new wood chip litter). A portion of the corn and all soybean meal were ground with a hammermill (2.4mm screen) to about 400µm, while the coarse corn was ground to with a roller mill to about 1350µm.

Inclusion of coarse corn reduced feed intake throughout the experiment, without affecting bodyweight. Consequently, dietary inclusion of coarse corn improved feed conversion compared to fine–ground corn and mortality rate was lower for coarse corn.

New litter improved feed conversion only to 14 days of age. Mortality rate was reduced by new litter among birds fed the fine corn diet.

At 49 days, faecal nitrogen and litter moisture were lower and faecal pH was higher for birds fed the coarse corn diet. Litter form did not affect faecal characteristics.

Xu concluded that dietary inclusion of 50 per cent coarsely ground corn improved feed conversion and reduced faecal nitrogen without adversely affecting bodyweight, while coarse litter gave a marginal benefit in terms of broiler growth performance.

Optimum Particle Size of Soybean Meal and Maize for Broilers

Wilmer Pacheco³ from North Carolina State University presented work on the effects of particle size of maize (corn) and expeller-extracted soybean meal (ESBM) in broiler diets.

The experiment had a 2×2 factorial design with ESBM particle size (coarse, 1290µm and fine, 470µm) and corn particle size (coarse, 1330µm and fine, 520µm).

Birds fed fine corn or ESBM had a higher bodyweight at 19 days than birds fed the coarser forms. Similarly, birds fed fine corn or ESBM had a higher feed intake at 19 days than birds fed the coarser materials.

A significant ESBM × corn particle size interaction revealed that birds fed fine ESBM and fine corn had significant lower ileal protein digestibility than the other treatments.

The larger particles (>1300µm) depressed feed intake, which resulted in lower bodyweights of the chicks at 19 days but ileal protein digestibility was improved and there was a small positive effect on fat digestibility, concluded Pacheco.

DDGS and Canola Meal in Turkey Diets

Mahmoud Farahat⁴ of the University of Minnesota reported investigations into whether chloride addition to diets (0.22, 0.32 or 0.42 per cent) with different levels of alternative feed products could shift the dietary electrolyte balance to levels that could adversely affect turkey performance and litter moisture.

No differences were observed in bodyweight or average daily gain over the whole trial period (two to 14 weeks of age). Birds fed diets with DDGS or DDGS with canola meal consumed six per cent more feed daily than those fed the control diet based on corn, soybean meal and meat meal. No differences were found for chloride or diet × chloride interaction for bodyweight, daily gain or feed intake.

Feed efficiency was higher for birds fed diets containing DDGS or DDGS with canola meal, and a diet × chloride interaction was found for feed conversion. Litter moisture was higher for the ‘alternative’ diets but the differences from the control were not statistically significant.

Farahat concluded that attention should be paid to the dietary electrolyte balance and chloride level during incorporation of DDGS with canola meal in turkey diets as chloride levels higher than 0.22 per cent could be detrimental to feed efficiency.

AME of Fats Evaluated for Broiler Chickens

A digestibility study conducted to determine the nitrogen-corrected apparent metabolizable energy (AMEn) of various lipid sources in broiler chickens was presented by Raj Murugesan⁵ of Iowa State University.

The 22 dietary treatments comprised seven different oil sources (soy oil, corn oil, choice white grease, poultry fat, methyl soyate esters and two different blends of animal–vegetable fat) fed at three, six or nine per cent inclusion rates, in addition to a basal diet that did not contain fat.

The AMEn values (kcal per kg) were determined for each oil source from the equations and are as follows, soy oil, 8,121; corn oil, 7,801; choice-white grease, 8,883; poultry fat, 7,827; methyl soyate, 7,975; AV blend-I, 8,092; and AV blend-II, 7,480.

Direct comparison of the excess energy contributed by the three–per–cent diets against the energy determined through the slope of the regression line equations for each of the oil sources provided an average of 69 per cent increase over the energy value derived from the equations. This increase in estimated energy by difference in comparison to slope-ratio analysis can be attributed to an extra–caloric effect of the additional fat due to increased digesta transit time and absorption rate of dietary energy, concluded Murugesan.

Nutrient Effects

Calcium and Phosphorus Requirements of Heritage Broilers

M.J. Da Costa⁶ of North Carolina State University described a study to evaluate the effects of calcium and non–phytate phosphorus levels during the grower phase (18 to 35 days of age) on bone biomechanical properties and leg abnormalities of Heritage broilers.

Common starter and finisher diets were fed from days 1 to 17 and 36 to 49 of age, respectively. Treatments consisted of 16 diets containing combinations of four levels of calcium (0.46, 0.62, 0.78 and 0.94 per cent) and four levels of non–phytate phosphorus (0.23, 0.30, 0.37 and 0.44 per cent).

Male tibia ash increased as calcium and non–phytate phosphorus levels rose although in females, only calcium had a linear effect on bone mineralisation. Non–phytate phosphorus levels had a linear effect on male bone mineral content and bone mineral density. Female bone strength was affected by a calcium × phosphorus interaction, and it responded linearly to calcium in males.

According to Da Costa, calcium and phosphorus in grower diets influenced bone traits and the prevalence of leg problems but did not influence walking ability in Heritage broilers.

Carryover of Lysine from Broiler Breeders to Progeny

Two experiments were reported by Leonel Mejia⁷ of Mississippi State University into the performance of the progeny from broiler breeder hens fed diets differing in digestible lysine.

In Experiment 1, treatment diets were fed from 35 to 45 weeks of age. Treatment 1 and 2 diets were formulated with commonly used feed ingredients and provided daily digestible lysine daily intakes of 1,200 (IDL) and 1,010mg per hen per day (ID), respectively. Treatments 3 and 4 were composed of semi-purified diets formulated to contain digestible lysine intakes of 1,010 (SPL) and 600mg (SP) per hen per day, respectively. Chicks corresponding to eggs collected from week 42 were grown to 56 days of age.

Chick weight at hatch was lower for those that came from the SP and SPL–fed hens but 42– and 56–day bodyweights were similar for all treatments. Marginal improvements in feed conversion were seen at 42 and 56 days for chicks from ID–fed hens over IDL hens.

For Experiment 2, diets were fed to hens from 24 to 42 weeks of age. Treatment 1 was a corn and soybean meal–based diet formulated to have a digestible lysine intake of 1,000mg per hen per day (CS1,000). Treatments 2, 3 and 4 had the inclusion of DDGS with digestible lysine intake levels of 1,000 (DDGS1,000), 800 (DDGS800) and 600mg (DDGS600) per hen per day, respectively. Progeny performance was evaluated from eggs collected at weeks 26, 31 and 36.

Chick hatch weight was similar for all three hatches.

Birds from hens at 26 weeks and fed DDGS600 diets had lower bodyweight, carcass and breast weight, and higher back half weight at 42 days of age. No effects were observed for any parameter at 56 days.

Grow–out studies performed on eggs laid during weeks 31 and 36 revealed that digestible lysine intake levels had no effect on live performance or carcass characteristics of the progeny in these experiments. However, Mejia concluded that the impact of dietary lysine in the breeder hen diet on progeny performance requires further evaluation.

Optimum Level of Canthaxanthin for Older Broiler Breeders

Professor John Brake⁸ of North Carolina State University reported the results of a trial in which broiler breeders that had been exposed to hot summer conditions were given diets containing 0, 3, 6 or 9mg canthaxanthin per kg diet from 45 to 62 weeks of age. Average hatchability and fertile hatchability of the flock was 87.6 per cent and 92.6 per cent, respectively, at 44 weeks of age.

Over the trial period, percentage hen–day production (49.1, 49.3, 51.6 and 50.9 per cent), percentage fertility (94.7, 94.9, 95.3 and 93.1 per cent) and percentage fertile hatchability (94.0, 95.2, 96.2 and 95.3 per cent) exhibited a dose–related increase from 0 to 3 to 6mg canthaxanthin per kg diet, followed by a decrease at 9mg per kg.

These data suggested that the optimum dosage of canthaxanthin to support reproductive performance in older broiler breeders was approximately 6mg per kg diet of both males and females, concluded Professor Brake.

Standardised Ileal Amino Acid Digestibility of Feed Ingredients for Hens and Broilers

Sunday Adedokun⁹ of Purdue University, working with Evonik–Degussa Corporation, presented standardised ileal amino acid digestibility (SIAAD) of five bakery by-product (BBP), three corn, three soybean meal (SBM), and one wheat middling (WM) samples in 21–day–old broilers and laying hens aged 30 or 50 weeks of age.

Standardisation was by correcting for basal endogenous amino acid (EAA) losses using a nitrogen-free diet (NFD).

Results from the study confirmed the observation from previous studies that amino acid digestibility from the same feed ingredient may be different in broilers and laying hens. Furthermore, the researchers concluded that variations in digestibility values within each feed ingredient underscores the fact that there may be siginficant variation within the same feed ingredient from different sources.

Nutrition × Health Interactions Investigated

Glutamine Utilisation and Coccidiosis Vaccination

Vaccines have proven to be a good strategy to prevent coccidiosis but the process of immunity acquisition needs to be approached from a nutritional point of view as well if complete success in broiler performance is to be achieved, according to F.J. Mussini¹⁰ from the University of Arkansas. It has been reported that the amino acid, glutamine, plays a key role both in the gastrointestinal tract and the immune system, and its utilisation could be beneficial to coccidiosis–vaccinated broilers.

In the study, day–old male chicks were vaccinated at a commercial hatchery with a coccidiosis vaccine and randomly allocated to one of four treatments: 0, 0.5, 0.75 and 1.0 per cent glutamine to 28 days and a common diet from 28 to 42 days.

Body weights were significantly improved at 21 and 28 days for all the treatments; feed conversion was reduced with the inclusion of glutamine, showing a positive trend although the reduction was not significant. There were no significant differences at 42 days in body weight and feed conversion.

Mussini concluded that glutamine proved to be beneficial during the process of immunity acquisition, improving broiler performance significantly until 28 days and maintaining the body weight difference until the end of the experiment.

Calcium, Phosphorus and the Necrotic Enteritis Pathogen

Diet composition and nutrient balance can have a critical impact on intestinal integrity during exposure to enteric pathogens, reported Diego Paiva¹¹ of Virginia Tech, working in conjunction with AB Vista to investigate the effects of dietary calcium, phosphorus and phytase on broiler performance during exposure to Clostridium perfringens.

The 35–day trial used a factorial design, which included two levels (0.6 and 0.9 per cent) of a highly soluble calcium source, two levels of available phosphorus (0.3 and 0.45 per cent) and two levels of phytase (0 and 1,000FTU per kg). Day–old birds were placed on litter from a previous flock that exhibited clinical signs of necrotic enteritis.

Birds began exhibiting clinical signs of necrotic enteritis on day 9, and elevated necrotic enteritis–associated mortality persisted until day 26.

Mortality was influenced by the main effects of dietary calcium or phytase.

The results suggest a high level of soluble calcium in the diet may influence necrotic enteritis–associated mortality, according to Paiva, and bird performance was affected by interactions of calcium, phosphorus and phytase during exposure to C. perfringens and the necrotic enteritis outbreak.

New Investigations into Optimising the Use of Feed Enzymes

Simultaneous Feeding of Protease and Carbohydrase Enzymes

Anti-nutritional factors in grains, such as wheat and barley, can decrease digestive efficiency and thus decrease the nutritive value of the feed ingredients, according to I.B. Barasch¹² of North Carolina State University, working in a team with BioResource International, Inc. Exogenous enzymes, such as carbohydrases (CH) and proteases can be added to animal feed to improve nutrient utilisation, feed conversion and body weight gain.

The objective of the two studies reported was to determine whether the protease reduced the effectiveness of the carbohydrase. In study 1, the basal diet was 30 per cent wheat and 20 per cent barley and in study 2, it was 15 per cent wheat and 40 per cent barley.

The treatments consisted of a positive control with high fat, a negative control with low fat, and low–fat diets containing a commercially available carbohydrase, protease or both.

The data from these studies, according to Barasch, showed that there was no interference of the protease on the carbohydrase activity and that the protease used in this study can be used in combination with commercial carbohydrases.

Effects of Phytase on Broilers Vaccinated against Coccidiosis

Broiler performance, apparent ileal amino acid digestibility (IAAD) and small intestinal pH and morphology were evaluated in a factorial experiment with dietary phytic acid (PA), phytase and a live coccidia oocyst vaccine and reported by Regina Lehman¹³ of Virginia Tech, working in a team with AB Vista.

Day-old broilers were either spray–vaccinated with a live vaccine or received no vaccine. Birds were allocated to one of four diets: low PA without phytase, low PA with 1,000FTU per kg phytase added over the top, high PA without phytase, and high PA with 1,000FTU per kg phytase added over the top. Low– and high–PA diets were formulated to contain 0.21 and 0.29 per cent phytate–phosphorus, respectively, while maintaining similar available phosphorus levels.

The addition of phytate and phytase to nutritionally adequate diets altered intestinal morphology and pH, according to Lehman. Phytase at 1,000FTU per kg improved intestinal morphology and IAAD, and changed pH in the gastrointestinal tract by alleviating the anti–nutrient effects of phytate, especially in young broilers.

Efficacy of a Mycotoxin–Degrading Enzyme

Mycotoxins are a potential threat in poultry production, leading to decreased performance and impaired health. Karin Naehrer¹⁴ of Biomin Holding, reported an experiment conducted at the SAMITEC Institute in Brazil to evaluate an experimental feed additive containing a fumonisin–degrading enzyme (FUMzyme®) in diminishing the toxic effects of aflatoxins (Afla) and/or fumonisins (FUM) added to broiler rations.

Addition of aflatoxins and/or fumonisins added to broiler rations negatively influenced the final body weight and the feed intake. In animals challenged with fumonisins (and aflatoxins), the biomarker for fumonisin exposure – the sphinganine:sphingosine ratio – was significantly higher.

Naehrer concluded that affected parameters like final body weight, feed conversion and sphinganine:sphingosine ratio were improved by the addition of the experimental feed additive in the birds exposed to mycotoxins.

Effects of Enzymes on Ileal Digestibility of Maize and Wheat Diets

Two studies with 21– or 42–day–old male broilers were performed to evaluate changes on the ileal energy contribution of substrates in response to xylanase and amylase without (XA), or with protease (XAP) in four diet types, reported Luis F. Romero¹⁵ of Danisco Animal Nutrition. Both studies used a factorial arrangement of treatments with two base grains (corn–soy or wheat–soy diets); two levels of fibrous protein ingredients (without or with 10 per cent corn–DDGS and five per cent canola meal); and three enzyme levels (a negative control with 500FT per kg phytase (NC); NC with XA, or NC with XAP (Axtra XAPTM, Danisco Animal Nutrition).

Across diet types, starch digestibility increased with XA and XAP compared to the NC but no differences were observed between XA and XAP. XA and XAP increased protein digestibility at 21 days but only XAP increased protein digestibility compared to NC at 42 days. Both products increased fat digestibility compared to the NC at 21 and 42 days. Compared to NC, XA increased ileal digestible energy (IDE) by 52 or 87kcal and XAP increased it by 104 or 152kcal per kg dry matter at 21 days and 42 days, respectively.

Enzyme × protein ingredient interactions were not evident for starch, fat or protein digestibility, concluded Romero. Enzyme × grain interactions were present for starch digestibility at 21 and 42 days, and for fat digestibility at 21 days. No enzyme × grain or enzyme × fibre ingredient interactions were observed for IDE. Energy digestibility effects of enzymes were consistent across diet types.

References

All papers were presented at the International Poultry Scientific Forum in Atlanta, Georgia, US in January 2012.

1 Nusairat B., R. Qudsieh, C.R. Stark, V.R. Pantalone and J. Brake. Effect of low phytate and normal phytate soybean meal and dietary corn particle size on male broiler performance and nutrient digestibility to 21 days of age
2 Xu Y., C. Stark, P. Ferket and J. Brake. Effect of roller mill ground corn inclusion and litter type on broiler performance and fecal characteristics
3 Pacheco W., C. Stark, J. Brake and P. Ferket. Evaluation of ESBM and corn particle size on broiler performance.
4 Farahat M., E-S. Hassanein, W. Abdel-Razik and S. Noll. Effect of incorporation of DDGS and canola meal to turkey diets on the dietary electrolyte balance, performance, and litter moisture
5 Murugesan G.R., B. Kerr and M. Persia. Evaluation of energy values of various oil sources when fed to broiler chickens
6 Da Costa M.J., E.O. Oviedo, M.R. Dalmagro, P.L. Mente, K.N. Claassen, A. Mitchell, H. Engster and R. Mitchell. Effects of calcium and phosphorus levels during the grower phase for Heritage broilers: bone mineralization, strength and leg health
7 Mejia L., K. Lopez, C. McDaniel, H. Parker and A. Corzo. Evaluation of carryover effects of dietary lysine intake by Cobb 500 broiler breeder hens on progeny live performance
8 Brake J. A dosimetry study of the effects of canthaxanthin in broiler breeders from 45 to 62 weeks of age
9 Adedokun S., P. Jaynes, R. Payne and T. Applegate. Standardized ileal amino acid digestibility of feed ingredients in laying hens and broilers
10 Mussini F.J., S.D. Goodgame, C. Lu, C.D. Bradley, S.M. Fiscus and P.W. Waldroup. A nutritional approach to the use of anticoccidial vaccines in broilers: glutamine utilization in critical stages of immunity acquisition.
11 Paiva D., C. Walk, F.W. Pierson, R. Dalloul and A. McElroy. Dietary calcium, phosphorus and phytase effects on broiler performance during a natural exposure to Clostridium perfringens.
12 Barasch I.B., J.L. Grimes, P.E. Biggs, J.D. Garlich and J.J. Wang. Effect of a protease on a commercial carbohydrase when fed to broiler chickens.
13 Lehman R., H. Wladecki, C. Walk, A. Cowieson and A. McElroy. The effect of dietary phytic acid and phytase on performance and small intestinal health of coccidia-vaccinated broilers.
14 Naehrer K. and C. Mallmann. Effects of aflatoxins and fumonisins on performance of broilers and the efficacy of a feed additive containing fumonisin degrading enzyme.
15 Romero L.F., P.W. Plumstead and V. Ravindran. Ileal digestibility of energy, starch, fat, and protein in corn- or wheat-based broiler diets containing exogenous carbohydrases and protease.