Although the International Poultry Scientific Forum held immediately preceding the International Poultry Expo has an emphasis on broiler production, some of the 159 platform presentations and 100 posters related to aspects of the nutrition and health of flocks producing shell eggs. The significant categories and individual presentations are reviewed:
Based on the high cost of ingredients, producers are evaluating enzymes, prebiotics and probiotics as additives to enhance feed efficiency.
Scientists at North Carolina State University in conjunction with Diamond V evaluated XPC, a yeast fermentation product on the performance of both white and brown strains. It was demonstrated that hen-day and hen-housed production, and the proportion of extra large eggs was enhanced by supplementation.
GalliPro Max, a Bacillus subtilis probiotic produced by Chr. Hansen that was evaluated in Brazil, increased egg production by 2.6%, egg weight by 1.4% and egg mass by 3.7%.
Combinations of enzymes are now available as commercial products. Danisco Animal Nutrition launched XAP combining a xylanase, amylase and protease formulated for corn-soybean meal-DDGS diets. Although trials were conducted on broiler chicks, the effect on diets for commercial hens would be beneficial since the additive improved amino acid digestibility especially when diets were supplemented with DDGS and canola meal. The enhancement in feed conversion ratio and the ability to reduce cost by downgrading nutrient specifications demonstrated in broilers would extend to commercial egg producing flocks.
Studies conducted in Brazil showed that enzyme supplementation allows reformulation of diets to achieve a lower feed cost without affecting either egg production or egg weight.
With the increase in cost of corn, higher levels of DDGS are now used in laying diets. The beneficial effect of enzyme supplementation was considered by investigators at the University of Kentucky, Nutrition Research Alliance in cooperation with Alltech. At a level of 23% DDGS inclusion, feed intake was significantly decreased and egg weight was improved by supplementation at both 15% and 23% inclusion. The negative effects of high levels of DDGS can be overcome by including an enzyme complex, Allzyme SSF in diets.
Scientists at the University of South Carolina in conjunction with colleagues from Denmark investigated the genetics of feather picking. Modern techniques incorporating microarray expression profiles were applied to strains selected for either high or low feather picking in comparison with controls. Certain differences were noted in the expression scores of transcripts between the high and low feather picking populations. It was also determined that the gene expression among population characterized by either severe or gentle feather picking was different. It is apparent that the heritability of feather picking and the neural processes involved are extremely complicated. Until mechanisms are defined, the industry will have to rely on phenotypic selection by the primary breeders and environmental modifications to reduce the prevalence of the condition. This topic may be of greater significance than at present as the industry transitions from caging groups of 4 to 5 hens to colony groups with over 100 birds per compartment.
Protein and Amino Acids
Studies conducted at North Carolina State University were conducted to evaluate the effect of either 16% or 18% crude protein on production from 18 to 42 weeks of age. Hen-day production responded positively to a 16% protein diet produced in an experimental facility compared to the 18% level. There was no effect of protein content on feed consumption, livability or egg quality. Most nutritionist now ignore crude protein content when formulating diets for laying flocks but concentrate on supplying adequate levels of critical rate-limiting amino acids to flocks. This is critical to attain the objective of minimizing feed cost per dozen eggs produced.
Various challenge models for Mycoplasma gallisepticum (MG) were evaluated at the USDA-ARS Poultry Research Unit. Intratracheal and eye drop installation were compared and the additional effect of administering infectious bronchitis virus vaccine was examined. Intratracheal infection stimulated a higher antibody response to MG but this route induced airsaculitis. Administration of Poulvac MycoF at six weeks of age subsequently protected pullets from airsacculitis when subsequently challenged with a field strain of MG of low pathogencity. Simultaneous administration of IBV vaccine intensified the effect of MG as denoted by tracheal thickness and lesions score.
E. coli is a significant opportunist pathogen in commercial flocks. Strains of E. coli vary in virulence although mechanisms associated with this characteristic have not yet been defined. The study conducted at the National Autonomous University of Mexico applied an embryo lethality test to differentiate between virulent and avirulent isolates. Attempts are underway to correlate virulence with specific genes which were identified, applying multiplex PCR technology. These studies may result in specific laboratory procedures to identify strains of E. coli which have the potential to induce airsaculitis and peritonitis. It is noted that the epidemiologic significance of E. coli septicemia has declined in recent years due to adoption of vaccination as a preventive measure together with improved ventilation and other management strategies.
New technology for measuring antibodies against the most frequently encountered poultry diseases have been developed by Luminex Corporation. The study conducted in conjunction with Tyson Foods showed that magnetic liquid micro sphere array assay could simultaneously test for antibodies against IBDV, NDV, IBV and reovirus. Luminex Poultry Serology reagents and standard protocols have been developed which correlate with ELISA technology. When installed in suitably equipped laboratories Luminex assays may prove to be less expensive and generate rapid results which will enable producers to fine-tune vaccination programs.
A Lactobacillus probiotic protected chicks from infection with Salmonella Heidelberg when administered orally or subcutaneously. Administration of the probiotic FloraMax developed at the University of Arkansas reduced cecal colonization and the presence of the organism in lymphoid tissues compared to untreated controls.
Disinfection of eggshells using ultraviolet light and hydrogen peroxide was evaluated for breeder eggs. A beneficial effect from UV treatment was confirmed. Although these trials considered hatching eggs the same principles are applicable to commercial eggs. It is noted that European grader installations now incorporate UV radiation. This is due in part to the fact that eggs are not washed in Europe and accordingly some form of physical decontamination is required to reduce bacterial surface counts on the shell surface.
Studies conducted at the National Autonomous University of Mexico compared shell thickness at the poles and the equator in eggs derived from flocks aged 29 weeks. The study concluded that a measurement of shell thickness at the equator of the egg provides a reliable determination of shell thickness alleviating the need to measure thickness at three points.