Teaching the principles of least-cost poultry feed formulation utilizing the Solver function within a computer software workbook.

A Microsoft Excel workbook, User-Friendly Feed Formulation with Data from Australia (UffdAu.xlsm), has been developed for teaching feed formulation techniques to tertiary level, university students. It runs under both Microsoft Windows and Apple iOS operating systems. The example ingredient composition matrix is based on the Australian Feed Ingredient Database to illustrate the biological and econometric principles of least-cost feed formulation. The nutrient data are based roughly on recent primary breeder company recommendations. The workbook is easily adapted to appropriate ingredients, nutrients, and prices most relevant to the students, wherever it is used. The workbook uses the linear routines of Excel's Solver add-in under the Data heading in the header Ribbon. There is a worksheet illustrating how to adapt non-linear responses such as exogenous enzymes to typical linear models using a step function. Additional worksheets illustrate how proximate analysis can be interpreted in modern analytical chemistry terms and, how various feed energy measures are related to feed composition. UffdAu.xlsm is available free of charge from the Poultry Hub Australia website (https://www.poultryhub.org).

Assessment of potential enhancing effects of a carbohydrase mixture on phytase efficacy in male broiler chicks fed phosphorus-deficient diets from 1 to 18 days of age.

A total of 540 one-day-old male broiler chicks were used to evaluate the potential enhancing effects of a mixture of 2 commercial carbohydrase preparations on phytase efficacy. A nonphytate phosphorus (nPP) deficient diet (0.15%) was supplemented with different levels of phytase (0X, 1X, 2X, and 3X of recommended level of 500 phytase units per kg of feed), individually or in combination with different levels of a mixture of 2 commercial carbohydrase enzymes [0X, 1X, and 2X of recommended level (X = 0.2 g per kg of feed; a mix with predominantly xylanase and ß-glucanase activity)] to determine their effects on performance and bone development. A standard response curve was developed using graded levels of nPP (0.15 to 0.45%) from dicalcium phosphate in a diet with no phytase supplementation to estimate the phosphorus equivalency of the different enzyme combinations. Each diet was fed to 6 replicate pens of 5 male chicks from 1 to 18 d of age. Phytase at normal usage levels of 500 phytase units per kg of feed was effective (P < 0.05) in improving BW, increasing feed intake, reducing mortality rate, and increasing toe and tibia ash without significantly influencing feed conversion. Addition of extra levels of phytase (2X and 3X) significantly (P < 0.05) improved toe and tibia ash without further affecting performance traits. The carbohydrase mixture failed to improve performance or enhance phytase efficacy. The phosphorus equivalency of phytase was dose dependent, with estimates of 0.100, 0.123, and 0.213% for 1X, 2X, and 3X supplementation levels of phytase, respectively, based on tibia ash. In conclusion, results indicate that increasing the level of phytase resulted in significant improvements in utilization of dietary nPP, whereas the carbohydrase preparation had no significant effects on performance or had limited effects in enhancing phytase ability in young broiler chicks.

Assessment of yeast cell wall as replacements for antibiotic growth promoters in broiler diets: effects on performance, intestinal histo-morphology and humoral immune responses.

The study compared the effects of an antibiotic growth promoter (AGP), yeast (Saccharomyces cerevisiae) and yeast cell wall (YCW) on performance, microbiology and histo-morphology of the small intestine and humoral immune responses in Ross 308 broilers. The treatments (eight replicates/treatment, n = 12/replicate) were negative control (NC, without AGP), positive control (PC, supplemented with bacitracin methylene disalicylate, 400 mg/kg), Y and YCW (supplemented with yeast and YCW, respectively, 1000 mg/kg). Live weight at 42 days improved (p = 0.086) in the PC, Y and YCW groups. Feed conversion ratio was better (p = 0.039) in the YCW group compared with the other groups. Antibiotic growth promoter in the PC group shortened the villi in duodenum (p = 0.044). Mucosal Escherichia coli number was higher in the PC group (p < 0.001), whereas in the digesta E. coli number was lower (p = 0.001) in the PC, Y and YCW groups in relation to the NC. Mucosal Salmonella populations increased (p = 0.0001) in the PC group, whereas in the digesta, all treatments reduced the Salmonella (p = 0.0001). Following oral challenge with Salmonella pullorum, YCW increased E. coli numbers on the mucosa (p < 0.001) whereas in the digesta the Y group had lower (p < 0.0001) number of E. coli. In the digesta, Salmonella count was lower in the YCW group compared with the other treatments (p < 0.01). Yeast cell wall -treated birds exhibited better (p < 0.05) humoral immune response against Newcastle disease which was far more persistent over time than in any other treatments. It was concluded that the yeast and the yeast cell wall may have effects identical to BMD on performance of broilers and thus may constitute an effective replacement strategy in the dietary regimens for broiler chickens.