Current methods for feed formulation are based on minimizing costs,not maximizing profits.Complex models of bird growth and reproduction as functions of genetic,feed and other environmental variables are being develop...Current methods for feed formulation are based on minimizing costs,not maximizing profits.Complex models of bird growth and reproduction as functions of genetic,feed and other environmental variables are being developed,but their adaptation has been slow.The development of profit maximizing models will evolve to center on the production functions of broilers and layers.The production functions are the relationship between the value of products(mainly meat and eggs)and the cost of feed.The production function is the tool used to maximize profits subject to all the various inputs,not just feed or nutrition.The production function is subject to the law of diminishing returns.The most profitable output levels are those where the marginal value(price)of the meat or eggs is just equal to the marginal cost of the inputs including feed,housing,processing and all other costs.Anything that affects the production function,bird genetics,feed quality,housing and environment,will be considered to maximize profits for the poultry firm.The profit maximizing models of poultry firms will improve as various technical improvements are made:metabolizable energy to describe ingredients will evolve to net energy systems that consider that the heat production(and therefore energetic efficiency)of broilers is different depending on the ingredients used to formulate the feed and the environmental temperatures under which they are reared.Amino acid needs will include a method to find the birds’needs for the nonessential amino acids.“Digestible”amino acid assays will differentiate between digestion and absorption to best balance various sources.The carbohydrate fractions of feed ingredients will be determined to optimize the use of exogenous enzymes.The value of meat and egg co-products will reduce overall costs(e.g.,organic fertilizer for crop enhancement).Future profit maximizing production models will be ever evolving processes where field conditions and results are continually being utilized to re-calibrate the technical models so that the management team can use them with cost and return projections to decide on the best choices of inputs and outputs.展开更多
It has been demonstrated that the fiber content of oilseed meals and total amino acids(AA)in distillers'grains products affects standardized ileal digestibility(SID)values from swine assays and that total protein ...It has been demonstrated that the fiber content of oilseed meals and total amino acids(AA)in distillers'grains products affects standardized ileal digestibility(SID)values from swine assays and that total protein concentration affects the AA digestibility in assays using chickens.This analysis was conducted to test the hypothesis that the total AA content of test samples affects the SID assay results.Databases containing total AA profiles and SID values of 20 feedstuffs commonly fed to pigs from 2 sources,AMINODat 5.0(Evonik Industries,2015)and the Nutrient Requirements of Swine,12th edition(NRC,2012)were used to compare AA concentration effects on standardized ileal digestibility coefficients.Databases were compared with AA and SID available in both data sets.The total AA values were similar for the 2 databases with an R2 of 0.979(P<0.001).The linear relationship between digestibility co-efficients from the 2 databases was highly significant,an R2 of 0.810(P<0.001).Both databases had increased SID values with increasing AA contents within and across feed ingredients.The SID=f(AA concentration)relationship was confirmed with an individual paper.Since SID,as typically measured,is a function of both digestion and absorption,both processes following MichaeliseMenten kinetics,SID=f(AA concentration)may simply be a natural phenomenon.Other reasons for the relationship were explored.Methods of estimating endogenous AA losses and misapplication statistical procedures may contribute to variation in results and at least partially explain why SID=f(AA concentration).展开更多
In this paper,we discuss the theory behind calibration curve experiments and their application to a zinc(Zn)bioavailability study with broiler chickens.Seven replicates of 16 male commercial broiler chicks were fed st...In this paper,we discuss the theory behind calibration curve experiments and their application to a zinc(Zn)bioavailability study with broiler chickens.Seven replicates of 16 male commercial broiler chicks were fed starter diets for 14 days.Six diets had different levels of a potential Zn source and one was a positive control with standard industry levels of Zn for comparison.Four commonly used methods of calculating bioavailability means and confidence intervals(CI)from a calibration curve(standard curve)experiment to estimate the bioavailability of a new zinc source in broiler chickens were compared.The methods compared were the following:1)the Counter-Intuitive Method uses a multiple-range test to compare unknown test and standard samples;2)the Intuitive Method uses standard linear regression and inverts the equation to predict Zn bioavailability for each replicate of test samples;3)the Abductive Method uses Graybill's Equation,based on theory and observation,to estimate CI's;and 4)the Sophistic Method uses reverse regression,and calculates Zn bioavailability values directly from the equation.The Counter-Intuitive Method only gives information about which standards the test samples are,or are not,significantly different from respectively(average available Zn not predicted).The Intuitive Method ignores error about the standard curve and theoretically cannot estimate the CI directly(X±SEM=107.5±15.8 mg Zn/kg).The Sophistic Method underestimates and overestimates the test sample mean values above and below the mean of the standards,respectively(X=96.6 mg Zn/kg).The Abductive Method has an advantage over the other methods:The mean prediction estimation is consistent with theory(107.5±6.1 mg Zn/kg;X±SEM).When test or“unknown”samples are near the mean of the standard samples,the CI is smaller than when near the extremes of the calibration curve.When calibration curve error is small(R^(2)>approximately 0.95),there is little advantage to using the Abductive Method,but when calibration curve error is larger,as in many bioassays with growing animals,the Abductive Method improves the accuracy of the CI calculations.The Abductive Method was used to demonstrate the influence of the number of replicate samples on experimental power and cost.展开更多
文摘Current methods for feed formulation are based on minimizing costs,not maximizing profits.Complex models of bird growth and reproduction as functions of genetic,feed and other environmental variables are being developed,but their adaptation has been slow.The development of profit maximizing models will evolve to center on the production functions of broilers and layers.The production functions are the relationship between the value of products(mainly meat and eggs)and the cost of feed.The production function is the tool used to maximize profits subject to all the various inputs,not just feed or nutrition.The production function is subject to the law of diminishing returns.The most profitable output levels are those where the marginal value(price)of the meat or eggs is just equal to the marginal cost of the inputs including feed,housing,processing and all other costs.Anything that affects the production function,bird genetics,feed quality,housing and environment,will be considered to maximize profits for the poultry firm.The profit maximizing models of poultry firms will improve as various technical improvements are made:metabolizable energy to describe ingredients will evolve to net energy systems that consider that the heat production(and therefore energetic efficiency)of broilers is different depending on the ingredients used to formulate the feed and the environmental temperatures under which they are reared.Amino acid needs will include a method to find the birds’needs for the nonessential amino acids.“Digestible”amino acid assays will differentiate between digestion and absorption to best balance various sources.The carbohydrate fractions of feed ingredients will be determined to optimize the use of exogenous enzymes.The value of meat and egg co-products will reduce overall costs(e.g.,organic fertilizer for crop enhancement).Future profit maximizing production models will be ever evolving processes where field conditions and results are continually being utilized to re-calibrate the technical models so that the management team can use them with cost and return projections to decide on the best choices of inputs and outputs.
文摘It has been demonstrated that the fiber content of oilseed meals and total amino acids(AA)in distillers'grains products affects standardized ileal digestibility(SID)values from swine assays and that total protein concentration affects the AA digestibility in assays using chickens.This analysis was conducted to test the hypothesis that the total AA content of test samples affects the SID assay results.Databases containing total AA profiles and SID values of 20 feedstuffs commonly fed to pigs from 2 sources,AMINODat 5.0(Evonik Industries,2015)and the Nutrient Requirements of Swine,12th edition(NRC,2012)were used to compare AA concentration effects on standardized ileal digestibility coefficients.Databases were compared with AA and SID available in both data sets.The total AA values were similar for the 2 databases with an R2 of 0.979(P<0.001).The linear relationship between digestibility co-efficients from the 2 databases was highly significant,an R2 of 0.810(P<0.001).Both databases had increased SID values with increasing AA contents within and across feed ingredients.The SID=f(AA concentration)relationship was confirmed with an individual paper.Since SID,as typically measured,is a function of both digestion and absorption,both processes following MichaeliseMenten kinetics,SID=f(AA concentration)may simply be a natural phenomenon.Other reasons for the relationship were explored.Methods of estimating endogenous AA losses and misapplication statistical procedures may contribute to variation in results and at least partially explain why SID=f(AA concentration).
文摘In this paper,we discuss the theory behind calibration curve experiments and their application to a zinc(Zn)bioavailability study with broiler chickens.Seven replicates of 16 male commercial broiler chicks were fed starter diets for 14 days.Six diets had different levels of a potential Zn source and one was a positive control with standard industry levels of Zn for comparison.Four commonly used methods of calculating bioavailability means and confidence intervals(CI)from a calibration curve(standard curve)experiment to estimate the bioavailability of a new zinc source in broiler chickens were compared.The methods compared were the following:1)the Counter-Intuitive Method uses a multiple-range test to compare unknown test and standard samples;2)the Intuitive Method uses standard linear regression and inverts the equation to predict Zn bioavailability for each replicate of test samples;3)the Abductive Method uses Graybill's Equation,based on theory and observation,to estimate CI's;and 4)the Sophistic Method uses reverse regression,and calculates Zn bioavailability values directly from the equation.The Counter-Intuitive Method only gives information about which standards the test samples are,or are not,significantly different from respectively(average available Zn not predicted).The Intuitive Method ignores error about the standard curve and theoretically cannot estimate the CI directly(X±SEM=107.5±15.8 mg Zn/kg).The Sophistic Method underestimates and overestimates the test sample mean values above and below the mean of the standards,respectively(X=96.6 mg Zn/kg).The Abductive Method has an advantage over the other methods:The mean prediction estimation is consistent with theory(107.5±6.1 mg Zn/kg;X±SEM).When test or“unknown”samples are near the mean of the standard samples,the CI is smaller than when near the extremes of the calibration curve.When calibration curve error is small(R^(2)>approximately 0.95),there is little advantage to using the Abductive Method,but when calibration curve error is larger,as in many bioassays with growing animals,the Abductive Method improves the accuracy of the CI calculations.The Abductive Method was used to demonstrate the influence of the number of replicate samples on experimental power and cost.
