Rapid Techniques for Feed Evaluation: Scope and Limitations

Poultry diets are formulated primarily using cereals and protein meals (corn, wheat and soybean meal) as the main ingredients. There is noted shift in using coproducts from cereals and oilseeds in poultry diets due to availability and relatively lower cost. However, there is wide variation in the nutritional values of both conventional feedstuffs and coproducts, which creates a necessity of developing routine evaluation techniques to detect these variations in order to formulate balanced diets and achieve optimal animal performance. Currently, the approaches being used to evaluate the nutritional values of ingredients in animal diets are based on values obtained from a) wet chemistry b) tables, c) predictive equations, d) in vitro studies, e) near infrared spectroscopy (NIRS), and f) in vivo studies. Wet chemistry analysis is the basis of some nutritional analysis. In vivo studies are considered the best method to get the nutritional value of any feedstuff. However, using an animal model for routine evaluation is not practical due to logistical limitations such as costs and time involved and ethical concerns. Hence, there is the utmost need for rapid feed evaluation techniques that is reliable and logistically practical. The in vitro methods to determine the nutritional value and digestibility have been found to be more reliable than the table values and predictive equations, especially for grains. However, the accuracy of these in vitro methods in determining the digestibility of the co-products is not very high. In vitro fermentation study can provide some functional characteristics of feedstuffs which are not well considered presently, but has potential to be used. ___________________________________________________________________ Department of Human Nutrition, Food and Animal Sciences, College of Tropical Agriculture and Human Resources, University of Hawaii at Manoa, Honolulu, HI 96822, USA. Email: [email protected] Proceedings of the NZ Poultry Industry Conference, 2016. Vol. 13 85 The NIRS is being used widely and can serve as a better feed evaluation technique not only in determining the nutritional value of feedstuffs and feed but also in diagnosing the differences between the results of the in vitro and in vivo methods. Although NIRS method is expensive in setting up the instrument and developing calibration, it delivers reliable outputs along with high economic efficiency once the method is established. Moreover, collaboration among the industry partners to provide services on calibration data and results are making it as the most practical tool for rapid feed evaluation technique at present. In conclusion, each of these tools has some advantages and disadvantages. Thus, it is not easy to make a clear recommendation on which one is the best method for rapid feed evaluation that can be applied in all conditions.