368 Applying physics and math to describe chemistry and biology at the plant/animal interface

Abstract Monitoring the diet consumed by grazing animals and relating that to health and performance is a task dating back to the origins of herding and pastoralism. Visual assessment of plants and animals by knowledgeable individuals has and will likely continue to be the most common manner of obtaining this information. It is part of the culture of livestock rearing and so even with the advent of modern analytical methods, adoption may be slow until the demographics of the industry change toward practitioners who have grown up with technology as part of their culture. Recent discussion within the rangeland profession has revolved around the art and science of grazing management, and thus grazing animal nutrition. These two skill sets are not mutually exclusive. I contend that art is the skilled application of science. With respect to the science, near infrared spectroscopy (NIRS) has been applied to determine the chemical content of feeds and forages. Fecal NIRS has been used to determine diet quality and composition in herbivores and results of this analysis can generate inputs to nutritional balance software that subsequently project animal performance. As described in the title, this presentation will involve a discussion of physics, math, chemistry, and biology. Regarding physics, the absorbance and reflection of near infrared energy by a population of chemical bonds ultimately described mathematically via multivariate statistics. Statistics that quantify the relationships between spectra and reference methods. Chemistry in this application quantifies constituents of interest in plant tissue consumed which are related to biology by way of intake, digestion, metabolism, and elimination of said grazed material. When projections of grazing animal performance are merged with landscape scale remotely sensed vegetation indices, the result is a powerful decision support system, provided by science, that facilitates the skill of the grazier; the artist if you will.