Submitted to: Florida Cattleman
Publication Type: Trade Journal
Publication Acceptance Date: September 5, 2006
Publication Date: September 25, 2006
Citation: Coleman, S.W. 2006. Estimating Forage Quality of Grazing Ruminants (Part 2). Florida Cattleman.70(12):85-88
Meeting the nutritional needs of a mother cow through the different physiological stages of reproduction, lactation and recovery from parturition is very important to sustained productivity. Having a calf and nursing it to weaning every year is quite a task. Consuming sufficient high quality forage to sustain the various physiological functions is often constrained by either inadequate supply of forage on offer, or compromised quality of the forage. Because of the difficulty of actual determination of intake and diet quality of grazing animals, indirect methods have been used by researchers to estimate those attributes without having to harvest the pasture and carry it to pen-fed animals. Marker systems used by researchers are very laborious and require laboratory support. Since feces is the product of eroding and synthesizing digestive processes and consists of residues of feed and plant tissue and of components of microbial and animal origin, then feces should contain information about the amount and characteristics of the diet. The fecal index method for determination of intake and (or) digestibility does not require forage sampling but is based on a predictive method requiring calibration with in vivo data. This means intake must be determined by some technique (e.g., markers) to serve as the reference method for developing prediction equations, even though they are quite laborious. Once calibrated, fecal indices can be implemented by producers since only a grab sample of fresh feces need be taken from the pasture where the animals are grazing. A summary of six studies using near-infrared reflectance spectroscopy show that indeed the method may have merit for estimating intake of large numbers of cows.