Received: 12 July, 2007. Accepted: 23 September, 2007. Invited Review Fresh Produce ©2007 Global Science Books Forage Quality: Techniques for Testing Cecilia L. Fulgueira 1* • Susana L. Amigot 1 • Mónica Gaggiotti 2 • Luis A. Romero 2 • Juan C. Basílico 3 1 Centro de Referencia de Micología, Facultad de Cs. Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, S2002LRK Rosario, Argentina 2 INTA Rafaela Ruta 34 km 227, 2300 Rafaela, Argentina 3 Facultad de Ingeniería Química, Universidad Nacional del Litoral, Santiago del Estero 2829, S3000AOM Santa Fe, Argentina Corresponding author: * cfulgueira@yahoo.com.ar ABSTRACT Forage quality refers to how well animals consume a forage and how efficiently the nutrients in the forage are converted into animal products. Six major factors affecting forage quality: maturity (harvest date), crop species (differences between grasses and legumes), techniques of harvest and storage, environment (moisture, temperature and amount of sunlight), soil fertility, variety or cultivar. Also, weeds, insect pests, plant diseases and presence of bacteria, molds, and/or some of their metabolites, e.g. mycotoxins can negatively affect forage quality. Recommended tests for determining forage quality are: dry matter (DM), pH, crude protein (CP), available protein, amoniacal nitrogen (as % NH 3 /TN), acid detergent fiber (ADF), neutral detergent fiber (NDF), lignin and ash. Energy values such as total digestible nutrients (TDN), net energy (NE) and relative feed values (RFV) can be calculated from these core analyses. There are two methods used to analyse such variables: the traditional chemistry analysis and the newer, near infrared reflectance spectroscopy (NIRS) analysis. Currently, the quality of a forage has been evaluated only through those chemico-fermentative parameters. However, recent studies propose to incorporate the analysis of microbiological parameters such as fungal propagule counts, the presence of Aspergillus fumigatus and mycotoxins (aflatoxins and deoxynivalenol) as decisive parameters of forage acceptability. Forage quality information is important for formulating nutritionally balanced rations, evaluating forage management practices (growing conditions, timing of harvest, and handling from harvesting to utilization) and marketing and pricing forages. _____________________________________________________________________________________________________________ Keywords: chemico-fermentative evaluation, feedstuffs, fungal contamination, mycotoxins, silages CONTENTS FORAGE CONSERVATION SYSTEMS .................................................................................................................................................. 121 Hays....................................................................................................................................................................................................... 122 Silages ................................................................................................................................................................................................... 122 Haylage or round bale silages ................................................................................................................................................................ 122 FORAGE QUALITY ................................................................................................................................................................................. 122 Factors that influence forage quality...................................................................................................................................................... 122 Forage quality evaluation ...................................................................................................................................................................... 123 Sensory evaluation ............................................................................................................................................................................ 123 Forage sampling................................................................................................................................................................................ 123 Chemico-fermentative evaluation ..................................................................................................................................................... 123 Nitrogen values ................................................................................................................................................................................. 124 Fibers ................................................................................................................................................................................................ 124 Minerals ............................................................................................................................................................................................ 124 Calculated energy values................................................................................................................................................................... 125 Microbiological evaluation ............................................................................................................................................................... 125 Forage bacteria.................................................................................................................................................................................. 125 Fungal contamination of forages ....................................................................................................................................................... 126 Toxic – fungal analysis ..................................................................................................................................................................... 128 Fungal propagule counts – Identification of isolates ......................................................................................................................... 128 Mycotoxins ....................................................................................................................................................................................... 129 ACKNOWLEDGEMENTS ....................................................................................................................................................................... 129 REFERENCES........................................................................................................................................................................................... 129 _____________________________________________________________________________________________________________ FORAGE CONSERVATION SYSTEMS Current systems of dairy and beef production demand deeper knowledge of the production processes and quality of every available feed (Bruno et al. 1998). Although they may vary according to region, cattle-rearing production sys- tems are based upon the direct grazing of forage resources with supplementary feeding, such as: grains, crop by-pro- ducts, and stored forages like hay or silage, etc. These me- thods make it possible for the feed management of herds to improve and to become more cost-effective (Taysom 2002; Beltzer 2003). Forage conservation arises out of the need to rationally profit from the excess of pastures – lucerne, winter soilage, etc. and of annual crops that have been specially grown for ensilage – maize, sorghum, oat, ryegrass, soya, etc. (Ro- mero et al. 2003). These conservation processes had been previously used