Intersociety Forage Evaluation Symposium

T HE grasslander’s common measuring unit of pasture or other forage production is green or dry weight yield per acre. While this is satisfactory for some purposes, the altimate use of "grass" is for livestock production, and when animals are introduced as the measuring units, numerous factors become involved in determining the final production obtained. It is only in recen~t years that interrelationships between forage yield and quality and animal response have been closely studied and partly understood. The Grassland Improvement Steering Committee of the American .Society of Agronomy found ’by correspondence that there was sufficient interest in these problems among the members of ’this Society and members of ’the American Society of Animal Production, ’the American Dairy Science Association, and The American ’Society of Range Management to warrant holding an intersociety symposium on forage evaluation. This symposium was held in conjunction w~th. the annual meeting of the American Society of Agronomy at Purdue University, in August 1958. Representatives appointed by each society first agreed upon the type of program desired, then decided on the general subject matter areas to be covered (’to ’be ’based primarily on original research results), and ,finally agreed upon the research workers ’to be asked to present papers in these areas. The contributions of these individuals and teams of workers are presented in the eight papers which follow. Major progress in forage evalua’tion can be made only in the light of information on ’the part that individual factors play in producing animal response. ’Certainly, forage intake and the digestibility of the forage dry matter and its ,feed nutrients are major factors influencing animal response to forage condition. These factors are thoroughly discussed by M. E. McCullough; ’the ’techniques are described in detail by Harris, Cook, and Butcher, and are considered by Weir, Meyer, and Lofgreen. A major problem for ’both animal and forage scientists ha~s been a method of forage sampling ’that accurately represents the forage actually consumed by the grazing animal. The advantages of the use of the esophageal fistula for this purpose are fully brought out ’by Weir et al. and mentioned by Harris et al. The importance of not overlooking selective grazing by different classes of animals and under different forage conditions is also very well covered by Weir et al. Forage workers have been prone to consider .higher forage protein contents synonymous ~4th higher forage quality. Several of the papers stress ’the far greater need of animals for energy ’than for protein, and Max Kleiber points out in detail ’the specific and different need and use of protein vs. energy ’for animal .production, also the inefficiency in the use of excess protein as a source of energy. Range cond,ifions present somewhat different and additional problems in forage evaluation ’than do most improved pastures. The paper by Harris et al. points out some of these difficulties and solutions to them. Some range plants