1. Agricultural and Food Research Council (AFRC). 1993. Energy and Protein Requirements of Ruminants; CAB International, Wallingford, UK.
2. Official Methods of Analysis;AOAC International,2000
3. An adjustable metabolism stall for cattle;Aschbacher;J. Anim. Sci.,1970
4. Aprendizaje temprano a la ingesta de concentrado en alpacas Huacaya;Castro;Rev. de Investig. Vet. del Peru.,2017
5. Measurement of in vivo Forage Digestion by Ruminants. Forage Quality, Evaluation and Utilization;Cochran,1994