ارزيابي مدل رشد گوساله هاي پيش نشخوار كننده براساس انرژي خالص و پروتئين قابل هضم ظاهري

Evaluation of a prerumiant calves growth model based on net energy and apparently digestible protein

A model was designed according to NRC (2001) equations, which simulates growth of preruminant calves based on three different indexes (Energy, Apparently digestible protein and mean of them). Results showed that the best estimation of calves weight in different ages was based on energy index (RMSD=7.251). Also model estimations of calves weight were generally greater than observations, so there were positive MBE values with RMSD=11.549, 16.705 and 7.251 respectively for mean index, apparently digestible protein and energy. Daily weight gain estimation according to energy index was lower than observed data, so MBE value was negative (RMSD=0.250). About the other two indexes (Apparently digestible protein and mean index), results showed that model estimations were greater than observations with positive MBE values (RMSD=0.241 and 0.307 respectively). Model made an over estimation about dry matter intake with positive MBE value (RMSD=0.666). According to model estimation trends, this model is a start point for designing a complex model. With respect to correct determination of observations trend, it seems a suitable model.