Prediction of Dry Matter Intake of Lactating Cows in Summer

Results of 134 feeding trials by lactating cows under high temperature conditions (more than 20°C of minimum temperature) were used to predict dry matter intake (DMI) in summer. The equation obtained was as follows: DMI= 0.0128BW+0.343FCM+0.083R/C-0.372CP+0.229 TAVE+0.088 HAVE-7.00 R2=0.683 RSD=1.56 (BW: body weight, kg, FCM: fat corrected milk yield, kg, R/C: roughage ratio, %, CP: crude protein, %DM, TAVE: average temperature, °C, HAVE: average relative humidity, %). This equation was suggested that DMI in summer was controlled by heat production described by BW, FCM, R/C and CP, and environments which affected heat losses.