Effects of imposed feed intake variation on acidosis and performance of finishing steers

Four metabolism and two finishing trials were conducted to determine the ef fects of imposed feed intake variation on acidosis and performance of finis hing steers. In Metabolism Trial 1, four ruminally fistulated steers were l imit-fed and subjected to either a constant amount of feed per day (C) or l ow intake variation of .7 kg/d (LV). No treatment differences were found fo r intake or measures of acidosis. Metabolism Trial 2 was conducted similar: ly to Metabolism Trial 1 with treatments of C and high intake variation of 1.4 kg/d (HV). Treatment HV increased (P < .05) acidosis, as indicated by t he area of ruminal pH below 5.6. In Metabolism Trial 3, four steers were fe d at ad libitum levels of intake and subjected to three levels of intake va riation: ad libitum intake with no imposed intake variation (AL), LV of .7 kg/d, and HV of 1.4 kg/d. No treatment differences were found. In Metabolis m Trial 4, six ruminally fistulated steers were fed at ad libitum levels an d subjected to three levels of intake variation: AL, LW of .9 kg/d, and HV of 1.8 kg/d. Average ruminal pH increased (P < .05) and area of ruminal pH below 5.6 decreased (P < .05) as level of intake variation was increased. I n Finishing Trial 1, 75 steers were assigned to eight pens and two treatmen ts: AL or HV of 1.8 kg/d. Dry matter intake increased (P < .05) from AL to HV. Daily gain and gain/feed were not affected by treatment. In Finishing T rial 2, 94 steers were assigned to 12 pens and two treatments: AL or HV of 1.8 kg/d. No treatment differences were noted in DMI, daily gain, or gain/f eed. Therefore, results of these trials indicate that intake variation of u p to 1.8 kg/d does not increase acidosis or decrease performance of finishi ng steers fed at ad libitum levels of intake.