Response of Growing Lambs to Clinoptilolite or Zeolite NaA Added to Corn, Corn-Fish Meal and Corn-Soybean Meal Diets

Sixty-three Suffolk-sired ram and ewe lambs (33 kg mean body weight) were fed ad libitum individually for 10 wk in a 3 × 3 factorial arrangement of diet treatments based on corn (C), corn-fish meal (FM) or corn-soybean meal (SBM) diets to which 2% clinoptilolite (a natural zeolite), 2% zeolite NaA or no zeolite were added. Daily weight gain to 4 wk was greater for males than for females (<.01) and for lambs fed diets containing SBM or FM (333 and 313 g/d, respectively) than for those fed C (264 g/d; P<.01). This difference persisted to 10 wk and there was no difference in daily gain of lambs fed SBM vs FM at either 4 or 10 wk. The mean gain of lambs fed FM or SBM diets in the presence of clinoptilolite was 11.5% greater than in its absence throughout the 10-wk experiment. There were no interactions between diet and sex or between protein level or source and zeolite additions to the diet with respect to weight gain or feed intake. Lambs fed SBM or FM had higher plasma urea-N at 4, 8 and 10 wk than those fed C (<.01). Lambs fed SBM had depressed plasma inorganic P at 8 and 10 wk compared with lambs fed FM. Lambs fed zeolite NaA had lower plasma inorganic P at 4 wk (<.01) than those fed clinoptilolite. Clinoptilolite and zeolite NaA had no effect on plasma urea-N or on plasma Ca. Leg conformation score, percentage of kidney fat and carcass quality score were unaffected by diet or sex, while carcass weight was greater in males than in females. The data provide no evidence of differences in weight gain or carcass traits of growing lambs fed FM compared with SBM as a protein supplement in high concentrate diets, but are suggestive of a beneficial effect on weight gain of 2% clinoptilolite, but not of 2% zeolite NaA addition to diets containing FM or SBM.