Whole wheat grain feeding of lambs. I. Production responses to mineral buffer supplements

Abstract

Thirty-nine crossbred lambs off pasture and weighing about 27 kg were group-fed on lucerne chaff and whole wheat grain ad libitum in yards over a 3-week adaptation period. All animals were then offered whole wheat grain plus 1½% ground limestone ad libitum for 19 weeks.

Addition of mineral buffer supplements of 1/1 Na₂HPO₄ and NaHCO₃ (buffer I), or a 1/1/1/1 mixture of Na₂HPO₄, NaHCO₃, KHCO₃, and CaHPO₄ (buffer II) as 2% of the grain offered, resulted over the 22-week experimental period in significantly better food intakes and liveweight gains and decreased food conversion ratios as compared with those shown by control sheep fed on wheat grain and limestone (P < 0.01).

Buffer supplements significantly raised the rumen pH above values for control animals (P < 0.01), decreased the total rumen volatile fatty acid concentration(P < 0.05), and lowered the proportion of acetic acid and increased that of propionic acid (P < 0.05). Caproic acid was detected in significant quantities in the rumen fluid of all sheep.

Wheat sickness caused the removal of 25% of control sheep fed on wheat grain and limestone; 21% of sheep given buffer I died from a urolithiasis-like condition; no deaths occurred in sheep given buffer II.

Administration of 2.5 x l0⁶ i.u. injectible vitamin A to half the animals over the first 10 weeks of the experiment seemed to cause neither benefit nor harm.