Effect of administration and ruminal presence of chromic oxide controlled release capsules on herbage intake of sheep

Abstract

Abstract Measurement of herbage intake by grazing sheep may be simplified if chromic oxide intraruminal controlled release capsules (CRC) are used. Two experiments were conducted to determine whether the ruminal presence of CRC affected voluntary herbage intake. In Experiment 1, conducted indoors with twenty 8-month-old rams offered lucerne chaff ad libitum, faecal output (P < 0.05) and feed intake (P < 0.10) were significantly lower in the 10 sheep dosed with Mark II type CRC, irrespective of their initial liveweight, compared with those which had not been dosed. In Experiment 2, faecal outputs, measured by total collection, of yearling rams with or without Mark III CRC (n = 16/group) were not significantly different. This suggests that sheep dosed with the Mark III capsule, which has a more flexible wing structure and bulbous tip than the Mark II design, should behave in a similar manner to their untreated counterparts in grazing studies and provide unbiased estimates of herbage intake. The suitability ...