The effect of herbage allowance on intake and performance of ewes suckling twin lambs

Abstract

AbstractThe effect of herbage allowance on the herbage intake and performance of ewes and their twin lambs at pasture was investigated. Daily herbage allowances of 40,80.120 and 160 g organic matter (OM) kg‐1 ewe live weight, based on herbage mass measured to ground level, were offered during the first 12 weeks of lactation.The sheep were grazed rotationally around four paddocks of a perennial ryegrass pasture for 7‐day periods and herbage mass, extended tiller length and digestibility of the herbage consumed by the animals were estimated. Herbage intake by the ewes was estimated during weeks two to twelve and live weights were recorded weekly: during the last two weeks of the experiment grazing behaviour of one ewe on each treatment was recorded continuously.Herbage intakes by the ewes (164, 1–81, 2–42 and 268 ± 0153 kg d‐1) and live weight gains of the lambs (202, 245, 274 and 300 ± 7–3 g d‐1) increased with increasing herbage allowances. Herbage intakes by the ewes and growth rates of their lambs increased up to a herbage allowance which was over five times the amount of herbage eaten by the ewes.As the animals reduced herbage mass and sward height, biting rates by the ewes during grazing increased by 4 (± 0·08) bites min‐1 cm‐1 and masticating rates decreased. Mastications reached a maximum of 90 (± 3·5) min‐1 at a sward surface height of 9 cm.