Management of poor quality pastures for maximum animal performance during summer

Abstract

A trial was carried out near Greymouth on the west coast of the South Island in 1987 and 1988 to determine production responses of thin and fat ewes to two feeding treatments from weaning to mating. At weaning in early January, 192 three-year-old Perendale ewes were individually condition scored and allocated into two equal-sized groups of thin (mean condition score = 2.7, mean liveweight = 4 1.4 kg) and fat (mean condition score = 3.3, mean liveweight = 46.8 kg) ewes. From weaning to the start of mating in mid-April, each thin and fat ewe group were split evenly and grazed in a leader and follower system. The leader group was preferentially fed by having fust choice while the follower group had the second choice of pasture. The pasture was of low nutritive value because of a low content of ryegrass and white clover and a high content of unimproved grasses, dead material and weeds. Preferential feeding resulted in significant increases in liveweight (+4.5 kg for thin ewes, +5.1 kg for fat ewes) and condition (+0.26 condition score units for thin and fat ewes) compared with follow-up feeding. Increases in ovulation rate at the start of mating from preferential compared with follow-up feeding were higher for thin (1.35 vs 1.01) compared with fat (1.44 vs 1.21) ewes. There was little difference in the response in wool production to preferential feeding for thin (1 .O 1 vs 0.82 kg/ewe) compared with fat (1.11 vs 0.91 kg/ ewe). Preferential feeding of thin ewes and the use of fat ewes to follow-up and clean out pastures from weaning to mating reduced the range of ewe liveweight at mating (42-54 kg) compared with grazing thin and fat ewes in a follow-up role (36-60 kg). This would help standardise individual ewe feed requirements and allow ewes to be grazed in one mob during autumn and winter. Preferential feeding of thin ewes from weaning to mating was tested on twocommercial sheep farms and resulted in similar changes in ewe liveweight and condition as found in this reported trial. Keywords preferential, follow-up, feeding, ewes, liveweight, condition, ovulation rate, wool production