J.F. COMPTON1, K.B. ADDISON2, D.G. CAMERON3, D.C. NICOL4 and K.L. BUTLER5
1Queensland Department of Primary Industries Research Station, P.O. Box 20, South Johnstone 4859.
2Formerly Queensland Department of Primary Industries, Brian Pastures Pasture Research Station, Gayndah 4625, now 101 Woongara Scenic Drive, Bargara 4670.
3Formerly Queensland Department of Primary Industries, G.P.O. Box 46, Brisbane 400 1, now 15 Tin Can Bay Road, Goomboorian, via Gympie, 4570.
4Formerly Queensland Department of Primary Industries, P.O. Box 1143, Bundaberg 4670, now Breedlink Cattle Services, P.O. Box 814, Armidale 2350.
5Formerly Queensland Department of Primary Industries, P.O. Box 6014, Rockhampton Mail Centre 4702, now Department of Agriculture and Rural Affairs, Princes Highway, Werribee, 3030.
In March 1973, a pasture of Siratro, lotononis, Bryan plicatulum and Narok setaria was planted into 48.6 ha of recently cleared, low-layered woodland/forb heath of the northern coastal lowlands (Wallum) with appropriate establishment and subsequent maintenance fertilisers. A herd of about 30 crossbred (Brahman based) cows + 1 bull and calves grazed initially 34.2 ha (later 31.8 ha). From weaning, the progeny were run 6 to a paddock at 1.0, 1.25, 1.66 and, from May 1977, 2.5 weaners/ha on the remaining area. The cow herd was changed in August 1978 to one based on Sahiwal crosses. Both pasture and animals were monitored from May 1975 to May 1980.
As grazing pressure increased, Siratro and setaria content decreased and lotononis, plicatulum and native species increased. At no stage, was there less than 1000 kg/ha dry matter on offer, and plant-leaf nitrogen was usually above 0.7% N. Phosphorus levels also remained above 0.10 to 0.12%. Faecal nitrogens were lowest in June/July of each year (1.3 to 1.4%) and in 1975 (1.1%). A calving percentage of 84 to 96% was achieved in all years except 1980, when it was 70%. Annual calf growth rates declined as the pasture aged, from 0.97 kg/day in 1974–75 to 0.66 kg/day by 1980. At the 3 lower stocking rates of the weaners, the pastures and animal daily liveweight gains were stable but were declining with time at 2.5 weaner/ha.