Sheep productivity in an Astrebla grassland of south-west Queensland.

Abstract

A grazing study conducted between 1979 and 1983 assessed the seasonal trends of ewe productivity in Astrebla grassland in south- western Queensland. This study was designed originally to compare productivity on two pastures with different compositions, however, these differences in pastures composition were not achieved. Large differences in liveweight, wool growth and reproductive performance occurred between years in response to differences in pasture growth resulting from large variation in the seasonal incidence of rainfall. Rainfall effective for plant growth, both forbs and grasses, resulted in a high quality diet which resulted, in turn, in increased sheep productivity. Reproductive performance was particularly sensitive to the quality of the ewes diet around the time of lambing through the effect of diet quality on lamb survival and growth rate. It is suggested that the effect of rainfall on reproductive performance is pasture.

Impact of prescribed burning on Acacia nilotica seed banks and seedlings in the Astrebla grasslands of northern Australia

“…The concern is that Astrebla takes many years to re-establish from seedlings in arid areas of western Queensland. This and previous studies (Scanlan, 1980;Orr et al, 1988) show that major pasture species are not lost as a result of fire if pasture is spelled from grazing afterwards. No impact was detected on Astrebla lappacea or Iseilema vaginiflorum percentage in the pasture or frequency of occurrence when sheep and cattle were excluded from the burnt plots.…”

Growth Performance and Plasma Metabolites of Grazing Beef Cattle Backgrounded on Buffel or Buffel-Desmanthus Mixed Pastures

“…In the Mitchell-grass-dominated pastures, the non-grass proportion in sheep and cattle diets was high during the wet season and reduced in the dry season. The authors attributed the trend to high palatability of the non-grass pasture species encouraging higher preference when available, but consumption dropped with a decrease in availability during the dry season [ 56 , 77 ]. In grass-dominated pastures consisting of just 2% forbs, cattle consumed up to 15% non-grass during the dry season, indicating high forb selection [ 56 ].…”

Effect of herbage in Astrebla spp. pastures in northwest Queensland on lamb survival

“…The results of these experiments indicate that a reduction in the availability of forbs in the pasture grazed by pregnant ewes is likely to improve lambing performance when the forb content in Mitchell grass pastures is between 7 and 49 % of total pasture biomass. Forb species are more nutritious than the grasses that grow on the Mitchell grass downs (Lorimer 1976;McMeniman et al 1986), and in pastures of low forb content (2-9%) Orr et al (1988) suggested that increased reproductive performance may be caused by an improvement in diet quality associated with a higher yield of forbs. A lower C 3 content in the diet of ewes grazing paddock F"2 in Expt 3 than in other paddocks shows that they consumed a diet low in palatable C 3 forbs.…”

“…The regression equation relating lamb marking percentage to total forb yield in Expts 3 and 4 (Eqns 2 and 4, respectively) indicated that increasing the access of sheep to forbs in late pregnancy will cause the lambing percentage to be lower. Orr et al (1988) suggested that improved nutrition caused by more forbs in the pasture would increase lambing percentage when the proportion of forbs in the pasture is low. Once the forb content of the pasture reaches 5-7% of the total biomass or greater, inadequate nutrition no longer limits lambing performance.…”

“…, -. v , ,"'"", Industries, Arid Zone Institute, PO Box 519, Longreach, y i e l d respectively; Orr et al 1988). Qld 4730, Australia.…”