Oesophageally fistulated cattle, sheep and I goats were grazed together to study species diet preferences from 2 different tropical grass-legume pastures during 3 seasons (summer, autumn, winter). In one pasture, Brachiaria decumbens (signal grass) was the dominant grass and in the other pasture, Paspalum plicatulum. Each pasture had a common suite of tropical legumes, mainly Desmodium intortum (greenleaf desmodium), Macroptilium atropurpureum (siratro) and Macrotyloma axillaris (axillaris). Axillaris was the major legume available in summer and autumn and greenleaf desmodium was the major legume in winter. There was no significant effect in any season of the basal grass available on the composition of the diet selected by the different species. Both goats and cattle had a high preference for legume leaf during summer and autumn, with goats having a higher preference (34-75% of diet) than cattle (1245%). Sheep selected against legume (5-19% of diet) and had a high preference for grass leaf (58-74% of diet) in all seasons. Cattle selected grass in preference to legume (greenleaf desmodium) in winter. Goats showed the greatest discrimination against both grass and legume stem. In summer sheep selected a higher quality (in vitro digestibility) diet (62.7%) than did cattle (53.4%) and goats (51.2%). In both autumn and winter cattle and sheep selected diets of similar digestibility (range 58.6-63.6%). In vitro digestibility of the extrusa samples was significantly (P<0.05) correlated (r = 0.74) with the proportion of grass selected. It was concluded that in their grazing preferences, goats were more like cattle than sheep. The different preferences of sheep and goats for tropical legume leaf was associated with location of these legumes in the sward, goats browsing from the top down and sheep grazing from the bottom of the sward.
A grazing trial with beef cattle was conducted on three grasses, Paspalum plicatulum cv. Rodd's Bay, Brachiaria decumbens cv. Basilisk (signal grass) and Panicum maximum cv. Hamil, in the first year. P. maximum was replaced by Digitaria decumbens (pangola grass) in the second and third years. There were three stocking rates (3.0, 3.75, and 5.0 steers/ha), plots were fertilized with 300 kg N/ha, in two replicates. Animal liveweight gain was low; maximum values were 650 kg/ha for pangola grass, 640 kg/ha for signal grass and 400 kg/ha for P. plicatulum. Liveweight gain was only poorly correlated with rainfall, because low winter temperatures retarded pasture growth. Correlations between liveweight gain and individual green leaf percentage in each species were high, particularly for P. plicatulum, which had only 2% green leaf in winter. Weight loss on plicatulum was therefore high in winter, and overall performance poor, even though this species had the highest percentage of green leaf in summer. Signal grass showed a higher tolerance to grazing at 5.0 steers/ ha than the other grasses. Over most of the year, except in winter when only small amounts of green leaves were available, plicatulum had the lowest phosphorus percentage, sometimes below the 0.12% suggested as the critical dietary phosphorus percentage for cattle. Over all grasses, nitrogen and phosphorus concentrations were linearly related (r = 0.98). From this experiment, P. plicatulum was shown to be a poor grass for beef production and, for this grass and the other two species at this site, beef production using 300 N kg/ha could not be financially viable.
A pasture of Lotononis bainesii and Digitaria decumbens cv. Pangola at Mt Cotton, south-east Queensland was mown on six occasions at intervals of ca. 3 months and after each mowing was subjected in 1 day to the treading intensity expected from sheep grazing at 0, 7, 14, 21 and 28/ha. A movable corridor and folds were employed to walk the sheep the required number of times on eight replicates of each treatment.Lotononis regrowth was negatively related to sheep treading intensity, whereas Pangola was highly resistant to treading and grew vigorously from underground buds on rhizomes and from persisting stolons. Young lotononis seedlings were more vulnerable than older seedlings which had branched; plants developed from autonomous nodal roots were more resistant than seedlings. Attention is drawn to the contractile growth of the hypocotyl following epigeal germination which leads to a buried crown.Lotononis plants were short-lived, and seedling regeneration of ca. 27 and 47 plants/ m 2 occurred in the late summer of the 2nd and 3rd year after sowing. Soil seed reserves averaged 16900/m a . Studies might be undertaken of management systems directed to favouring lotononis plant replacement through accretion to seed reserves, seedling regeneration through the creation of 'gaps', and seedling survival through judicious timing of grazing.companion study which sought to separate the INTRODUCTION treading component of stocking rate through varyTreading, defoliation and excretion are the main ing the intensity of treading in a management consequences of animals grazing pasture. The system which imposed uniform defoliation (moweffects of treading or the hoof action of the animal ing) and minimized variation in animal excretory have a long-recognized importance for the produc-return. tivity and plant relations of temperate climate MATERIALS AND METHODS pastures, which may be mediated through direct T h e r i m e n t ( E x p t 2) w a s c o n d u c t e d at the effects on the pasture (Edmond, 1958) and also on U n i v e r s i t o f Queensland Mt Cotton Research soil characteristics (Gradwell, 1965) which indirectly g t a t i 4Q k m s o u t h . e a s t o f B r i s b a n e ) Australia, influence pasture growth and persistence. No Q n ftn a p e a c o n t i w i t h t h e 8 t o c k i n g r a t e studies of treading and tropical pasture legumes e r i m e n t p rev iou S l y described, which received have appeared; negative effects of rolling (Gillard ^ s a m e a t i o n u n t i l J u n e 1 9 7 6 ( P o t t & 1969) or treading (Hunt, 1979) have been reported Humohrevs 1983) for subtropical grasses.T h e r e wef ' e five t r e a d i n g i n t e n s ities,' equivalent' The influence of sheep stocking rate on the growth t o stocking rates of 0, 7, 14, 21 and 28 sheep/ha, and the pathways of persistence of the legume w hi c h were replicated eight times in a randomized Lotononis bainesii when planted with the sod-complete block arrangement. These were applied forming grass Digitaria decumbens cv. Pangola o n s j x occasions at intervals of ...
Australian cashmere goats and Border Leicester x Merino sheep grazing an oats-rye grass pasture were used to study the effects of stocking rate (20, 40, 60 animals/ha) on growth, intestinal parasite burdens and haematology of the 2 species and on the persistence and productivity of the crop grazed. Goats and sheep were either grazed alone or together over a 12-week period to determine the interaction between the species. Liveweight gain decreased with both stocking rate and time on experiment. At the highest stocking rate all animals lost weight between weeks 9 and 12. During the first 9 weeks of grazing, sheep had significantly (P<0.05) higher liveweight gains than goats at all stocking rates; but the rate of decline in liveweight gain with increased stocking rate was similar in both species, whether they were grazed alone or together. Mean values for sheep were 161, 133 and 105 g/day, and for goats 101, 84 and 59 g/day at stocking rates of 20, 40 and 60 animals/ha. Under the same drenching regime, goats were more severely infested by intestinal parasites than sheep as indicated by significantly (P<0.05) higher concentrations of parasite eggs in faeces and lower packed cell volumes and haemoglobin concentrations in blood. Oats was the major contributor to green feed available at all stocking rates, although rye grass yields increased in the later stages of the trial, particularly in high stocking rate paddocks. At the end of the trial, high yields of oat stem remained in the paddocks grazed by goats and goats plus sheep, suggesting that sheep grazed both leaf and stem but goats selectively grazed oat leaf. The availability of green leaf (oat + rye grass) per animal was closely related to liveweight gain in any period, although these relationships were different for sheep and goats.
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