Diet composition of cattle grazing Stylosanthes - grass pastures in the seasonally dry tropics: the effect of phosphorus as fertiliser or supplement

1998 ◽  
Vol 38 (1) ◽  
pp. 7 ◽  
Author(s):  
D. B. Coates ◽  
R. P. Le Feuvre
Keyword(s):  
Diet Composition ◽  
Isotope Analysis ◽  
Cattle Grazing ◽  
Diet Selection ◽  
Wet Season ◽  
Seasonally Dry ◽  
Stylosanthes Hamata ◽  
Dry Tropics ◽  
Extractable P ◽  
Induced Changes

Summary. The effect of phosphorus (P) on diet selection in cattle grazing pastures based on Stylosanthes hamata cv. Verano andS. scabra cv. Seca in the seasonally dry tropics was studied in 3 grazing trials on soils with inherently low P status ( 5 µg/g bicarbonate-extractable P). The contribution of Stylosanthes (stylo) to diets was estimated at regular intervals (approximately monthly) using carbon isotope analysis of faeces. Feeding P supplement increased the proportion of stylo in the diet but the effect was seasonal and variable, being most pronounced during the late wet and early dry seasons when dietary stylo proportions are usually highest. The results indicated that P supplement influenced diet selection through its effect on dietary P status such that cattle with a deficiency of dietary P select a lower proportion of stylo than those with higher P intakes. The effect of fertiliser P on dietary stylo content was also variable. The dominant effect was via fertiliser-induced changes in pasture botanical composition. Higher stylo proportions in the diet of heifers grazing unfertilised pasture compared with those grazing fertilised pasture were associated with increasing stylo dominance in unfertilised pastures as opposed to grass dominance in fertilised pastures. At the same time there was evidence of a fertiliser treatment effect that was consistent with dietary P status influencing diet composition. In the grass-dominant pastures, unsupplemented cattle on low P pasture selected less stylo than those grazing pastures of higher P status due to more frequent fertilising but there was no difference where P supplement was fed. A strong seasonal preference for grass early in the wet season, reinforced by a generally reduced preference for stylo in cattle with diets deficient in P, probably hastened the development of stylo dominance in unfertilised pasture where P supplement was not fed.

Diet selection by cattle grazing Stylosanthes-grass pastures in the seasonally dry tropics: effect of year, season, stylo species and botanical composition

1996 ◽  
Vol 36 (7) ◽  
pp. 781 ◽  
Author(s):  
DB Coates
Keyword(s):  
Cattle Grazing ◽  
Diet Selection ◽  
Dry Season ◽  
Major Influence ◽  
Botanical Composition ◽  
Wet Season ◽  
Seasonally Dry ◽  
Dietary Preference ◽  
Dry Tropics ◽  
Opportunity For Selection

The dietary preference of cattle grazing Stylosanthes-based pastures in the seasonally dry tropics of North Queensland was studied using faecal carbon ratios (S13C) to determine grass-legume proportions. Estimates were made at monthly intervals for several years in 1 experiment to determine the effect of year, season and botanical composition on dietary stylo proportions. In another experiment, the effect of stylo cultivars (Verano and Seca) on dietary preference was monitored for 17 months. Where pastures provided ample opportunity for selection, cattle showed a strong preference for grass in the early wet season and in the late dry season. The proportion of stylo in the diet increased during the wet season and reached peak proportions (as high as 80%) in the late wet season or early dry season. Dietary stylo proportions decreased as pastures dried off and as the stylo shed leaf or became more stemmy. The length of the wet season and the amount and distribution of rainfall had a major influence on the seasonal pattern of diet selection. Stylo rarely fell below 20% in the diet. On an annual basis, stylo accounted for about 45% of the diet which was appreciably higher than the proportion of stylo in the pasture. Dietary stylo proportions were higher on Seca-based pasture than on Verano-based pasture. The avoidance of stylo in the early wet season was less pronounced with Seca compared with Verano. Later in the season Seca was the dominant dietary component for a much longer period than Verano. The effect of botanical composition on dietary grass-legume proportions varied between and within years. Correlations between grass-legume proportions in the pasture and in the diet were highest in the late dry season and early wet season when preference for grass was strongest. At the end of the wet season when cattle preferred stylo, dietary stylo was not related to pasture stylo content except in a drought year. Averaged over the full year, dietary stylo content was significantly correlated with pasture stylo content in all years and the correlation was highest in a drought year when there was a high level of utilisation and less opportunity for selection. A simple model relating dietary stylo to pasture stylo was developed and is discussed.

Soil respiration in the seasonally dry tropics near Townsville, North-Queensland

Soil Research ◽  
1990 ◽  
Vol 28 (5) ◽  
pp. 737 ◽  
Author(s):  
JA Holt ◽  
MJ Hodgen ◽  
D Lamb
Keyword(s):  
Soil Respiration ◽  
Root Respiration ◽  
Respiratory Activity ◽  
Major Effect ◽  
Wet Season ◽  
Untreated Soil ◽  
Seasonally Dry ◽  
Respiration Rates ◽  
Dry Tropics ◽  
Total Soil Respiration

The contribution of root respiration to total soil respiration has been examined in an Australian tropical semi-arid woodland. Respiration rates were estimated by measuring CO2 released from untreated soil and from soil where roots had been severed and were extensively decomposed. The amount of C released as CO2 by soil respiration was estimated to be 3800 kg ha-1 year-1, and by root respiration to be 1500 kg C ha-l year-1. Soil moisture was found to have a major effect on soil respiration, with temperature being less significant. Consequently, most respiratory activity in the soil was confined to the relatively short wet season, with respiration rates being much lower during the dry season.

Limited impact of irrigation on the phenology of Brachychiton megaphyllus: a deciduous shrub that flowers while leafless during the tropical dry season

2015 ◽  
Vol 31 (5) ◽  
pp. 459-467 ◽  
Author(s):  
Patricia J. Bate ◽  
Donald C. Franklin
Keyword(s):  
Soil Moisture ◽  
Reproductive Activity ◽  
Dry Season ◽  
Reproductive Phenology ◽  
Wet Season ◽  
Canopy Development ◽  
Seasonally Dry ◽  
Dry Tropics ◽  
Tap Root ◽  
Leaf Flush

Abstract:A suite of woody plants inhabiting the seasonally dry tropics flower while leafless during the dry season, raising intriguing questions about the role of moisture limitation in shaping their phenology. Brachychiton megaphyllus is one such species, a shrub of open forests and savannas in northern Australia. We documented leaf and reproductive phenology of 14 shrubs, and irrigated a further 15, to determine if soil moisture affected leafiness and reproductive activity. Brachychiton megaphyllus showed first flower buds shortly after the cessation of wet-season rains, and budded and flowered throughout the dry season. In some plants, leaf flush occurred prior to the first rains. Rates of fruit set and maturity were very low. Irrigation did not significantly influence leaf shoot or subsequent canopy development. Contrary to expectation, irrigation decreased the production of buds and flowers though it had no impact on the production of fruit, a response for which we suggest a number of hypotheses. Phenological responses to irrigation may have been limited because B. megaphyllus responds primarily to cues other than soil moisture and is buffered against seasonal drought by a large tap root. This suggests mechanisms by which flowering while leafless may occur in a range of species.

The growth of Urochloa accessions in grazed swards with Stylosanthes near Townsville, north Queensland

1985 ◽  
Vol 25 (1) ◽  
pp. 61 ◽  
Author(s):  
JG McIvor
Keyword(s):  
Perennial Grass ◽  
Grazing Pressure ◽  
First Year ◽  
Wet Season ◽  
Low Level ◽  
Seasonally Dry ◽  
Stylosanthes Hamata ◽  
Annual Grasses ◽  
Tropical Areas ◽  
High Yields

Six Urochloa accessions (U. mosambicensis cv. Nixon, CPI 46876, CPI 47 167 and U. oligotricha CPI45607, CPI47122, CPI 47 124) were grown with Stylosanthes hamata cv. Verano and S. scabra cv. Seca in individually fenced, fertilized swards near Townsville, Queensland, for 5 years. The swards were grazed by single steers for 2 days at 6-weekly intervals (equivalent to a stocking rate of 1 steedha). Two grazing regimes were used: grazing throughout the year (high grazing pressure); and grazing during the dry season only (low grazing pressure). There was good establishment of Verano but Seca and all Urochloa accessions established poorly. In subsequent years there were few U. oligotricha seedlings but there were substantial numbers of U. mosambicensis seedlings. Most seedlings died during their first year and in the final year of the study the number of perennial Urochloa plants ranged from 1 /m2 (CPI 47 122) to 1 7/m2 (CPI 46876). Yield and proportion of Urochloa were low during the first year but later increased for the U. mosambicensis accessions, particularly CPI 46876, which out-yielded all other accessions in the final 3 years. High yields of Urochloa were associated with low yields of Verano and annual grasses. High grazing pressure reduced the total pasture yield. Verano was always a major component, especially at high grazing pressure. The proportion of Seca increased from an initial low level but then declined again to a very low level. There was very little native perennial grass at high grazing pressure. The proportion of grass in the swards was highest at the start of the wet season and then declined; in contrast, the proportion of legume increased during the wet season. The value of Urochloa species in seasonally dry tropical areas and their management in pastures are discussed.

Selection of perennial grasses as a component of legume-based pastures on light-textured soils in the dry tropics of Queensland

1994 ◽  
Vol 34 (3) ◽  
pp. 355 ◽  
Author(s):  
TJ Hall ◽  
RW Walker
Keyword(s):  
Native Species ◽  
Perennial Grass ◽  
Genetic Material ◽  
Grazing Pressure ◽  
Perennial Grasses ◽  
Wet Season ◽  
Environmental Evaluation ◽  
Seasonally Dry ◽  
Dry Tropics ◽  
Andropogon Gayanus

Adaptation indices for introduced perennial grasses were derived for a site in the seasonally dry tropics of North Queensland to determine the suitability of grasses as a component of sown legume pastures. Grasses are required to replace native species that are intolerant of the heavy grazing pressure imposed on these legume-based pastures. Agronomic, production, morphological, and reproductive data on 143 accessions of 20 perennial grass genera were compared from 1983 to 1987. The grasses were grown in rows in a grazed Seca and Verano stylo pasture. The seed production potential of 40 Digitaria accessions grown in swards under irrigation was also assessed. The stoloniferous species Bothriochloa pertusa, Digitaria milanjiana, D. taatalensis, B. insculpta, and Urochloa mosamhicensis had the highest adaptation indices under continuous grazing. Digitaria accessions with the ability to produce appreciable viable seed were identified. Andropogon gayanus, a tussock species, had the highest yield and most spread in the first 2 years in the absence of wet season grazing. The potential of B. pertusa and D. milanjiana for stabilising legume pastures has been identified, and the need for wet season grazing management of tussock species has been shown. The range of genetic material in D. milanjiana requires further environmental evaluation.

Foraging ecology of the agile wallaby (Macropus agilis) in the wet - dry tropics

2002 ◽  
Vol 29 (4) ◽  
pp. 347 ◽  
Author(s):  
Simon C. Stirrat
Keyword(s):  
Seasonal Changes ◽  
Diet Composition ◽  
Foraging Ecology ◽  
Foraging Strategy ◽  
In Vitro Digestibility ◽  
Wet Season ◽  
Dry Tropics ◽  
Seasonal Environment ◽  
Herbage Quality

Seasonal changes in diet composition and diet preferences of the agile wallaby (Macropus agilis) were investigated in East Point Reserve, Darwin. The wallabies were almost exclusively grazers in the wet season when the nitrogen content and in vitro digestibility of herbage were high. Evidence suggests that wallabies rarely browsed in the wet season. The diet consisted mainly of non-leguminous forbs, reflecting the abundance of these plants in the study site, but the wallabies showed higher preference for grasses and legumes. In the dry season herbage quality was poor and the wallabies grazed on available green grasses and forbs but also broadened their diet considerably to include a range of alternative foods, including browse, leaf litter, fruits, flowers and roots. A flexible foraging strategy allows agile wallabies to exploit a range of resources in this highly seasonal environment where periods of food shortage may be long and their duration unpredictable.

Gut fill in cattle: effect of pasture quality on fasting losses

1985 ◽  
Vol 40 (3) ◽  
pp. 455-463 ◽  
Author(s):  
A. V. Goodchild
Keyword(s):  
Live Weight ◽  
Growing Season ◽  
Dry Season ◽  
The Other ◽  
Wet Season ◽  
Seasonally Dry ◽  
Dry Tropics ◽  
Pasture Quality ◽  
Grazing Cattle ◽  
Gut Fill

ABSTRACTAn abrupt fall in live weight of grazing cattle occurs at the beginning of the growing season in the seasonally dry tropics. In an experiment with grazing crossbred bulls in central Tanzania designed to monitor changes in gut fill, 16 were slaughtered in the dry season and 14 in the early wet season. Bulls were measured and weighed before, and weighed after, a 20-h fast and then slaughtered. Gut fill was measured and empty body weight (EBW) calculated.During fasting, the ratio gut fill/EBW fell from 0·291 to 0·217 in the dry season and from 0·207 to 0·119 in the wet season. Heart girth/EBW1/3 was 0·2577 and 0·2567 m/kg1/3 in the dry and wet seasons respectively.It was concluded that live weight before or after fasting is seriously affected by season and can give biased predictions of EBW change. On the other hand, heart girth is little affected by season and can be used to monitor relative increases or decreases of EBW within animals.

Diet selection and liveweight performance of steers on Stylosanthes hamata-native grass pastures

1980 ◽  
Vol 31 (2) ◽  
pp. 379 ◽  
Author(s):  
CJ Gardener
Keyword(s):  
Stem Elongation ◽  
Perennial Grass ◽  
Diet Selection ◽  
Similar Rate ◽  
Dry Season ◽  
Wet Season ◽  
Native Grass ◽  
Stylosanthes Hamata ◽  
Large Bulk ◽  
Native Pasture

Diet selection in S. hamata-native grass pastures was studied over 25 months at Lansdown, north Queensland, In oesophageally fistulated steers. The results were uscd to interpret the relationship between winter rainfall and liveweight gain of steers on pastures with and without S. hamata. Steers selected green grass leaf early in the wet season (December-February), but preferred S. hamata in March when stem elongation and flowering occurred in the native grasses. They then continued to eat a high proportion of legume during the dry season until rain fell. At Lansdown, this may occur from 4 to 23 weeks after the pastures hay off. After the rain, the steers ignored the large bulk of mouldy dry legume, selecting instead both green and dry grass. Seed and green leaf of S. hamata made their greatest contribution to the diet at the end of the wet season when retained on the standing plant and easily accessible to cattle. Small amounts of seed and dried leaf were licked off the ground before rain fell. The nitrogen content of the diet in the S. hamata-native grass pastures rose to a peak in April and did not fall below 1.0% during the study. The level in July was twice that recorded for the native pasture. Cattle gained weight during the wet season at a similar rate for all pastures. After March steers on S. hamata-native pasture continued to gain weight longer onto the dry season than those on native pasture in three out of four years. Much of the additional weight gains of steers on S. hamata were lost with the advent of winter rain, especially at the high stocking rate from which the perennial grass component had been lost. The value of S. hamata cv. Verano in the greatly differing climatic environments existing in northern Australia is considered.

scholarly journals Seasonal changes in water quality and macrophytes and the impact of cattle on tropical floodplain waterholes

2012 ◽  
Vol 63 (9) ◽  
pp. 788 ◽  
Author(s):  
N. E. Pettit ◽  
T. D. Jardine ◽  
S. K. Hamilton ◽  
V. Sinnamon ◽  
D. Valdez ◽  
...  
Keyword(s):  
Water Quality ◽  
Seasonal Changes ◽  
Aquatic Macrophyte ◽  
Plant Cover ◽  
Critical Role ◽  
Dry Season ◽  
Nutrient Concentrations ◽  
Wet Season ◽  
Dry Tropics ◽  
The Impact

The present study indicates the critical role of hydrologic connectivity in floodplain waterholes in the wet–dry tropics of northern Australia. These waterbodies provide dry-season refugia for plants and animals, are a hotspot of productivity, and are a critical part in the subsistence economy of many remote Aboriginal communities. We examined seasonal changes in water quality and aquatic plant cover of floodplain waterholes, and related changes to variation of waterhole depth and visitation by livestock. The waterholes showed declining water quality through the dry season, which was exacerbated by more frequent cattle usage as conditions became progressively drier, which also increased turbidity and nutrient concentrations. Aquatic macrophyte biomass was highest in the early dry season, and declined as the dry season progressed. Remaining macrophytes were flushed out by the first wet-season flows, although they quickly re-establish later during the wet season. Waterholes of greater depth were more resistant to the effects of cattle disturbance, and seasonal flushing of the waterholes with wet-season flooding homogenised the water quality and increased plant cover of previously disparate waterholes. Therefore, maintaining high levels of connectivity between the river and its floodplain is vital for the persistence of these waterholes.

scholarly journals Evapotranspiration seasonality across the Amazon basin

2017 ◽  
Author(s):  
Eduardo Eiji Maeda ◽  
Xuanlong Ma ◽  
Fabien Wagner ◽  
Hyungjun Kim ◽  
Taikan Oki ◽  
...  
Keyword(s):  
Amazon Basin ◽  
Regional Climate ◽  
Root Water Uptake ◽  
Environmental Drivers ◽  
Seasonal Patterns ◽  
Wet Season ◽  
Important Indicator ◽  
Seasonally Dry ◽  
Basin Scale ◽  
Terrestrial Water

Abstract. Evapotranspiration (ET) of Amazon forests is a main driver of regional climate patterns and an important indicator of ecosystem functioning. Despite its importance, the seasonal variability of ET over Amazon forests, and its relationship with environmental drivers, is still poorly understood. In this study, we carry out a water balance approach to analyse seasonal patterns in ET and their relationships with water and energy drivers over five sub-basins across the Amazon basin. We used in-situ measurements of river discharge, and remotely sensed estimates of terrestrial water storage, rainfall, and solar radiation. We show that the characteristics of ET seasonality in all sub-basins differ in timing and magnitude. The highest mean annual ET was found in the northern Rio Negro basin (~ 1497 mm year−1) and the lowest values in the Solimões River basin (~ 986 mm year−1). For the first time in a basin-scale study, using observational data, we show that factors limiting ET vary across climatic gradients in the Amazon, confirming local-scale eddy covariance studies. Both annual mean and seasonality in ET are driven by a combination of energy and water availability, as neither rainfall nor radiation alone could explain patterns in ET. In southern basins, despite seasonal rainfall deficits, deep root water uptake allows increasing rates of ET during the dry season, when radiation is usually higher than in the wet season. We demonstrate contrasting ET seasonality with satellite greenness across Amazon forests, with strong asynchronous relationships in ever-wet watersheds, and positive correlations observed in seasonally dry watersheds. Finally, we compared our results with estimates obtained by two ET models, and we conclude that neither of the two tested models could provide a consistent representation of ET seasonal patterns across the Amazon.

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