The Chemical Composition and Nutritive Value of Grasses from Semi-Arid Areas of Karamoja as Related to Ecology and Types of Soil

Bredon, R. M.; Wilson, J. K.

doi:10.1080/00128325.1963.11661913

Cited by 22 publications

(6 citation statements)

References 3 publications

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“…Most nutrients in the vegetation of rangeland ecosystems are generally present in quantities that are non-limiting for herbivores (Kreulen, 1975;Hinnant & Kothmann, 1982). Owen-Smith & Novellie (1982), however, have found that some mammalian herbivores in South African savannas may be energy-limited, and available evidence suggests that East African herbivores are nitrogen-limited for at least part of the year (Bredon & Wilson, 1963;Sinclair, 1974Sinclair, , 1975.…”

Section: Discussionmentioning

confidence: 99%

“…Concomitant with the large seasonal changes in plant biomass are equally large and important changes in nutrient content and digestibility. Generally, the grasses and forbs of the herb layer have relatively high digestibility (French, 1957;Minson, 1971) and high concentrations of N, P, and other nutrients (Plowes, 1957;Bredon & Wilson, 1963;Taerum, 1970;Sinclair, 1975) soon after growth resumes at the onset of the rainy season. During this period of early growth, concentrations of crude protein in grass leaves are approximately 8-2O%, while forbs have higher concentrations ranging from 15 to 30% (Juko & Bredon, 1961;Dougall, Drysdale &Glover, 1964;McKay & Frandsen, 1969).…”

Section: Introductionmentioning

confidence: 99%

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Seasonal changes in the nutrient content of East African grassland vegetation

Boutton

Tieszen

Imbamba

1988

African Journal of Ecology

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Summary Significant seasonal changes in the concentrations of N, P, K, and Ca were observed in the herb layer vegetation at Nairobi National Park and Masai Mara Game Reserve in Kenya. These changes were related to the alternation of wet and dry seasons. Live forbs typically had the highest concentrations of all nutrients, especially N and Ca, at both locations. Standing dead and litter compartments showed less seasonal variation and had the lowest concentrations of all nutrients except Ca when compared with those of other compartments. Standing stocks of all nutrients were higher at Nairobi National Park than at Masai Mara due to larger litter and standing dead compartments resulting from lower grazing intensity and a lower frequency of fire. Most of the aboveground nutrients at Nairobi National Park appeared to be recycled through the decomposer pathway, while a large proportion of the standing stock at Masai Mara appeared to be recycled through the excreta of large mammalian herbivores and through fires. The crude protein content of the live grass compartment fell below maintenance levels required for ruminants (5% crude protein) during September 1980 and February 1981 at Nairobi National Park and during June and July 1980 at Masai Mara Game Reserve. Thus, herbivore populations in these preserves may be limited by shortages of nutritionally adequate food during dry seasons, as previously reported for other regions in East Africa.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Seasonal changes in the nutrient content of East African grassland vegetation

Boutton

Tieszen

Imbamba

1988

African Journal of Ecology

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“…(c) The quality of the diet ingested is superior to the quality shown by chemical analysis of the available browse (Bredon, Torrell & Marshall, 1967). (d) It increases the requirement for fibrous roughage (Bredon & Wilson, 1963), which giraffe satisfy by feeding on old broad-leaf foliage. (e) It increases the total time spent feeding.…”

Section: Plant Part Selectionmentioning

confidence: 99%

The feeding ecology of a selective browser, the giraffe (Giraffa camelopardalis tippelskirchi)

1984

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A herbivore can manipulate certain factors of its feeding behaviour in order to achieve the metabolic requirements for reproduction. These factors include the choice of habitat in which to feed, the selection criteria for choosing food items, and the time allocated to feeding or devoted to other energy‐consuming activities. The manipulation of these behavioural factors by giraffe in the Serengeti National Park, Tanzania is analysed in relation to the seasonal changes in the quantity and quality of the food resource. The pattern of habitat choice demonstrates seasonal movements by giraffe across the drainage catena in response to differences in the rates of browse production between woodland types. Giraffe show a positive inter‐specific selection for the minor food items with a low available biomass, and utilize the dominant species in approximate proportion to their availability. Plant part selection is shown for the flushing shoots with very high protein contents. Selection criteria include a significant selection for phosphorus, and in the dry season a selection for high energy material by breeding females. With the high nutritional qualities of the diets, negative criteria such as secondary chemical compounds are important. Patterns of browse selection are correlated with inter‐specific seasonal changes in plant phenology. Giraffe devote more time to foraging as the biomass and quality of the food declines in the dry season. Energy is conserved by minimizing energy‐consuming activities at the most demanding times of day.

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“…Bredon,Harker & Marshall (1 963) found that the degree of digestibility of dry grass-the digestibility coefficient (DC)-was related to the % crude protein (CP) in the diet of cattle by DC = 100.89 log CP -44.45 and this gives zero digestibility at 2.76% crude protein. But protein and energy assimilation remain low even above this level due to the inhibition of the rumen micro-organisms untiI a higher quality at intake is attained: the minimum level of crude protein for maintenance in tropical cattle has been estimated to lie between 4% and 8% with most measurements approaching 5% (French, 1957;Plowes, 1957;French et al, 1957;Bredon & Wilson, 1963;Agricultural Research Council, 1965;Milford & Minson, 1966). The value of 5% crude protein has been used in Fig. I to indicate the minimum maintenance level.…”

Section: The Qualit! Of Food In the Serengetimentioning

confidence: 99%

“…This was confirmed by empirical observations of cattle (Hancock. 1954;Campling, Freer & Balch, 1961). Because of this, there is a level of protein content in the food below which it becomes uneconomical to digest; the energy expended is too high, and the rate of nitrogen intake is less than the rate of nitrogen excretion.…”

Section: Introductionmentioning

confidence: 99%

The natural regulation of buffalo populations in East Africa: The food supply as a regulating factor, and competition*

Sinclair

1974

African Journal of Ecology

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Summary Evidence is presented to show that both the quality and quantity of food available to a buffalo population falls below the minimum maintenance requirements of that population at certain times of the year. In the Serengeti grasslands there was a shortage of the only good quality component, grass leaf, in the dry season, with the result that the animals consumed an increasing proportion of poor quality food such as grass stem. By the end of the dry season the diet had dropped in quality below the minimum maintenance level. In areas such as Mt. Meru where there was a more continuous growing season, the high density of animals kept the standing crop of leaf at a low level. During the cooler dry season the growth of leaf became insufficient in quantity for the maintenance requirements of the population. These two quite different situations suggested that food shortage was a more general phenomenon in eastern Africa. Various measurements of feeding behaviour were made. Total grazing time per 24 h did not differ between seasons but ruminating time may have increased as the season became drier and could have been a response to the more fibrous food. Analysis for cycles of activity showed that there was more temporal organization during the dry season. These changes in activity cycles appeared to be related to the increase in energy expenditure produced by heat stress and sweating. Old animals with poor teeth did not compensate for the poor food supply by changing their feeding behaviour. There was a positive relationship between annual rainfall and mean crude density in different areas of eastern Africa, indicating that regulation was taking place. Since rainfall determined the amount of available food, it could have operated through the food supply. On a finer scale it was found that the extent of the preferred riverine habitats was also related to density. Thus rainfall, the extent of riverine habitat and perhaps soil moisture were three limiting factors that determined mean density and all could have taken effect through the food supply. As a result of initial selective grazing the amount of available leaf declined as the dry season progressed to the extent that by the end of the season the proportion of this component in the diet fell to a very low level. The impact of the population on its limited food supply indicated that intra‐specific competition was acting as the cause of regulation. Measurements of wildebeest eating the same food in the same habitats as buffalo showed that inter‐specific competition was also taking place. A small proportion (7“) of the wildebeest population could have reduced the buffalo population by approximately 18o,‘, from its potential population size. The buffalo population in the Serengeti was regulated by adult mortality which was caused by undernutrition as a result of food shortage. This food shortage was caused by intra‐ and inter‐specific competition. The effect of predation and disease was to hasten the response of the population to changes in the food supply. The limiting...

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The Chemical Composition and Nutritive Value of Grasses from Semi-Arid Areas of Karamoja as Related to Ecology and Types of Soil

Cited by 22 publications

References 3 publications

Seasonal changes in the nutrient content of East African grassland vegetation

Seasonal changes in the nutrient content of East African grassland vegetation

The feeding ecology of a selective browser, the giraffe (Giraffa camelopardalis tippelskirchi)

The natural regulation of buffalo populations in East Africa: The food supply as a regulating factor, and competition*

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