Management of kikuyu (Pennisetum clandestinum) for improved dairy production.
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Date
2007
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Abstract
South African dairy farmers have generally used kikuyu pasture to tide them over from one ryegrass
season to the next, and as a result of its resilient nature, have assumed careful management of it to be
unnecessary. This has resulted in its mismanagement which is unaffordable in current times where
the profitability of dairy farming is increasingly dependent on low input, pasture-based systems.
Kikuyu pasture may play a larger role in supplying nutrients to dairy cattle over the summer months
in future as the alternative home produced feed sources such as silage and perennial ryegrass become
increasingly unaffordable. Improving animal production from kikuyu is difficult as there is little
information relating kikuyu pasture management to dairy cow performance. Efficient utilization and
quality of temperate pasture have been more comprehensibly researched. The relations discovered
between the chemical compounds in temperate grass species have been applied to tropical pastures
such as kikuyu with limited success and often confusing results. For example, crude fibre in kikuyu
was found to be positively related to digestibility. In South Africa, much research has been done on
the use of kikuyu in beef production systems. This information has been applied to dairy farming
systems with limited success, owing to the higher metabolic demands of dairy animals. Pasture
farming needs to become more precise to improve pasture quality and hence milk yields as research
trials focussing on stocking rate and grazing system comparisons have yielded results that are too
general with little application at the farming level. A need for integrated and flexible management of
animals and pastures has been recognised. The grazing interval is a key aspect in improving pasture
and animal performance and fixed rotation lengths and stocking rates have been identified as being
detrimental to performance. The relation between growth stage and pasture quality has lead
researchers to identify plant growth characteristics, such as pasture height and leaf stage, as signs of
grazing readiness. At the four and a half leaves per tiller stage of regrowth, the chemical
composition ofthe kikuyu plant is more in line with the requirements ofthe dairy cow, with the leaf
to stem ratio at its highest. The primary limitation of kikuyu pasture is a lack of energy, particularly
readily fermentable carbohydrate, which makes the fermentation of structural carbohydrates difficult
and dry matter intakes are reduced. Other limitations to animal performance include high cell wall
constituents, low calcium, magnesium and sodium content and antinutritional factors such as nitrate
and insoluble oxalate. These deficiencies and antinutritional factors are in some cases unique to
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kikuyu pasture, meaning that kikuyu specific supplementation may be the key to improving
performance from dairy cattle grazing kikuyu pasture. The objectives are to evaluate current kikuyu
management systems in South Africa and their impact on dairy cow performance and to evaluate the
use of pasture height and burning as quality control tools.
Description
Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2007.
Keywords
Kikuyu grass., Dairy cattle--Feeding and feeds., Pastures--Management., Kikuyu grass--South Africa--Management., Dairy cattle--South Africa--Performance records., Proteins in animal nutrition., Prescribed burning., Kikuyu grass--Quality., Dairy farming., Theses--Grassland science.