A RESEARCH study in the Kgatleng District of Botswana by the University of Botswana in 2008 found that the farmers’ common practice of overstocking cattle to make up for drought losses made ecosystems more vulnerable and risked long-term damage to cattle herds by depleting scarce biomass.
The study further predicted that by 2050, the cycle of mild drought is likely to become shorter – 18 months instead of two years, for the region, due to climate change.
Deforestation impacts the carbon cycle, as well as the global and regional climate, and causes the habitat loss of many species including grassland areas.
Deforestation can also create fragmentation, allowing the survival of only patches of habitat in which species can live.
If these patches are distant and small, gene flow is reduced, habitat is altered, edge effects occur and more opportunities for invasive species to intrude occur.
In Zimbabwe, grazing during the winter dry season, usually the months from May to November, becomes depleted due to continual grazing with no re-growth and by recurring, uncontrolled veld fires.
One should also ensure that fireguards are made early.
The quality of the available herbage also decreases due to frost, bleaching by the sun, accumulation of carbohydrates and lignocelluloses (known as anti-nutritional factors)
Stover is defined as the dry stalks and leaves of plant material such as maize, wheat and mhunga, among others, after the ears have been harvested.
Hay and cereal stover which are good sources of food for winter survival of cattle in the Highveld is essential for the winter months.
Vlei grazing areas are best utilised in winter compared to top land grazing as they are marshy and may pose serious liver fluke problems in summer.
Grazed in situ, stover is a low quality roughage (about three percent crude protein (CP) and 5,9 MJ/kg air dry), animal performance on stover being initially enhanced by grain gleanings of about 100-200kg/ha.
Grass, cut and conserved as hay at the early flowering stage, may contain six-to-nine percent crude protein (CP) content with 50 percent total Total Digestible Nutrients (TDN).
Stover and hay can also be ammoniated to improve its nutritive value for better animal performance.
The main limiting nutrient in fodder and stover is protein; urea is often used to improve the nutritive value of these roughage materials.
The CP content in treated stover can be raised from one-to-three percent to 10-12 percent.
CP levels fall from eight-11 percent during summer to one-to-three percent in winter, while total digestible nutrient content falls from about 80 percent to about 50 percent from summer to winter respectively.
Water supplies also become depleted and the available water often becomes warm, stale and fetid.
There is loss of weight and body condition among the cattle, reversing the gains made in summer.
As temperatures soar, the first flushes of grass appear and with it, an increased risk of plant poisons.
Everything poisonous is the first to be green!
Cattle farmers must be watchful of cattle poisoning, which usually occurs in spring when new, lush grazing wilts or is frosted.
Losses of up to 30 percent body weight in cattle may be tolerated purely for survival purposes.
However, if cows lose up to 16 percent of their body weight, they are unlikely to re-concieve during the next bulling season.
Protein supplementation of cattle in winter can convert body mass losses to gains and increase calving rates by four-to-five percent and weaning weights by 18-45kg/head.
There are vast differences in the response of different classes of stock to supplementary feeding.
Since ‘blanket’ supplementation of all stock may be uneconomic, experts recommend it makes better business sense to supplement breeding stock; the most profitable response being obtained from pregnant heifers and immature cows as well as weaners, followed by pregnant mature cows.
The profitability of protein supplementation can be increased by sorting the stock into categories with different priorities and requirements.
For specific supplementation, one should feed the right amounts of supplement to achieve specific performance targets.
Strategic stock feeding reduces feed costs and increases profit margins for the farm.
If available funds do not permit supplementation of all stock categories, priority should be given to heifers as well as second and third calvers since they give maximum response.
To enable strategic supplementation, a pregnancy diagnosis is imperative in order to determine which animals are pregnant and which are not and facilitate some sorting of the herds.
Protein supplementation should begin early, before animals start to lose body condition and weight, and the feeding should be on a regular basis.
Do not feed on a stop-start basis.
Feeding should be at around the same time every day; otherwise cattle will waste a tremendous amount of grazing time waiting.
Always ensure there is plenty of clean water for the cattle to drink.
An animal expends about 42kJ of metabolisable energy per kilometre of walking distance.
Areas with failing water supplies are also more susceptible to veld fires and should be exploited early.
The various forms of protein supplements include licks, meals and cakes, cubes and blocks.
Examples of licks are the urea or molasses that are usually fed in drums with a rotating tyre and should be checked regularly.
Meals and cakes are expensive to use as winter supplements for range animals.
They should be given on a daily basis in feed troughs.
Feed troughs also tend to favour the strongest animals in the herd, which may not be the best breeders when there is rapid degradation of the land around them.
However, rubber troughs or half drums can be used so that feeding venue can be changed daily.
Cubes should also be given on a daily basis; dribbled from an open sack off the end of a slowly moving tractor.
This allows even the weakest animal in the herd a chance at the cubes.
Since cattle are good at picking cubes from the ground, the feeding venue can be changed daily. Blocks are the most commonly used form of protein supplement.
Intake of animals being supplemented protein in block form is controlled by the hardness and salt content of the block.
These are fed about three times a week and usually weigh 15kg or 30kg with 30-50 percent CP content.
In this country, farmers have a tendency to purchase what would appear to be the cheapest maintenance blocks, which usually have a CP content of 30 percent and urea content of six percent.
However, the higher CP content blocks are better for two main reasons.
Rather than feeding blindly above the general recommended levels; farmers should study the critical targets for their own animals and circumstances and thus feed accordingly.
This requires periodic weighing and condition scoring of animal samples in each herd to monitor performance.
Mature cows may show no or little response to supplementation; feeding in-calf breeding cattle, as early as is economically possible is important.
Start at very low levels, gradually increasing until after calving down at which time feed can be quickly increased.
The secret of profitable protein supplementation is to bring cows just to the critical weight or condition necessary for conception and to achieve specific live weight gains in weaners.
Farmers should wean early to prevent cows getting too thin in the dry season
A group of one-year-old steers gained an average of 320g/day in 122 winter-feeding days on chicken litter at ART Farm. However, this product is not so palatable and may need to be mixed with chopped roughage or grain and molasses to mask the offensive smell.
A combination of the non-protein nitrogen and quickly degradable energy benefits the efficiency of utilisation of both.
Supplementary feeding is a fine blending of management tools, of observation and foresight.
Feed to achieve specific targets and take periodic sample weights to monitor performance.
It is important for indigenous cattle farmers in Zimbabwe to be cognisant of bulk grazing and stover on reserve on the farm and of the water situation in the paddocks in order to be able to formulate a winter cattle management programme, to maximise the potential of supplementary feeding for the cattle.
Dr Tony Monda holds a PhD in Art Theory and Philosophy and a DBA (Doctorate in Business Administration) and Post-Colonial Heritage Studies. He is a writer, lecturer, musician, art critic, practising artist and corporate image consultant. He is also a specialist art consultant, post-colonial scholar, Zimbabwean socio-economic analyst and researcher. For views and comments, email: tonym.MONDA@gmail.com