For farmers to effectively manage grazing livestock they need to understand the stocking rate of their farms. Stocking rate is the number of animals grazing a unit area in a given time and is measured in terms of Animal Unit (AU) for large stock or Dry Sheep Equivalent (DSE) for small stock.
One AU is equivalent to 400 Kg and one DSE to 40 Kg.
For example the following classes of animals can be standardized as follows:
|A calf (1 – 8 months)||0.35 AU|
|Weaner (8 – 12 months)||0.4 AU|
|Steer (1 – 2 years)||0.87 AU|
|Breeding cow||2.00 AU|
|Lamb (2 teeth)||0.5 DSE|
|Breeding ewe||1.7 DSE|
The stocking rate influences livestock production in the farm. Production decreases as stocking rate increases. At high stocking rates production per animal and per hectare is reduced relative to high but comparatively safe stocking rate. Grazing pressure which is the ratio of feed demand to feed available is so high that animal demand exceed supply and overgrazing results in decline of pasture productivity and death of some plants which will further increase the grazing pressure. Death of some animals may occur after the crash point.
So the objectives of grazing management is to maintain high production for good quality forage for the longest period, maintain favorable balance between herbage species in pasture mixtures (grass / legumes mix), achieve efficient utilization of herbage produced, achieve high animal production and to regulate ectoparasites.
The stocking rate of the farm can be increased by the following systems of grazing animals:
This is a system of grazing in which animals are fed on grass or other feeds in a stall. Farmers establish highly productive fodders like Bana grass, French Cameroons, Guatemala grass, giant setaria, or sweet potato vines. These fodders are managed to ensure enough feed is available throughout the year. Forages can be conserved in form of Hay or Silage during the peak growing season to be utilized during the dry season.
The are many benefits of zero grazing because it:
- Allows for more efficient utilization of forage since there are no losses from falling and trampling
- Fencing and supply of piped water is dispensed with except at the zero grazing enclosure
- Animals are protected from heat
- There is greater control measure of bloat especially if forages are wilted before feeding to the animals
- There are reduced chances of animals getting infected with parasites because they do not move about.
However the flip side is that the system is labor intensive and there are high costs incurred in fodder establishments, maintenance and constructing the zero grazing shed.
The success of zero grazing is dependent on feeding. Adequate feed, water and minerals should be provided to the animals. The feeds include cut and carry fodder, crop residue, agro-industrial waste (brewers waste, pyrethrum marc). These roughages can be utilized for average daily milk production of 8 – 10 litres without supplementation. Animals producing over 10 litres per day require supplementation with concentrates at a rate of 1 to 1.5 Kg/litre of milk above the daily 10 litres.
Farmers should try to utilize what is available in the farm for maintenance and only use concentrates for high yielders.
Semi – zero grazing
This involves grazing animals during the day and then feeding animals on fodder or crop residues, agro-industrial byproducts as supplements at night.
Animals under semi-zero grazing system require 9 kg of fresh napier grass per animal per day as night feeding supplementation. Fodder should be chopped into small pieces to increase the DM intake. Long pieces lead to lots of wastage. The intake is also affected by plant species. For equal chop length it has been found that the DM intake for maize is higher than that of napier.
Animals should be grazed for at least 12 hours. If confined for more than 12 hours then there is a need to supplement the grazing or else the system will have detrimental effect on animal production. If conditions in the night boma are favorable milk production of 6 to 8 litres per animal per day is possible without the night shed confinement seriously affecting the yield.
Semi – zero grazing has many benefits such as:
- Less labor for feeding than in the zero grazing system
- The system allows farmers to have a higher stocking rate since animals are supplemented with fodder, crop residues and industrial byproducts.
- Facilitates collection of dung which can be utilized as manure or in the production of biogas
- Animals are protected from wild game and stock thieves