Principles of haymaking using tropical grasses and legumes
Hay is a very popular form of forage preservation that provides an important source of animal feed in smallholder farming systems. Commonly hay can be prepared from fresh grass, forage legumes such as: cowpeas, velvet bean and lablab. During haymaking, forage is harvested by cutting and is left to dry in the sun until the moisture content reaches about15-20% dry matter, at which stage it is stored safely. Hay is classed as a roughage, i.e., a feed with over 18% crude fibre and under 20 % crude protein in its dry matter (DM); in practice, most hays have a feeding value well below these levels. It is rarely a complete food and must be used as part of an overall feeding system. Crop residues, straws and stovers, mainly but not exclusively from cereals, are also important as lean-season feed for ruminants, and are often used in association with hay.
Steps in haymaking
- Plants should be harvested by cutting at the appropriate stage of growth. As the plant matures, its herbage yield increases and nutritive value decreases. Therefore, hay should be harvested at a stage of growth when both the nutritive value (chiefly forage digestibility and protein content) and the herbage yield are optimized usually at flowering time.
- Forage intended for making hay should be harvested when the farmer is confident there will be three or more days of sunny weather.
- Harvesting is best done in the morning, to allow the cut forage to start drying during the remaining part of the day when the stomata (tiny breathing holes on leaf surface) are still open.
- Resource-constrained farmers can use hand-held sickles (or slashers) to cut grass and legume crops. Where resources permit, tractor mounted mowers can also be used to harvest the pastures.
- Leaf and stem material is normally covered with wax-like material (cuticle) on its skin (epidermis), to protect the plant from unwanted water loss.
- Water lost as by transpiration occurs through the stomatal apertures. To hasten drying, forage can be physically treated at the moment of cutting or immediately afterwards.
- The objective of such treatment is to bruise or press the herbage so as to break the skin and its cuticle and, thus, avoid stomatal resistance during drying. This can be achieved by putting the forage on a hard surface and rolling a 200-liter steel drum, covered in mesh wire, over it.
- Cut and conditioned herbage must then be turned several times to speed up the rate of drying. The process of turning the hay soften it up and allows the air and sunshine to penetrate the herbage, hastening drying. Turning must be done once or twice a day. However, if the hay is turned too frequently, particularly when it almost dry, will cause the leaves to shatter (and break into pieces). Legume hay is especially prone to leaf shatter.
- Bailing hay too early (when moisture levels are greater than 23%) will trap moisture inside the bale and promote the growth of thermophilic t. bacteria, causing spoilage from heating and even burning of the haystack. Late baling (when moisture levels are around 15-16%) will cause the leaves to shatter, due to extreme dryness.
- The ideal moisture content for baling varies from 18-22%, depending on forage species. In the absence of a baling machine, using their feet smallholder farmers can compress the hay in portable wooden crates or pits (90cm long x 60cm wide x 60cm deep) dug into the ground.
- Proper storage is a critical step in making high-quality hay.
- Hay bales should be stored in well-ventilated farm sheds that also provide sufficient cover from the rain.
- It is important to ensure that the sheds or barns do not expose the hay to very moist conditions causing spoilage from moulds.
- Hay sheds can be built using simple materials, such as wooden poles and grass thatching.
- Wooden pallets or a raised platform can be used to avoid placing the hay directly on the shed floor.