Hay Production Lecture Notes

Objectives

• Describe the process of making hay
• Explain the importance of hay
• Be able to make and feed hay to livestock

Making Hay

• Hay:
  • Dry ‘grass’ material prepared in the field by cutting growing crop
  • Usually at the early inflorescence stage.
  • Herbage is cut, dried, and removed to a storage place.
• Objective: reduce the moisture content of the herbage to less than 25% so that bacterial and fungal growth is suppressed.

Cut and Cured Hay

• Generally of higher feed value compared to standing hay.
• More effort goes into its preparation than for standing hay.
• Hay making during the dry season (low humidity) is relatively simple; achieved by sun drying.

Obtaining Reasonable Quality Hay (e.g., 10% CP)

• Grass should be:
  • Cut at early flowering stage
  • Dried quickly (in less than a week)
  • Stored safely in a dry place.
• Earlier cuttings give better hay but yields are lower.
• Grass is difficult to dry if cut at the peak of the rainy season.
• Late cutting also gives poor quality hay.

Hay Curing in Dry Areas

• Grass can cure on the ground and be ready for stacking in two days (provided it's dry and stacks are placed on dry ground).
• Such hay can keep easily for two years.
• Termites, rats, and mould destroy improperly stored hay.

Moisture Loss in Hay Making

• Water loss causes closure of the stomata in cut herbage.
• Moisture loss must then occur through the cuticle (less permeable).
• Damaging the cuticle by mechanical methods would increase moisture loss.
• The rate of drying diminishes with the drying process.
• Leaves dry 10-15 times more rapidly than stems, leading to leaf shattering.
• When herbage is cut, drying is more rapid on the surface of the swath.
• Poor air circulation through the swath and the depth of the swath worsen the problem.
• Immature herbage gives a swath of greater depth.
• Objective: create swath conditions conducive to rapid and uniform drying.

Hay Making Processes: Conditioning

• Conditioning: Procedures or treatments to enhance the drying process (turning, tedding, laceration/bruising).
• Objective: Reduce the period when the crop is at risk (out in the field).
• Certain kinds of mowers (e.g., the flail or the drum) increase the drying rates.
• Conditioning procedures are complementary.
• Another objective is to produce uniformly dried hay.
• Moist patches are subject to mould, which may spread.
• Conditioning operations should increase the drying rate while ensuring uniform drying.

Avoiding Uneven Drying

• Techniques that produce swath of uneven thickness should be avoided since they often result in uneven drying.
• When hay is unevenly dried, it is difficult to remedy the situation.
• Conditioning by machine usually results in increased nutrient losses.
• In good weather gently treatments (e.g., turning) are recommended since they result in least damage to the crop.

Conditioning Techniques

Turning

• Simplest (easiest and cheapest) and most used technique.
• Aim: Invert the swath to increase air flow and transfer hay to relatively dry ground.
• There is a drying gradient in the swath and inversion will expose the relatively un-dried parts to the atmosphere consequently increasing aeration.
• Most useful when used in conjunction with other techniques.

Tedding

• Means grabbing and repositioning gently to leave the material looser than before.
• The swath of hay becomes denser as the herbage settles, impeding air flow.
• Tedding assists air flow through the swath.
• There is a marked increase in the drying rate when the swath is tedded.
• Tedding also improves the uniformity of drying.
• Frequent tedding is more effective than a single operation.

Bruising / Laceration

• Slicing through the cut herbage in order to enhance moisture loss
• Stems of herbage will dry more slowly than leaves.
• Bruising the plants will reduce this differential uniformity of drying.
• Laceration using a flail mower, a roller or a combination will rectify this problem.
• Substantially greater drying rates are achieved by this technique than those obtained by tedding.
• When the time required for reaching optimum moisture content for storage is reduced, then the risks of damage to hay due to poor weather will be diminished
• However, nutrient losses are higher in bruising compared to tedding or turning.
• Dry matter losses: physical losses, termites, rodents, when cutting, shattering of leaves, laceration, etc.

Timing of Conditioning

• Conditioning is most effective when it occurs close to or at the time when the crop is cut.
• Herbage is less prone to mechanical damage in the early stage therefore any severe or ‘heavy treatment’ such as bruising should be applied at this stage.

Hay Preservation

• In certain circumstances, it may be difficult to achieve moisture contents less or equal to 25%.
• If stored under such moisture conditions there is progressive deterioration due to fungal or bacterial action.
• Temperatures in the bale will decrease (\downarrow) and mould could increase (\Rightarrow) health problems.
• Interest in storing hay at high moisture content has led to the use of preservatives.
• Various fungicides have been tried. E.g. propionic acid, anhydrous ammonia and various hydroxides e.g. NaOH

Preservation Examples

• Propionic acid: is used at 1-1.5% of the crop from 30-50% Moisture content.
• Ammonium propionate: effective at similar levels as propionic acid but is more potent.
• Anhydrous ammonia: also effective but hay has to be enclosed in plastic sheets.
• Hydroxide treatment: is very effective and if successful has an added benefit of increasing the digestibility of hay.
• It is important that the preservative be uniformly distributed through the hay. Anhydrous ammonia has this advantage.

Artificial Drying of Crops

• The simplest and cheapest form of artificial drying is by use of forced air ventilation at ambient temperature.
• During the wet season this is unlikely to be adequate and the farmer will have to provide some means of heating the air.
• The purchase and use of more complicated driers is likely to be very expensive.

Qualities of Artificial Driers

• Artificial driers have high to medium temperature inputs and have the ability to dry large quantities of herbage over a short period of time.
• The type of equipment will depend on the crop, the quantity of material to be dried and the economic returns of the dried products.

Advantages of Artificial Drying

• It can be done at any time, day, night, wet or dry.
• Harvesting of the crops can be done over a short period of time and stored thereby removing the need for daily cutting.
• Artificial drying gives a product of higher feeding value than sun - cured hay: it curtails respiration and fungal action and dries the crop in a shorter period of time than sun - drying which may denature some nutrients.
• The loss of nutrients per unit area of land is less compared to sun - cured hay.
• Less space is required than for sun - cured hay i.e. when drying

Disadvantages of Artificial Drying

• The equipment is very costly to buy and to operate.
• It requires service and back - up and skills to operate.

Stages in Making Hay

• Cutting the swath
• Wilting the grass
• Conditioning the cut grass
• Windrowing the cut herbage
• Collecting and baling the grass
• Appropriately storing the hay

Forage Harvesting Equipment

• Small scale forage harvesting equipment include the sickle and the scythe
• Mowers and combine forage harvesters are used for large scale operations
• Two types of mowers used are:
  • Cutter bar mower
  • Rotary mower
• The cutter bar mower has two plates, one of which is stationary i.e. the ledger plate
• The moveable plate is called the sickle section or knife section

Rotary Mowers

• Rotary mowers have one or more rotating blades mounted horizontally
• Are generally used for cutting weeds, stalks and brush
• Due to their low height, rotary mowers are commonly used to clear weeds under trees in orchards

Forage Harvesters

• May be categorized into three groups
  1. Single chop machines: use a flail to cut the crop and produce a chop length of approx. ≥150mm. They can be used for direct cut or picking up of wilted material
  2. Double chop harvesters: cut the crop twice, firstly by flail and then again with a knife. The can also be used for direct cutting of herbage or collection of wilted material
  3. Precision chop harvesters: are meant for use with wilted herbage to produce chop lengths of 3-60 mm

Essential Components of Forage Harvesters

• Pick up device to pick up the forage that has been cut either by the mower or the harvester’s own mower attachment
• Auger or elevator to carry the cut (or picked) fodder to the chopping unit
• Chopping mechanism or shredding or chopping the cut herbage into small particles

Storage of Hay requirements

• For the hay to maintain its quality and quantity, the following must be adhered to:
  1. The hay should be kept dry
  2. It should also be kept at uniform temperature
  3. The hay should be protected from insects and excessive exposure to solar radiation
  4. Rodents and all other pests should be excluded

Challenges in Making Hay

• Hay making is difficult / impracticable on a very large scale in many areas because of the following reasons.
  • Much of the land is unsuitable for mowing because of its topography, ditches, rocks, angles and big trees.
  • Low yields per hectare make hay making uneconomic and biased towards the tropics.
  • Grass reaches the appropriate growth stage for hay making at the peak of the rainy season. At this time, the weather conditions make hay making difficult or impossible and liable to heavy losses of DM or nutrients.

Other Challenges in Hay Making

• In extreme cases spontaneous combustion caused by proliferation of thermophilic bacteria can occur when the moisture content of hay is too high.
• This usually occurs when hay is in a loose form.
• Another risk is the production of mould - resulting in:
  • low intakes
  • increased nutrient losses
  • decreased feeding value
  • hazard to human health. “Farmer Lung”.
• Other challenges