Lucerne is the only perennial legume planted as a commercial crop to produce high quality hay. With good haymaking weather and management an irrigated lucerne crop produces 7-10 cuts per year with an average commercial hay yield in Queensland of 2.5 t/ha/cut (15-25 t/ha/year). An 18% moisture content is normal for freshly baled lucerne hay. Individual crops have been recorded up to 40 t/ha/year. Irrigation or regular rainfall ensures a consistency of lucerne regrowth between cuts.
Rain falling on drying hay can seriously downgrade its quality by causing it to mould. On average, one or two cuts per year are damaged or lost in this way.
Peak periods of hay demand in Queensland are winter and early spring, when natural grazing sources are low and lucerne growth is slow, even with highly winter-active varieties. Adding to this demand are horse owners participating in the State’s winter racing program, in shows, pony clubs, and from those on recreation farms. This demand increases the purchase price of hay in winter, at times by up to triple its summer equivalent.
Good quality lucerne hay is commonly baled in summer and stored for sale in winter when higher prices cover the extra handling and storage costs associated with the practice. In short-term storage nutritional loss is small, but up to 10% weight loss can occur as hay dries below 180/0.
As hay is a bulky, low-density commodity, providing permanent weatherproof storage can be expensive. Many smaller hay users prefer to buy hay, as it is required, to avoid this cost.
Properly harvested lucerne hay is a high quality feed with up to 700/0 digestibility and crude protein of around 200/0. The most nutritious part of a legume plant is its leaf. Lucerne leaves average 500/0 of plant weight, are 650/0 digestible and contain up to 700/0 crude protein. This explains why leafiness has always been associated with prime quality lucerne hay. Other features are a green colour, a pleasant aroma, fine stems and freedom from weeds and trash.
When to cut
Early cutting will produce very nutritious hay, but its dry matter yield will be low because immature foliage is high in moisture and low in fibre. Conversely, later cutting will improve dry matter yield but reduce nutritional value and digestibility. (Refer also to Chapter 1, Understanding lucerne).
Because there is always a compromise between hay yield and quality, growers have to strike a balance in deciding on cutting interval. Use the plants themselves as the best indicator of when to cut. Lucerne should be cut when the regrowth shoots coming away from the crown of the plants are 1-2 cm long, i.e. still below the mower height. This is still the pre-flowering stage for modern lucerne varieties. General commercial practice in Queensland is to cut properly irrigated lucerne about every four weeks in summer and less frequently in winter, according to the variety. Even highly winter-active lucerne varieties in Queensland will require a minimum 6— to 7-week cutting interval in winter.
The cutting interval is sometimes reduced when leaf disease or insect damage threatens the potential yield and quality of a crop approaching cutting maturity and cutting is carried out in preference to applying a chemical control.
The appearance of new shoots from the crown shows that the existing foliage is mature and that food reserves used to produce this foliage have been fully replenished. Early mowing, or damage to shoots from late mowing could eventually shorten the life of a lucerne plant by exhausting its reserves of stored energy. See Chapter 1 for more explanation of this principle.
Curing lucerne hay
Temperature, humidity and wind movement controls the drying or curing rate of hay. Warm dry air will rapidly absorb moisture from the evaporating surface of the drying crop. As air temperature decreases, its capacity to hold moisture declines. At night, water may condense out of the air as dew.
The best drying conditions occur when light wind moves hot dry air around, and through, a curing hay crop .However, cold, dry air, although unable to absorb as much water vapour as warm air, can still be an effective drier if it keeps moving (for example, a moderate westerly wind).
Lucerne leaves have very fine petioles, or leaf stalks, that break easily if the hay crop is too dry when worked with haymaking machinery. Very dry leaves are also easily broken into small fragments. Broken leaves do not get baled. Working very dry lucerne hay causes leaf loss of 25-500/o, compared with 3-40/o for moister hay. It is impossible to work lucerne hay without some leaf loss, so the fewer times it is handled the less it is damaged, especially when cured and ready for baling. See Table 8.3 on page 60 for details of mechanical losses that can be expected.
Although modern hay curing is highly mechanised, several rain-free days in summer, and several weeks in winter, are still needed to cure hay. Predicting fine haymaking weather demands a combination of weather forecast data and local knowledge, but inevitably, in an average rainfall year, some curing hay will get wet.
Feed value testing of hay
Buyers of hay are increasingly buying hay on the basis of actual laboratory-determined feed values, as opposed to the more traditional hay quality attributes of colour, softness, leafiness, stalkiness, fragrance, etc. This is particularly true of the intensive animal industry users such as dairies and feedlots.
Growers and buyers of hay have access to feed testing laboratories in Queensland, including:
• Casco Agritech Toowoomba, 214 McDougall Street, Toowoomba, Q 4350. Ph 4633 0599.
• Symbio Alliance Laboratories, 47 Manilla Street, East Brisbane, Q 4169. Ph 3391 7558.
• Check Yellow Pages for other laboratories.
The sampling and dispatch of hay samples is of critical importance in the usefulness of the laboratory test results. Consult the laboratory prior to sampling and dispatch to obtain instructions on these important aspects.