The earliest use of the "haylage in a day" concept was probably back in the day of sickle bars, where the entire cutting width was laid out behind the mower. As mower designs changed and width increased, the entire mowing width was merged by the mower into a narrower swath. The result of narrower swaths is slower dry down and the potential for greater quality loss.
Forage researchers note that the quality of the forage that reaches the cow's mouth is dependent on three factors: when you start harvesting, how long it takes for you to complete the harvest and how much quality is lost during harvest. How much quality is lost during harvest is affected by HOW you harvest hay crop silage.
The plant continues to respire during the wilting and drying process of cut forages. This respiration process consumes plant sugars (energy) in plant cells and produces oxygen and water. The longer it takes forages to dry to the ideal moisture content for chopping, the longer the forage is respiring in the field. Respiration of these cells continues until the plant is fermented as a haylage crop or dried sufficiently as a hay crop. In addition to energy losses, dry matter losses can be significant. How producers manage their hay swath can greatly affect the time of haylage harvest. Wide swath management allows forages to dry more rapidly and shortens the time from cutting to harvest to minimize this post harvest respiration period.
The drying rate of forage crops is influenced the most by sunlight reaching the forages, which in turn increases the swath temperature and reduces humidity. A full width swath increases the drying surface of the swath by 2.8 times. In many trials, it has been shown that moisture reductions from 85% to 60% can be reached in as little as 5 to 7 hours, hence the term "Haylage in a Day". The bottom line is that the forage produced with minimal respiration results in higher nutrient content of the forage.
Think about laundry drying. A dense pile of laundry does not dry and neither does a narrow swath of haylage. The rate of water loss is dependant on the amount of the laundry or forage that intercepts sunlight. The greater the amount of surface area exposed to sunlight, the greater the affect on the drying rate. This affect is even greater than conditioning or turning the mowed swath.
Another factor found to affect drying rate for haylage is to not condition the crop. Conditioning crimps plant stems and disrupts the "plumbing" system of the plant. If left intact the plant plumbing system will function until whole plant moistures drop to approximately 60 to 65%, the ideal moisture for haylage. Conditioning is important for making dry hay, as the crimping allows additional moisture to leave the stems at moistures below 60%.
Clearly the management of a forage swath can have a huge impact on the rate of drying. Open your forage harvesting equipment to get maximum sunlight interception and "Haylage in a Day".