Hey, it’s hay time, but how safe is your hay for storage or feeding?

With cooler spring temperatures and above average rainfall during spring the Riverina is facing one of the best hay making season it has seen in years. But are seasonal conditions too good for hay making?

With extremely thick stands of cereal, lucerne, vetch and clover/pasture crops the major concern hay producers will face is with safe storage of hay, which could have higher than expected moisture levels. There is a narrow range of moisture levels suitable for making hay. Stored hay will heat if it is stored too wet and field losses due to leaf shatter can exceed 25% if baled too dry.

Large bales retain more of the heat generated than small bales and are more likely to heat at lower moisture levels. Heat damage appears as brown or charred hay in the middle of the bale. When making large bales it is important to bale hay at a moisture content no higher than 14 to 16 per cent. Other factors including bale size, density and how it is stored can also influence the risk of heating, with smaller bales generally being better than large square or round bales due having a relative larger surface area, which can dissipate heat better.

Hay baled at 25% to 35% moisture can result in spontaneous combustion. High moisture can also result in lower quality feed as hay baled above 20% moisture in addition to heating can also go mouldy affecting nutritional quality of feed and increasing the potential risk of sickness and disease in livestock when fed, as some moulds are toxic and may cause sudden death or longer-term health problems such as liver damage.

In addition to wet and cooler weather extending curing time with uneven drying due to thickness and maturity of crops, weeds present or machinery used, another key factor this spring to increase risk of hay heating could be the variation in levels and type of plant water soluble carbohydrates (WSC) or sugars present in the forage.

Nitrate and nitrite poisoning of livestock needs to be taken into consideration, as nitrate levels found in plants is affected using nitrogen containing fertilizers, low soil sulphur and molybdenum levels, cloudy or cold weather, herbicide application such as phenoxy herbicides and part2,4-D, and wilting. The level of nitrate in plant tissue also depends on plant species, stage of maturity, and the part of plant cut for hay. As nitrate is usually higher in younger plants and is in the bottom third of stalks. This is a common for canola hay.

So how do you find out what moisture level is in your hay? Options available, include:

  • Paddock Inspection: it is always best to check your windrows in the early afternoon prior to the baling before the night air comes in. Particular attention should be taken to inspect all parts of the windrow especially underneath, on the ground, on corners and headlands, and anywhere a tractor wheel may have run over them.
  • Bull Bar Test: as part of paddock inspection, taking a cereal hay sample that contains a head or a node, placing it on a flat surface (such as a bull bar) and hitting the head and or the node with a hammer. If this leaves moisture on the surface or the hammer, then the sample is not ready for baling.
  • Moisture Meters: in-baler meters tend to be used as a guide to relative, but not absolute moisture. Contractors use a calibrated electronic moisture meter, and the best results seem to come from monitoring the moisture of the crop once baling has started.
  • Microwave oven test: this involves taking a sample of the fodder from the windrow and removing all moisture by heating it in the microwave and calculating the moisture percentage based on the oven dried weight compared to the initial wet weight.
  • Testing in storage: if unsure once hay has been baled and put in storage it should be tested for moisture over consecutive days (using moisture meter or microwave) to ensure stack temperatures are not increasing.
  • Feed testing: approved feed testing facilities offers a comprehensive commercial laboratory testing service for the analysis of animal feed including hay, silage and grain, mixed feeds and total mixed rations, pastures, and forages. Feed testing provides accurate results and prompt turn-around time, for many quality components including moisture %, dry matter % (DM), crude protein (CP), metabolizable energy (ME mj/kg), neutral detergent fibre (NDF), dry matter digestibility (DMD), water soluble carbohydrates (WSC), and nitrate (as NO3).

Further information can be found at:

Effects of heating on feed value of hay Factsheet

Nitrate and nitrite poisoning in livestock PrimeFact

Quality of hay and how to get it

Feed quality service

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