Conserving Feed: Introduction

New ryegrass varieties characteristically produce high quality and high yielding winter and spring growth. Often however, this production is in excess of what your livestock require. You have spent time and money on establishment and ongoing nutritional requirements of an improved pasture so it would be a waste not to take advantage of the high quality and yield produced. Surplus pasture can be conserved by cutting for hay or silage and utilised in a time where feed is low. Conserving high quality pasture and maintaining that quality is a balancing act between the plant growth stage, weather conditions and storage.

Conserving Feed: Yield & quality

Plant growth stage will determine the quality and yield (particularly with ryegrass pastures). The table below emphasises the effect of growth stage on quality and yield of ryegrass. While the metabolisable energy and the crude protein levels are higher in the vegetative state (indicating a higher quality) the potential yield is slightly lower than a more mature plant. Ideally you should cut pastures in the late vegetative to early reproductive growth stages before quality deteriorates with plant maturity.

The effect of growth stage on quality and yield of ryegrass

Growth Stage	Metabolisable energy (MJ†/kg DM‡)	Crude protein (% DM‡)	Potential Yield (t DM‡/ha)
Vegetative (30 cm)	9.7 - 11.0	14.0 - 22.0	2.0 - 3.0
Head emergence (45 cm)	9.0 - 10.5	12.0 - 20.0	2.5 - 4.5
Flowering	8.0 - 9.0	8.5 - 18.0	2.5 - 5.0
Mature Seed	6.0 - 8.0	3.5 - 7.5	2.2 - 5.0

† MegaJoules; ‡ Dry Matter. Shaded figures indicate best values.
Source: Topfodder Successful Silage NSW Agriculture

Conserving Feed: Time of cutting

When to cut, as highlighted above is often a compromise between quality and yield. Timing of cutting is also determined by wilting rate. Wilting rate simply refers to drying out the pasture to achieve a desired dry matter (DM) content. A quicker wilting rate is better hence time of cutting should coincide with ideal drying conditions. Unfortunately this typically coincides with a later plant growth stage.

Conserving Feed: Storage

Although many high quality crops are harvested efficiently, there can be significant losses of DM and quality if the storage system is inadequate. These losses for silage are due to excessive respiration, effluent loss and aerobic spoilage in the stack or bales. For hay, losses are primarily caused by growth of fungi or moulds and chemical reactions that bind up some nutrients and reduce nutritive value. Adequate storage will minimises these losses and ensure a high quality feed source when you need it.

Silage and hay are effective ways to manage pasture surpluses and so improve pasture utilisation.