Silage: Both a Cost and an Asset - How Does Yours Stack Up?

John Galvin, B&T Drystock Adviser, Teagasc Galway/Clare, discusses the importance of silage quality testing to optimize livestock nutrition and manage winter feed costs effectively.

As November approaches, winter truly begins in the west, even though the recent weeks have allowed for extended grazing, despite dwindling grass supplies on many farms. Grass silage remains the primary winter forage, whether in round bales or pits, with 1st cuts, 2nd cuts, and surplus grass from fields comprising the feedstock. This creates a potential for substantial variation in silage quality. Testing silage is essential for all farmers, yet silage sampling rates among Irish farmers remain low, representing a missed opportunity to optimize feed quality.

While on-farm assessments, using sight, touch, and smell, can provide some insights into dry matter, preservation levels, and general feed value, these methods are approximate at best. Given that silage crops constitute one of the largest costs on most farms, feeding silage to different livestock groups without understanding its nutritional adequacy is a missed chance for efficiency.

Dry Matter Digestibility (DMD)

When analyzing silage, the most critical measure of quality is Dry Matter Digestibility (DMD), as it correlates with crude protein and mineral levels in the grass. DMD estimates silage energy content and helps predict potential live weight gains or milk yields, guiding meal supplementation rates effectively.

Target Silage Quality

This year, most spring-calving suckler cows are in good condition after sufficient summer grazing. For these animals, 65 DMD silage should meet their needs when fed to appetite. However, first and second calvers should ideally be penned together and given 70 DMD silage or 65 DMD silage with a 2 kg meal supplement.

The beef trade is strong, both for live sales and finishers in factories, but regardless of prices, best practices for wintering cattle remain the same. As shown above, high-quality silage is essential for weanlings, stores, and finishing animals. Tempting as it may be to rely on silage alone, knowing the quality is key. Weanlings and stores need an optimum daily gain of 0.60 kg/day, as exceeding this incurs higher meal costs unless the animals are suited to premium export markets. Gains below 0.5 kg/day can lead to protein deficiencies, stunted growth, and lower attractiveness in the mart.

Comparing Good vs. Poor Silage

As illustrated, low-quality silage has no role in diets for young, growing cattle. The added cost of concentrate supplements and the potential penalties from feeding lower-quality silage make it financially unfeasible. For finishing cattle, there is similarly no place for inferior silage. A continental steer close to finishing weight (100-120 kg from target) requires 75 DMD silage and 4-5 kg of high-energy concentrates (€3.10/day) to gain 1 kg of live weight (yielding 0.60-0.70 kg carcass weight) per day. Achieving similar weight gains with 65 DMD silage would double concentrate requirements, making ad-lib concentrate feeding a more viable approach.

These scenarios underscore the importance of silage testing, enabling well-informed decisions on meal or concentrate supplementation across various livestock. Particularly with high-quality silage (70-75 DMD), savings are possible when feeding dry suckler cows by restricting their intake to 80% of their appetite, which could save nearly two bales per cow over winter.

How to Test Silage

To accurately test silage, take a fresh sample from the middle of the pit or combine samples from multiple bales. Mix them in a clean bucket, place the sample in a large freezer bag, and send it to the lab promptly, ideally early in the week to avoid weekend transit. High-quality silage testing costs less than a bale and provides invaluable information on one of winter’s most significant farm inputs.