First winter nutrition: silage digestibility and concentrate supplementation to maximise compensatory growth

Emily Roskam Niall Kerins Mark McGee

In beef production systems, feed provision is the single largest direct cost incurred, accounting for approximately 75% of total costs of production; therefore, focusing on feed (cost) efficiency enhances farm profitability. Of the predominant feedstuffs available, grazed grass is lowest cost, purchased concentrate is the most expensive and grass silage and other conserved forages are intermediate (Further information: Producing beef from grass-forage-based systems). Because of the comparatively lower cost of efficiently produced grazed grass, pasture-based beef production systems have evolved to optimise the contribution of high-nutritive value grazed herbage to lifetime intake of feed, and to providing grass silage and concentrate as efficiently and at as low a cost as feasible.

Compensatory growth

‘Compensatory growth’ is the ability of an animal to undergo accelerated growth when offered high nutritive value feed ad libitum after a period of restricted nutrient intake. In grass-based beef systems this physiological response can be exploited during the first winter to enhance feed cost efficiency of weanling cattle. This is achieved by providing an energy-restricted plane of nutrition (i.e. grass silage and low-to-moderate levels of concentrate) to sustain a moderate animal growth rate during the ‘expensive’ indoor feeding period. Subsequently, when cattle are turned out to ‘low-cost’ pasture in spring, with an unrestricted supply of high nutritive value herbage on offer, they have an accelerated growth rate. Research at Teagasc Grange has shown that a live weight gain of 0.5-0.6 kg/day through the first winter is optimal for maximising compensatory growth potential in weanling steers and heifers (and even suckler bulls) following turnout to pasture. In other words, feeding greater quantities of expensive concentrate to achieve high growth rates during the winter was wasteful, as the animals that achieved the moderate growth rate with lower concentrate inputs caught up to their initially heavier counterparts during the grazing season. Animals that are growing too slowly (<0.5 kg/day) during the winter fail to compensate sufficiently at pasture to meet target weights later in life, leading to increased age at finishing and increased costs of production.

Silage digestibility and concentrate supplementation

Beef cattle rarely consume sufficient grass silage to achieve their production potential and as a result, energy-rich concentrates are routinely supplemented in practice. The primary role of concentrates is to compensate for the deficit in nutrient supply from forage. Dry matter digestibility (DMD) is the primary factor determining the nutritive value of forage.  ‘High-digestibility’ silage (e.g. >72% DMD) supports better animal growth and reduces concentrate requirements, whereas ‘low digestibility’ silage (e.g. <67% DMD) necessitates higher supplementation to maintain target growth rates (Table 1). Therefore, to more accurately determine concentrate feeding levels required to meet target growth rates, it is essential to test a representative sample(s) of silage to determine DMD and other nutritive and preservation characteristics. Average grass silage DMD in Ireland is 67%, indicating a typical requirement of 1.5 kg concentrates/head/day during the first winter; however, this will vary substantially across farms (Further information: Making quality silage on beef farms).

Table 1. Concentrate supplementation necessary for weanlings to achieve ~0.6 kg live weight gain/day and the respective cost during the first winter period for grass silage differing in dry matter digestibility (DMD)

Concentrate feed ingredients

Once the concentrate supplementation rate has been determined, the type of concentrate ration offered should be decided, paying close attention to the energy density, main ingredients, and the protein levels of the ration. At Teagasc Grange, the ‘standard’ concentrate offered in most beef production system studies contains 862 g rolled barley, 60 g soya bean meal, 50 g molasses and 28 g minerals and vitamins per kg fresh weight, prepared as a coarse mixture.

There is considerable variation in the quality of concentrate mixes available on the market and it is important to carry out some assessment before selecting a suitable ration. The following questions should be considered to help interpret the information provided on the label:

What is the energy density of the concentrate ration?

Energy is the primary limiting nutrient for growing cattle in grass-based systems and, as such, should be the main consideration when selecting a commercial concentrate. Energy content is not required to be stated on the label; however, it should be available on request and should always be verified. When dealing with growing animals, energy is expressed as Unité Fourragère Lait (UFL), where 1 UFL is equivalent to the net energy value of 1 kg air dried barley. See Table 2 for energy and protein values of common concentrate ingredients. An energy value of 0.93–0.94 UFL/kg concentrate as fed (~1.08-1.09 UFL/kg dry matter, (DM)), including ‘minerals’, is a minimum target for growing animals. Care must be taken when interpreting energy values (or any nutritional information) as they may be expressed in different forms including, on an as fed (fresh weight) or DM basis and with or without minerals/vitamins. Consequently, adjustments must be made where appropriate; water and minerals do not provide ‘energy’ (or protein).

Table 2. Energy and protein content of concentrate feed ingredients

What are the concentrate ingredients in descending order?

Ingredients are listed in descending order of inclusion (i.e. the highest inclusion rate appearing first) in concentrate feed mixes. Do not assume all ingredients are of similar quality. It is vital that the first 3-4 ingredients listed have a high energy content (>0.90 UFL/kg as fed). Assess the likely energy value of the concentrate by reviewing each ingredient and avoid rations where low-energy feeds (e.g. sunflower meal) are one of the main ingredients.

What is the crude protein content of the concentrate ration?

Crude protein is often overemphasised when selecting rations. While CP must be declared on the label, energy remains the primary driver of animal performance on grass-forage-based diets. High-protein rations (18–20% CP) are appropriate for animals in late-gestation and early-lactation; however, for growing cattle that are offered good quality silage, excess protein represents an unnecessary cost both financially and environmentally. Soyabean meal is a high-quality, protein-rich ingredient with a strong amino acid profile and a high proportion of rumen bypass protein; however, it is also relatively expensive. More cost-effective alternatives for increasing dietary protein include maize distillers, rapeseed meal, beans and peas (Table 2).

Research at Teagasc Grange indicates that weanling steers and heifers generally do not require additional protein supplementation when offered barley-based concentrates alongside high-DMD grass silage with moderately high (>13.5%) CP concentration. However, suckler-bred bull weanlings have shown a small but significant response to additional protein with barley. Responses to protein supplementation are more likely where grass silage is of moderate-to-low DMD and/or low protein content (<13.5% CP).

Are minerals included in the concentrate ration?

Mineral and vitamin supplementation should be included in all beef rations, typically included at 2.5% as fed.

What is the price of the concentrate ration?

Price should not be the only factor when selecting a ration. Comparisons should be made based on similar energy, protein, and mineral specifications expressed on a DM basis.

Turnout date to pasture in spring

Due to the comparatively lower cost of grazed grass, extending the length of the grazing season means that expensive feedstuffs are replaced with lower cost grazed grass and the cost of production is reduced. Additionally, there are reduced slurry handling costs. Research at Teagasc Grange has shown that 3-week earlier turn out of weanling cattle to pasture in spring (mid-late March vs early-mid April) resulted in a transitory benefit in live weight gain, which was not statistically significant by the end of the grazing season due to compensatory growth of the animals turned out later. However, early turn-out permitted cattle to graze designated silage ground in the first rotation, leading to increased nutritive value of the silage crop for the subsequent winter. From an environmental point of view, extended grazing reduces total methane emissions as fresh grass diets emit less methane per unit of feed energy consumed than grass silage.

Turnout date is ultimately determined by grass supply and grazing conditions, which are a function of soil trafficability and weather. For example, at Teagasc Grange, in 2025, suckler-bred weanlings were turned out to pasture on 5 March and dairy-beef weanlings on 25 February, whereas in 2026, turnout was delayed to 16 March and 8 March, respectively, reflecting the significant differences in rainfall between the two years.

Conclusion

The first winter represents a pivotal stage in the lifetime productivity of beef cattle, where nutritional management has lasting impacts on growth performance, efficiency, and profitability. By targeting appropriate housing weights, optimising daily live weight gain, aligning concentrate supplementation with silage quality and turning cattle out to pasture as early as possible in spring, farmers can maximise the efficiency of production and profitability.

Compiled and edited by Mark McGee and Paul Crosson, Teagasc, Grange Animal & Grassland Research and Innovation Centre, and first published in BEEF2026 – Driving Sustainable Performance, additional reading from BEEF2026 is available here.