Cattle are now entering the second half of the grazing season. The management of grass over the next three months will influence how heavy cattle are in autumn and how much meal will be required for finishing animals.

When cattle are turned out early to spring grass in the correct body condition (fit, not fat) they will benefit from compensatory growth. These cattle can achieve daily liveweight gains of 1kg to 1.5kg/day from a grass-only diet from March to June, depending on the animal type.

Cattle that were consuming high levels of meal feeding up until the point of turnout will achieve less compensatory growth, while cattle that had meal removed for three to four weeks pre-turnout will have had a higher growth response. Likewise, younger cattle will have a higher growth response to spring grass than older cattle.

Grass quality

Where grassland management is generally good and cattle are maintained on high-quality grass swards, growing cattle should continue to gain close to 1kg/day of liveweight from now until early autumn from a grass diet. As autumn progresses, dry matter intake is reduced, which will reduce liveweight gain unless concentrates are offered.

For cattle to be gaining 1kg/day from grazed grass from now until autumn, they need to be grazing grass with a higher leaf and lower stem content. Grass swards that have headed out need to be topped or grazed out using a group of lower priority stock to clean off, e.g. dry cows or ewes. Do not force growing cattle to graze off sward with a high percentage of stem.

Table 1 outlines the feed value in two grazing swards that can be commonly found at this time of year. Sward 1 (pictured) is a sample taken from grazing paddocks that where grazed out tight in early June and topped on stock removal. The sward was dressed with 27 units of CAN and allowed to grow for 18 days before cattle resumed grazing.

Sward 2 (pictured) is a sample taken from grazing paddocks that were not grazed out tight over late May due to heavy rainfall. As a result, when grass growth surged in June there was a heavy build-up of grazing covers. Cattle were unable to clean off the grass as it had turned to stem.

The results in the table show that both swards have a high feed value. However, as sward one is mostly digestible leaf, the grazing animals will be able to better utilise this grass and therefore have a higher daily liveweight gain.

For cattle to be thriving to their potential, they should have a dry matter intake of around 2% of their body weight. A 450kg store bullock should be eating 9kg DM daily. This will be possible on sward one as the grass is more digestible – therefore the animal will have a higher grass intake.

With sward two, cattle intakes will be lower because there is more stem present, which is harder to digest. If the animal’s digestion is slowed down, then intake will be reduced, meaning the animal is eating less grass per day. The animal will not be eating the 2% of its bodyweight. A realistic intake will be closer to 1.5%, which is similar to many silage intakes.

As the growing animal is taking in less energy and protein, its liveweight gain will be reduced. As the fibre content in sward two is higher than sward one, the nutrient content is less readily available. Cattle grazing on swards similar to sward one will be gaining close to 1kg/day of liveweight over the rest of the summer. Cattle grazing on sward two will probably be gaining 0.7kg to 0.8kg/day at best.

The difference in DMD may initially appear small, but is roughly the equivalent of feeding 0.75kg/day of meal, which could support an increase in daily liveweight gain of up to 0.2kg/day. The samples were taken using a quadrant. All grass inside the quadrant was clipped down to 4cm to represent grazing animals which is probably influencing the high feed value of sward two.

As the amount of headed and rejected grass in sward two increases, its feed value will most likely drop back to somewhere in the region of 64 to 68 DMD, which will see a bigger difference in liveweight gain potential in animals grazing the two swards. The difference in DMD at this stage is similar to feeding 2.5kg/day of meal to cattle grazing on sward one.

From Table 1, it is clearly evident how good-quality grass can possess a higher feed value than concentrates. Most purchased rations will have a UFL of 0.95 and protein content of 14% to 16%. While dry matter is lower in grass, good-quality swards are capable of sustaining high performance without concentrates at this stage of the season.

Grass alone can finish most cattle types at this point of the year. Considering the protein values of grass, anyone planning to kill cattle off grass and feeding meal should only be offering rolled barley to increase energy intakes.

The high protein value in sward one reflects some of the residual nitrogen from fertilizer that was applied to the sward.

Grass sugars in both swards are good. With high grass sugars, it re-affirms the benefit of removing strong grass covers as baled silage at this time of year and using this grass as a high feed value winter forage.

Grazing costs

Taking a standard cost of €50 per tonne DM for grazed grass, every 1kg DM costs 5c for a grazing animal. A 450kg store has a grazing cost of 45c/day. If it is gaining 1kg/day of liveweight, it has a daily income of €2.20 based on typical MartWatch data.

However, as this animal has to generate a sale value to cover its own feed costs and the feed costs involved with keeping the suckler cow, the grazing cost of the cow (650kg) should be added to this. This brings the grazing cost to €1.10/day. There are no fixed costs accounted for in this example.

The grazing cost of the cow is often overlooked by producers. The combined cost shows the importance of getting as much liveweight gain from grass as possible to stand any chance of making a profit. Taking concentrates at €260/t, every 1kg of meal in the diet adds 26c to the grazing cost, which quickly erodes the profit margin.

The more days the animal gets at grass and the more weight gain from grass the better. Taking the store animal at 450kg, if grazed on swards similar to sward one, then its housing weight should be around 550kg when housed in October.

Having a heavier animal housed off grass means there is a shorter intensive finishing period when costs are higher. Having a lighter animal at housing means there is a store period required which eats back into the margin built up at grass.

At a daily gain of 1kg/day, the animal has a carcase gain of 0.55kg/day at 55% kill-out. At €4/kg beef price, the animal is generating €2.20/day in income. Taking the grazing costs outlined for the animal and cow, there is a margin of €1.10 over feed costs for every day at grass. Over a 200-day grazing season, there is a margin over €220 built up from grass.

Over a 100-day finishing period, a 550kg housed steer eating an average diet of 20kg silage (€25/t) and 8kg meal (€260/t) has a daily feed cost of €2.28/day.

At €4/kg beef price and a kill-out of 55%, the steer is generating €2.20/day in income, which is a loss of 8c/day.

Over the 100-day finishing period, this amounts to €8, which is subsidised by the €220 margin over feed costs that was built up at grass. Fixed costs are still excluded from this example.

The animal grazing on swards similar to sward two for the rest of the summer will realistically be gaining around 0.5kg/day liveweight, bringing its housing weight in October to approximately 500kg. This animal is too light to start pushing to finish, so a short store period is required first.

At 0.5kg/liveweight gain, the animal is generating an income of €1.10/day and is therefore only covering its feed cost and that of the carrying the suckler cow on farm. Therefore, there is less chance of the animal making a margin if taken through to slaughter unless liveweight gain, or beef price increases.

The emphasis now for beef producers is to keep grass quality as high as possible and get cattle finished as quickly as possible when they are housed this autumn.