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Beef Productivity from Grazed Grass
by Adam May, Beef and Sheep Product Manager
Good grassland management is essential to maximise beef output. The main objectives being to produce high yields of grass and to manage both the grass and the cattle to ensure high intakes and animal performance, while at the same time avoiding underutilisation of the sward and grass wastage. These objectives are best achieved by turning cattle out as early as is practicable in the spring, maintaining the correct sward height throughout the grazing season and ensuring that cattle feed requirements are closely matched to the rate of grass growth by good grassland management. This year, despite input costs remaining high relative to other feedstuffs, grazed grass is still far and away the cheapest source of feed.
Early turnout of cattle to grass is critical. The Department of Agriculture and Rural Development (DARD) funded research undertaken at Hillsborough has clearly shown improved animal performance by turning both finishing and store cattle out to pasture early. In one study, continental cattle turned out to pasture 6 weeks earlier than normal, i.e. on 14th March, produced carcasses 23kg heavier than their counterparts which remained indoors on grass silage and concentrates until 2nd May. In another more recent study, store cattle turned out to pasture 3 weeks earlier on 5th April were 23kg live weight heavier at housing than their counterparts which remained housed until 22nd April. Results indicate that turning out to pasture up to six weeks early in spring can offer substantial economic benefits.
In addition to improved animal performance early turnout cuts production costs by reducing the requirement for winter feed as well as the volume of manure/slurry to spread.
During the grazing season it is essential to manage the stocking rate in line with grass growth to ensure cattle have access to a high quality grass sward. This is best achieved by ensuring grass growth equals grass demand. Grass quality depends on the stage of maturity of the plant which can be determined from the height of the sward. As grass grows the proportion of stem within the plant increases. A sward of long stemmy grass has a lower nutritional value and is less palatable than a short green leafy sward. Grazing the sward down tight (5cm) in the early grazing season minimises seed head production and promotes a leafy sward for the rest of the season. Maintaining appropriate sward heights to maximise grass utilisation and animal growth potential are more easily achieved with a rotational grazing system compared to set stocking; paddocks can be taken out for silage production during periods of high grass growth. In a rotational grazing system, to achieve maximum levels of gain with high levels of grass utilisation, swards should be grazed down to 5cm during spring – early summer, increasing to 6cm in late summer and 8cm in autumn.
On farms with growing and finishing cattle, six to eight paddocks or similar sized fields are ideal to optimise growth rates and pasture management. It may be an unpalatable fact, but continual grazing reduces grass production and can limit growth rates as cattle cannot graze sufficient DM intake; their bite size is limited on short grass and the number of bites/day is a finite figure making concentrate feeding necessary to maintain optimum daily liveweight gain.
Set growth rate targets for the cattle and check their performance against those targets. Steers should be gaining at least 1kg/head/day and heifers at 0.8kg/head/day. If they are not, then the grazing quality or quantity is not sufficient To achieve this, steers need to be eating 8kgDM/day of grass that is at least 11.5ME, and heifers 7.5kgDM/day. This is a lot of fresh grass requiring an intake of between 40kg and 50kg of grass/day.
Concentrates at pasture
Feeding concentrates to cattle at grass has its benefits, although cattle on good grass should not require supplementing until after mid July unless grazing is short or forward stores need to be marketed quickly. Then consider:-
- target productivity (Dlwg)
- animal intake requirement
- sward quality and quantity
before purchasing feeds.
Target growth rate for lambs
It is important to maintain high lamb growth rates throughout the grazing season. Target growth rate should be 300g per day up to weaning and 250g per day post weaning.
Effective grassland management is the key to maximising lamb performance. From eight weeks of age, lambs become increasingly dependent on grass supply. This stage of lamb growth often coincides with the deterioration of grass quality as a result of increased stem content in swards.
At weaning, lambs should be moved to swards with grass covers of 2200kgDM/ha (sward height 6-7cm). Swards which have been rested or silage aftermaths later in the season are ideal.