15 August 2011

7 minute read

How can the potential of grass be harnessed in beef systems?

In the future, the main technical efficiency that be increased on beef farms is the conversion of grass into meat. While we have been used to direct payments in the past two decades, by 2015 we will almost certainly see a reduction in these payments and a move towards higher stocking rate beef systems, something which has been restricted by environmental schemes, etc. in recent years. The main area where the potential of grass can be harnessed on beef farms is by increasing grass utilisation across the main grazing season.

Increasing grass utilisation

Beef farms currently have low stocking rates. The top third National Farm Survey (NFS) cattle farms are stocked at 1.7 livestock units (LU)/ ha with the top third of eProfit Monitor cattle farms stocked at 1.95 LU/ ha. Nationally cattle farms are stocked at 1.1 LU/ha. Within these stocking rates there is considerable scope to increase the proportion of grass in the grazing animal’s diet.

While there are a variety of beef systems practised commercially, overall grass utilisation is low national at approximately 4.8 t DM/ha. To begin examining where grass utilisation can be increased, the grazing season must be broken into the three main grazing periods - spring, summer and autumn.

Spring grass utilisation

Early spring grazing has beneficial effects on animal and sward performance. Turning animals out to grass early can substantially reduce the overall concentrate and grass silage feed budget. During the early grazing season (February – April), a balance must be found between feeding animals adequately to sustain high animal performance and conditioning the sward for the late spring/summer grazing season. Generally on beef farms this can be easily achieved by turning out priority stock in early spring.

The clearest path to increasing grass utilisation is to utilise spring grass efficiently. The spring rotation planner can be used effectively to ration grass in spring. The spring rotation planner is available from your local Teagasc advisor or the Teagasc website www.teagasc.ie. There are a number of important benefits to grazing animals in early spring:

• Reduced feed costs
• Reduced labour input
• Reduced slurry accumulation
• Increased animal performance

The key aspect of spring grazing management is to maintain a flexible approach. Priority stock should be turned out to grass first in spring. A number of recent experiments have taken place with differing livestock showing the benefits of spring grazing. At Grange in 2010, a study compared the effect of early turnout of spring calved suckler cows and their calves with a comparative group retained indoors.

The study took place from 1 March to 29 March. A number of performance increases were observed for the early turnout group - milk yield per cow increased by 18 per cent, average daily gain (ADG) of the calves increased by 22 per cent during the study, and increased by 6 per cent overall to weaning. The financial benefit of earlier spring grazing was a saving of approximately €1.54/cow/day in feed costs and higher milk yield.

The reduced requirement for slurry storage is not factored into this cost saving. This increase in efficiency driven by a simple management practice, could be a key driver of increased production potential across beef farms.

Mid season grazing management

During the main grazing season, the objective is to have an all grass diet and ensure that ADG is close to or in excess of 1 kg/day. From late April onwards grass turns from vegetative (leafy) to reproductive (stemmy). This is an important management issue for grassland farmers. For each 1-unit increase in organic matter digestibility (OMD), grass dry matter intake (GDMI) is increased by 0.20 kg/animal. Increasing herbage allowance results in small increases in GDMI.

The aim must be to increase the quality of the grass allocated rather than the quantity offered; this is achieved by ensuring there is a high quantity of leaf in the sward. The key management objectives during the grazing season is to maintain grass quality while offering the target herbage allowance. The move to grazing lower grass covers of 1300-1700 kg DM/ha, while maintaining a rotation length of 17-21 days has helped the pursuit of increased grass quality in the May to July period. During the mid-season, when a plant starts to head it produces a reproductive stem. This changes the balance of the plant from producing green leaf to producing high stem proportions. Green leaf content is directly related to grass digestibility. A 5.5 per cent change in leaf content is equal to a 1-unit change in digestibility.

Poorly managed swards can result in large reductions in green leaf content to just 50 per cent leaf during the reproductive period. Well grazed swards (4.5 – 5 cm post-grazing sward height) will contain a high proportion of leaf. Beef farmers must adopt a policy of offering swards with high leaf content throughout the season.

Main season grazing management can be difficult when stocking rates are low on farms and the easiest way of rectifying this is to increase the carrying capacity of the farm with extra stock. The tendency on all livestock farms is to graze high pregrazing yields throughout the main grazing season, but this is not the correct way forward to ensure high performance.

In the last two years the adoption of the wedge based technology, whereby the target pre-grazing herbage mass is set at 1300-1700 kg DM/ha, has been adopted on dairy farms and should be used also in beef farm grazing management. Allocating grazing cows swards of approximately 1500 kg DM/ha strikes the correct balance between animal performance and grazing management efficiency. A previous study showed that when the policy of continually targeting lower pre-grazing herbage masses is adopted, then it is possible to quickly run into grass deficits across the grazing season.

Autumn grazing management

As in spring, the focus of autumn grazing management is to increase days at grass and increase animal performance, it is also necessary to set the farm up on the final rotation to grow grass over the winter and provide grass the following spring.

There are two key periods in autumn: (i) the period of autumn grass build up and (ii) managing the final rotation. Generally rotation length should be extended from 10 August. The focus of this period is to gradually build pre-grazing herbage mass, targeting covers of 2000- 2300 kg DM/ha in mid-September. Pre-gazing covers >2500 kg DM/ha are difficult to utilise and should be harvested as surplus (round bales).

Removing paddocks after the first week of September should be avoided if possible. Such paddocks have only one rotation left for grazing at that stage. Removing these paddocks n September is too late as there will be inadaquate regrowth to make any meaningful contribution in the last rotation. Surplus paddocks should be removed in August. Decisions can be easily made if the farm cover targets are achieved at the right time. Many farmers fall into the trap of building cover too late and are pushed into harvesting excess grass in September.

Key points for autumn grazing management;

• Build rotation length from 10 August, increasing rotation length from 28 days to 35 days in mid-September.
• Highest farm cover should be achieved in mid to late September.
• The first paddock required for spring grazing should be closed on 10 October, in slower grass growing regions closing may begin earlier. Sixty per cent of the herbage available for grazing next spring will be the grown once these paddocks have been closed.
• Each 1 day delay in closing from 10 October to 11 December reduces spring herbage mass by 15 kg DM/ha/day.
• Have at least 60 per cent of the farm closed by the end of the first week of November.
• All paddocks should be grazed to a post-grazing height of 4 cm during the last rotation to encourage winter tillering.

Conclusion

The competitive advantage for Irish beef production in the coming decades will depend on increased and more efficient utilisation of grass for the sustainable production of high quality meat.

The proportion of annual feed intake contributed by grazed herbage will have to increase to the highest amount practical. This will require the widespread adoption of best practise grassland and grazing management techniques.

A stronger focus on increasing grass utilisation throughout the grazing season will need to take place on beef farms, the key periods to increase grass utilisation are in early spring and late autumn. The beef industry has huge potential to deliver a substantial increase in grass utilisation.