Growing your potential; Grass-to-Beef
Grazed grass is the cheapest source of energy for ruminants and is capable of supporting high levels of animal performance. Nicky Byrne, Donall Fahy and Michael O’Donovan have some advice.
Introduction
The implementation of grass-based production systems will ensure the economic and social sustainability of drystock farms. Ireland’s comparative and competitive advantage as a beef producer arises from the ability to grow and utilise grass. Grazed grass is the cheapest source of energy for ruminants and is capable of supporting high levels of animal performance. Beef systems implementing high levels of grassland management to support improved animal performance and output/ha have a lower carbon footprint per kg of beef produced. Such systems have favourable animal welfare, as cattle have free access to pasture over an extended grazing season ranging from 250-300 days across the country. These competitive advantages differentiate Irish beef products, helping gain access to some of the highest value and specification markets in the world.
Nationally beef farms are lowly stocked at 1.1 LU/ha, but there is considerable scope to increase stocking rate across beef systems depending on the farms ability to grow and utilise grazed grass (Table 1). Nationally across drystock farms grass utilisation is low at an estimated 5.6 t DM/ha, which is only 58% of its potential. To maximise grass production and utilisation grazing management, soil fertility, drainage, infrastructure and sward composition need to be optimised and better managed on farms. Calf-to-beef systems need to focus on maximising output/ha using minimal imported feed, targeting 80% of animal’s lifetime feed requirement coming from grass and silage. Central to the success of calf-to-beef systems is regular measurement and management of grass to ensure its supply and quality throughout the grazing season.
Grazing infrastructure
Good grazing infrastructure (paddocks, roadways, water, etc.) is necessary to maximise grass growth, utilisation and to help maintain sward quality whilst reducing labour. On many drystock farms the number of paddocks is inadequate resulting in a long residency time (>72 hours). The result of this extended residency time is reduced grass utilisation as cattle will opt to graze regrowths. This will lead to reduced DM production and sward quality, delayed fertiliser application and ultimately poor animal performance. The grass plant can only support 3 actively growing leaves, if a fourth emerges the oldest leaf will begin to die reducing sward quality. During the mid-season it takes 7 days for a grass leaf to appear. To strike a balance between quantity and quality the optimum time to graze is when the plant has 2.5-3 actively growing leaves. The number of days it takes to reach the 3 leaf growth stage should determine your farms rotation length, this is typically 21 days during the mid-season (3 leaves × 7 days). To determine the number of paddocks needed on your farm divide rotation length by the desired residency time.
21 days ÷ 2 day residency time (48hr) = 12 paddocks per animal group
Forty eight hour paddocks offer flexibility as animals don’t have to be moved as often and are less restricted, large enough for machinery operations and they can be split temporally in times of difficult grazing conditions. The size of the paddock should be determined by the demand of your grazing group. To calculate the size of your paddocks you will firstly need to know the daily demand of your herd. Typically calf-to-beef animals are allocated approximately 2% of their bodyweight on a daily basis. Paddocks should be grazed at a target of 1300 kg DM/ha. An example of a herd of 50 steers, weighing 420 kg is as follows;
(420 * .02 = 8.4 kg DM/day) * 50 steers = 420 kg DM daily demand
420 (daily demand) ÷ 1300 (cover) = 0.32 ha needed daily
48-hour paddock = 0.65 ha
Access to paddocks is important, particularly during the shoulders of the grazing season. A road network will facilitate an extended grazing season and management of livestock. The specification of farm roadways will be determined by their intended use and level of traffic. On many farms grass tracks/spur roadways serviced by a main gravel roadway are sufficient, as the level of traffic from cattle grazing 48-hour paddocks would be far less than that experienced on dairy farms.
Grazing management for calf-to-beef systems
Increasing grass growth with early spring grazing
Spring grass is highly digestible, high in protein and DM content and will support higher animal performance, with each kg DM having 1.03 UFV. Dairy-calf-beef systems must be focused on utilising early spring grass, to achieve higher animal performance and displace concentrate use. Calf-to-beef systems are in a good position to start grazing early in the spring as yearlings are relatively light (300-330 kg) minimising sward damage and they will have a low grass DM demand initially. Aside from direct animal benefits, swards grazed in spring (February-early April) have higher growth rates throughout the year compared to swards ungrazed during this period. Previous research comparing early versus late turnout to pasture in spring, found that swards grazed in February subsequently grew more grass in the second rotation compared to ungrazed swards (90 vs 82 kg DM/ha/day, respectively). Most beef farms in Ireland are finishing the first rotation too late and are losing out on the benefits of early spring grass. If calf-to-beef farms don’t start grazing early in the spring this is likely to occur as grass demand will be low, pushing out the start of the second rotation, this will also be compounded by higher production costs during the early half of the spring.
The aim in spring is to increase the proportion of grass in the diet of the grazing animal while at the same time budgeting to ensure sufficient grass until the start of the second grazing rotation in early April. Spring grazing should start in February/March and continue until early April. Farmers can control demand by gradually turning out priority stock (lighter cattle) from an early stage in the spring to ensure sufficient grass until the start of the second rotation. The end of the first rotation varies from farm to farm. If turnout is too late on farms and the first rotation is too long, pre-grazing yields will be too high, grass quality will deteriorate and achieving a post-grazing residual of <4 cm will be difficult as utilisation will be reduced.
Spring grazing management
Average farm cover at turnout should be 600 to 700 kg DM/ha. The spring rotation planner should be followed, with an aim of having 30% of the farm grazed by the March 1st, 60% by March 17th and first rotation complete by April 1st, on heavy soils these targets can be reduced by 10% for the respective dates. During the first rotation it is critical to graze paddocks tightly, targeting a post-grazing height of 3.5 to 4 cm. This will condition the sward removing any dead material accumulated over the winter, stimulating new leaf growth, improving sward quality in subsequent grazing rotations. Quality grass silage >72% DMD is critical for calf-to-beef systems, thus it is important to get silage swards grazed before closing. Silage ground should be closed by the first week in April. Calf-to-beef farms should be aggressive with first cut silage, closing 50 to 60% of the farm area. This is important as demand grows from a low base across the year, peaking in the late summer/autumn reducing the area available for second cut silage. Closing a large proportion of the farm will also condition the sward with leafy after-grass ideally suited for calves.
Mid-season grazing management
The main challenge mid-season is to maintain sward quality as grass goes through the reproductive growth stage. Weekly farm cover measurement is critical at this point as grass growth is high requiring a rotation length of 18 to 21 days and maintaining pre-grazing covers of 1300 to 1600 kg DM/ha and a post-grazing height of 4 to 4.5 cm. From grass budgeting farmers can identify when growth will exceed demand requiring paddocks to be skipped and removed as high quality baled silage. These paddocks once exceeding target grazing yield should be taken out as early as possible and not allowed bulk up as this will reduce their regrowth capacity, creating the risk of a grass deficit occurring later. Calves should have access to leafy swards throughout the grazing season, after-grass will satisfy this but when that becomes too strong, a leader follower system can be adopted, allowing calves graze ahead of older cattle on the farm, giving them more selection and not forced to graze out swards. This process will optimise sward utilisation and calf performance through high intakes of digestible leaf whilst minimising parasite challenge.
Autumn grazing management
Planning for spring begins the previous autumn as the majority of grass available for early grazing has been grown over the autumn/winter months. The feed value of autumn grass is less than that of spring grass so there are many advantages to preserving its supply for the following spring when higher levels of animal performance are achievable. To do this farms have to start building farm cover by slowing down the grazing rotation from August 10th, extending it by 10 days/month until mid-October when rotation length reaches 45 days. This will mean grazing pre-grazing covers of 2000 to 2300 kg DM/ha.
Grass has to be budgeted over the autumn to allow animals remain outdoors until mid-November. The ‘Autumn 60:40 planner’ is a simple tool used to manage grass supply, outlining the farm area which needs to be closed by set dates to ensure sufficient supply in spring, whilst allowing animals graze late into the autumn. The general rule of thumb is to start closing paddocks between October 5th and 10th, and have 60% grazed by November 7th and 100% grazed by December 1st. On heavier soils these dates can be at least 2 weeks earlier. Research has shown that every day delay in closing after October 10th spring-grass supply is reduced by 15 kg DM/ha. At housing the average farm cover should be in the region of 500 to 600 kg DM/ha. Dairy calf-to-beef systems DM demand peaks in the autumn making it difficult to build farm cover. Demand needs to be reduced which can be done by introducing concentrates into the diet of finishing cattle or housing them on a finishing diet of silage and concentrate, allowing lighter weanlings enjoy an extended grazing season whilst building farm cover. This will also take pressure off housing and slurry storage facilities as in a 21-24 month system a large proportion of cattle will be slaughtered by the time weanlings are housed.
Conclusion
Dairy calf-to-beef systems must focus on output/ha, optimising animal performance from a grass-based diet (80%). Each farm is different and stocking rate should be dependent on the ability to grow and utilise grass with minimal imported supplement. To achieve this, farms must be set up for grazing, with good paddock and roadway infrastructure to aid in grassland management. Grass measurement and budgeting is important to ensure the supply and quality of grass throughout the grazing season.
Summary
- Profitable calf-to-beef production is based on utilising large quantities of grazed grass to produce quality beef at low cost.
- Stocking rate is dependent on the farms ability to grow and utilise grass.
- Early spring grazing is necessary to promote increased sward and animal performance.
- Grazing infrastructure will help maximise grass utilisation.
- To increase grass utilisation, pre-grazing herbage mass, post-grazing sward height and rotation length need to be well managed.
- Grass measurement and budgeting are key elements of grazing management