Requirements Of Future Grass Based Systems (Beef)

Ireland's temperate climate and resulting grass production advantage allows the Irish to exploit the competitive advantages associated with grass-based production systems compared with high input systems, says Michael O'Donovan from Teagasc.
calendar icon 20 January 2011
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Beef Production Systems

There are now, approximately the same number of dairy and suckler cows (1.1 million of each) in Ireland. There are a wide range of beef production systems in use with the two predominate systems today being the grass based dairy calf–to-beef system and suckler calf-to-beef system.

Dairy calf-to-beef

The standard Irish system for taking spring-born male calves from the dairy herd through to finish as steers at 24 months of age, was largely developed on research farms with heavy soils (Keane, O’Riordan and O’Kiely, 2009; Flynn, 1979). In the earliest form of this system Friesian steers were used and grazed grass constituted almost the sole source of feed between March and November, while the average grass silage:concentrate (DM basis) input during the winter was 3.5:1 (Table 3; Flynn, 1979). The guidelines for this early version of the system provide little detail regarding grazing management practices other than to advise that SR should be at a level appropriate to the grass growth and utilisation potential of the farm, and that calves would be rotationally grazed ahead of yearlings (Table 4 and 5; Flynn, 1979). The current calf to beef system described by Keane et al. (2009) has grass, silage and concentrate in the proportions of 2.9:1.7:1, respectively, with grazed grass comprising just over half of the feed (51 per cent; Tables 3).

Table 3: Feed inputs to steers in spring-born dairy calf-to-beef (24 month) systems in 1979 and 2009

Feed (kg) Flynn (1979) keane et al. (2009)
Milk replacer DM 15 25
Grazed grass DM Not specified 2450
Grass silage DM 1800 1460
Concentrates DM 510 850

The advent of anabolic implants in the early 1980’s resulted in a direct increase in carcass weight and carcass output/ha (Table 5; Keane, Flynn and Harte, 1986). With the banning of anabolic implants after the mid-1980’s carcass weight per animal and carcass output per ha decreased. In order to retrieve this loss, SR was relaxed and concentrate input increased so that by the late 1980’s the output which had been possible a decade earlier with implants was now achieved without them, but carcass output/ha was lower (Table 5; Harte, 1989). Intensification continued into the early 1990s (Table 5; Keane and Drennan, 1991) and was further improved by the replacement of half of the Friesians with Charolais x Friesians and an increase in concentrate input (Keane and Darby, 1992). The system was then de-intensified in order to maximise profits following the reform of the CAP in 1992 together with the need to conform with an upper SR limit of 2 LU/ha for eligibility for the special beef premium and the declining carcass weight threshold for eligibility for selling carcasses into the EU intervention scheme. By the mid 1990s the system sought to minimise costly inputs such as calves and concentrates and maximise carcass value and premia entitlements. This resulted in Friesian and Charolais steers being finished at 24 and 30 months, respectively (Table 5; Keane and Drennan, 1995). In anticipation of future decoupling of premia from cattle in the CAP, the system was modified to achieve an output of 1000 kg carcass/ha using Charolais x Friesian steers (Table 5; Keane and O’Riordan, 1998). Thus, cattle were turned out earlier to pasture and grazed the silage area until the normal turnout date, the number of paddocks in the grazing area was doubled, and herbage in excess of that required for grazing was harvested as round bale silage. Approximately 0.54 of the animals lifetime weight gain was derived from grazed grass, 0.24 from grass silage and 0.22 from supplementary concentrates.

Table 4: Target live weight and carcass weight for steers in spring-born dairy calf-to-beef (24 month) systems in 1979 and 2009

  Flynn (1979) keane et al. (2009)
Liveweight (kg)
----End of first summer grazing 190 240
----End of first winter indoors 265 320
----End of second summer grazing 445 510
----End of second winter indoors 555 650
Carcass weight (kg) 290 350
Source: Derived from National Farm Survey and Authors' Estimates

The current day system is illustrated in Tables 3 and 5. There is a major emphasis on maximising the intake of grazed grass during an extended grazing season, while the average grass silage:concentrate (DM basis) input during the winter is 1.7:1. The rate of individual animal growth has increased considerably between 1979 and 2009 (Table 4), with the increase coming during both the grazing season and the winter period (mainly due to an increase in the rate of supplementation with concentrates and a consequent reduction in silage intake).

The most immediate constraining limitation to further increasing carcass output/ha is the SR rate restrictions that have been imposed as a result of various EU policies. To show the potential that exists to considerably increase beef output/ha when finishing steers at 24 months of age on a grass and grass silage diet, O’Riordan and O’Kiely (1996) described how achievable increases in grass production, in the proportion of annual feed intake contributed as grazed grass, and in the quality and efficiency of utilisation of grazed grass and grass silage, could increase carcass output from 553 to 970 kg/ha year.

Suckler calf-to-beef

The evolution of Irish suckler beef systems based on spring-calving cows rearing their own calves through to weaning at the end of the first grazing season, and with the weanlings taken through to beef within the system, is summarised in Table 6. Many of the same market forces described above for dairy calf-to-beef systems (i.e. SR restrictions imposed as a result of EU policies, availability/withdrawal of anabolic implants, etc.) also impacted on developments within suckler calf-to-beef systems. Major changes in the system from 1976 to 2010 have included the replacement of traditional early-maturing beef breed sires with late-maturing ‘continental’ breed sires, the replacement of early-maturing by late-maturing beef breeds in the cross breeding of suckler cows, higher animal growth rates, finishing male progeny as bulls and at a younger age, an earlier start to the grazing season (from mid-April to early March) resulting in an increased contribution of grazed grass to total intake, an increased input of concentrates, a reduced requirement for grass silage, an increase in carcass output/ha and an increase in the number of cow units (cow plus progeny through to finish)/ha. The proportional DM contribution of grazed grass, grass silage and concentrates per cow unit per year within the Grange system was approximately 0.57, 0.39 and 0.04, respectively, in 1976 and is currently 0.6, 0.3 and 0.1 respectively. The target is to move the feed inputs to corresponding values of 0.65, 0.25 and 0.10 for grazed grass, grass silage and concentrate, respectively, in the next three years.

Silage production on Irish farms

Apart from providing feed primarily for the winter, the production of grass silage also facilitates efficient grazing management, recycling of nutrients from slurry and biological control of internal parasites. Just over 1 mn of ha Irish grassland is harvested for silage at least once during the year (CSO, 2001), and grass silage is made on 87 per cent of Irish farms (Table 11). The average proportions of this total area harvested for first, second and subsequent cuts of silage were 78, 21 and 1 per cent, respectively. These proportions vary among enterprise, with dairy farms placing the highest emphasis on taking a second cut (69:30:1) and sheep farms the least (92:8:0). The emphasis on second and particularly on third harvests of grass for silage has declined in recent years, and this trend is likely to continue as the length of the grazing season increases into the shoulders of the grazing season.

At least twice as much land is used for silage-making on farms involved in dairying (20 ha or more) compared to other enterprises, with the smallest areas being on cattle rearing (7.9 ha) or sheep (7.1 ha) farms (Table 11). Round bale silage (99 per cent of all baled silage) is made on 74 per cent of all farms, and although it is popular across all enterprises (Table 11) and farms sizes, it is particularly common (and often the primary silage-making system) on cattle rearing (84 per cent) and sheep (81 per cent) farms, and smaller sized (82 per cent) farms. In many cases where it is a secondary system (usually dairy farms), it is used tactically to remove grass from paddocks that are surplus to the short-term needs of the herd (thereby facilitating improved grazing management and overall animal nutrition) or to remove small yields that would be difficult or expensive to successfully ensile.

Most estimates of silage digestibility during the past few decades have shown annual national average DM digestibility’s between 630-700 g/kg. Grass for silage preservation should always be of good quality and, on average this has been the case (Wilson and O’Kiely, 1990; Keating and O’Kiely, 1997). However, these national averages masked a proportion of unsatisfactorily preserved silages which were more frequent when grass was harvested at an early stage of maturity during wet weather conditions.

Table 11: Scale and characteristics of grass silage production in Ireland within different farming enterprises

  Dairying Dairying/ cattle Cattle rearing Cattle fattening Mainly sheep Tillage All systems
per cent farms making silage 99 98 90 82 71 75 87
Average area of silage (ha/farm)1
- first cut 14.7 14.4 7.0 8.5 6.5 8.0 9.7
- second cut 6.3 5.5 0.9 1.4 0.6 1.7 2.6
- later cut 0.4 0.1 0 0 0 0.1 0.1
- total 21.3 20.0 7.9 9.9 7.1 9.8 12.4
Average area (ha/farm/year)2
- precision chop 15.8 15.3 2.3 4.9 2.1 5.9 7.3
- single/double chop 1.5 1.5 0.9 0.8 1.1 0.6 1.0
- round baler 3.8 2.8 4.6 4.2 3.9 3.0 3.9
1 & 2 differences in total ha/farm between 1 and 2 due to omission of large square bale, pick-up wagon and other minor harvesting systems from 2
Source: Teagasc, National Farm Survey (2002)

Due to the emphasis on grazing silage swards early in spring, crops used for silage production need to grow rapidly between spring grazing and the first silage harvest, and to re-grow rapidly where a second harvest of silage is required. It is desirable that grass cultivars be developed that use soil N more efficiently and/or have a lower requirement for N input. Optimal seed mixtures that boost yield and persistency due to synergies between compatible grasses (Helgadóttir et al., 2008) must be identified. Grasses in a mixture should have similar heading dates to make it easier for a farmer to estimate the optimal growth stage at which to harvest the crop.

Grass clover systems

Current grazing systems employ management practises which are optimised for grass growth, with minimal focus on clover. Grass clover swards are not regularly used despite the low national average SR in Ireland. In New Zealand, despite higher stocking rates, clover is an integral component of grazing dairy systems (Woodfield, 1999). The challenge is to integrate clover more into grazing systems and to develop an understanding of the interactions between grass and clover under grazing. Humphreys et al. (2009) reported high levels of milk solids output (1000 kg/ha) from a reasonable SR (2 cows/ha) in high clover content systems. Genetic improvements in white clover have resulted in 1 per cent annual improvements in herbage yield, N fixation and resultant animal performance (Woodfield, 1999). Recent innovations in New Zealand using semi hybrid clover in grazing systems are encouraging. A recent evaluation of semi hybrid clover showed that it produced 50 per cent more DM than conventional clovers over three years. The need for clover is clear in grazing systems, but its successful integration into these systems on farms has yet to be achieved.

January 2011

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