Performance targets for resilient beef production
Summary
- A major source of inefficiency in beef cattle production systems is failure to meet performance targets.
- Achieving high animal performance is critical if animals are to be slaughtered younger.
- Where key performance targets are not met, this has large negative ramifications for the profitability and environmental footprint of beef production systems.
Introduction
The source of calves for Irish beef production come from the national herd of 2.4 million cows, of which currently 63% are dairy cows and 37% are suckler cows. Due to the abolition of milk quotas in the European Union, rapid expansion of the Irish dairy herd has meant that proportionately more beef is now derived from dairy-bred compared to suckler-bred animals. The suckler cow herd consists mainly of crossbreds of which, 75% are late-maturing breeds and 25% are early-maturing breeds. Eighty-five percent of suckler calves are the progeny of late-maturing sire breeds of which, 37% of the total are Limousin, 33% are Charolais, 5% are Simmental and 2% are Belgian Blue, with the remaining 15% the progeny of early-maturing sire breeds (10% Angus, 4% Hereford). In the dairy herd, 93% of cows are Holstein-Friesian, and 50% of dairy calves are the progeny of Holstein-Friesian sires (provide replacement heifers), and 36% are the progeny of early-maturing (21% Aberdeen Angus, 15% Hereford) and 7% the progeny of late-maturing (mainly Limousin and Belgian Blue sires) beef breeds. Consequently, in terms of beef cattle production, the predominant ‘raw material’ from the suckler herd is late-maturing genotypes, and from the dairy herd is Holstein-Friesian and early-maturing beef × Holstein-Friesian genotypes.
Calf births in Ireland are very seasonal with 91% of dairy calves born in the first six months of the year, and 75% in the three peak months, February to April. Calving in the suckler herd is later, with 76% of cows calved in the first-half of the year, and 52% in the peak months of March to May. Therefore, most Irish beef production systems entail a spring-born animal, which has implications for principal slaughter periods.
In 2021, 1.4 million ‘prime’ cattle (steers, young bulls and heifers) were slaughtered, with males accounting for 59%; within the male cattle slaughtered, steers accounted for 84% and young bulls the remainder. Nationally, mean carcass weight for steers, young bulls and heifers in 2021 was 356 kg, 371 kg and 313 kg, respectively; 22% of steers, 35% of young bulls and 6% of heifers had carcasses heavier than 400 kg. In terms of carcass fatness, 25%, 4% and 47% of steers, young bulls and heifers, respectively, had a carcass fat score of ‘4-’ or greater. This compares with the commercially-acceptable minimum carcass threshold for fat classification of 2+, and implies that a relatively high proportion of steers and heifers are ‘overfat’, which is a costly production inefficiency. Currently, mean slaughter age nationally for suckler-bred and dairy-bred steer genotypes ranges from 26.3-28.1 months and from 26.6-27.7 months, respectively. Corresponding ranges for heifers are 24.6-26.4 and 24.3- 26.0 months of age (see page 228).
Growing concern with climate change has resulted in proposals to further reduce national greenhouse gas (GHG) emissions. The beef sector can contribute to meeting these emission targets by increasing the biological efficiency of production systems, and reducing animal slaughter age.
Importance of grass
Due to the considerably lower comparative cost of grazed grass as a feedstuff suckler and dairy-bred beef production systems in Ireland are predominantly grass-based, and ‘designed’ to optimize the seasonal supply of pasture. A key objective is to increase the contribution of high-digestibility, grazed grass to the lifetime intake of feed, through as long a grazing season as possible, while simultaneously achieving high individual-animal performance. The foundation underpinning good grass production and utilisation is having adequate soil fertility, unimpeded drainage, targeted application of fertilizer and good grazing infrastructure, coupled with appropriate grazing management practices. However, the seasonality of grass growth and inclement grazing conditions means that an indoor ‘winter’ period, of varying duration, occurs on practically all Irish farms and the main feed costs on beef farms relate to this period, and especially when feeding finishing cattle.
Therefore, providing sufficient grass silage of appropriate digestibility for the indoor winter period – high dry matter digestibility (>72% DMD) grass silage for all growing-finishing beef cattle, and moderate-digestibility grass silage (~67% DMD) for ‘dry’ suckler cows in good body condition – is a crucial component of grassland management and feed selfsufficiency in beef production systems. Because of their relatively greater cost, concentrate feedstuffs should only be used ‘strategically’, to rectify deficits in forage nutrient supply at key points in the lifecycle in order to achieve target growth and carcass fatness levels.
The level of concentrate supplementation depends on the nutritive value of forage offered (higher digestibility forage requires less concentrate to achieve the same performance), the target growth required (e.g. ‘store’ or ‘finishing’ period) and the animal ‘type’ (e.g. breed, gender, genetic merit). The grass-forage’ component of the feed budget for contrasting grass-based suckler- and dairy-beef steer research systems ranges from 82-96% for sucklerbeef and 77-88% for dairy-beef systems
Figure 1. Feed budget composition for spring-born, grass-based, suckler calf-weanling plus weanling-to-beef, and dairy calf-to-beef research systems, with slaughter at different ages (20-month = end of ‘first’ grazing season; 22- & 24 months = during & end of ‘second’ winter, respectively; 26- and 28-month = during ‘third’ grazing season
Grass-based beef production system targets
Many types of beef production systems are operated commercially, depending on factors such as the animal origin (suckler- vs. dairy-bred), progeny gender (steers, heifers and bulls (see pages 166, 208, 212 and 216)), on whether it is a ‘component’ - selling/buying live cattle at different ages (e.g. ‘weanling’, ‘yearling’ or ‘store’ cattle) or a partially (e.g. weanling-to-beef, store-to-beef) or fully (e.g. calf-to-beef) ‘integrated’ system, and ultimately the slaughter age/target market. For the purposes of clarity, animal performance targets for integrated suckler and dairy calf-to-beef systems are depicted in Figure 2; the same principles apply to other ‘component’ systems.
Suckler cow productivity targets
The lifetime productivity of suckler cows begins with the onset of puberty and thereafter is determined by critical events comprising age at conception, age at first calving, duration of the postpartum interval for each consecutive calving, and conception and pregnancy rate, which is ultimately manifested as calving interval and number of calves weaned over her lifetime. Reproductive targets for a suckler cow herd include an average age at first calving of 24-months, calf mortality of less than 5%, a calving rate of greater than 0.95, an empty rate of less than 5%, a calving-to-calving interval of 365 days, compact calving, with 80%calving in 6 weeks (Figure 2) and a ‘long’ productive life. A target age at first-calving of 24-months is important as it provides the foundation for maximum potential lifetime productivity – ‘unproductive’ older replacement heifers are inefficient. Attaining a calvingto-calving interval of 365 days, through operating a compact calving season, and good animal husbandry in terms of meeting cow nutritional requirements and body condition score levels after-calving to ensure resumption of oestrous, is essential. As the calf is the primary output of a suckler cow, the number of calves born is fundamental to productivity; thus, attaining a calving rate as close to one as possible (i.e. each cow in the herd produces a calf every year) is essential. Central to seasonal spring-calving suckler systems is the alignment of calving date with onset of the grazing season in spring, which means that the relatively higher nutritional requirements of lactating spring-calving cows can be met with lower-cost, high-nutritive value grazed grass. This ‘date’ will differ from region-to-region and is a function of prevailing grass growth commencement date plus soil type, climate and thus grazing ‘conditions’. Additionally, the suckler cow must produce sufficient colostrum and milk and ultimately rear a healthy, vibrant and heavy weanling that achieves lifetime growth targets with desirable carcass characteristics.
Growth targets for spring-born suckler- and dairy-bred calves
Grass-based suckler systems entail spring-calving cows (~March) rearing their own calves until weaning at the end of the grazing season at about 8 months of age, following which the ‘weanlings’ are housed; concentrate supplementation (~1 kg/day) is usually provided shortly before weaning to support the weaning process. In grass-based dairy-beef steer production systems, spring-born calves are artificially-reared on milk replacer and concentrates over an indoor rearing period of approximately 8 weeks, turned out to pasture in summer (~May) at 85-90 kg, and housed at the end of the grazing season (~October/November); concentrate supplementation (~1.0 kg/day) is usually provided at the start and end of the grazing season.
Animal growth rate is a significant driver of beef farm profitability and is largely a function of feed ‘quality’ and quantity, animal genetics and herd health.
Adequate calf passive immunity, derived through timely ingestion of sufficient quantities of quality colostrum, optimised early-life nutritional management coupled with appropriate parasite and animal health strategies during this time period (and subsequently), are critical to ensure that suckler and dairy-bred calves can meet their production potential. Target preweaning live weight gains of dairy calves are 0.7 kg /day, and subsequently at pasture 0.8 kg/day (Figure 2). Target live weight gains of spring-born single-suckling un-supplemented calves on well-managed rotationally grazed systems typically exceeds 1.2 kg daily over the grazing season, although this is heavily influenced by cow milk yield.
Figure 2. Animal performance targets for spring-born grassbased suckler and dairy steer calf-to-beef production systems
At the end of the ‘first’ grazing season, spring-born dairy weanlings are about 90-100 kg lighter than their suckler-bred counterparts (Figure 2). Despite the fact that these contrasting breed types differ markedly in their intake relative to weight (dairy-bred consume more than suckler-bred), feed efficiency (dairy-bred poorer than suckler-bred) and carcass traits (dairy-bred have inferior kill-out proportion, and carcass weight and conformation score compared to suckler-bred), animal management and live weight gain targets from housing at the ‘first’ winter until slaughter are broadly similar for both suckler-bred and dairy-bred production systems.
‘First’ winter growth targets
During the ‘first’ winter indoor (‘store’) feeding period, animals consume a ‘restricted energy’ diet based on grass silage ad libitum and supplementary concentrates (e.g. 1.0 kg fresh weight/day). A target live weight gain of 0.5-0.6 kg/day through the first winter is acceptable for steers, heifers (and bulls) destined to return to pasture in spring (Figure 2).
This feeding regime is designed to minimise winter feed costs and subsequently exploit compensatory growth on cheaper-produced pasture, which further avails of the economic efficiency of grazed grass over conserved forages and concentrates (See p 196).
Second’ grazing season growth targets
During the ‘second’ grazing season (~March-October/November) a target live weight gain of ~0.9-1.0 kg/day should be attainable without meal supplementation (Figure 2). Appropriate grazing management practices include, turning cattle out to grass as early as possible in spring and ensuring an adequate supply and intake of good ‘quality’ leafy grass, by avoiding excessively high pre-grazing herbage masses and excessively low post-grazing sward heights (See p 204).
Finishing spring-born steers at about two years-of-age involves an ‘expensive’ final indoor winter feeding period. As grazed grass is considerably cheaper than grass silage or concentrates, early finishing of cattle from pasture in autumn before housing (~20-months of age), reduces total costs per animal. Because a commercially-acceptable carcass fat score (minimum target of 2+) is currently a primary market requirement, the propensity of cattle to deposit subcutaneous fat is important to ensure they have an adequate carcass fat cover. One strategy is to provide concentrate supplementation (e.g. 3-4 kg/day) to animals during the finishing phase at pasture (See p 196).
‘Second’ winter and ‘third’ (short) grazing season growth targets
Alternatively, at the end of the ‘second’ grazing season steers are re-housed and offered high-digestibility grass silage supplemented with concentrates. Animals destined for finishing at ~22 to 24 months of age receive a moderate allowance of concentrate (e.g. 4-5 kg daily, depending on silage DMD) with a target live weight gain of 1.0 kg /day (Figure 2). In contrast, steers destined to be turned out to pasture for part of (3-4 months) a ‘third’ grazing season and finished at pasture at 27-months of age receive a much lower (e.g. 1 kg/day), if any, concentrate allowance. Similar to the ‘first’ winter, their target live weight gain is also only 0.5 kg/day in order to further exploit compensatory growth during the subsequent short grazing period (Figure 2).
Importance of performance targets
Where key performance targets described earlier (i.e. both animal- and production system-related) are not met, this has large negative ramifications for the profitability and environmental footprint of beef production systems. For example, the impact of age at firstcalving and calves/cow/year in spring-calving suckler systems, and calf mortality, grazing season length, daily live weight gain, and age at slaughter in both suckler and dairy-beef systems, on profitability and GHG emissions is summarised in Figures 3 and 4. For both the suckler and dairy-beef production systems reducing biological efficiency mostly resulted in reductions in profitability on a per animal basis, and concurrently increases in GHG emissions ‘intensity’ (per kg ‘product’ produced), albeit the magnitude of the effects differed across the systems. This inverse relationship implies that reducing GHG emissions to meet national climate targets is generally associated with greater profitability of grassbased beef production systems.
Figure 3. Effect of increasing age at first-calving (24 vs. 36 months), reducing calves/cow/ year (96% vs. 0.91%), increasing mortality (4.1% vs. 8.6%), reducing grazing season length (one month) in a spring-calving suckler calf-to-weanling system, and increasing mortality (0.9% vs. 4.4%), reducing grazing season length by one month, reducing daily live weight gain (ADG, -8%) and increasing slaughter age by one (animals remain at pasture), or two (animals require housing) months, in a suckler weanling-to-beef system, on the percentage change in net margin/head and GHG emissions (per kg live weight (LW) for the calf-toweanling, and per kg carcass for the weanling-to-beef, system))
Figure 4. Effect of increasing mortality (5.9% vs. 10.0%), reducing grazing season length by one month and increasing slaughter age by one (animals remain at pasture) or two (animals require housing) months, on the percentage change in net margin/head and GHG emissions in a dairy calf-to-beef system In the production system examples provided, increasing slaughter age by one month (i.e. from ~20 to 21 months) resulted in animals having an additional month at pasture, and by two months (from 20 to 22) resulted in animals having to be housed for a second winter, with associated increases in GHG emissions per kg product. Because these cattle were older at slaughter, total GHG emissions per animal (t/head) increased too, by 7 and 23% in the suckler weanling-to-beef system, and 9% and 26% in the dairy calf-to-beef system, for theadditional one and two months of age, respectively. This highlights the potential role of reducing slaughter age as a GHG mitigation strategy for beef producers.
