M. McGee
Teagasc-IGFA Nutrition Conference - June 2014
Feed Efficiency in Beef Finishing Systems
M. McGee,
Teagasc, Grange Animal & Grassland Research and Innovation Centre, Dunsany, Co. Meath
Introduction
Beef producers are in the business of converting feed into animal product as cost
efficiently as possible. Feed provision accounts for over 75% of direct costs of beef
production. Relative to concentrates or conserved forage diets, grazed grass is
generally the cheapest feed source on grass-based farming systems (Finneran et al.,
2012). Due to the considerably lower comparative cost of grazed grass as a feedstuff,
beef production systems should aim to increase animal output from grazed grass.
Nevertheless, primary feed costs on beef farms relate to indoor (winter) feeding periods
and particularly, feeding of finishing cattle. For example, within grass-based, suckler
calf-to-beef steer systems on research farms, about two-thirds of the feed consumed
annually is comprised of grazed grass, with the remainder made up of grass silage
(27%) and concentrates (7%). The latter are mainly fed to the finishing cattle.
However, when this feed budget is expressed in terms of cost (land charge included),
the outcome is very different, in that grazed grass makes up only 44% of total feed cost,
whereas grass silage accounts for 39% and concentrates accounts for 17% of total feed
costs. This means that even small improvements in feed (cost) efficiency at these times
has a relatively large influence on farm profitability.
Economic sustainability of beef production systems therefore depends on optimising
the contribution of grazed grass to the lifetime intake of feed and on providing silage
and concentrate as efficiently and at as low a cost as feasible (Crosson et al., 2014;
O’Kiely, 2014).
Feed Efficiency
There are many different contexts, approaches and measurements of feed efficiency in
beef cattle production ranging from the individual animal to the production system
operated. In the context of the animal, traditionally, feed conversion ratio (FCR) (i.e.
feed:gain) or its mathematical inverse, feed conversion efficiency (i.e. gain:feed), was
the measurement of choice. However, the use of this ratio in cattle breeding
programmes generally leads to selection of faster growing animals that have a larger
mature size and thus, a higher feed requirement. This has particular negative
ramifications for the cow component of suckler beef production systems because of the
proportionately higher (overhead) costs associated with it. In essence if an increase in
feed requirements of the breeding cow herd offsets the gains in growth efficiency, there
will be no change in production system feed efficiency.
An alternative measure of feed efficiency, that is genetically independent of growth and
body size, is residual feed intake (RFI) – also known as net feed efficiency and net feed
intake. Residual feed intake is defined as the difference between an animal’s actual feed
intake and what its predicted feed intake should be based on bodyweight and level of
performance. Therefore, efficient animals eat less than expected and have a negative or
lower RFI value, whereas inefficient animals eat more than expected and have a positive
or higher RFI value. Research at Teagasc and UCD has shown that in any population of
cattle, within breed, there can be in excess of 20% difference between the most efficient
compared to the least efficient animals for the same level of growth and performance
(e.g. McGee, 2009; Kelly et al. 2010; Crowley et al., 2010; Lawrence et al., 2012;
Fitzsimons et al., 2014 –Table 1). Furthermore, these feed efficient cattle produce less
M. McGee
Teagasc-IGFA Nutrition Conference - June 2014
methane (Fitzsimons et al., 2013) and consequently, have a lower environmental
footprint. We have also demonstrated significant genetic variance in the trait (Crowley
et al., 2010) and that, genetically, it is not antagonistically associated with desirable
growth or carcass traits in growing beef cattle (Crowley et al., 2011).
Table 1: Intake and performance of beef cattle with high (Inefficient), medium and low
(efficient) RFI
RFI1
RFI2
RFI3
Hig Med Lo Sig High Med Lo Sig. Hig Med Lo Sig.
h
.
w
.
.
w
h
.
w
DMI
6.3 5.9 5.5 *** 10.2 9.6 9.0 *** 7.3 6.8 6.2 ***
(kg/day)
Live weight 31 327 33 NS 522 523 51
NS
25 255 25
NS
(kg)
6
0
2
4
2
ADG (kg)
0.6 0.61 0.6 NS 1.66 1.63 1.5 NS 1.5 1.49 1.5 NS
0
0
3
2
4
Source: 1Lawrence et al., 2012; 2Fitzsimons et al., 2014; 3Kelly et al., 2010
The challenge is, therefore, to reliably and cost-effectively identify these feed efficient
animals and proliferate their genetics through structured animal breeding programmes.
A large research programme funded by DAFM has commenced at Grange to address this
and to also determine if there are genotype x age or environment interactions for feed
efficiency.
Factors affecting Feed Efficiency
Live weight and live weight gain
For finishing cattle, approximately two-thirds of feed consumed is used for body
maintenance (i.e. to maintain physiological functions). As maintenance is largely a
function of weight, a heavier animal requires more feed to maintain itself, and
furthermore, for a fixed rate of live weight gain, the feed energy required is higher for
heavier animals (e.g. Table 2). Consequently, feed efficiency is better with lighter, fast
growing animals.
Table 2: Theoretical energy requirements of finishing bulls
weights and growth rates
Average daily gain
(kg)
Live weight (kg)
450
500
550
0.0
4.4
4.8
5.1
1.0
6.0
6.5
6.9
1.2
6.5
7.0
7.5
1.4
7.0
7.6
8.1
1.2 vs. 1.4
0.5
0.6
0.6
(UFV/day) at different
600
5.5
7.4
8.0
8.7
0.7
650
5.8
7.9
8.6
9.4
0.8
M. McGee
Teagasc-IGFA Nutrition Conference - June 2014
Source: INRA
Duration of Finishing period / Slaughter weight
Growth in animals is defined as accretion of protein, fat and bone. In cattle some parts,
organs and tissues grow relatively more slowly than the animal overall, and so become
decreasing proportions over time, while others grow relatively faster and become
increasing proportions (Keane, 2011a). With increasing slaughter weight, the
proportions of non-carcass parts, hind-quarter, bone, total muscle and higher value
muscle decrease, while the proportions of non-carcass and carcass fats, fore-quarter
and marbling fat all increase (Keane, 2011a). Energetically, efficiency of accretion of fat
is approximately 1.7 times that of protein but because more water is stored with
deposited protein than with deposited fat, lean tissue gain is four times as efficient as
accretion of fat tissue (Owens et al., 1995). As carcass weight increases, the proportions
of bone and muscle decrease and the proportion of fat increases, but the rates of these
changes differ amongst breed types (Keane 2011b).
Daily live weight gain over the finishing period is not constant. In general, it is higher at
the beginning and declines, often progressively, with increasing duration of finishing
period. For example, in steers offered concentrates ad libitum over 132 days average
daily live weight gain was 25% lower for the second half of the finishing period
compared to the first half (Caplis et al., 2005). The decline in daily live weight gain can
be attributed to an increase in gut fill at the initial stages, fixed or declining intake
relative to increased weight (and maintenance requirements), and increased fat
deposition. As fat deposition requires more energy than protein deposition, more feed
is required to produce a kilogram of fat. The proportional fall in daily live weight gain
over the finishing period is largely a function of the fatness of the animal and thus, is
generally greater at high feeding levels and with more mature animals.
The practical implications of this are that feed efficiency deteriorates, and the feed cost
per kg live weight and carcass gain increases, with increasing length of finishing period.
Avoiding overly long finishing periods and ensuring that animals achieve minimum
carcass fat score without impairing carcass value are ways to reduce feed requirements
and costs.
Breed type / Genetics
There is broad agreement across countries on the ranking of beef breeds for production
and carcass traits (Keane, 2011a). Differences between dairy and early-maturing beef
breeds in growth and slaughter traits are small, but the latter have lower feed intake
and better carcass conformation. Late-maturing beef breeds also have lower feed intake
and better carcass conformation and in addition, have a higher growth rate, kill-out
proportion and carcass muscle proportion (Keane, 2011a). Therefore, in general, beef
breeds and beef crossbreds are more feed efficient than beef x dairy breeds, who in
turn, are more efficient than Friesian and Holstein. Within the beef breeds, latematuring breeds are more feed efficient than early-maturing breeds, especially in terms
of muscle production.
For example, in terms of RFI (MJ/day), an analysis of performance data (offered a high
concentrate diet) from the national bull performance centre in Tully, Co. Kildare showed
that of the five main breeds used nationally, Aberdeen Angus and Hereford were the
least efficient, Charolais and Limousin were the most efficient, with Simmental being
intermediate (Crowley et al., 2010). The difference between the least and most efficient
breeds was ca. 14%. There was also large variation in feed efficiency within breeds. A
M. McGee
Teagasc-IGFA Nutrition Conference - June 2014
study at Grange comparing Holstein/Friesian and suckler-bred beef cattle (slaughtered
as bulls at 15 months of age or as steers at 24 months of age) showed that overall, the
beef breeds gained about 23% more live weight during the finishing period per unit of
energy consumed than dairy breeds (Clarke et al., 2009). However, because of the
higher kill-out proportion and the greater proportion of meat in the carcass of beef
compared to dairy breeds the percentage of meat produced per unit of energy
consumed was on average 51% greater for the beef than dairy breeds.
It is important to bear in mind that comparison of intake and efficiency data for cattle
breed types must be interpreted in the context of the production system operated and
animal age / slaughter end point of the comparisons, as the ranking could vary with
changes in these factors (Keane, 2011a).
Gender
Bulls are inherently more “efficient” for beef production than steers, upon reaching
puberty, due to naturally occurring male steroid hormones (O’Riordan et al., 2011).
Published comparisons of steers versus bulls are predominantly based on dairy and
dairy x beef animals. A review of studies carried out at Teagasc, Grange comparing bulls
and steers of similar breed, reared under similar management on the same diet and
slaughtered at the same age showed that, on average, live weight gain was 8.4% higher,
carcass weight was 9.5 % heavier and lean meat yield was 20% greater for bulls than
steers (Fallon et al., 2001). Similarly, data from Hillsborough, Northern Ireland, showed
that compared to comparable steers reared in the same way, bulls produced 10% more
live weight, 14% more carcass, 21% better carcass conformation, 20% more lean meat
and 17% more saleable meat per kg feed consumed (Steen and Patterson, 1994).
Likewise, a review of mainly North American data showed that mean growth was 17%
higher, carcass fat was 35% lower and feed efficiency was 13% better for bulls than
steers (Seideman et al., 1982). Equally, a review of data from mainly continental
European countries, illustrated that, on average, intake of bulls was 1% higher, growth
was 20% higher, carcass fatness was 27% lower and feed efficiency was 17% better
than for steers (Boucque et al., 1992). Differences in favour of bulls are generally more
pronounced at higher feeding/feed energy levels and with increasing slaughter weight.
In practice, bulls and steers are generally reared in different production systems
involving different levels of feeding, particularly in winter, different lifetime ratios of
grazing to indoor feeding and different ages and weights at slaughter. This means that
the effects of “gender” are confounded with production system factors. The combination
of these factors largely determines differences in performance obtained between bulls
and steers commercially.
Compensatory growth potential
Compensatory growth is the ability of an animal to undergo accelerated growth when
offered unrestricted access to high quality feed after a period of restricted feeding or
under-nutrition. Exploitation of this biological phenomenon is recommended for
feeding weanlings (or ‘store’) cattle over the expensive indoor winter period following
which they are turned out to pasture in the spring to graze cheaper produced grass (e.g.
Keane, 2002; McGee et al., 2013).
However, compensatory growth may also be
expressed during the indoor finishing phase by cattle that experienced sub-optimal
growth earlier. For animals previously grazing pasture this sub-optimal animal growth
may be due to inadequate supplies or quality of grazed grass. Even where grass supply
is adequate and nutritive value is high, compensatory growth indoors following a period
M. McGee
Teagasc-IGFA Nutrition Conference - June 2014
at pasture is clearly evident with some categories of cattle such those with high
potential for growth.
Indoor finishing
Concentrate feeding level
Grass silage is the basal forage on most beef farms in Ireland. Most of the variation in
net energy content of grass silage is associated with its digestibility, which in turn is
mainly determined by the stage of growth of the grass plant at harvest. It is well
established that the performance of beef cattle increases with increasing grass silage
digestibility, with increases in carcass gain of ca. 33 g/day per 1% unit increase in silage
digestibility where silages were offered as the sole feed and 21-29 g/day per 1% unit
increase in silage digestibility when supplemented with concentrates at 0.20 to 0.40 of
total dry matter (DM) intake (McGee, 2005). Similarly, in a more recent review of the
literature Keady et al. (2013) concluded that overall, each 1% unit increase in grass
silage digestibility increased carcass gain by 24 g/day. As forage DM intake decreases
with increasing levels of supplementary concentrates, the effect of forage digestibility
diminishes to the extent that at high (0.80 of the diet) concentrate feeding levels silage
digestibility had no effect on carcass gain (McGee, 2005). Likewise, Keady et al. (2013)
reported daily increases in carcass gain per 1% unit increase in silage digestibility of
35g, 26g 17g and 8g for silage:concentrate ratios of 100:0, 80:20, 60:40 and 40:60,
respectively. Conversely, each 1 unit decline in digestibility of grass silage requires an
additional ca. 0.4 kg concentrate daily to sustain performance in finishing cattle (Keady
et al., 2013).
Substitution rate
Even high quality grass silage is incapable of sustaining adequate growth rates to
exploit the growth potential of most cattle. The conventional method of overcoming the
deficiencies in nutrient supply from grass silage is to supplement with concentrates. An
important factor affecting nutrient intake of cattle when supplementing forage, is
substitution rate i.e. the decrease in forage dry matter intake per unit of concentrate
intake. Increasing the level of concentrates in the diet reduces forage intake but
increases total DM intake with the magnitude of the decrease in forage intake usually
greater with forage of higher digestibility (McGee, 2005). For diets containing low to
moderate levels of concentrate (<0.47 of dietary DM intake) substitution rates range
from 0.29 to 0.64 kg silage DM per kg concentrate DM with high digestibility grass silage
(McGee, 2005). Studies where higher levels of supplementation were offered have
reported a curvilinear increase in total DM intake implying a progressively decreasing
intake of forage with increasing concentrate level (Caplis et al., 2005; Keane et al.,
2006). At the higher levels of supplementation (0.55 to 0.85 of total DM intake)
substitution rates between 0.55 and 1.15 kg silage DM / kg concentrate DM for
successive increments of concentrates are found (McGee, 2005).
The effect of energy supplement type or protein supplementation on the intake of grass
silage is unclear with conflicting reports across studies (McGee, 2005).
In contrast to expectations from published feed table values, increasing the proportion
of concentrate in the diet of beef cattle does not necessarily increase the digestible
energy value of the total diet, in particular where grass silage of higher digestibility is
fed (McGee, 2005). This negative associative effect is often attributed to a depression in
fibre digestibility in the rumen and in the total digestive tract from the inclusion of
M. McGee
Teagasc-IGFA Nutrition Conference - June 2014
rapidly fermentable carbohydrates in grass silage-based diets. Consequently, dietary
energy intake often mirrors total DM intake with increasing concentrate feeding level
(McGee, 2005).
Growth response
The response in live weight and carcass growth rate to concentrate supplementation
(increasing from ~2 kg to >9 kg/head daily) is generally curvilinear (e.g. Figure 1). This
means that the incremental growth response generally declines as concentrate feed
level increases (e.g. Table 3). Additionally the growth response is lower for high
digestibility grass silage than for medium digestibility silage (McGee, 2005).
Consequently, the economically optimum input of concentrates is higher with lower
digestibility silage. For a fixed rate of gain less concentrates are required with high
digestibility silage, and due to a progressive decline in the response to concentrates,
high digestibility grass silage plus a moderate level of concentrates can achieve close to
the same level of performance as achieved on high concentrate diets (McGee, 2005).
In general, the growth response to concentrate supplementation is higher in animals of
high growth potential than those of lower growth potential (e.g. Figure 1).
Fig. 1: Growth response to concentrate supplementation
1.4
1.2
1.0
ADG
(kg)
0.8
0.6
Bull
0.4
Steer
0.2
0.0
1
2
3
4
5
6
7
Concentrate (kg/day)
8
9
10
Source: McGee 2014 (unpublished)
Table 3: Daily live weight and carcass weight response of steers fed grass silage to
incremental increases in concentrate supplementation (expressed as dietary
proportion)
Response
Dietary concentrate1
Dietary concentrate2
Ad
0.30
0.55
libitum
0.38
0.75
Ad libitum
Live weight (g /kg
DM)
174
54
38
177
45
75
Carcass (g /kg DM)
110
41
42
102
31
68
Source: 1Caplis et al. 2005; 2Keane et al. 2006
Optimum level of concentrate feeding
In order to determine the optimum or breakeven level of concentrate supplementation,
for finishing cattle, estimates of carcass efficiency (kg concentrates per kg carcass),
silage substituted (kg DM per kg carcass gain) and the true costs of grass silage and
M. McGee
Teagasc-IGFA Nutrition Conference - June 2014
concentrates are required. Table 4 provides guidelines on the cost per kg of carcass
gain at various concentrate prices and feeding levels, assuming that the remainder of
the diet is high quality grass silage. The results show that the cost per kg carcass
increases with increasing concentrate feeding level. It is acknowledged that some
minimum level of concentrates (~3 kg /day) is necessary otherwise the animals won’t
finish. Assuming a breakeven point of 385 c/kg carcass, the optimum concentrate
feeding level is between 5 and 6 kg when concentrates cost €300/t. This increases to
~7 kg when concentrate costs fall to €250/t, and continues to increase progressively as
concentrate costs fall further.
Table 4: Cost (c/kg) of carcass gain for steers
Feeding level
Concentrate costs (€/t)
(kg/day
concentrate)
175
200
225
250
275
300
3
117
147
178
209
239
270
4
119
155
190
225
261
296
5
124
165
207
249
290
332
6
159
214
268
323
378
433
7
172
242
312
382
452
522
8
180
280
380
480
580
680
Silage substituted valued at 15.0 cents/kg DM
Where silage DMD is poor (e.g. 60%) and/or in short supply, and animal growth
potential is high, feeding concentrates ad libitum should be considered. Of particular
concern when feeding concentrates ad libitum, particularly cereals, is the rapid
fermentation of high levels of starch to organic acids resulting in acidosis. Therefore, it
is critical to ensure; (i) gradual adaptation to concentrates, (ii) minimum roughage
inclusion (~10% of total DM intake) for rumen function, (iii) meal supply never runs
out and, (iv) that a constant supply of fresh water is provided.
Concentrate type
Barley vs. Wheat vs. Oats
Although feed nutrition databases indicate that the feed energy value of wheat is 3-9 %
superior to that of barley, in practice the difference is negligible for beef cattle. In
experiments carried out in Teagasc Grange, carcass weight gains and feed conversion
efficiency to carcass gain were not significantly different between rolled barley and
rolled wheat (6 kg fresh weight - equivalent to 0.52 of total dry matter (DM) intake)
offered with grass silage ad libitum (Drennan et al., 2006). It made no difference
whether the concentrates were offered in one (6 kg) or two (3 kg each) feeds daily.
Similarly, a review of feeding trials of cattle fed high concentrate diets primarily from
North America found no significant difference in average daily gain, DM intake or feed
to gain ratio between barley or wheat averaged across a range of processing methods.
There is less information on the feeding value of oats relative to barley. The published
feed energy value of oats is 85-94% that of barley. A study in Finland comparing rolled
barley and rolled oats fed as a supplement to finishing bulls on a grass silage-based diet
showed that the energy value of oats was 7% lower than barley (Huuskonen, 2009).
Native Cereals vs. Other Cereal and Non-cereal Feed Ingredients
M. McGee
Teagasc-IGFA Nutrition Conference - June 2014
The effect of replacing half the barley in a barley-based concentrate ration with maize meal
(plus sufficient soyabean meal to ensure adequate dietary protein) on the performance of
young bulls offered concentrates ad libitum was evaluated at Grange (Keane, 2008).
Results showed that intake was higher for the maize-based ration but there was no
difference in carcass weight or carcass traits between the two rations.
In addition to cereals, a wide variety of other feed ingredients are available and used
extensively in beef rations in Ireland. In practice, this means that beef rations
formulated to have similar energy and protein concentrations, can range from being
high in starch (of varying rumen degradability) to being high in digestible fibre and
consequently, providing a variable balance of nutrients for absorption. Replacing starch
with digestible fibre in the concentrate increased the live weight/carcass weight gain of
cattle offered grass silage-based diets in some studies but not in others (McGee, 2005).
However, in these studies, concentrate feeding level and silage quality differed widely.
Differences between concentrate energy sources should be more evident at higher
concentrate feeding levels. A more recent study at Grange compared intake and
performance of finishing cattle offered concentrates formulated to have similar energy
and protein levels, but contrasting in ingredient composition, either as a 5 kg/day
supplement to grass silage or ad libitum (plus 5 kg fresh weight grass silage) (McGee et
al., 2006, 2009). Ingredients ranged from, rapidly fermented starch (barley-based), to
slowly fermented starch (maize-based), to rapidly fermented starch + fibre or fibre only
(pulps-based). Intake, production and carcass traits were unaffected by concentrate
energy source, whereas increasing concentrate feeding level increased all production
and carcass traits except kill-out proportion and carcass conformation. Concentrate
energy source had no effect on rumen pH or fermentation parameters when offered as a
supplement to grass silage but significantly altered the end products of rumen
fermentation when offered ad libitum. Similarly, Cuveleir et al. (2006) found no
significant difference in live and carcass weight gain between the starch- (barley) and
fibre-based concentrates when offered ad libitum to bulls. Collectively, this implies that
(net) energy (and protein) levels of beef rations are more important than ingredient
content per se.
At present there are a number of DAFM-funded studies on-going at Teagasc Grange
evaluating feed ingredients including, maize distillers, wheat distillers, soya hulls, palm
kernel meal, maize meal, and flaked toasted maize, for inclusion in beef rations (Magee
et al.; Lenehan et al. - unpublished).
Protein supplementation
For finishing steers or heifers offered well-preserved, high digestibility grass silage
there is no response to additional protein with barley (McGee, 2005). Similarly, with
young finishing bulls offered high digestibility grass silage, adding soyabean meal to a
barley-based concentrate gave no improvement in intake, live weight gain, carcass gain
or carcass fat score. The barley had 11.5 to 12.9 % crude protein (CP) /kg DM. From
review of the literature Huuskonen et al. (2014) reported that for cattle fed grass silagebased diets increasing dietary crude protein concentration increased live weight gain
but the responses were quantitatively very small - 1.4g per 1g/kg DM increase in
dietary crude protein concentration. Furthermore, the response in daily live weight gain
was not significantly different for bulls vs. steers and heifers or for dairy vs. beef breeds.
Additionally, the effect of crude protein concentration declined with increasing body
weight. They concluded that there was generally no benefit from using protein
supplementation for beef cattle fed grass silage-based diets providing the supply of
M. McGee
Teagasc-IGFA Nutrition Conference - June 2014
rumen degradable protein is not limiting digestion. There is evidence that finishing
cattle are likely to respond to supplementary protein in barley-based concentrates only
when grass silage has moderate to low digestibility and/or low protein content (McGee,
2005).
Similarly, an experiment at Grange with young bulls of high growth potential offered a
barley-based concentrate ad libitum without (11.6 % CP/kg DM) and with soyabean
meal (concentrate = 14.3 % CP/kg DM) showed no differences in slaughter weight,
carcass weight and carcass traits (Keane, 2005). There was an increase in live weight
gain due to soyabean meal inclusion in the early part of the finishing period (related to a
higher intake) but those not given soyabean meal compensated subsequently.
Pasture-based finishing
Due to the seasonality of grass growth, herd feed demand usually exceeds supply in the
autumn. This is particularly so on beef farms because, due to accumulated animal
growth, feed requirements increase as the grazing season progresses, whereas grass
growth declines after mid-summer. Furthermore, all else being equal, when compared
with spring grass, autumn grass often has a lower feeding value. Research at Grange has
shown that even on well managed pasture with adequate supplies (daily dry matter
allowance of 20 g/kg live weight) of high digestibility grass, live weight gain of finishing
cattle in autumn was only ~0.75 kg/day. This contrasts with much higher gains (>1
kg/day) obtained earlier in the season. In practice, animal performance is often
substantially less than this. Consequently, options for finishing of cattle in autumn
generally involve concentrate supplementation at pasture or finishing indoors (e.g.
Keane and Drennan, 2008; Keane and Moloney, 2009; 2010; McNamee et al., 2012).
As grazed grass is considerably cheaper than grass silage (or concentrates), early
finishing of cattle at pasture in autumn, before housing becomes necessary, is less
costly. In situations where complete finishing at pasture is not possible, short-term
supplementation at pasture is often worthwhile as it still reduces the requirement of
more costly conserved forage. For example, the build-up or adaptation period to
concentrates may be implemented at pasture prior to indoor finishing. Diet aside, there
are also the obvious substantial costs associated with feeding cattle indoors compared
with grazing.
Concentrate feeding level at pasture
Animal response to concentrate supplementation while grazing will primarily depend
on the availability and quality of pasture and level of supplemented concentrate.
Research at Grange shows substitution rates for finishing cattle grazing autumn pasture
supplemented with concentrates ranging from 0 to 0.81, with marginal values at higher
levels of supplementation in excess of 1.0 in some studies. In other words, where grass
supply was restricted, substitution rates were very low, but where grass supply was
adequate, increasing the level of concentrates reduced grass intake but usually also
increased total dry matter and energy intake.
Consequently, carcass growth response to concentrate supplementation at pasture in
autumn is higher where grass supply is low and where grass quality is poorer and,
declines as concentrate supplementation level increases. Studies at Grange have shown
that at adequate (~20 g/kg live weight) grass allowances in autumn, feeding ~0.50-0.75
kg of concentrate per 100 kg live weight resulted in carcass growth responses between
30 and 110 g carcass per kg concentrate (e.g. Keane and Drennan, 2008; McNamee et al.,
M. McGee
Teagasc-IGFA Nutrition Conference - June 2014
2012). In practice, feeding this moderate level of concentrates will likely result in
carcass growth responses at the upper end of this range.
On-going research at Teagasc, Grange is evaluating the response to concentrate
supplementation at pasture, in both bulls and steers, at different stages of the grazing
season (O’Riordan et al.; Marren et al.; McMenamin et al.; Lenehan et al. - unpublished).
Concentrate type at pasture
In autumn the diet of grazing cattle is generally unbalanced, in terms of energy and
protein, because there is usually excess degradable protein in autumn grass. Research
at Grange has shown dietary energy rather than protein is the limiting factor and
supplementation with concentrate energy sources is required. Three studies at Grange
showed that animal performance was similar for starch-based (barley) or fibre-based
(pulp) concentrates as supplements to autumn grass.
References
Boucque, CH.V., Geay, Y. and Fiems L.O. 1992. Bull Beef Production in Western Europe
In: World Animal Science, C5. Beef Cattle Production, (Eds. R. Jarrige, and C.
Beranger), Chapter 10: 307-321.
Caplis, J., Keane, M.G., Moloney, A.P., O’Mara, F.P., 2005. Effects of supplementary
concentrate level with grass silage, and separate or total mixed ration feeding, on
performance and carcass traits of finishing steers. Ir. J. Agric. Food Res. 44, 2743.
Clarke, A.M., Drennan, M.J., McGee, M., Kenny, D.A., Evans, R.D. and Berry, D.P. 2009.
Intake, live animal scores/measurements and carcass composition and value of
late-maturing beef and dairy breeds. Livestock Science 126: 57-68.
Crosson, P., McGee, M. and Fox, P. 2014. Technologies underpinning grass-based
suckler beef systems. In: Beef 2014: ‘The Business of Cattle’. Wednesday 18th
June 2014, Teagasc, Grange, Dunsany, Co. Meath, p14-19. ISBN: 978-1-84170606-1.
Crowley, J.J., McGee, M., Kenny, D.A., Crews Jr., D.H., Evans, R.D. and Berry, D.P. 2010.
Phenotypic and genetic parameters for different measures of feed efficiency in
different breeds of Irish performance tested beef bulls. Journal of Animal Science
88: 885-894.
Crowley, J.J., R.D. Evans, N. McHugh, T. Pabiou, D.A. Kenny, M. McGee, D.H. Crews, Jr., and
D.P. Berry 2011. Genetic associations between feed efficiency measured in a
performance-test station and performance of growing cattle in commercial beef
herds. Journal of Animal Science 89: 3382-3393.
Cuvelier, C., Cabaraux, J.F., Dufrasne, I., Clinquart, A., Hocquette, J.F., Istasse, L., Hornick,
J.-L., 2006. Performance, slaughter characteristics and meat quality of young
bulls from Belgian Blue, Limousin and Aberdeen Angus breeds fattened with a
sugar-beet or a cereal-based diet. Anim. Sci. 82, 125-132.
Drennan, M.J., McGee, M., Moloney, A.P., 2006. The effect of cereal type and feeding
frequency on intake, rumen fermentation, digestibility, growth and carcass traits
of finishing steers offered a grass silage-based diet. Ir. J. Agric. Food Res. 45, 135147.
Fallon R.J., Drennan, M.J. and Keane, M.G. 2001. Bull beef production. Occasional Series
No. 2. Grange Research Centre, Teagasc, 16 pages.
M. McGee
Teagasc-IGFA Nutrition Conference - June 2014
Finneran, E., Crosson, P., O'Kiely, P., Shalloo, L., Forristal, D. and Wallace, M. 2012.
Stochastic simulation of the cost of home-produced feeds for ruminant livestock
systems. Journal of Agricultural Science (2012), 150, 123–139.
Fitzsimons, C., Kenny, D.A. and McGee, M. 2014. Visceral organ weights, digestion and
carcass characteristics of beef bulls differing in residual feed intake offered a
high concentrate diet. Animal 8:6, 949–959.
Fitzsimons, C., Kenny, D.A., Deighton, M., Fahey, A.G. and McGee, M. 2013. Methane
emissions and rumen fermentation variables of beef heifers differing in
phenotypic residual feed intake. Journal of Animal Science. 91:5789-5800.
Huuskonen, A., 2009. The effect of cereal type (barley versus oats) and rapeseed meal
supplementation on the performance of growing and finishing dairy bulls offered
grass silage-based diets. Livestock Science 122: 53-62.
Huuskonen, A., Huhtanen, P. and Joki-Tokola, E. 2014. Evaluation of protein
supplementation for growing cattle fed grass silage-based diets: a meta-analysis.
Animal (In press).
Keady T., Hanrahan, S., Marley, C.L. and Scollan N.D. 2013. Production and utilization of
ensiled forages by beef cattle, dairy cows, pregnant ewes and finishing lambs - A
review. Agricultural and Food Science 22: 70-92.
Keane, M.G. 2002. Response in weanlings to supplementary concentrates in winter and
subsequent performance. Occasional Series No. 4, Teagasc, Grange Research
Centre, Co. Meath, Ireland, 36pp.
Keane, M.G. 2005. Response to dietary protein in finishing cattle of high growth
potential. Proc. Agric. Res. Forum, 14th and 15th March 2008, p83.
Keane, M.G., 2008. Comparison of barley and maize/barley based finishing diets for
young bulls. Proc. Agric. Res. Forum, 12th and 13th March 2008, p88.
Keane, M.G. 2011a. RANKING OF SIRE BREEDS AND BEEF CROSS BREEDING OF DAIRY
AND BEEF COWS. Teagasc, Occasional Series No. 9, Grange Beef Research Centre
March, 2011.
Keane, M.G. 2011b.
RELATIVE TISSUE GROWTH PATTERNS AND CARCASS
COMPOSITION IN BEEF CATTLE. Teagasc, Occasional Series No. 7, Grange Beef
Research Centre March 2011. 23 pages
Keane, M.G. and Drennan, M.J. 2008. A comparison of Friesian, Aberdeen Angus ×
Friesian and Belgian Blue × Friesian steers finished at pasture or indoors.
Livestock Science 115, 268–278.
Keane, M.G. and Moloney, A.P. 2009. A comparison of finishing systems and duration for
spring-born Aberdeen Angus × Holstein-Friesian and Belgian Blue × HolsteinFriesian steers. Livestock Science 124, 223-232.
Keane, M.G. and Moloney, A.P. 2010. Comparison of pasture and concentrate finishing of
Holstein Friesian, Aberdeen Angus × Holstein Friesian and Belgian Blue ×
Holstein Friesian steers. Irish Journal of Agricultural and Food Research 49, 11–
26.
Keane, M.G., Drennan, M.J., Moloney, A.P., 2006. Comparison of supplementary
concentrate levels with grass silage, separate or total mixed ration feeding, and
duration of finishing in beef steers. Livest. Sci., 103, 169-180.
Kelly, A.K., McGee, M., Crews, Jr., D.H., Fahey, A.G, Wylie, A.R. and Kenny, D.A. 2010.
Effect of divergence in residual feed intake on feeding behavior, blood metabolic
variables and body composition traits in growing beef heifers. Journal of Animal
Science 88:109-123.
M. McGee
Teagasc-IGFA Nutrition Conference - June 2014
Lawrence, P., Kenny, D.A., Earley, B. and McGee, M. 2012. Grazed grass herbage intake
and performance of beef heifers with predetermined phenotypic residual feed
intake classification. Animal. 6:10, pp 1648–1661.
McGee, M., 2005. Recent developments in feeding beef cattle on grass silage-based
diets. In: Park, R.S., Stronge, M.D. (Eds.), Silage production and utilisation. Proc.
of the XIVth International Conference (a satellite workshop of the XXth
International Grassland Congress), July 2005, Belfast, Northern Ireland.
Wageningen Academic Publishers, pp 51-64.
McGee, M. 2009. What feed efficiency in the suckler cow has to offer beef farmers. Irish
Grassland Association Journal 43, 125–131.
McGee, M., O’Kiely, P. and O’Riordan, E.G. 2006. Intake, growth, carcass traits and
plasma metabolites in finishing steers offered contrasting concentrate energy
sources at two feeding levels. Proceedings of the Agricultural Research Forum
2006, Tullamore, 15th and 16th March, p101.
McGee, M., Owens, D. and O’Kiely, P. 2009. Quantification of nutrient supply in foragebased diets for beef cattle. End of project report. Project No. 5215, Beef
Production Series No. 86. ISBN 10-1-84170-528-4.
McGee, M., Drennan, M.J. and Crosson, P. 2013. Effect of concentrate feeding level in
winter and turnout date to pasture in spring on biological and economical
performance of weanling cattle in suckler beef production systems. Irish Journal
of Agricultural and Food Research. In Press.
McNamee, A., O’Riordan E.G. and McGee, M. 2012. Effects of supplementary
concentrates when grazing in autumn on performance of dairy crossbred steers
finished at pasture or indoors. Proceeding of the Agricultural Research Forum
12th and 13th March 2012. p86.
O’Kiely 2014. Grass silage. In: Beef 2014: ‘The Business of Cattle’. Wednesday 18th June
2014, Teagasc, Grange, Dunsany, Co. Meath, p52-53. ISBN: 978-1-84170-606-1.
O’Riordan, E.G., Crosson, P. and McGee, M. 2011. Finishing male cattle from the beef
suckler herd. Irish Grassland Association Journal 45: p131-146.
Owens, F.N., D.R. Gill, D.S. Secrist, and S.W. Coleman. 1995. Review of some aspects of
growth and development of feedlot cattle. J. Anim. Sci. 73: 3152-3172.
Seideman, S.C., Cross, H.R. Oltjen, R.R. and Schanbacher, B.D. 1982. Utilisation of the
intact male for red meat production: A review. Journal of Animal Science 55: 826840.
Steen, R.W.J and Patterson, D.C. 1994. Production of beef from young bulls using high
forage diets. 67th Annual Research Report 1993-4, Agricultural Research
Institute of Northern Ireland, 29-38.