background image
35
Forage & Nutrition
Guide 2018
are critically important to specific markets. Retail markets are
the most discerning. Familiarise yourself with exactly what
your processor will be looking for.
It takes four times more energy to put on a kg of fat compared
with lean muscle. While there are substantial breed and
gender variations, in general at condition score 2, the fat
content of a kg of live weight gain will be 10-20 per cent but
at condition score 4, it will be almost four times that.
Therefore, as you increase the fat cover, live weight gain slows
down. Some feeds (especially those high in fat) contribute
directly to fat deposition but growth stage, breed and gender
are major drivers with well-shaped bulls (E and U grade
continentals) the most challenging, especially at young
slaughter ages.
Performance and cost per kg of gain are synonymous. Based
on our technical team's many farm visits, the main factors
limiting performance were:
Forage quality both grass and silage (see notes below):
Excess starch and sugar (cereals and beet crops),
resulting in sub-clinical and clinical acidosis;
Protein deficiency (mainly where there are ample home
grown starch and sugar sources such as grain and beet
products). Energy must be balanced with protein to
achieve efficient use of it;
Effective and digestible fibre (diets with high cereal and
root content need long fibre);
Clean water access and availability (nose bowls are
inadequate, especially when shared between pens).
Cattle need 5-6L of water per kg of dry matter (DM)
consumed;
Animal health (metabolic issues as well as pathogenic
challenges);
Comfort (including stock density); and
Management of feeding (introduction, transition and
change).
THE IMPACT OF FORAGE QUALITY
Based on our experience of analysing silage on beef farms, the
average dry matter digestibility (DMD) is 64 per cent. Silage of
that quality will have a large bearing on costs/efficiency. Table
1 shows the impact of increasing the DMD to 68 per cent (with
a saving equivalent to 5,500 on 100 cattle).
IN THE SHORT-TERM
Finishing cattle off grass makes a lot of sense. Once the
peak of spring grass has passed, achieving the required
performance from beef cattle becomes more challenging as
herd feed demand starts to outstrip supply and the quality
of the grass starts to drop. A large proportion of the energy
intake is used for body maintenance and, as the body gets
bigger, that requirement increases.
Over the course of the grazing season, animals grow and use
more of their intake for maintenance. The totally number of kg
of livestock will increase significantly and performance from
grass will drop. Table 2 shows the results of a trial carried out
at Teagasc, Grange. The 2.5kg and 5kg feeding rates would
increase margin by 35-60/head at current feed costs.
Once cattle have to be housed for fattening, the cost per
kg of liveweight gain increases 50 per cent compared with
grass-based finishing. Research has proven that even when
grass is plentiful and of good quality, feeding 0.5kg/100kg
bodyweight makes sense from both a performance and a
margin perspective. At this level of supplementation, the
effects are synergistic and there is practically no grass
displacement. As an example, this means feeding 3kg to a
600kg steer. As we approach autumn grass, this feeding rate
can be doubled on the basis of economic return.
Remember:
Feeding at grass will accelerate daily live weight gain;
Cattle fed concentrates will have higher kill out
percentages (two per cent) and higher grades (0.5) than
cattle straight off grass (Grange trials) and will help
producers achieve grade and fat score targets required
by the Quality Pricing System (QPS); and
Get cattle out before the usual autumn price drop.
525-700kglive
weight
Continental beef
breeds 68% DMD
Continental beef
steers 64% DMD
DLWG
1.51kg
1.25kg
Carcase yield/kg
399
399
Cost/kg LWG
1.74(302)
2.04(357)
Daystofinish
116
141
Tonnes of silage
(100 cattle)
302
296
Tonnes of conc.
(100 cattle)
81
99
FCE (kg DMI/kg
DLWG)
8.84
10.06
Table 1.
Source: French
etal,2001
Grass only
Grass +
2.5kg conc.
Grass + 5kg
conc.
Liveweight gain
(g/day)
519
718
1138
LM X suckler-
bred steers
533
542
549
Carcase weight
(kg)
307
329
348
Carcase gain (g/
day)
392
657
877
Table 2.