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16
Forage & Nutrition
Guide 2018
of grazed grass, while at the same time using a below-average
amount of concentrate. At the average stocking rate of 2.7
cows per ha, these customers are producing 1,334kg of milk
solids per ha. This figure compares favourably with research
performance that is regarded as the industry target in Ireland.
The use of diet feeders on these farms can also be a risk-
averse strategy when cow numbers stocking rate are
increasing and when, during weather events, diets can be
supplemented with forage-based supplements.
So, how do we supplement to ensure that we look after the
cow and still manage to hit our key performance indicators?
Based on the InTouch cow example above (500kg of milk
solids stocked at 2.7 cows per ha), the next series of diagrams
represents the amount of grass and supplement required, as
well as the timing of this supplement.
Diagram 1 represents a typical grass growth curve for the year,
which could be typical of this year, in which we are getting a
`slow start' to the year. The growth per ha has been divided by
the stocking rate to give us the grass grown per cow.
If we superimpose the demand of this cow producing 500kg
of milk solids on top of this graph, we see at a glance that this
cow will need major feeding until the end of April, for a small
period in late August and resuming in late September, starting
the run into winter. But we are not finished yet.
Diagram 3 outlines that while we are producing a lot of grass
mid-season, we have a cow that is only capable of eating
approximately 16kg of grass. The grey area in the graph is,
therefore, capping maximum intake at 16kg for that cow. Now
48.0
45.0
42.0
39.0
36.0
33.0
30.0
27.0
24.0
21.0
18.0
15.0
12.0
9.0
6.0
3.0
0.0
48.0
45.0
42.0
39.0
36.0
33.0
30.0
27.0
24.0
21.0
18.0
15.0
12.0
9.0
6.0
3.0
0.0
Grass gr
o
wth & demand (k
g DM/
c
o
w/
da
y)
Grass gr
o
wth & demand (k
g DM/
c
o
w/
da
y)
Grass growth/supply/cow
Grass demand/cow
Grass supply/growth/cow
12-Jan
26-Jan
09-F
eb
23-F
eb
09-Mar
23-Mar
06-Apr
20-Apr
04-Ma
y
18-Ma
y
02-Jun
16-Jun
30-Jun
14-Jul
28-Jul
11-A
ug
25-A
ug
06-Oct
20-Oct
03-No
v
08-Sep
22-Sep
17-No
v
Diagram 1: Typical grass growth curve divided by stocking rate (cows/ha).
Diagram 2: Grass demand of cow based on yield (yellow) as a function of grass grown/cow.
305-day lactation
12-Jan
26-Jan
09-F
eb
23-F
eb
09-Mar
23-Mar
06-Apr
20-Apr
04-Ma
y
18-Ma
y
02-Jun
16-Jun
30-Jun
14-Jul
28-Jul
11-A
ug
25-A
ug
06-Oct
20-Oct
03-No
v
08-Sep
22-Sep
17-No
v