Friday, August 15, 2014

Improving Feed Efficiency: Feed Efficiency Project Releases Decision Support Tool

The Beef Feed Efficiency Project has released a new decision support tool. The tool is an Excel spreadsheet in which producers can enter data on a group of cattle with growth and feed intake data. Click here to download the Excel file.

The spreadsheet is pre-loaded with some example data. Depending on how you define efficiency, the animals rank quite differently. Let's consider the example data in the "Many Wts +fatRFI" tab. (See the "notes" tab for further explanation about the traits reported or this factsheet released by the project.)

If we look at Feed:Gain ratio (F:G) Ear Tag 3 is top ranking animal.

Ear Tag
ADG
Met.Mid Wt.
DMI
Fat
F:G
3
5.24
207
21.0
0.30
4.01
5
5.06
205
23.0
0.25
4.54
1
4.62
179
22.0
0.20
4.76
6
4.52
213
23.0
0.23
5.09
4
4.81
203
26.0
0.15
5.40
7
4.30
208
24.0
0.30
5.59
8
3.16
190
23.0
0.31
7.27
2
3.29
159
24.0
0.25
7.30

But, these rankings are strongly driven by average daily gain (ADG).

We could also rank the animals by Adjusted Feed:Gain ratio (Adj. F:G).

Ear Tag
ADG
Met.Mid Wt.
DMI
Fat
Adj. F:G
3
5.24
207
21.0
0.30
3.79
5
5.06
205
23.0
0.25
4.33
6
4.52
213
23.0
0.23
4.67
4
4.81
203
26.0
0.15
5.20
1
4.62
179
22.0
0.20
5.21
7
4.30
208
24.0
0.30
5.26
8
3.16
190
23.0
0.31
7.46
2
3.29
159
24.0
0.25
8.98

These rankings are very similar, except that Ear Tag 1 dropped from 3rd to 5th. This adjustment accounts for the size differences between animals. Ear Tag 1 was smaller compared with 6 and 4 during the test, thus it required less feed.

If we rank by residual average daily gain (RG), again Ear Tag 3 and 5 top the list. But, Ear Tag 7 and 2 move up on the list because they gained more weight than we would have predicted based on their feed intake, body weight, and fat thickness.

Ear Tag
ADG
Met.Mid Wt.
DMI
Fat
RG
3
5.24
207
21.0
0.30
0.39
5
5.06
205
23.0
0.25
0.37
7
4.30
208
24.0
0.30
0.24
2
3.29
159
24.0
0.25
0.15
4
4.81
203
26.0
0.15
0.11
1
4.62
179
22.0
0.20
-0.07
6
4.52
213
23.0
0.23
-0.59
8
3.16
190
23.0
0.31
-0.60


If we rank by residual feed intake (RFI) now Eag Tag 6 is top ranking.

Ear Tag
ADG
Met.Mid Wt.
DMI
Fat
RFI
6
4.52
213
23.0
0.23
-1.2
1
4.62
179
22.0
0.20
-1.2
8
3.16
190
23.0
0.31
-0.6
3
5.24
207
21.0
0.30
-0.2
5
5.06
205
23.0
0.25
0.5
2
3.29
159
24.0
0.25
0.7
4
4.81
203
26.0
0.15
0.9
7
4.30
208
24.0
0.30
1.2

The animals at the top of the list ate less than we would have predicted based on their ADG, body size, and fat thickness. An issue with selecting on RFI is that under-performing animals can rank well for RFI. An example of this is Ear Tag 8 which ranks third for RFI but only gained 3.16 pounds per day.


point of view
"point of view" by Chris Blakeley 
Depending on whether we look relative to feed intake or growth, we get different answers. The rankings depend on our point of view. So which measure should we use? 

Theory and profit motivations point us to the economic index. In this index feed intake and growth are weighted by their economic importance. So, rather than a breeder arbitrarily deciding which trait is most important, we let the market and profit dictate the weighting of each trait. The index in the decision tool is based on the work of Rolfe et al. 2011.

Ear Tag
ADG
Met.Mid Wt.
DMI
Fat
FE Index
3
5.24
207
21.0
0.30
-$114.66
5
5.06
205
23.0
0.25
-$23.14
1
4.62
179
22.0
0.20
$41.69
6
4.52
213
23.0
0.23
$51.46
4
4.81
203
26.0
0.15
$111.09
7
4.30
208
24.0
0.30
$122.41
8
3.16
190
23.0
0.31
$282.59
2
3.29
159
24.0
0.25
$328.56

Watch for more updates from the Beef Feed Efficiency Project as they work to improve the genetic prediction of efficiency.
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