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- December 15, 2011
Selecting for Fat Improves Lamb Survival in Merinos
- Details
Selecting for Fat Improves Lamb Survival in Merinos
Recent field observations made by SRS® Merino breeders, Mark and Vicki Murphy, of Karbullah Poll Merino Stud, Goondiwindi, Queensland, suggest that lamb survival was increased when rams with high Australian Sheep Breeding Values (ASBV) for Eye Muscle Depth and Fat Cover were used. By contrast, lamb survival was about 20% lower when sired by rams with low breeding values for muscle and fat (see Table 1 below).
During the last decade there has been a significant shift in many Merino flocks to selection for meat production to increase profitability. However, the focus of the meat industry on meeting the wants of the consumer for lean cuts by selecting against ‘fatness’ has come at a cost of Merino reproductive performance.
An early adopter of ASBVs, Mark Murphy said that strategic use of breeding values has significantly increased profitability for the Karbullah flock and his commercial clients.
“By using ASBVs in tandem with the SRS® Breeding System, we have observed that sheep with the genetic capacity to lay down muscle mass with high fat cover early in life are able to maintain good body condition during drought, pregnancy and lactation, and rear more lambs with fewer lamb losses,” Mr Murphy said.
The Karbullah results back up a previous study by CSIRO Livestock Industries, Murdoch University and the Sheep CRC. It demonstrated that selecting for a combination of higher carcass muscling and higher growth, while not selecting against fat, produced better all-round results than breeding for either higher muscling or higher growth alone.
Lead researcher in the project, Dr Mark Ferguson of Murdoch University & Department of Agriculture and Food, Western Australia, assessed the ‘whole of farm value’ of fat and concluded that fatness should be maintained, or increased in the Merino.
“We found that the whole of farm benefit of a genetic increase in fat was a direct function of its effects on reproduction. In addition there was a positive YFAT effect on lamb birth weight when ewes were on restricted nutrition during pregnancy,” Dr Ferguson said.
SRS® studbreeders are among the leading users of Australian Sheep Breeding Values (ASBVs) through the national MERINOSELECT program. The SRS® Group looks set to achieve its goal of having 100% of its 40 registered studs using ASBVs by the end of 2011.
Table 1: Field Observations – Karbullah Poll Merino Stud
|
Sire |
Number of Lambs Born |
% Lambs Weaned |
Yearling Breeding Values
|
|
|
Eye Muscle Depth (mm) |
Fat Cover (mm) |
|||
|
High muscle and fat sires:
|
||||
|
A |
41 |
100 |
1.6 |
0.9 |
|
B |
41 |
97 |
1.6 |
0.7 |
|
C |
40 |
97 |
1.6 |
0.9 |
|
D |
72 |
96 |
2.0 |
1.0 |
|
E |
64 |
95 |
0.8 |
1.2 |
|
F |
54 |
85 |
0.7 |
0.9 |
|
Low muscle and fat sires:
|
||||
|
G |
35 |
88 |
- 0.8 |
0.1 |
|
H |
73 |
79 |
- 1.0 |
- 0.8 |
|
I |
46 |
79 |
0.0 |
0.4 |
|
J |
57 |
77 |
- 1.9 |
- 0.9 |
Commercial producers using the SRS® Breeding System have seen major improvements in survivability and reproductive fitness across a wide range of Australian environments, from the Snowy Mountains of New South Wales to the hot and vast pastoral country of Longreach, Queensland. Most SRS® Merino flocks see lamb marking outcomes of 120 to 130%. This high fertility is associated with the SRS® sheep type being plain bodied with a calm temperament, high milk production and instinctive maternal bonding – All of which enhance lamb survival.
Contact:
Ian Smith - CEO of the SRS® Group
0417 020 429
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