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The aim of the Bentley flock is to produce breeding rams to fit the
requirements of each customer and improve the performance of their flock. By selecting
stock rams with specific EBVs we are able to produce rams that excel in specific traits
to meet these requirements. The accuracy of using Estimated Breeding Values was reinforced
to us during a farm trial in 2006.
The trial was conducted to outline the performance and thus, financial
benefits of using service sires with high Estimated Breeding Values. Previous trials had
already illustrated the increased performance available to sheep producers through selecting
rams based on performance figures, and we aimed to reinforce that message.
We selected ewes with similar performance figures and served them with
two different rams: A sire from the Top 10% of the National flock (Index £4.43) and a sire
from the Bottom 50% (Index -£0.08).
The trial contained 11 sets of twins by each sire, with 9 ram lambs and
13 ewe lambs in each group. All lambs were reared as twins under an identical management
system.
The lambs were analysed for birth difficulty, vigour and suckling ability
during the first 3 days of life. The lambs were weight recorded at birth and at regular
intervals throughout the trial. The lambs were finally back-fat scanned at 20 weeks of age.
The results showed that the difference in the average performance of the
ram's progeny directly correlated to the difference in the rams EBVs. This is shown in the
table below.
|
| Bottom 50% Sire
| Top 10% Sire
| Difference
| | Trait
| Sire
EBV
| Lamb
performance
| Sire
EBV
| Lamb
performance
| Sire
EBV
| Lamb
performance
| |
|
|
|
|
|
|
| | Weight (kg)*
| 2.52
| 50.48
| 10.35
| 58.52
| 7.83
| 8.04
| | Muscle depth (mm)*
| 1.55
| 28.12
| 3.16
| 29.8
| 1.61
| 1.68
| | Fat depth (mm)*
| -0.07
| 3.68
| 0.56
| 4.57
| 0.63
| 0.89
| |
|
|
|
|
|
|
| | Birth Weight (kg)
|
| 4.9
|
| 5.1
|
| 0.2
| | Age at 40kg (days)
|
| 101.2
|
| 90.9
|
| -10.3
| | Age at 45kg (days)
|
| 114.7
|
| 103
|
| -11.7
| | * Data adjusted for age
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The major difference found between the two sires was the faster growth
rates found in lambs by the top 10% sire. Progeny of the top 10% sire reached a slaughter
weight of 40kg, 10.3 days earlier than the progeny of the bottom 50% sire. Assuming that
lambs were eating 1kg of concentrates (£140/tn) each day and grass cost 12p/day, the lambs
sired by the top 10% ram were £2.62 cheaper to rear to a light slaughter weight. If this
difference was accumulated over a 500 ewe commercial flock (1.5 lambs reared), the farmer
would increase their profits by £1965/year.
We feel it is therefore essential that we consistently improve our stock
through performance recording to provide our customers with genetics that can help them prosper.
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