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 | ||||||
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 £1,965/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.