Maternal EBVs help select female replacement

Beef producers are regularly told of the merits of using EBVs to boost growth rates and maximise carcass yield but, as EBLEX’s Sam Boon points out, they can now form breeding decisions for female replacements

A recent study supported by the EBLEX Beef Better Returns Programme has shown that using estimated breeding values when choosing a stock bull can substantially increase returns both for finishers and for breeders producing female replacements.

The first part of the study examined the performance of calves sired by two recorded Sussex bulls and identified a £30 a calf premium gained through better growth rates and carcass weights.

Performance

During 2005/06 the two bulls sired 67 calves in John Lewis’ Kent-based Holm Place Sussex herd. The performance of the calves was tracked and recorded and the data have been analysed by Signet to assess how they relate back to each bull’s EBVs.

From their EBVs (see table), both are good Sussex bulls. Bull A has excellent genetics for ease of calving and a beef value just outside the top 25% for the breed. Bull B has a 400 day weight EBV and beef value in the top 10%. Interestingly the bull with the heaviest 400 day adjusted weight was not the one with the highest EBV for 400 day weight. This shows how important it is to use EBVs rather than raw data when selecting a bull. The heaviest bull at a sale is not always the one with the best genetics for growth.

The 200 and 400 day weight EBVs for the two bulls would suggest a 5kg (half of 26kg minus 16kg) and 15kg (half of 71kg minus 41kg) difference in the average weights of their progeny at 200 and 400 days of age, respectively. In reality the difference in calf growth rates was far greater than predicted by the EBVs.

In this example a 30kg advantage at 400 days of age could easily generate an extra £30-£40 a head for a producer finishing beef cattle – a return that could be worth several thousand pounds over the lifetime of the bull.

Consistent

These findings are consistent with several recent studies in the Limousin breed where the growth rates of calves sired by high EBV bulls have exceeded predictions. This is good news for both the pedigree and commercial producer – indicating that the progeny of bulls with high EBVs are excelling under good commercial management.

Mr Lewis says that on judging by sight alone, he prefers the poorer of the two bulls for producing calves with good conformation figures. “I think this proves that EBVs are more accurate at predicting how the bull’s progeny will perform. The other bull is better at producing good heifers for breeding.

Maternal traits feature strongly within the overall breeding strategy of the Holm Place herd, which has been performance recording for more than 20 years. While growth and carcass traits have improved, breeding potential for calving ease has also risen.

“By taking notice of EBVs you can gradually improve your conformation, growth rates and maternal traits,” continues Mr Lewis. “Of my heifers last year I kept 10, sold eight privately off the farm to a regular customer in Hampshire, sold two for slaughter, and the rest averaged £1042 a head at auction.”

Case study

• M K D Hind
  
• Mayfield, East Sussex

An increasing number of beef producers are breeding their own female replacements. This is mainly due to difficulties in sourcing first cross dairy bred heifers with the right genetics to produce hard wearing suckler cows, and health concerns around bought-in animals.

In the beef enterprise of M K D Hind, Mayfield, East Sussex, maternal breeding decisions come to the fore in both their pedigree Sussex herd and in the breeding of commercial suckler replacements.

Farm manager Brenda Hide believes the selection of high performing breeding stock is extremely important. “EBVs have a vital role to play when it comes to maternal traits, which cannot be assessed visually in bulls. Once we have considered the structural soundness of a potential stock bull, we spend time looking at the bull’s EBVs, starting with growth and carcass traits.

“We’re finishing cattle at 12-14 months of age, so it is important any sire coming to Mayfield can produce well fleshed progeny that will finish off grass with acceptable fat cover. We look for sires with good 200 and 400 day growth EBVs, and a high muscle depth EBV. We also avoid bulls with extremely high or low EBVs for fat depth.”

This combination means the bulls’ progeny will comfortably make the 280-330kg target carcass weight Mrs Hide requires for the local butchers that the farm supplies.

Sires used to breed female replacements also need to have good 200 day milk EBVs. Mrs Hide comments that within any breed there are breeding lines that are poorer milkers and this can be particularly noticeable when maiden heifers are calving at a young age.

While the Sussex is renowned for its ease of calving, attention is still required when selecting a bull to minimise the risk of calving problems. Mrs Hide advises caution when using a bull with a very high birth weight EBV, as this can lead to problems – particularly on smaller framed cows.

Where possible a bull with a positive calving ease EBV should also be sought. Where females are being retained check the bull’s maternal calving ease EBV to see how easily his daughter’s progeny will be born.

The Mayfield herd is part of a Sussex breeding group looking to increase the frequency of polled cattle within the breed. The Scottish Agricultural College (SAC) estimates the benefit in using a naturally polled bull compared with one with horns could be worth an extra £1.20 a calf, due to the labour involved in dehorning.

There will be other significant advantages in avoiding any potential check in the calves’ development. While the frequency of polled genetics within the Sussex breed is relatively low, the process is made easier through the infusion of Red Angus genetics and subsequent backcrossing with Sussex breeding lines to retain the polling gene.