Holstein Friesian breeding myths are thing of the past
THERE has been considerable commentary recently on the benefits of crossbreeding. Before I discuss these I would like to outline the pros and cons of the predominant breed in Ireland, the Holstein Friesian. It is well known that past breeding policies, selected aggressively for milk production, also -- unknowingly -- selected for reduced health and fertility. Because of this, the Holstein Friesian has been branded as an unfertile breed.
Results from around the world, including Moorepark, comparing Holsteins to other breeds have shown that the Holsteins used in those tests had inferior fertility to the other breeds or crossbreeds.
However, other studies have also documented that considerable differences in fertility exist within the breed. This is shown by the completed experiment at Curtin's Farm, Moorepark, which compared three different groups of Holstein Friesians differing in EBI and ancestry. Irrespective of whether the animals were of North American or New Zealand ancestry, the high EBI animals had better fertility than the low EBI ones.
Across three years, 90-93pc of the higher EBI animals were served in the first 21 days of the breeding season, with 62-68pc in-calf seven weeks into the season.
Although we can say, on average, the Holstein Friesian has poor fertility, targets set in the 1970s for reproductive performance can still be achieved if the correct Holstein Friesian is used.
The original motivation for the development of the EBI was to provide an easy-to-interpret tool to accurately identify Holstein Friesian sires with high milk solids, good fertility and health, and that stayed in the herd. The 'a + b -- c' milk pricing system, currently in operation here, has been included in the EBI since its introduction in 2001. At that point, Ireland had one of the largest focuses on fertility in its breeding goal. Since then, the emphasis on fertility in other countries has increased and now Ireland is nearer the average, with more emphasis on milk production.
As EBI developed it was expanded to include cows and stock from other breeds. It removes heterosis so that the EBI is only what is expected to be passed on across generations. The weighting placed on traits in the EBI changed over the years and new traits were introduced, including calving performance and beef merit.
The new maintenance sub-index, will this year be included in the EBI. All other things being equal, this new sub-index penalises heavier cows as it costs more to rear them; a heavier cow is still rewarded for a heavy carcass in the beef sub-index.