Guernseys go it alone in merit index ratings

21 September 2001

Guernseys go it alone in merit index ratings

THE current indexes for genetic selection hold little relevance for Guernseys so the English Guernsey Cattle Society are introducing the Guernsey Merit Index (GMI).

According to the societys Digby Gribble, the Profitability Index (PIN), with a weighting of 1:6 for fat to protein, has led to a fall in butterfat within the breed and reduced profits for Channel Island milk producers.

"PIN also gives no type merit information and, because Profitable Lifetime Index figures are historical, any type or short herd life problems associated with a particular bull are already in the herd by the time his PLI falls," he adds.

The GMI is the result of MDC-sponsored work at the Roslin Institute. Breeding priority has been given to increasing fat yield, with revised PIN figures rated 1:2 for fat to protein.

New linear type scores within the index, calculated from pedigree records, can also indicate sires which improve udder and legs/feet. "This type merit information will result in a better future for the breed," says Mr Gribble. Lower somatic cell counts are another goal of the GMI.

James Simpson, Genus Breedings dairy production manager, believes the index is a progressive move for the Guernsey breed. "However, producers should use the index to make a shortlist of potential sires, then make individual mating decisions based on what particular improvement is needed." &#42

See more