15 August 1997

Top notch rams make for a

faster finish

Using high genetic rams on commercial ewes has enabled one Norfolk-based producer to finish stock faster. Jonathan Riley reports

FASTER lamb growth rates and better conformation achieved by progeny of high genetic merit rams can offset the rams purchase price within the first breeding year.

Thats according to Suffolk sire reference scheme member and pedigree Suffolk breeder Bob Fletcher. He runs 60 pedigree Suffolks and 550 Vendeen cross North Country Mule ewes at Manor Farm, Houghton St Giles, Norfolk.

A sire reference scheme member for four years, Mr Fletcher explains that rams are ranked using a scheme index compiled by Signet.

The index is an overall assessment of the economic value of an animal, combining estimated breeding values for an eight-week weight, a 20-week weight plus muscling and fat depths.

Scores for these traits are combined to form an overall EBV index which can then be compared with other reference scheme animals of the same breed. This provides a prospective buyer with information of which animals will perform best.

Since the Suffolk schemes inception in 1990, this has led to a consistent improvement in measured traits.

At eight weeks old the average weight of 1996-born lambs in the sire reference scheme was 1.5kg higher than the average lamb born in 1990. By the time lambs were 20 weeks old the gap had widened further; lambs born in 1996 were 3kg heavier than lambs born six years ago at the same stage, with an extra millimetre of eye muscle.

According to performance data from the reference scheme a ram of this quality would have an index of about 173.

By comparison Mr Fletcher has just bred a ram with an index of 323 by consistently breeding from rams selected with high EBVs for muscle depths and growth rates and lower fat depths than the average scheme rams.

The top index ram was 4.26kg heavier at eight weeks old, 8.8kg heavier at 20 weeks, has 6mm more muscle and 0.2mm less fat than the scheme average. This culminates in an index of 323 – the highest so far achieved.

"When put to the ewes, the ram will pass on half of this performance benefit to the lamb," says Mr Fletcher.

"Therefore, a conservative calculation for a tup of this quality is that he will increase carcass weight by 2.5kg a lamb."

"If a flock had a lambing percentage of only 150% this would mean an extra 4.5kg of meat produced a ewe, worth £13.50 a ewe. When this is then multiplied by the number of ewes served in a year by one ram – say 50 – this adds up to a total of £700 extra revenue which would cover the cost of the ram in the first year," he says.

In addition, because these lambs are growing faster they produce an 18kg carcass an impressive three weeks ahead of other lambs.

"Not only does this reduce creep costs – which are considerable when lambs are consuming a kg a day up to finishing – but lambs hit the market earlier and so achieve better returns," says Mr Fletcher.

"As lambs are growing rapidly we have to weigh and handle them once a week to ensure they dont go over the required carcass weight," he says.

Because the flock lambs in January this performance means all lambs are marketed by mid-June. Marketing is further aided by synchronising ewes which means the flock lambs in a five-day period and lambs can be sold in large even-sized batches.

Sold on a deadweight basis lambs grade at an average between R and U and a fat class of 3L.

"Over-fatness is not a problem because lambs are still growing fast when they are sold and we have sold lambs with carcasses up to 31kg within fat class 3L," says Mr Fletcher. &#42

Norfolk producer Bob Fletcher: Use of high index Suffolk tups over his Vendeen x North Country Mule ewes is boosting lamb growth rates and carcass conformation.

HIGH INDEX RAMS

Produce progeny which:

&#8226 Have better muscling.

&#8226 Weigh 2.5kg more at 20 weeks.

&#8226 Finish three weeks earlier.