Sheeplan keys to wiser purchasing

Press, 15 January 1982, Page 8

Sheeplan keys to wiser purchasing

The success of the national sheep recording scheme. Sheeplan, in providing performance data and predictions to buyers has necessitated an explanation of how purchasing of some rams with lower indexes and breeding values could be good economic sense. The sheep and beef officer for the Ministry of Agriculture and Fisheries in Christchurch. Mr Lindsay Galloway, has drawn attention to the keenness of buyers to go for rams with the highest over-all index number on the • Sheeplan selection list and ignore those with lower or minus indexes.

But depending on the intention of the buyer, other information on the standard Sheeplan two-tooth ram selection list could be of more importance than the fact that a ram has a low over-all index.

Such buyers could buy cheaply and wisely by being more familiar with and using all the information the selection list contains and not being over-reliant on the index.

Mr Galloway explained that the really important columns on the selection list occurred in the middle of the printout sheet and were headed index, number of lambs, weaning weight, latest weight and fleece weight. The index is derived from the other items, which are called breeding values. All stud breeders using Sheeplan will have the index and lamb number columns on their selection list but may have only one or a combination of the other three columns.

He also explained that the index was heavily weighted towards fertility. Up to 80 per cent of the index was an expression of the fertility potential carried in the ram.

"It is a much more important decision for a buyer to select a stud using Sheeplan than the decision of what ram to buy," said Mr Galloway. This was because studs on Sheeplan. and especially studs of breeds where Sheeplan membership and selection for high fertility was compulsory, such as Coopworth and Borderdale, were using Sheeplan to cull out low fertility and could expect a regular increase in lambing percentages.

“It could be much better to buy a lower index ram from a stud with a high

fertility record than to buy on total eye appraisal from a farm where no records are kept." he said. This also applies when a stud breeder has consistently used high index sires and places importance on ewe selection through Sheeplan.

Mr Galloway again emphasised that Sheeplan did not provide a comparison between different studs. Higher indexes on one stud said nothing about lower indexes at one down the road. because Sheeplan largely measures performances within a flock relative to the average of that flock. Sheepfarmers who are selecting for higher fleece weights or higher weaning weights could, by dealing with a Sheeplan stud with a proven fertility record, derive considerable benefit from the breeding value columns when making their selections.

"If a farmer has got a fertility level he is happy with then he could select rams that are going to maintain the fertility, have a minus index, but can highlight fleece weight or weaning weight," he said.

Because of the low heritability of fertility, that genetic trait is the hardest to increase but just as it is slow to increase so it is slow to decrease.

"This gives the opportunity for selecting on the breeding values rather than the index and thus buying very wisely," said Mr Galloway.

The latest listing of Sheeplan flocks is now available from M.A.F. offices. It includes a section on guidelines for ram buyers. “The average breeding

value for each trait in the flock is close to zero," says the publication. "A breeding value with a plus sign shows that a ram is above average in that trait, and a breeding value with a negative sign shows it is below average for that trait in the flock.

"It is important to realise that from an 'improver' flock, a ram with a negative breeding value may still increase production for that trait in the buyer's flock." The booklet explains that the two-tooth selection list also contains the flock summary which shows how much culling the breeder has done. Negative breeding values must be seen in the light of this culling. "For example in a heavily culled flock, negative breeding values are still above the average of the total number of animals before they were culled," says the booklet. It also explains in more detail how the index is arrived at using the relative economic values for extra lambs, extra kilograms of weaning weight, extra kilograms of hogget liveweight and extra kilograms of wool.

Because an extra lamb is of much greater economic benefit than extra weight or extra wool the index (which is a combination of the breeding values) acquires its considerable weighting towards fertility. Interpreting of breeding values is explained in detail including the necessity to halve each figure (because only half the sire’s genes are passed to his progeny) when using breeding values to predict the gains from above average sires.

The national sheep recording scheme, Sheeplan, was started by the Ministry of Agriculture and Fisheries in the mid 1970 s with the objective of providing computerbased performance data for stud sheep breeders so as to raise the production of the national flock.

During the 1981 year 1138 flocks were on the Sheeplan records and they contained 355,408 ewes.

The acceptance of Sheeplan has been greatest among the largest stud breeders and thus some 50 to 60 per cent of all stud sheep in New Zealand are now on Sheeplan, representing the flocks of 30 per cent of registered breeders.

The scheme is run on the M.A.F.’s computer and its

officers throughout the country act as agents for the collection of returns filled in by the studs participating and give advice on the system.

The current cost in the first year for 100 ewes registered would be about $lO7, including the registration fee of $35 and the lambing, weaning, hogget shearing and sire summaries. That cost rises to $169 for 200 ewes and $253 for 300 ewes.

Used properly Sheeplan can be a powerful flock management tool and the regular performance print outs provide stud breeders and the farmers who come to buy valuable predictive data on the likely effects of taking a particular sheep into the buyer’s flock.