The High Country Index

At Meadowslea we specialize in producing hill bred Angus bulls for the High Country callteman – bulls that do the job and don’t break down, producing moderate size cows that handle the tough conditions and come in with a good calf every year.

Now as a service to our commercial clients Meadowslea has developed two customized selection indexes to further assist in selection of bulls that have genetics tailor made for the high country.

Background
Big bulls with high growth and milk figures, or that have low fat levels do not work in the high country. More importantly their daughters are not productive or very fertile under high country conditions .Many of the new, imported and popular sires being used in NZ fall into this category!

The NZ Angus Assn has been producing a “Self Replacing Index” for a number of years but it is more suited to an easier environment and higher feed levels than the native NZ high country production systems.

We therefore decided to develop an index specifically designed for the unique environment of the South Island native hill country.

Development
We engaged the assistance of senior Australian Beef Breeding consultant Bob Freer formerly of A.G.B.U. (Animal Genetics and Breeding Unit), University of New England, Armidale, N.S.W. Australia.

Bob is widely respected as one the top Australian cattle “minds” and has had first hand experience improving the profitability of some of the largest herds in Australia. Bob has made numerous trips to NZ and has assessed a number of herds in the NZ high country.

He shared our view that special Bull selection criteria is needed in this environment to ensure long term profitability for beef producers.

Two indexes have been developed for the different production systems in the NZ High Country.

The Indexes Explained

High Country Weaner Index
This index is a powerful selection tool for the commercial breeder marketing all weaner steers and surplus heifers off native country.

Target Environment
This index is developed for Angus Herds run and calved on native tussock country with no supplements fed to cows. Cows required to store energy as fat on their backs during any periods of feed surplus and to draw on those energy reserves for prolonged periods of feed shortage, of both quality or quantity of feed.

Emphasis
This index places strong selection pressure on maternal traits, aiming for a highly fertile moderate sized cow that can carry enough condition to handle the winters yet produce an attractive weaner with good growth and carcase performance.

Limits
The harsh environment puts a limit on a cow’s optimum size and production levels. Bulls with 600 day growth, and milk EBV’s above breed average, or that have fat depth EBV’s below breed average are not eligible for the High Country Weaner Index.

ie: any bulls with 600 day growth EBV's of greater than +86 kg, or milk EBV,s of greater than +12kg, or that have Rib and Rump fat EBV figures less than -0.2mm are not  eligible for the High Country Weaner Index.

High Country Finishing Index
This is a powerful selection tool for the commercial breeder, on tussock country, marketing surplus steers and heifers finished on grass at between 18 and 30 months of age.

Target Environment
This index is again developed for Angus herds run on tussock country with no supplements fed. Cows given a slightly better feed opportunity to build up energy fat reserves than for the weaner index. Surplus Steers and heifers finished at 18 to 30 months but expected to spend part of that period on tussock country.

Emphasis
This index places more emphasis on an extended growth curve and carcase traits than the weaner index but still applies strong pressure on cow size, fat and fertility.

Comparison with the NZ Angus Assn “Self Replacing Index”
The High Country Indexes place more selection pressure on moderate cow size and fertility to ensure that the daughters of bulls selected are the right type for the harsh hill country conditions.

Using Indexes for Sire Selection

- by Bob Freer, Senior Australian Cattle breeding consultant.

Selection Indexes take the hard work out of knowing how much emphasis to give each of the growth, fertility, maternal and carcase EBV’s when selecting a commercial herd sire.

Instead of studying 15 or more EBV’s you now only need to look at a single $ value that reflects commercial profitability.

An index is in fact a multi-trait EBV that calculates the optimum emphasis to place on available EBV's for a given production system – reflecting differences in the earning capacity of a sire, per cow joined, in a self replacing commercial herd.

Indexes focus on what drives profit in a commercial situation (profit drivers) and the relative economic value of those drivers to the breeding goal. The EBV's are then weighted and allow bulls to be ranked on index value for a defined production system.

Indexes are reported as an EBV, in units of relative value ($'s) for a given market.

They reflect both short-term profit generated by a sire through the sale of his progeny, and the longer term profit generated by his daughters in a sustainable cow herd.

A feature of indexes is that they account for essential compromises between traits, such as the flow-on effects of selection for increased growth rate on birth-weight and cow maintenance. These are accounted for when indexes are calculated, for example – in the High Country Indexes, high growth rates are discounted because of  the additional maintenance cost of running a heavier cow.

Bulls can be compared using selection index values in the same manner as comparing them using EBV's for single traits.

As for EBV's Indexes don't estimate the level of performance of individual animals, rather than the difference in performance between individuals.

Comparing the lifetime profitability of two bulls using the High Country index

Example:  Two bulls are used with High-Country indexes of +$40 and +$20 and mated to genetically similar cows. If each Bull mates 200 cows in his life time, the first bull will generate $2000 more profit during its lifetime than the second bull ( $20 difference in the 2 bulls indexes over 200 cows = $4000 divided by 2 because a bull only passes half his genes on to his progeny = $2000 ).

 

© Meadowslea Romney & Angus Stud, Mount Cook Road, Fairlie | site by moderndesign