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.
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.
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
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 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 to finish easily at 18 to 30 months and attracting all the market premiums.
The index we have developed is designed to place emphasis on traits that we think are very important to high country beef production. The main trait that we think is important is the ability to re-breed in this harsher environment. This index places more emphasis on those EBVs that relate to fertility, namely days to calving, scrotal size and fat cover. In addition it puts the handbrake on mature cow size more than other published indexes and we think this is important for cows in the harsher environments.
All the time this index is highly correlated to the NZ Angus self-replacing index but we feel it is important to tweek the emphasis on some of these traits to make it relevant to the production systems of most of our clients.
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 ).