The first project is spread over five large-scale commercial farms: Tautane Station in southern Hawke’s Bay, Whangara Farms north of Gisborne, Rangitaiki Station east of Taupo, Mendip Hills Station in north Canterbury, and Caberfeidh Station in south Canterbury.
For the past two years a total of 2100 mainly Angus and Hereford cows on these farms have been mated using fixedtime artificial insemination to five sire breeds – Angus, Hereford, Simmental, Charolais and Stabiliser – with known EBVs.
By recording several traits related to reproduction, growth, carcase and survival it is hoped to prove that EBVs do work in a commercial environment in NZ.
The project is also looking to develop new economically relevant EBVs to demonstrate best industry practice and new breeding technologies (eg: genomics) and show that the commercial investment in these is viable.
The programme is in its infancy but the first meaningful results are starting to emerge. The first calf weaning weights across all five sire breeds have revealed that for each additional 1kg increase in a bull’s EBV for weaning weight there has been a 0.41kg increase in the weaning weight of its progeny.
This compares favourably with the theoretical figure of 0.5kg. Dr Steve Miller of AgResearch, Invermay, is in charge of the second project that aims to unravel some of the mysteries of what is driving maternal performance in the beef herd.
At a recent B+LNZ Genetics forum in Feilding, Miller said that much of the research on the subject had been done late last century. Some of its conclusions are:
- Cows that have the ability to store condition on their backs during times when feed is plentiful demonstrate better reproductive performance when feed is scarce
- The most efficient cows are those that are fed enough to be able to fully express their reproductive potential and the growth potential of their calves via their milk, and
- Bigger cows eat more than smaller cows, as do cows that produce more milk.
Four South Island farms – Mt Linton Station, Haldon Station, Longspur and Orari Gorge Station – and 3800 cows are involved in the programme.
The most efficient cows are those that are fed enough to be able to fully express their reproductive potential.
The cows are mainly Hereford and Angus, both stud and commercial. All animals have their DNA recorded and are weighed and condition scored pre-calving, at calf marking and at weaning.
The two years of data collected so far shows that below BCS 6 an average cow’s ability to get in-calf falls away abruptly. Fertility is largely unaffected at higher condition scores.
BCS is extremely dynamic throughout the year, particularly in commercial herds. For example, at weaning on Haldon Station in 2014, average BCS was 6-6.5.
This dropped over winter to 5-5.5, climbed again to a little over 6 at calf marking, then dropped a little to weaning.
Condition score varies most between cows at weaning. Dr Neil Cullen from Ruakura has been collecting condition scores, liveweights on cows and calf weaning weights on Haldon Station for seven years. His analysis of this data has revealed that:
- BCS is a moderately heritable trait (about 0.27), meaning it is under significant genetic control
- Cow liveweight is a relatively highly heritable trait at 0.43, and
- Heritability is at its highest at weaning because of the greater variation between measurements taken at this time.
The genetic correlation between BCS at pre-calving, mating and weaning is close to 1, which means the genetic ranking of cows within the herd will remain the same regardless of when their condition scores are taken.
The same applies to cow liveweight. Project three is being done at Limestone Downs in Waikato by Dr Rebecca Hickson of Massey University. It involves inseminating 800 dairy cows to Angus and Hereford bulls. The purpose of the trial is to:
- Identify beef genetics suitable for dairy beef
- Quantify the value of recorded versus unrecorded beef and Jersey bulls, and
- Use sires linked to B+LNZ Genetics’ Beef Progeny Test and the Sire Benchmarking Project in Australia.
No reportable results have yet been produced by this project because it has been running for only a short time.
KEY POINTS
- Early results from the progeny test project suggest that every extra 1kg of a bull’s EBV for weaning weight will produce an additional 0.41kg of weaning weight in his progeny
- Analyses of seven years of data from a large beef-cow herd showed that both BCS and liveweight are under some genetic control and will respond to genetic selection
- Weaning is the best time to record these traits but the genetic ranking of animals will not change regardless of when they are recorded, ie: pre-calving, mating and weaning.
