Fit for a king
Sunday, 5 November 2017
VetScript Editor's pick: November 2017
Sheep milking is on the increase in New Zealand as dietary and rural land use trends transform a once fringe activity into a potentially lucrative industry.
Professor Roger Morris, of MorVet, has played an advisory role in developing the DairyMeade breeding programme. Here he tells how a veterinary epidemiologist came to be involved with a pioneering sheep breed.
New Zealand has produced a number of sheep breeds designed for local conditions, but until recently had not produced a breed designed for milking. The DairyMeade breed, produced specifically for this purpose through 20-plus years of selective breeding, has a rather unusual breeding history, not least because of my involvement – a veterinary epidemiologist whose work mostly involves global disease control, not sheep genetics.
The breed was established by Miles and Janet King of Kingsmeade Artisan Cheese. The Kings approached me initially for advice on importing new genetic material to contribute to their flock, which they had been using since its establishment to produce artisan cheeses.
Kingsmeade cheese, it should be noted, is highly regarded – it was even served
to Prince William and Catherine, Duchess of Cambridge when they had dinner with the prime minister at Premier House.
After discussing the challenges of genetic imports to New Zealand with the Kings, I suggested that we needed to evaluate the merit of their current flock to decide the best way forward, rather than assuming that imported genetic material would be beneficial.
Having worked with dairy herd records for decades and battled with poor and incomplete on-farm recordkeeping, I was amazed to find that the Kingsmeade flock had almost perfect breeding records dating back to its inception, including full parentage data and production records for virtually every animal.
Given the long history and the quality of the pedigree data, I proposed seeking recognition of the animals as a breed and involving a leading geneticist in designing a genetic improvement plan. The only problem was that the data was all in paddock diaries, and had to be transferred to a spreadsheet for analysis. With assistance from some students, Miles King transferred all the data on more than 5,000 animals from 11 generations into a form suitable for genetic analysis. The paddock diary records were clearly and meticulously written, and hence fairly easy to transcribe into the spreadsheet.
The second issue was that, while there had been careful selection throughout the breeding programme, it had been based mainly on qualitative assessments of genetic traits, rather than quantitative measurements of the type that geneticists prefer. With guidance from Professor Nicolas Lopez-Villalobos of Massey University, the Kings have progressively implemented quantitative measurements over the past few years. Current measurements include the birthweight of lambs, litter size, weaning weight, milk yield measured once a month, milk composition, body weight of ewes and a range of conformation measurements.
The various measurements are weighted by their economic importance and combined into an economic productivity index for each animal, which will be refined over time as more data is accumulated.
This year, Nicolas presented the results of an estimate of direct and maternal genetic effects on weaning weight in the DairyMeade population to the annual meeting of the New Zealand Society of Animal Production.
Further steps in the genetic improvement programme are planned, including incorporating the use of single nucleotide polymorphisms (SNPs) to aid in the genomic prediction of breeding values within the breed.
Another important step was to register the breed with the New Zealand Sheepbreeders Association, which could then provide certified pedigree data to overseas buyers. Because comprehensive genetic data was available and the required number of daughter flocks were operating, registration was approved last July, and the DairyMeade Breed Committee was established.
The breeding programme that led to the development of the DairyMeade breed was established in 1996. In 1992, 11 pregnant East Friesian milking ewes and four rams were imported through the Silverstream quarantine site. In March 1996 supplies of purebred East Friesian semen for artificial insemination were made available.
Kingsmeade had selected 80 ewes for insemination, comprising mainly Coopworth ewes and a small number of Border Leicester ewes. Animals were selected to ensure they had appropriate height and body conformation, so that the progeny would be suitable for machine milking. These animals were inseminated, and the progeny were used to build the nucleus flock, and subsequently expanded to include purebred daughter flocks. Since 1996, the only introductions have been small numbers of purebred East Friesian animals and semen.
The decision to close the flock and focus on genetic improvement rather than importing additional European genetics turned out to be fortunate. Australia will now allow sheep genetic material imported from New Zealand only if the animals have had no realistic possibility of exposure to genetic material imported since May 2016 (when importations resumed).
An unexpected and intriguing development during the DairyMeade breeding programme was the appearance of animals with black fleece and face, and a white facial blaze and white stockings, from within an initially entirely white flock of sheep. Their milk production and other characteristics are the same as the white sheep, but they have a distinctive and attractive appearance. These sheep look exactly like the Zwartbles breed, which originated in the Friesland region of The Netherlands and is now popular in the UK and elsewhere as a milking breed. The East Friesian breed comes from the same region, so it would seem there has been some mixing of genes in the past!
The black-and-white animals have been separated into a subflock, and the lambs they produce have the same appearance. The sheep are resistant to sunburn and to the squamous cell carcinoma of the ear that occurs in some white animals. They seem ideal for lifestyle blocks because of their tractability and visual appeal.
Demand for white and coloured sheep is growing rapidly in New Zealand and overseas. Semen and embryos have been exported to China and Australia in the past year and there are clear signs of escalating demand for sheep and genetic material, and for sheep cheeses.
As a result, plans are afoot to broaden ownership of the flock and the cheese business through a share issue, which will allow the Kings to expand the nucleus flock using natural mating and embryo transfer for both white and coloured sheep, and to increase the number of daughter flocks contributing genetic data and boost cheese production.
Twenty years ago dairy sheep were an oddity in New Zealand, but the Kings’ vision in building a dairy genotype is now paying off handsomely.