Blackdale Stud and the Fertility Gene GDF9

March 2015

Blackdale Stud has an unusual fertility gene known as Growth Differentiation Factor 9

A recently discovered fertility gene present in sheep at Southland’s Blackdale Stud is just one of the tools available to farmers through Beef + Lamb NZ Genetics. The GDF9 gene was discovered in 2013 in Norway and stands for Growth Differentiation Factor 9. It’s believed the gene came to NZ through the foundation Texel ewes from Finland.

In molecular biology, a single nucleotide polymorphism (SNP) is a variation at a single site in DNA, and is the most frequent type of variation in the genome. Eleanor Linscott, Science Manager for Beef+Lamb NZ Genetics says the recently released 5K SNP chip can include new SNPs.  This allows SNPs identified in New Zealand or other countries to be included on the chip and validated across a wide variety of New Zealand flocks.

This SNP technology means that new SNPs can be added to the chip as and when required, and information about that SNP measured in industry at very little cost.

For example the current 5K chip included a GDF9 “increased fertility” SNP recently reported in Norwegian White flocks.  In Norwegian sheep breeds, one copy results in an increase of 0.4 in number of lambs born and two copies results in an increase of 0.8 (ie an extra lamb).  There are also no detrimental effects associated with this SNP (eg like Inverdale where two copies results in sterility).

The variant was found at a low level in New Zealand specific New Zealand flocks and its presence will allow rapid tailoring of number of lambs born in a wide variety of breeds, she says.

Initial testing showed a very low number of NZ animals were likely to have the GDF9 gene, however the Blackdale flock (Texel Coopworths) appears to have significant numbers from its first test samples. Four other main flocks also showed up the presence of the gene. Leon says “We believe we have uncovered a genetic resource for the whole industry. It could be hugely beneficial to lift the fertility of the whole national flock. We think it is appropriate that we get the research behind it first.”

He tells the story of how Peter first bought the ewe carrying the gene from Sheepac. “In the mid 1980’s, Peter was given the job of marketing Texel ewes and found one had produced 22 sons and about the same number of daughters from three embryo flushes. Some of the best rams were her sons, but she had been put out with the culls because she had a hernia resulting from the embryo transplant work. Peter rang the vet to ask if she could be stitched up and saved, and later in 1990 he bought this ewe from Sheepac. Two of her grandsons gave us a huge lift in lambing performance and we can track it from our flock records that they came from a Texel ewe graded up from Finnish Landrace in Finland.”

“Hoggets lambing from that line have lambed at 180% and mature ewes at 223%. Of the 100 descendants we know that there is a lift of something in the order of 50% for hogget lambing and 30% in the ewes above the normal level. We don’t know how many copies they were carrying, but that is an average of the descendants.

From here AgResearch scientist John MacEwan is doing more testing to see how prevalent the gene is, and then he will quantify the mutation in the NZ flock. “We don’t see production negatives from the gene.”

Last year they put half the Coopworth Texel flock at Blackdale to rams which carried the gene, and this year there are around 500 lambs on the ground from those crosses.

They have had enquiries from Western Australia, and have just sold a ram with a single copy of the gene to Merino NZ. “There are exciting prospects,” Leon says. “But with anything when you find a resource, you want to fully understand it before you go too wide and far. Key in my mind from a science side is that we have got something that looks really positive so let’s quantify it with some good data.”

Eleanor says for Beef + Lamb NZ Genetics, this gene is one discovery in a whole toolbox. “The Blacks have been involved with it from day one. As a research organisation having that farmer involvement is a crucial part of it. For us this gene is one of a multitude. What it means is that Leon can pick up a ram lamb which has just been born, and with the DNA tool he can tell more about this animal than ever before. Previously he would have had to wait for that ram lamb to have progeny on the ground before he had enough information. This tool speeds up each decision by about two years.”

The ear punch for DNA will give information on 22 different traits including facial eczema tolerance, number of lambs born, weaning weight, liveweight, etc, and that’s all available now. She says, “For the NZ sheep industry we are way ahead globally because of this test and because guys like Leon and Peter have supported the research for years and allowed us to get to this position. We couldn’t do it without them – they are the engine room of the industry. So with the newly born ram lamb either you can wait or take your DNA test now. It is such a no-brainer, it is amazing technology.”

“While ram breeders use this test, the person who benefits from the technology and gets a better animal which gives them more profit is the commercial farmer. It’s all about using the technology to be able to pick the animal, and use the genetics for profit. A lot of this is low-hanging fruit, because it is something you can change on your farm.”

Eleanor estimates that about 30% of the rams sold each year in NZ are from breeders who are already using this DNA technology. “These guys are influential and sell a lot of rams. They come and approach us, they are interested and want to be involved. From testing we did around the Sheep 5K product, we found breeders representing 30% of the rams sold each year were using it. Farmers like Leon and Peter have invested a lot of time and energy and because of that we have an amazing suite of technology tools available.”

“We want the commercial farmer to identify the rams that will help them lift their game. Our programme at Beef + Lamb NZ Genetics is about helping commercial farmers get that knowledge and driving that updated technology. It’s all about genetics for profit and buying a better ram – and using Beef + Lamb NZ levy money for this work.”