Our five key focus areas are reproduction, growth, meat, wool and survival.


ROMNEY: Mainstay
COOPWORTH: Production Plus
ROMWORTH: Built for Hill country
SUFTEX: The Sunday Roast

ROMNEY - Mainstay

The main focus at Grassendale is production, efficiency and constitution. We like to think of our Romneys as hardy, thickset, , reproductive,  resilient sheep.

We have zero  tolerance policy to poor feet, and a poor constitution, regardless of figures . We challenge the ram lambs with severe mob pressure and minimal drenching, which really identifies the ones who will thrive in our harsh hill country environment.

We monitor and collate information from the recorded flock ie Eye Muscle Scanning, Pelt thickness Scanning, Survival, Growth, Reproduction, Wool weights as well as noting mothering ability which is analysed by SIL, to ensure an ever improving genetic package for our clients!

Flock History

John Humes started the flock in 1978, after working for Holmes Warren for 4 and a half years and becoming hooked on the stud. His farm Raho Ruru was predominantly Turanganui Bloodlines and so it was an easy start. He initially went around the farm with a drench gun with red dye in it and identified the ewes with the best sets of twins. He started selling Raho Ruru rams in the 80’s. His flock grew and he had 1200 ewes , and sold 310 rams in his best year.

He worked closely with Holmes Warren and John Daniels, and it was from here the WRIG group was developed. (Wairarapa Romney Improvement Group).

After a genetics conference with  Professor Ray and Dorian Garrick, they asked the question why could the Romneys not produce the meat yield and fast growth rates like the exotics do, hence in 1992 an experiment/focus was set up within the WRIG group, with exceptionally positive and beneficial results to the entire WRIG groups flock on Meat yield and growth rates.

All WRIG group members selected 25 of their best ewes (selected on BV for LW8, of at least 2kg) and a focus flock was started, based at Raho Ruru. The ewes were A.Ied using the top 10 rams on SIL and the progeny was killed and meat yield measured. The data was related back to the ram lambs collated with the growth rate data and the top three rams were selected.

These three Rams were used over the whole WRIG flock at Raho Ruru by AI and the study was continued up to 2015. Results have been substantial with a huge increase in weaning weights and an increase in the value per head due to better grading and yield.

 So they have realised the potential to lift the commercial farmers lamb weaning weights by 5-10kg, with an added increase in value of $6-$12 per lamb!

The Raho Ruru flock was bought to Grassendale in 2015. On selection of the flock, we went through pens 12 sheep at a time, basically selecting the sheep which were more suited to hill country farming.  Specifically looking at body type eg angle and length of neck, depth of barrel and length of body. After this selection regime we came home with 650 of 900. It was a great result for us, a big thanks to the team at Raho Ruru.

We're proud to be members of the Wairarapa Romney Improvement Group

COOPWORTH - Production Plus

We purchased Valley Coopworths in 2010.

Since taking over we have focused on growth and meat and maintaining reproduction at a 200% + scanning, which seems to have cemented at this level. We annually eye muscle scan, and have also done some CT scanning at Lincoln university as well as footroot gene marker on sire rams.

We used some Embryo transfer as a tool to speed up genetic gain. And are on SIL, focusing on breeding a dual purpose ram.

The five key traits for us being, Reproduction, Growth, Meat, Wool and Survival.

Ross Seymour founder of Valley Coopworths in 1970, farmed in Tinui on a typical eastern hill country farm, although carrying capacity had been greatly increased,  the per head animal production had not changed to any great extent. So in the mid sixties, after going to a lecture at Massey university on genetics Ross decided to improve the performance of the breeding flock  by crossbreeding. He could see the British farmers doing so much better with there genetics.

His Romney flock had a lambing %under 100, so in 1963 the ewes were mated with Border Leicester rams for the first time, this increased the lambing by 30% and also produced lambs that could be sent to processers rather than sold store.

At a similar time there was an emerging group of farmers led by Sir William Dunlop and aided by Lincoln college who decided the answer was to interbreed the border cross sheep using strict selection based on performance. This resulted in the formation of interbred ram breeding flocks and the “Coopworth” breed of sheep.

Tirohunga followed this policy and  established a Coopworth flock, and became registered in 1970. The flock continued to maintain a high level of production and give very satisfactory financial returns. Ross became a founder and chairman of the Coopworth society and was in close contact with Lincoln genetics through all this development phase of the Coopworth breed.

By the late 70's Ross had 850 registered ewes. In the 80,s the stud was wound down to 40-50 ewes due to Ross moving to town and pending his son John moving to the farm, there was a few managers in this time.

In 1992 the flock transferred hands to John Seymour and a new stage of its development proceeded using technology and new techniques, like AI to obtain the use of high ranking progeny tested sires selected from the national flock . John screened top performing ewes out of his own commercial flock and built up numbers of the flock to 300 registered ewes, at this stage they were weaning 180-190%, with an average weaning weight of 30kg. Valley Coopworth produced the highest ranking ram in the NZOSR in 1999. Semen from  this ram was exported to Australia.

ROMWORTH - Built for Hill Country

It all started in 2009 when we put Coopworth Rams over our 5600 WRIG Romney commercial ewes. We then selected 700 in lamb, twin reared hoggets at a minimum weight of 43kg at the 1st of May.

The following year the selection then went onto 2tooths in lamb with twins, and having a condition score of three or over at the end of the winter rotation. They were also tipped over at this stage ensuring feet and structural soundness were of the quality required.

We also culled on aesthetical qualities, aiming for a deep barrel, short neck, straight topline, with no medulated fiber on skin around anus in a V shape (dag preventative).

These ewes then went on to scan %187 with %7 triplet , %15 single, %2 dry. We set stocked at 6.1pha on grade VI & VII class of land. We had a record docking of %155 and our average weaning weight was 30.5kg.

We repeated this process with the next age group to give us the numbers to gain genetic merit. These ewes have now gone through multiple dry summers and tough winters, with two autumn droughts and proven themselves worthy in condition and performance.

The result has been so consistant we are stabilising our commercial ewes with the Romworth.

For the 2015 mating we put 700 recorded Coopworth ewes selected on reproduction and survival to high growth rate/meat Romney rams. 

SUFTEX - The Sunday Roast

Grassendale Genetics purchased a Beltex Sire ram and a Suffolk Beltex cross  in 2017 at the South Island Sale.

This was the first Sale of Beltex in NZ, having only just come over from the UK. Watch this YouTube clip to learn about the Beltex.

We have crossed the Beltex and Suffolk/Beltex with our Suftex ewes, who are sharefarmed in Wainuioru.

Our Suftex flock was established in 1990 by Gordon Mackie in the Hawkes Bay who was wanting to produce high yield growth rate rams, focusing on the off mum slaughter date. He managed to purchase the first Texel Suffolk cross out of quarantine in New Zealand. He then purchased the Suffolk dispersal flock from Intercontinex and crossed these two. They scanned %165-170. The selection of rams was anything over 40kg at 85-90 days.

2020 sees our second Beltex ram auction on October 22nd.

Heres an example below, of the value-add in the Beltex cross.

SUFTEX - The Sunday Roast

The 4 lambs weighed 179.5 kg 2hours before going on the truck to the works, and were killed about 24 hours after that.

They weighed 179.5 kg, and as the carcass weights were 29.1 + 22.7 + 27.2 + 23.5  = 102.5, making a killing out 57.1

LambPre-slaughter Wgt (kg)Hot Carcass Wgt (kg)Meat Wgt (kg) Meat %
2549.029.1 (59.4%)23.4 (81.2%)
4147.027.2 (57.9%)21.6 (80.3%)
1142.523.5 (55.3%)18.7 (80.7%)
2341.022.7 (55.4%)17.9 (79.3%)


The 4 lambs weighed 179.5 kg 2hours before going on the truck to the works, and were killed about 24 hours after that.

They weighed 179.5 kg, and as the carcass weights were 29.1 + 22.7 + 27.2 + 23.5 = 102.5, making a killing out % 57.1.

What Our Clients are Saying

We have been using Grassendale Genetics rams for the past four years. We have a good base of Romney ewes and were looking to add more lambs plus build on our mothering and milking ability.

Grassendale Genetics in Tinui, is genuine, dry hill country in summer - a great testing ground for these Coopworth genetics, this farm will sort the men from the boys.

Since we have been using Grassendale Genetics we have moved our scanning from163% in 2013, to 183% in 2015 and docking from 135% to 146%. This year we scanned 188%. Grassendale Genetics are giving us the lift in production that we hoped they would.

Ben and Deb Morrison