Crossbreeding for Profit
Recent emphasis on the use of crossbreeding to improve stock production and profitability is currently an option available to all commercial farmers. However an intelligent approach to such a programe needs to be thought through to ensure both short term and long term gain.
The two main issues appear to be, firstly, what breed options may enhance aspects of current production,eg. reducing fibre diameteter, increasing fertility or survivability, targetting improved growth rates or improving carcass characteristics. And secondly, what options can be incorporated into a long term programe where some uniformity can be acheived".
The release of the joint venture AgResearch/Wools of NZ "Growbulk" sheep presents to sheep farmers an option consistent with both of the above criteria.
The Growbulk represents a 15 year breeding programme, towards a dual purpose sheep able to more consistently meet both processor and manufacturing demands for a high bulk, low micron wool displaying bulk characteristics of 27g/cm or over. With an emphasis on the need for dual purpose production the breed backgrounds involved in the Growbulk also enhance lamb growth rates and allow for superior muscleing qualities.
"We have been involved with the Growbulk in an evalueator role for three years which has enabled us to accurately compare the production traits of Growbulk*Romney cross sheep with pure breed Romneys, and East Freisan*Romney cross sheep."
"When first approached to be involved with the project we were fairly sceptical, especially after using East Freisan genetics which fell well short of projected claims.. However the breeding programme, breeding objectives and base breeds involved in the Growbulk project were very sound and we felt it was worth looking at.
From a commercial farmers point of view the results have been very exciting, exceeding all expectations and presenting a number of cross breeding options"
Over consecutive lambings ,the first cross Growbulk lambs have had a 15% higher lambing performance than the pure Romneys, and a 35% higher performance than the East Freisan cross under a similar management regime. The scanning potential from all three mobs was similiar with lamb survivability highlighting the different performances.
Growth rates up to the weaning period were superior in the Growbulk cross lambs, and in the subsequent 100 day period they also showed higher growth rates than both the Romney and the East Freisan cross.
Eye Muscle measurements during the Autumn period also demonstrated a superiority for the Growbulk cross, and a relative inferiority for the East Freisan cross compared with the Romney.
A trial with Alliance Freezing Co. to asses the yeild and grading characteristics of the Growbulk cross lamb, are showing a 2% higher yielding carcase.
Hogget and twotooth shearing has allowed a comparison on wool production, with the growbulk progeny demonstrating an increase in core bulk up to 32grams/cm3( averaging 27 grams/cm3) and a reduction of 2 microns in fibre diameter. Despite a 6% reduction in fleece weight the combined fleece traits are acheiving a premium return over standard crossbred fleece.
The strong uniformity of the cross lambs has been a further feature of their performance, with ewe lambs reaching an Autumn mating weight of 45kg, under commercial mob conditions, and following this up with a 95% lambing performance as hoggets.
In fact, what we have seen is a lift in dollar terms for every production trait with no change in management systems at all.
Commercial farmers can gain the initial advantage of heterosis in the first cross, and then maximise this vigour by crossing the ewe replacements retained back to their existing breed. This cross will not only enhance the current wool and carcass strengths, but presents itself as a very simple management programme not requireing the more complicated three way crosses often involved in a cross breeding operation and the resultant variations in both "type" and production.
Furthermore, the Growbulk represents an intelligent and compatible crossbreeding option over the existing traditional breeds of Romney,Coopworth and Perendale. The strengths of each breed are further enhanced and no compromise need be made in one trait to improve another.
A large part of the success of the Growbulk is due to the sound direction of those involved in the AgReasearch/WoolPro project from its inception, headed by Dr. Roland Sumner.
Firstly they have identified what particular characteristics are/will be in demand from world markets and have developed a dual purpose breed to meet those criteria. Meat Industry Representatives and Wool Processors have both expressed the respective need for a superior confirmation carcass, and a high bulk processing wool, while farmers know the importance of a higher fertility/higher survivability sheep.
They have used existing breeds already proven in New Zealand as the base for the Growbulk, and maximised the superior traits within those breeds towards that end.
Furthermore it takes a large part of the risk out of the crossbreeding option, becuase of its base from proven dometic breeds. While recognised now as a stable breed it has a genetic base of 1/2 romney, 1/4 poll dorset and 1/4 texel with AgResearch screening the county for the highest performing animals of each breed.
The Growbulk is not a "wonder sheep" that will turn around profitability overnight, but it is an option that adds value to each production trait, providing both short term gain and longer term benefits.
Our strategy at Rosedale is to continue breeding to Pure breed Growbulk
status with 1000 performance recorded ewes, while measuring halfbreed
and quarter breed progeny performance from 3000 Romney flock ewes,
before crossing that progeny back to a Romney. We have not failed
to recognise the contribution of the Romney towards the success
of our Growbulk cross with 1500 stud and performance recorded
ewes continueing to be mated to the Romney.
"Rosedale Growbulks will lift your returns in every production trait."