The impact of introducing East Friesian sheep into commercial ewe flocks and their potential for use in accelerated lambing systems

The potential benefits of managing East Friesian Polled Dorset cross ewes under an accelerated lambing system were investigated. The intended lambing system is based on the Cornell Star model where ewes potentially lamb five times in three years. This system has been run in Cornell for six and a half years and the average lambing interval of the Polled Dorset ewes run is decreasing annually showing the adaptation of these ewes to out of season breeding. The East Friesian sheep breed has been farmed in New Zealand under quarantine conditions at Silverstream since December 1992. The first release of the East Friesian from the quarantine was March 1, 1996 so that commercially their success as a crossbred sire in New Zealand can only be measured in an anecdotal manner. The East Friesian seems to have potential as a cross breeding sire to increase lamb growth rates (as a result of increased ewe milk production), produce leaner carcasses and to confer in higher prolificacy. The benefits of these characteristics may be used to their greatest advantage in a frequent lambing system. An accelerated lambing system using East Friesian Polled Dorset crosses was simulated using the computer simulation programme Lincfarm. Synthetic data was used to set up a basic farm model for the computer simulation. Under the assumptions used it is questionable whether East Friesian crosses run under an accelerated lambing system, are economically more viable for a small intensive block than a system involving conventional New Zealand sheep breeds under a traditional lambing system. The conception rates assumed in this simulation model may have been on the conservative so that when the benefits were compared against a traditional lambing system the potential benefits of an accelerated lambing system may not have been fully illustrated. If supplementary feeding inputs could be injected more economically into an accelerated lambing system this would also enhance the viability of the system. The results of this simulation study have highlighted the need for further scientific evidence of the biological validity of managing East Friesians in an accelerated lambing system in New Zealand and for further comparisons of the economics of an accelerated lambing system compared to a traditional lambing system. If East Friesian crosses could be successfully run under an accelerated lambing system in New Zealand the benefits achieved from the potential increased lamb growth rates would further enhance the advantage that could be reaped from producing heavy out of season lambs receiving a market premium and thus improving the profitability of the intensive lamb production.