With a strong demand for sheep meat, an improved lambing percentage is likely to be a large contributor to profitability on sheep farms¹ this season.
Nature has equipped ewes with an ability to respond quickly to their diet, a factor that farmers can use to their advantage if they want to shorten the lambing season and increase the lamb crop. But after a dry and hot summer, feed supplies may not be so bountiful and ewe condition less than ideal.
Ewes need to be in good body weight and condition for high ovulation rates at mating. Ewes of greater liveweight or those offered higher levels of nutrition prior to breeding are more likely to be multiple bearing². The so-called flushing effect, where ewes are fed additional feed to gain weight over a three to six-week period before breeding, is one way farmers can help lift reproductive performance².
The relationship between ewe liveweight and ovulation rate is curvilinear, with every additional gain in liveweight resulting in a smaller additional increase in ovulation rate before no further gains occur. Heavier ewes are less likely to respond to flushing than lighter ewes. Ewes of greater body condition score have higher reproductive performance but above a body condition score of 3.5, there is little further gain. If supplementary feed supplies are limited with preferential feeding to the light ewes and hoggets in the flock, they are the most likely to give the best return on investment.
Feeds that cause a positive change in liveweight prior to the breeding period should increase reproductive performance. Compound feeds offer a convenient and high energy option when forage quality or quantity is lacking. The level of protein and energy in the diet affects ovulation rate² so farmers can use grains or concentrate pellets as a supplement feed source to improve reproductive performance.
NRM Sheep Nuts are a multi-purpose mineralised and grain-based compound feed for sheep which are often fed on the ground with minimal waste. They contain added essential minerals including cobalt, iodine, manganese, selenium and zinc which are all linked to fertility in the animals.
NRM Sheep Pre-Tup Nuts have been specifically designed for the mating period. They contain a higher level of protein and energy to help support increased condition in both ewes and rams. They are a good option for situations where extra nutrients are required because of low pasture quality or extra weight gain is required. This is especially true for more prolific breeds and stud flocks where post-lambing care can accommodate a larger crop of lambs. Nuts should be introduced gradually and are typically fed at 150 to 200 g per head per day. They can be fed at higher rates if required.
For advice when supplementing nutrients for sheep, contact your local PGG Wrightson Technical Field Representative.
¹ Beef and Lamb NZ. 2013. Making every mating count.
² Smith, J.F. 1991. A Review of recent developments on the effect of nutrition on ovulation rate (the flushing) effect with particular reference to research at Ruakura. Proc. N.Z. Soc. Anim. Prod. 51: 15 - 23.