This Q&A session touched on a topic featured in the 2003/4 Genelink newsletter, with Denis providing his response at that time, and an updated response in current time.
Question: Do White Dorpers join successfully in October to December? Can you share your experiences?
Further to some discussion last year on whether White Dorpers join successfully in October to December, I wonder whether you have any further information?
My experience with White Dorpers has been:
3 ewes - lambed September 2002, joined late November 2002, lambed late July 2003 (gap between lambs was 10 months).
Conditions: drought but probably not sever compared to SA growing conditions.
1 ewe - similar to above but lambed 9 months later. Joining was effectively February - March and not earlier if an 8-month cycle was realistic.
I also joined 4 young ewes for the first time at 8 months old in October 2002. Lambs came in July 2003 at 18 months old, ie joining was not effective until February 2003.
Suffolk cross: Also with White Suffolk / White Dorper ewes joined with White Dorpers, I found that despite joining for earlier lambing, lambs mostly did not arrive until July 2003 at 18 months old, with February again being the effective joining time.
I have a range of ages of these sheep progressively younger, due to lamb from now. This may indicate better at what age they conceive and whether earlier than 18 months old at lambing occurs because of the time of year.
I would appreciate your comments partly because I am planning an AI program and wonder whether this would be better deferred to say November (for an 8-month lambing interval) until February when conception seems more reliable?
Denis' Reply in 2003:
It seems that with all the breeds we are running the optimum time is February to August and in fact very few mate in the Nov, Dec, January period (note: reply is relevant to that time in the Mallee country at Parilla in SA)
I would not do a program until February at the earliest and hold all my artificial breeding in White Dorpers to early March.
White Dorper matings in the "off period" only conceive at 50% here at best. In 2001 in that period all ewes were served but obviously some did not ovulate.
September matings in the other breeds have been up to 60% but the period only goes for about 6 weeks and then no more lambs even though the rams were in them.
Age does not seem to have a bearing on it - we mate as young as 7 months during the optimum breeding time. But outside of that period most will not get pregnant even if older. We are now only doing one mating per year - with the 3 times in two years we run into management problems with large numbers with feed and spare paddocks and keeping age groups of rams separate - then you start to drift and lamb at odd times and eventually have to hold over to mate at an ideal time or settle for a split and two matings - one in September and one in February for the ones that did not get pregnant in September.
Now this is what happens in South Africa and gives the illusion of breeding all year round - We found the same claims and same problems with the Boer goats. OK if you have lots of labour and many paddocks but when you get big numbers it can be real messy.
Over 13 years at Parilla in very seasonal climate we found that the full blood White Dorpers remained somewhat seasonal breeders and we avoided artificial breeding programs other than in the peak breeding season from March-July. We did find that the commercial sector of the sheep – Dorper with a dash of mongrel were much more reliable out of season breeders – timing to put rams in a couple of days after weaning gave high conception rates. The ram effect where ewes were totally isolated from any sight, sound or smell of rams and then drop in 6-8% ram groups seemed effective with a decent ram percentage allowing most to get covered on the first cycle. Of course this was not possible with the Stud flocks that were single sire mated in small paddock groups – the rams were kept about 6k away though.
Other than after drought reductions when it was critical to re-stock we changed management to reflect local conditions
Ewe lambs were taken out to 10-12 months resulting in higher pregnancy rate and more twins.
Lambing in December, January, and February was avoided because of lamb losses on 45 degree days – a couple of paddocks with scrub had water points moved into the scrub but one paddock had a clay pit out in the open left by the leases that grew potatoes and the sheep seemed to like the mineral mix water – that little fiasco cost 150 lambs on a couple of 45 degree days with no shelter around the dam.
We also ended up trying to avoid feed debit in unreliable rainfall and aimed lambing at the time of possible rain with the hope of green feed from pasture and planted crops – of course the stud sector was subsidised with bought in feed when needed.
This Q&A is simply a sharing of dialogue and thoughts on management and joining experiences that may be useful to White Dorper breeders. It is not necessarily the opinions or views of the Australian Dorper & White Dorper Association and/or its members.