Better feeding to improve scanning performance in a post-rut weaning system.
A 20 kilogram average weight gain in fawns over two months has been the big win from a 2016 trial of post-rut weaning at Cathedral Peak station. But counteracting the good was a disappointing scanning.
A 20 kilogram average weight gain in fawns over two months has been the big win from a 2016 trial of post-rut weaning at Cathedral Peak station. But counteracting the good was a disappointing scanning which has started manager Andy Dennis thinking of ways to improve this result on the Manapouri farm. Andy is a member of the deer industry’s Southland Advance Party. The pros and cons of pre- versus post-rut weaning have been well debated within the group.
“We’re getting the growth rate in fawns on mum through post-rut weaning but not the scanning performance and I want to see if better feeding will help improve that.”
For the 2016 trial a 10% sample of hinds were condition scored (recording a 3 average) and weighed, and the fawns drenched and weighed in March. The mixed-age mobs were put back on pasture whereas the 150 first fawners were put on 31.5ha of lucerne.
When weaned at the start of May the fawns were weighed – revealing the 20 kilogram increase. The hinds were again sample weighed and condition scored; weights of the sample appeared to have remained about the same although body score condition had picked up to 3.5. Andy assumed the pick-up in condition would be reflected in scanning performance across the herd. This proved to be true with the first fawners which recorded a 12% leap from the previous year to 98%. But overshadowing that figure was a disappointing 88% from the mixed-age hinds.
“I thought it would be better considering the autumn we had.”
Andy hopes that many of the questions he has around weaning management and reproduction performance will be answered in a follow-up trial next year comparing post-rut weaning and better feeding with pre-rut weaning.
“I want to see if I can use post-rut weaning and better feeding of hinds with fawns at foot to lift scanning by 5 or 6%.”
For the trial the 600 mixed age Red hinds, all mated to an elk, will be separated into three mobs of about 200. One mob will be weaned pre-rut and the other two post-rut. All hinds will be condition scored and weighed, and all fawns weighed to get starting comparison figures when the first mob is pre-rut weaned at the start of March. The pre-rut weaned fawns will be drenched with a multi-mineral, treated for internal parasites with dectomax injection and moved onto a young grass rotation. From the start of March one post-rut mob will be supplemented with lucerne balage and the other with barley.
Andy’s predicting that pre-rut weaning will lift scanning performance but increase animal health costs. “We’ll end up drenching them four times before their first winter which will increase costs and the likelihood of drench resistance which is becoming a problem on some farms. If we post-rut wean they’ll only need two drenches before winter.”
Andy is familiar with pre-rut weaning from his previous management experience at Mt Somers station. “It worked really well on the hill country because hinds gained weight and condition on the hill country during mating, and all culls and mobs could be sorted before the stag was introduced.”
At weaning the fawns went to a specialist finishing area. They were supplemented with grain if necessary, drenched a month later and gained between 8 and 16 kilograms before winter. But he thinks there is opportunity at Cathedral Peaks – and is keen to see through his Advance Party project – if fawns on mum over autumn in an intensive system will achieve high growth rates without comprising hind scanning and fawning date.
At a glance: Cathedral Peak station, Manapouri
Owners: Cam and Wendy McDonald
Manager: Andy Dennis
Area: 780ha including 345ha of deer fencing
10 % lucerne (Force 4)
8% cropped with kale, swedes or an Italian and red clover mix
3,400 ewes lambed
830 hoggets mated
150 finished steers
920 hinds mated
80 velvet stags
All progeny finished at over 55kgCW, 50% by mid-November
Scanning: 86 – 92%
Fawning: 84% (hinds to stag)
Information on lactating hind nutrition is available here: www.deernz.org/sites/dinz/files/DeerFact_FeedingHindsFawns_Web.pdf
Body condition score has a big impact on conception rates, for information on boosting Condition Scores to achieve high conception rates click here: www.deernz.org/deerhub/reproductive-wastage