TONY LEGGETT
Timing is everything when it comes to checking ewe udders for abnormalities and making a culling decision based on what you can see and feel.
Massey University veterinarian and researcher Kate Griffiths says Massey research into udder health suggests as many as 85% of farmers are checking udders at some point in the year, but there are no clear guidelines or agreement on what to look for, and more importantly, what to cull for.
Their plan is to produce an udder check video which helps farmers score udder faults and improve culling decisions. The video is being developed using data collected from an ongoing research project involving 1200 ewes.
With funding from Beef + Lamb New Zealand and the C Alma Baker Trust she hopes to have the video finalised before ewe mating starts in 2020.
The work to date initially focused on examining the range of udder and teat faults, and assessing the frequency they occur in. The Massey research has found that udder defects are relatively common in mixed-age ewes, ranging from 2-7%.
Kate’s work has highlighted the relationship between the score for a ewe’s udder, and the survival and growth of that ewe’s offspring.
“Initially, we palpated each udder on all 1200 ewes in the trial, then looked at things like udder depth, suspension of the udder, teat symmetry, placement, length and width,” she says.
Each ewe udder was palpated four times a year – pre-mating, set stocking time, docking and weaning –then lamb performance data was collected from birth through to weaning.
“We got great linking data to relate lamb survival and growth back to udder scores. Linking this back to the pre-mating score was important because farmers want to predict future performance and make decisions before ewes are mated,” Griffiths says.
The results of this work were very revealing when it comes to lamb mortality and the relationship between pre-mating and post-lambing udder score.
Lambs born to a ewe whose udder was hard on one or both sides at pre-mating had a 30% probability of mortality.
Lambs born to a ewe with lumps in one or both sides of her udder had a 40% probability of mortality.
Lambs born to ewes with ‘normal’ udder had a 12% probability of mortality.
“One message here is that if farmers are already scoring udders after lambing, then they could add a pre-mating check and have the option of eliminating some higher risk ewes at that point if they wanted to.”
Lambs born to ewes with lumpy or hard udders grew an average of 25g/day slower than normal udder lambs. The range was 5-35g/day difference.
“So, that’s just adding to the story. They will live but they will grow slower.”
Over a 100-day lactation period, those lambs would be 2.5kg/head on average lighter at weaning. If sold into the store market at weaning, that could be $8-$10/lamb lost.
“Remember, that is just the lambs that survive, so that needs to be included in any analysis,” Griffiths says.
When it comes to best timing for udder checking, Griffiths says if feed supply allows, a check 4-6 weeks after weaning is ideal.
“We found that of the ewes that have lesions at weaning, about 86% had the same lesions 4-6 weeks later.”
But more importantly, some ewes had developed new udder lesions in that period as well, suggesting that a cull 4-6 weeks after weaning is better than immediately at weaning.
“If farmers are running short on feed, then a check at weaning and cull at that point makes better sense. But if it’s feasible, you could do it twice, at weaning and then again 4-6 weeks later.”
However, Griffiths says it is important that ewes retained for breeding are re-assessed before mating the following year.
Further research will also include financial modelling.
“There’s a lot more we could investigate in time, from how ewes are fed leading up to weaning to feed differences, and whether or not lesions show up each year in the same place on the udder,” she says.
“How ewes are dried off comes up a lot, because farmers think of drying off dairy or beef cows. We don’t know the answer to that yet.”
“We have done lot of bacterial cultures here and we know it’s a real mixed bag of bacteria in a ewe’s udder, but we can’t really offer anything yet on post weaning mastitis prevention for instance,” she says.
