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Saturday 21 July 2018

Bulls versus AI debate comes into sharp focus this breeding season

File photo
File photo

Mary Kinston

Rainfall was an unprecedented 144ml for the month of April in our part of Kerry, so last weekend's turn in the weather was a long overdue boost to both dairy prospects and farmers' morale.

Within discussion groups there has been a strong debate this year to the merit of AI on the maiden heifers.

Bulls versus AI certainly has to be given due consideration, especially where facilities are poor or a farm is fragmented and it requires significant travel to and from the outside block where they are.

In addition, young stock are devils for walking pasture into the ground in wet conditions which may have added to the hardship if they have been kept indoors to limit this impact.

If stocking rate and grass covers allow, some farmers used to bring heifers onto the milking platform for mating.

Duration and routines vary considerably between farmers, but this year even a well established routine may have posed challenges given the conditions.

When changing systems, I can't help but stress the importance of having adequate bull power, especially where AI is hasn't been used at all this year.

An absolute minimum is one bull per 30 heifers in the paddock and where AI and synchrony has been used I would probably double or treble up on bulls.

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Last minute changes in systems presents different demands and having more bulls on the ground requires planning before mating. Consider your position and do what you have to do to cover one bull to 30 cows ratio.

Most of the farmers I work with use tail paint for heat identification, although automated systems are popping up in places.

There are many preparations of tail paint and a good majority of farmers often start off using some form of emulsion and then switch to proper tail paint once the cow had been inseminated as a method of identifying cows which have gone to service.

Given the conditions we have endured, this may be a year when you need to get a weekly handle on where mating results are at.

Pregnancy rate in cows is determined by submission and conception rates. If either are negatively affected, there is a likelihood of a poorer calving rate and increased empty rates.

As we progress through the first three weeks of mating it's important to assess submission rate. The target is 90pc plus.

On a 100-cow platform, with 100 milking cows, this means that 90 cows must be mated by Day 21. To be on target throughout these three weeks you need an average submission rate greater than four cows per day or 30 cows per week.

However, if less than 25pc are submitted per week, you potentially have a significant number of cows which are not cycling which will call for a reassessment.

Body condition score and feeding have significant impacts on submission rates and have been negatively affected on numerous occasions this spring. If a cow's body condition is at all sharp and pointy - especially on the hips, backbone and ribs - then putting these thin cows on OAD milking can be the most effective and rapid method to aid mating performance.

Another option is to scan non-cyclers to eliminate problems, especially in at risk cows, including those which had twins, metabolic issues, retained afterbirths or infections etc.

Teat condition

However, if a cow is healthy and less than 40 days post-calving the likelihood is that she just needs good feeding and time.

Conception rate can then be assessed during the fourth to sixth week of mating through the level of returns.

One final issue to consider is teat condition.

With cows having been exposed to mud, wet and cold, chapped and cracked teats are common so it's no surprise that SCC has become more challenging on some farms.

I can't help stress the importance of simply teat spraying to remedy this problem.

Use at least 15ml per cow per milking, ensuring that the whole surface of the teat is covered, adequately enough to see it drip off the teat.

As most teat sprays contain emollients such as glycerine, lanolin and glycan,using adequate teat spray can go a long way in adding teat condition and maintaining good SCC.

Where conditions are really poor, pre-spraying can be an additional help in maintaining teat health.

It's a simple step in the milking routine and if you go to the bother of teat spraying, make sure to do it well rather than just making a token effort.

Mary Kinston is a discussion group facilitator and consultant, and farms with her husband in Co Kerry


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