Farm Ireland
Independent.ie

Monday 19 November 2018

Contaminated silage a big risk for cows ahead of drying off

Purchasing silage can be a hit and miss affair
Purchasing silage can be a hit and miss affair
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Dan Ryan

Dan Ryan

The Indian summer experienced in the months of September and October has made an incredible difference to the mood of dairy farmers.

Excellent crops of silage were harvested right through the month of October, giving farmers the means to bridge the gap in fodder requirements for the winter months.

In my experience, this Indian summer was best seen in north Kerry where rain usually limits the opportunity to graze land successfully in the back end of the year. This year, cows have continued to graze full-time through the month of October. In addition, new reseeds have had an excellent opportunity to establish. There has been an opportunity to graze these new reseeds which have boosted milk production. In addition, there is also the benefit of induced tillering to create a closed sward next spring.

November will herald the onset of dry-off therapy for the majority of grass-based dairy herds.

Standard procedures involving intra-mammary antibiotic infusions will have to change. The risks of antimicrobial resistance cannot be overlooked.

Milk recording should be a standard management practice.

Instead, we have only 50pc of dairy herds using this excellent service. We have to improve the efficiency of milk production. Milk recording provides that vital link with excellent information on milk yield, solids and SCC.

There should not be a need to use dry cow antibiotic infusions in cows with a history of low SCC. Aside from the cost savings, you are playing your part in reducing antimicrobial resistance.

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The timing of drying off cows should take account of BCS. With excellent grazing conditions, farmers have been tempted to graze grass solely as a diet requirement. However, this has resulted in a significant loss in BCS over the past month.

Cows need to achieve a BCS of 3.0 at dry off eight weeks prior to calving. Unfortunately, this is not the case for over 70pc of cows approaching nine months' pregnant.

Farmers do not realise the financial gain to be made in cow survivability by having cows dried off on the correct BCS and locomotion score. Mature cows need two months dry, while first lactation cows need three months dry.

Do not focus on trying to build BCS when cows are dry; instead, use extra concentrate supplementation in the milking cow diet to achieve the desired BCS.

Contaminated silage

Many farmers will try to extend the grazing season this year, when ground conditions are still excellent even on heavy soil types. This is achieved by housing at night and feeding silage. I have noted on farm visits, an inordinate quantity of heated silage contaminated with mycotoxins being fed to cows.

This will challenge the immune system, resulting in foetal abortions often confused with an outbreak of salmonella. It is essential to keep fresh uncontaminated silage in front of cows approaching the dry off period associated with dry cow transition management. This is directly linked to future herd survivability.

Current management practices in conserving silage involving the raking of grass into large rows has resulted in contamination with soil and faeces with the consequent risk of high potassium silage.

This will result in a negative metabolic state of cows immediately after calving with reduced cow survivability.

It is essential that you know the quality of your silage for dry cows. Send samples for analysis to enable an accurate dry cow diet to meet the need of preventative health management centrally pivoted on experience of the herd during the eight-week period prior to calving and the first two weeks post calving.

The key factor here is that in excess of 70pc of herd health and future reproductive performance are linked to the experience of the cow during the dry cow/fresh cow transition period.

Finally, a note of caution regarding vaccination programmes. The best immune response to vaccination is achieved when cows are fit. Routine vaccination programmes should be conducted when cows are in optimal BCS approaching the dry off period.

Dr Dan Ryan is a bovine reproductive physiologist and can be contacted on www.reprodoc.ie

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