Farm Ireland
Independent.ie

Friday 24 November 2017

Ensuring cows go in-calf should take priority over input costs

Dan Ryan

Dan Ryan

Breeding programmes for spring calving herds are now in full swing. But the weather has created difficult conditions for heat detection, and poor grass growth rates over the past number of weeks won't help the situation.

Many farmers have resorted to grazing silage ground where possible. Where land is fragmented or heavy, farmers have had to rehouse cows by night.

All this chopping and changing is hard on the cow. Dietary changes at this time of year can be particularly stressful.

Stress leads to lower submission rates and pregnancy rates. My belief is that farmers should have a very singular focus during this period -- to maximise heat detection and pregnancy rates -- even if it means spending more on feed than was originally planned. And it is not just a case of providing enough drymatter. The diet has to be balanced for all the essential nutrients and also be in constant supply to meet the requirements for optimal reproductive performance.

Grazing conditions simply have not met these requirements over the past month. We are seeing the proof of this in our scanning records. They reveal heat detection rates of just 65pc after 3.5 weeks of breeding for a sample of 1,500 cows calved greater than 40 days. This is a far cry from the Teagasc target of 85pc pregnancy rate for the first six weeks of the breeding season. They are simply unrealistic for the vast majority of farmers.

MINDSET

Where are we going wrong? I think we need a mindset shift from a simplistic focus on input costs to a point where the requirements of the cow to establish pregnancy are the priority. This begins with the body condition score achieved at drying off in the previous lactation and its subsequent management.

The egg quality required for pregnancy is determined by management of the cow in the six-week period prior to breeding. Any form of stress is detrimental to reproductive performance. If this means a temporary extra feed cost, so be it. It will take a lot of feeding before you outweigh the €250 that a missed heat is estimated to cost.

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This focus on catering to the cow's every dietary need will need to continue over the next two months while cows establish pregnancy. This is the high risk period for embryonic death and, in my opinion, asking cows to graze down to 4cm -- or 'golf ball' grazing as it has become known -- is stressful on cows. The cow's tongue was not designed to graze in this way.

There is another hidden danger in grazing over the next few weeks even if and when growth rates recover. Cows will be grazing very lush grass which can result in acidosis. This needs to be managed by increasing the fibre content of the diet. How do you know if your cows are suffering from this condition? One of the simple clinical signs of acidosis is a decrease in milk butterfat to levels at or below milk protein percentage. But lower milk solids will be the least of your problems, because acidosis will inevitably result in an increased incidence of embryonic mortality.

The first cut of silage will take place on many farms over the next month. I think it makes sense to focus on making silage with a DMD in excess of 72, because this will give you a better chance of maintaining body condition scores during the dry cow period that I referred to earlier.

I've noticed that many silage contractors now chop the grass very short to facilitate easier harvesting, reduced transport costs and easier clamping.

However, this finely chopped silage can create digestive upsets, which need to be avoided in the transition periods pre- and post-calving.

Just ask

There is a straightforward solution to this issue, however. Simply ask your silage contractor to cut the grass coarsely and ban the fine precision chop if possible.

Scanning cows at this stage of the breeding season will enable both late calvers and those cows not detected in heat to either have reproductive problems rectified or induced into heat if fit for breeding. The alternative approach of a blanket synchronisation of heats for late calvers and those not detected in heat results in poor pregnancy rates.

Dr Dan Ryan is a bovine reproductive physiologist and can be contacted at www.cows365.ie

Indo Farming