24 November 2011

5 minute read

Dry matter intake (DMI)

It is often standard to see DMI fall in the two weeks around calving time - due to changes in hormones and gut capacity.

However this doesn't have to be as much as we expect, says Dr de Ondarza. A study carried out in British Columbia saw DMI only fall the day before calving.

Improving cow comfort during the transition period is one way to prevent DMI falling so drastically.

NEFA levels are one way to measure cow comfort. If a cow is comfortable, it will be eating and so NEFA levels will remain more level.

Dr de Ondarza asks how can we get cows eating more?

Studies have shown that a decrease in DMI is linked to an increased risk of meteritis and acidosis - both of which will affect production and fertility.

Feeding behaviour

High producing cows should be eating between nine to 14 meals a day, says Dr de Ondarza.

Research has shown that two total mixed ration (TMR) feedings a day increases feeding time by 10 minutes.

Similarly, more space at the feedbunk will result in less hostile interactions and more eating time per day.

Overcrowding really messes up feeding behaviour, says Dr de Ondarza.

Cattle are herd animals - and subsequently want to eat at the same time as others. Submissive cows will suffer in overcrowded areas as they will stand waiting by the bunk to get fed and miss out on feeding opportunities.

Fresh heifer management

Often overlooked is fresh heifer transition into the lactating herd, says Dr de Ondarza.

She advises that pre-fresh cows are checked hourly and moved to a calving pen or fresh cow pen when calving - not before.

Moving heifers straight after calving into the main lactating herd can have negative effects on heifer productivity.

They will immediately be competing for feed with older and bigger cows.

When freshly calved heifers are mixed with older cows, research suggests that DMI falls, less time is spent resting, milk production falls and body weight decreases.

This, Dr de Ondarza says, is why it is advisable to separate fresh heifers from older animals.

If freshly calved heifers lie down in a stall that they know is preferred by an older cow, one study suggested that they will ruminate forty per cent less than usual.

Keeping freshly calved heifers separated will also make the management of these animals much easier. Ideally they should be monitored frequently in order to detect any problems.

Dr de Ondarza says that whilst it is easier for larger farms to house cattle in different pens, the idea should be taken to smaller farms, as the benefits are numerous.

Rumination

A 54 inch (137 cm) wide stall is recommended for pre-fresh cows.

Of their day, cows should spend between three to five hours eating, 12 to 14 hours resting and seven to nine hours ruminating (cudding).

Dr de Ondarza says that a good test of rumen health t is that when observing a pen of cows - at least half of the resting cows should be cudding.

If cows aren't resting, she says, then less time will be spent eating and subsequently productivity will be affected.

Poor cow comfort will lead to cows spending more time standing - often in concrete alley ways, which can lead to problems with lameness.

Any cause of stress such as poor cow comfort, overcrowding, short pen stays, and heat stress will cause metabolic dysfunction, greater fat mobilisation and reduce milk yield.

Research from the University of Purdue showed that heifers that spent more time lying down and ruminating before calving, ate more in the run up to calving. This also affected their DMI and milk production during the first two weeks of lactation - both of which increased.

Dr de Ondarza says that as a nutritionist she can make a fantastic ration up - but the effectiveness of this ration all comes back down to management. If heifers are housed with mixed parity groups, overcrowding is apparent and resting space is inadequate, then performance will be compromised.

With cow comfort and management issues, she says it would be likely that a nutritionist would increase the ration with more peNDF (neutral detergent fibre) to reduce acidosis and more fat would be required - all increasing the cost of feed for the producer.

How does stress affect cows?

The above issues that have been mentioned, including mixing first heifers with older cows, short and numerous pen stays, lack of feed, overcrowding, uncomfortable stalls and heat stress, all cause stress.

Heat stress is a major issue in Europe, with little investment into fans in transition cow pens.

However, environment is not the only factor that affects cows stress levels, and the attitudes of staff can play a huge role in improving cow comfort.

Studies have shown that positive vocal and physical contact can improve milk production. It is essential for staff to know what they should be doing and why they are doing it, as often staff will only perform well if they understand what they are doing and the effects of the action.

Stress will change how a cow uses available nutrients, says Dr de Ondarza. It can increase fat mobilisation, suppressing immunity and leaving the potential for fatty liver.

When a cow is stressed she will reduce DMI and this can lead to metabolic dysfunction.

Concluding, Dr de Ondarza says that emphasis should be placed on maintaining cows appetite during the transition period. One way to achieve this goal is to ensure that a cow experiences minimum discomfort.

November 2011