Early management key to older heifer health

Early management key to older heifer health

Herd Management
The growth rate and body condition of heifers between weaning and calving should be monitored at least monthly.

The growth rate and body condition of heifers between weaning and calving should be monitored at least monthly.

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The key to having well-grown older heifers is to look after them really well as baby calves and to ensure that you achieve low morbidity and mortality rates in this period.

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I have been doing some ongoing work with dairy farmers in the UK and was recently asked by a vet if I could prepare a talk on the care of older heifers but fortunately, she did not define "older".

I agreed to do it but decided that to talk about the care of older heifers without any reference to early life management was like building a house without any foundations.

I did talk about older heifers but I preceded the discussion by saying that management in the post-weaning and pre and post-mating period is a comparatively insignificant contributor to lifetime production, compared to management in the first two to three months of life.

If this period is not managed in a way which achieves optimal health and growth rates, lifetime productivity and profitability has already been lost.

Weight which is not put on in the first two plus months of life will never be regained; compensatory growth for this early period does not exist.

Rearing costs to first calving do not change, no matter how long that animal stays in the herd. Most heifers do not reach breakeven point until their second lactation; those which have had a slow start in life may take longer.

Therefore, keeping all of your heifers in the herd past the end of their second lactation is the most effective way of recouping their rearing costs.

The key to having well-grown older heifers is to look after them really well as baby calves and to ensure that you achieve low morbidity and mortality rates in this period.

A dairy raising only its own replacements (i.e. not buying in any calves) should be able to achieve a mortality rate of less than 1 per cent and a morbidity rate of less than 5 per cent in calves up to a month or so beyond weaning (whether that is six or 16 weeks).

If not, it is economical to improve management to achieve these targets.

If bull calves are raised for beef, the same targets are and should be, attainable.

I know these targets are achievable in any climate and that it is financially beneficial to do this.

Up to date, UK stats are that 16pc of dairy heifer calves don't reach first lactation and 15pc don't reach the second.

This means 31pc cost money to feed but don't generate any income.

Closer to home but a decade ago, the Victorian figure for heifers which died or were culled before their second lactation was between 30 and 40pc and the Tasmanian figure was 48pc.

Both these figures suggest there is room for improvement in calf/heifer management.

Much of how a heifer performs in the dairy relates to early life care.

Early weaning and minimising rearing costs are not the most cost-effective way to rear heifers.

Management which minimises the number of replacement heifer calves which do not make it to their second lactation is the most cost-effective way of rearing replacements.

Setting and meeting health and growth targets at strategic points throughout life will help achieve this by delivering the most profitable cows into the herd.

The most profitable cows are long lived, calf regularly and easily, milk well and are healthy - no foot problems, mastitis, etc.

There are lots of decisions to be made prior to mating but one of the most influential ones is heifer body weight. - Jeanette Fisher

Much of this relates back to management in very early life.

One of the participants in the UK training session mentioned that he had cows in the herd which were on their fifth, sixth and seventh lactations; there are many similar aged or even older cows in herds in Australia and other countries.

These cows are the ones which are making money; their rearing costs are long since paid back and they must be healthy or they would have been culled when they were younger.

Key drivers of lifetime profitability are:

  • Early colostrum intake.
  • Early life (8/52) growth rates.

The postnatal period is one of the most critical "windows" for epigenetic regulation.

It is a period when feed conversion efficiency (FCE), milk production and reproductive capacity are set for life, therefore, establishing the basis for older heifer management starts young.

Early life growth rates are influenced by health status; calves which are sick or stressed will not be growing as fast as they should do.

Low morbidity and mortality rates in young calves are achieved by a combination of factors:

  • good management of pre-calving nutrition,
  • a clean calving area,
  • excellent colostrum management,
  • appropriate (but not necessarily expensive) calf housing,
  • high feeding rates,
  • cleanliness of the calf environment.

These factors have effects which carry on into later life because it is early life colostrum intake, health and growth which manipulate the young animal's genetic capability for lifetime feed conversion efficiency, reproduction and milk production.

Stress

Stress has a significant impact on growth rates and production levels in animals of all ages.

Very simplistically, mammals partition nutrients into various areas.

Protein and energy are used:

Firstly for maintenance - just keeping the individual alive, heart beating, lungs breathing, gut function, locomotion, etc.

Secondly, they are used for immune system function - defending the body against disease; anything which causes stress is challenging the immune system.

Lastly comes growth or milk production.

Only when the maintenance and immune system needs have been filled are nutrients diverted towards growth, foetal growth or milk production.

Stressors are cumulative and so the more stress there is in an animal's life, the more growth and/or production will be depressed.

For example, if weaned heifers were pastured in a very muddy paddock but everything else was perfect, the heifers might stay healthy.

But if you add freshly weaned heifers grouped with mated heifers, unpalatable or contaminated water supply, inadequate nutrient intake and cold, wintry weather and no shelter in paddocks, some heifers will break with clinical disease.

Pneumonia and coccidiosis are two common diseases which occur in such circumstances.

Post weaned heifers which are housed have more potential stressors than pastured animals but there are stressors which apply to both groups.

Overall, the most obvious causes of stress are:

The key to having well grown older heifers is to look after them really well as baby calves.

The key to having well grown older heifers is to look after them really well as baby calves.

  • Overcrowding of the lying (bedded) area or less than or equal to one free stall per animal.
  • A dirty or muddy environment, particularly with high ammonia levels.
  • Large age diversity in the group, leading to bullying of younger heifers.
  • Changes in group composition.
  • Vaccinations/dehorning.
  • Competition for space at feed and water points.
  • Extreme heat or cold, particularly for heifers pastured in bare paddocks.
  • Poor stockmanship - rough handling, shouting, excessive force when mustering, etc.

The most common stressors I see on Australian farms are nutritional stress and climatic/environmental stress - heifers not receiving the appropriate level of feed supplementation for their age and/or heifers paddocked without shelter from cold winds and rain.

Young heifers still have a low body weight to surface area ratio, so they chill easily.

On some farms, poor stockmanship is an issue, too.

Stress is difficult to measure; it is easy to think that adding stress to heifers' lives is not doing any harm.

"I'm running out of room for my weaned heifers - I'll just have to put those 10 freshly weaned calves in the paddock with the heifers from the autumn calving ... it won't do any harm."

How many times have we said that sort of thing?

How do we measure whether or not it has had an impact?

A good indicator of increased stress levels is the treatment rate for respiratory illness - has there been a spike?

Have ADG's dropped back?

Rest assured that any stress added to your heifers will be having a negative consequence, whether you are measuring it or not.

Stress and its impact on feed conversion

One of the consequences of stress/immune challenge is reduced FCE.

In heifers which have a severe immune challenge, resulting in clinical disease, poor FCE occurs because nutrients are diverted from growth into defending the body against disease.

For example, it is easily possible for weaned calves which become ill to halve their feed conversion ability, so instead of a DMI to ADG ratio of 4:1, it can easily blow out to 8:1.

This happens not only in calves with clinical disease but also in their pen mates, who might not be clinically ill but whose immune systems are under stress.

The cost of the extra feed per kilo of gain adds significantly to the cost of raising heifers when multiplied out over all the heifers in the herd.

As well as the cost of extra feed, the consequent delays in reaching growth targets and puberty have ongoing costs.

The longer the immune challenge continues, the higher the cost will be.}

Rumen development and post-weaning slump

Dairy farmers wean calves months earlier than they would be weaned if left on the dam. To achieve this, rumen development has to be accelerated.

Developing the rumen to the point of the calf becoming a functional ruminant takes time.

Calves weaned before they have a well-functioning rumen will suffer a post-weaning slump, lose weight and be susceptible to illness.

This post-weaning slump in growth rates can result in calves not meeting mating weight targets.

Establishing good rumen function early in life is fundamental in the development of a robust heifer which becomes a good milking cow.

The most accurate indicator of whether or not calves are ready to wean is concentrate intake. Weaning heifers when they are consuming 2kg concentrate per head per day will ensure that rumen development is sufficient for there to be no post-weaning check or slump in growth rates.

VFAs - which are important to rumen development?

Microbes in the rumen ferment starches into volatile fatty acids which are absorbed through the rumen wall into the bloodstream.

Volatile fatty acids are the main energy source for ruminants and for the micro-organisms in the gut.

The three main volatile fatty acids produced in ruminants are acetate, propionate and butyrate. Butyrate has been proven to be the main stimulus for rumen development; propionate plays a much smaller role.

Acetate, which is the VFA which comes predominantly from forage is an important precursor to milk production but contributes almost nothing to rumen development.

High quality forage contributes mostly propionate and a small amount of butyrate so is much less important.

Butyrate is the by-product of the digestion of starchy grains, therefore feeding grain to baby calves is critical to rapid rumen development.

Forage for pre-weaned calves

Calf rearers rely on information from many sources; some of these still recommend feeding young calves ad-lib forage from day one.

Reputable sources of calf rearing, information such as Dairy Calf and Heifer Association Gold Standards III, AHDB's Calf management manual and Dairy Australia's "Rearing Healthy Calves" manual, emphasise that ad-lib forage is detrimental to rumen development and early life growth rates.

In the pre-weaning phase grain alone is necessary for the accelerated development needed.

In most cases, whole grains contain enough fibre to meet the needs of young calves.

Pre-weaned calves have a high energy requirement relative to their ability to consume dry feed. If calves consume significant amounts of hay, which is comparatively low in nutrients, their intake of grain or pellets will be limited.

This happens because high fibre levels in the forage slow ruminal outflow which causes the animal to feel full for longer.

The calf is simply not able to ingest enough nutrients, and growth and rumen development slow as a consequence.

Muesli type grain mixes contain enough fibre to ensure good rumen development but if pellets are fed, it is advisable to add 5pc forage to ensure that fibre requirements are being met; chaffed lucerne is ideal.}

Post-weaning nutrition

Rumen size at time of weaning is small.

Even calves which have good rumen function at the time of weaning need to be fed a high concentrate diet after weaning.

Forage is not nutrient dense enough to comprise a high percentage of the diet of young calves, even after weaning.

Calves up to about the age of six months cannot eat enough high-quality pasture to provide them with the nutrients required to keep calves growing at the recommended rate.

Forage should be introduced slowly into the diet after weaning and should only comprise a small percentage of daily intake; up to about four months of age, forage should be limited to 10pc of the diet.

Young weaned calves still have small rumens so they need nutrient-dense feeds.

Calves will nibble on grass but a concentrated feed source should be fed daily.

The best indicator of whether or not calves are getting enough nutrients is growth rates; calves should grow at about 800-900 grams per day.

In most situations, this means continuing to feed decreasing levels of grain until at least six months of age or 180-200kg.

Forage equals fibre - essential after weaning

After weaning, forage is necessary to develop the musculature of the rumen and for proper ruminal function.

Once they are fully ruminant heifers need effective fibre for their rumens to function properly.

The best and cheapest source of effective fibre is straw.

Weaned heifers are still baby animals and still need concentrated sources of protein and energy to keep growing.

The "back paddock syndrome" is not uncommon in Australia.

Weaned heifers are sometimes put out in the back paddock or on an out block and do not receive the attention they deserve.

Only when mating time is looming is it discovered that heifers are under-conditioned and underweight.

Frantic efforts to get heifers up to target mating weights are usually unsuccessful; even if heifers do get in calf, it is likely they will end up as first lactation culls.

Fatty Udder syndrome - a worry or not?

Lots of farmers restrict intake in pre-pubertal heifers for fear of fatty udder syndrome.

Fatty udder syndrome happens when over-feeding, particularly of energy sources, leads to the deposition of fat cells instead of alveolar tissue (milk secretory tissue).

Between about three and nine months of age, a pre-pubertal heifer's mammary tissue undergoes a period of allometric growth.

Diets too high in energy during this phase of growth can contribute to the deposition of fat in the udder.

It is almost unheard of in pasture-fed heifers or in those fed a well-balanced ration, even a TMR.

Obviously, if there are less milk producing cells, the animal's productive capacity is reduced.

However, even when it does occur, the related cost of lost production is still less than the losses associated with the negative effects of underfeeding of pre and post weaned heifers.}

Limit feeding pre-calving

75pc of foetal growth occurs in the third trimester, so growth rates in this phase need to factor in the massive weight gain of the foetus and foetal membranes.

To continue the necessary growth trajectory for the heifer herself, ADG's will need to be about 500g higher than the previous ADG.

In Australia, some farmers limit feed cows, particularly heifers in late pregnancy in an effort to reduce the level of dystocia in the herd.

In fact, genetics plays the most important role in foetal size and unless animals are visibly overweight, which rarely happens in pastured heifers, all the farmer is doing is depressing the amount of milk that the animal will give after calving, since the mammary gland is secondary to the foetus in receiving the necessary nutrients to initiate lactation.

In the last couple of weeks of pregnancy, the heifer herself will put on almost no weight.

Apart from what she needs for maintenance, virtually all the nutrients she consumes will be going into the foetus and mammary gland/colostrogenesis.

Monitoring pre-mating growth

We all know the saying that "you can't manage what you can't measure" but how many people actually measure calf and heifer growth?

It is very hard to measure growth without scales.

I do not believe that weigh tapes, across all ages, all breeds and all users, provide an accurate enough estimate of weights to be a useful management tool.

Visual assessment has been proven to be very unreliable.

Research done in England by Penn State University found that veterinarians underestimated the weight of dairy cows 65pc of the time, and on average their estimate was off by about 65kg.

In the same study, dairy farmers underestimated body weight in 81pc of their attempts, and the weights were off by an average of just under 100kg.

It is impossible to make accurate decisions about nutritional inputs or suitability for mating if the actual weight of heifers is not known.

The cost of mating underweight heifers is significant and is a big contributor to the high cull prior to the second lactation.

Scales are a cheaper option than culling heifers year after year.

The growth rate and body condition of heifers between weaning and calving should be monitored at least monthly.

Once heifers are thin and harsh coated, future milk production has already been compromised.}

Pre-mating management

There are lots of decisions to be made prior to mating but one of the most influential ones is heifer body weight.

In year-round calving herds, heifers can be mated whenever they reach the target weight.

In block/seasonal calving herds, there is a temptation to mate heifers which are underweight, to get them to fit in with the calving cycle. If this happens, we know their chances of being early culls is high.

If you regularly have heifers which are not up to mating weight, review your growth rates/feeding protocols to avoid this occurring, so that heifers have better survival rates to second and third calving.

There is strong evidence that heifers which are mated underweight have more calving difficulties than heifers which calve underweight.

Do not be tempted to mate any heifer which is less than 55pc of medium/high average birthweight - she still has too much growing to do, 55pc should be an absolute cut off point.

Value for money spent on semen

If expensive semen is used but the heifers born from that semen are not managed to maximise their yield then it would be cheaper to buy a bull from Fred down the road and save money.

If heifers are being culled before their second lactation (i.e. before the heifers start to make a profit) then whatever was spent on the semen to produce those heifers has been wasted.

From an economical point of view, unless one has a secure market for reared dairy heifers, it may be best to decide how many replacement heifers are needed for the year, mate the top cows to the best sexed semen available and treat those calves like gold.

The rest of the herd can be mated to a beef bull and the calves either grown out as a separate enterprise or sold to a rearer.

The rearing cost/heifer does not change no matter how long a cow stays in dairy so it is best to do a good job and keep her there for years.

Age at first calving

It is universally acknowledged that calving later than 24 months is costly.

Research done by the Royal Veterinary College in London demonstrates that heifers which calve between 22 and 24 months:

  • Have a longer retention rate in the herd; (RVC - 62pc survival to five years for 24/12 calvers vs. 41pc survival for 26/12 calvers),
  • Have less calving problems and produce more lifetime milk than heifers which calve older than 24 months of age; (RVC stats - 24/12 calving = 25,000L/first five years; 26/12 calving = 20,400L/first five years).}
  • Underweight heifers}

Underweight heifers have:

  • Difficult calvings
  • Poor competition for feed
  • Lower feed intake
  • Less milk partly because their intake is less and partly because they are partitioning energy into growth instead of milk
  • Lower fertility and are less likely to get back in calf than well grown heifers.}

Calving management

Appropriate lead feeding of well grown heifers will minimise post-calving weight loss and metabolic issues, help reach peak milk early and increase chance of getting back in calf.

Anything which minimises stress related to calving will increase milk yield (manage to avoid DAs, dystocias, CPs).

The whole calving/first milking experience is stressful for heifers, so it can be useful to run heifers through the dairy before calving to acclimatise them to the experience and reduce some of the stress associated with entering the herd.

Herd position affects feed intake and stress levels.

Block calving means groups of heifers enter the herd together, which can help minimise stress and associated production loss.

Heifers should be weighed to ensure they are calving at more than 85pc mhbw and producing more than 85pc of herd production figures.

Providing heifers are calving at less than or equal to 24 months, the higher these two figures are, the more productive the animals will be and the more rapidly they will repay their rearing costs.

Management changes

{If you are considering making management changes, assess your current position before you start making changes.

This can help evaluate the benefits of change and track the rate of change.

Heifers take time to rear; profitable farmers spend that time doing a good job producing heifers which stay in the herd for many lactations.

Less effective farmers spend time playing catch-ups - pre-mating feeding in a scramble to reach target weights, more matings, pulling calves, culling, etc.

One course of action has a good return on investment, the other is a very inefficient use of resources.

Expensive facilities and top-quality equipment are not needed; just attention to detail and a commitment to getting things right.

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