Successful heifer rearing relies on rumen development


Rumen development has a huge impact on age of first calving and ultimately on the financial performance of a farm business. Dairy Farmer reports with Liz Newman, Advanced Nutrition.


Successful heifer rearing relies on rumen development

Despite the dairy industry largely agreeing that heifers should be calved at 22-24 months old, this is not always seen on-farm.

Liz Newman, heifer rearing specialist at Advanced Nutrition, says this is 'crazy' given the impact that not meeting this target has on overal lifetime production and rearing costs.

She says, "There can be several factors at play but by far the biggest influence on achieving an age of first calving (AFC) at 22 – 24 months is rumen development."

She continues, "I’ve worked with youngstock for 15 years and through my own research working with Advanced Nutrition, vets and industry experts, I’ve seen huge improvements in milk powders and starters. These can have a big impact on how we rear our heifers but if we don’t get rumen development right, these products aren’t going to help us achieve what we need to. When I’m on farm with our clients, before we discuss the merits of milk powders and starter feed, I look at the bigger picture. How is the rumen being developed and is it early enough to reach the AFC we are aiming for?"

The research is out there, there are numerous scientific papers from experts such as Jim Drackely and Alex Bach which show successful rumen development, the science behind it, and the impact it has on the animals’ life.

Financial Impact

Calving at 26 months rather than 24 months could cost up to £2,048 per heifer (see table). Ms Newman adds, "On top of this there are additional costs to consider if calving past 24 months which would include additional heifers required and their rearing costs."

Example of fiancial impact of age at first calving

 
Cost
Calving at 26 months instead of 24  £300 per heifer
Reduced lifetime yield* £1,748 per heifer
Total cost £2,048 per heifer
In addition if calving at 26 months an extra three heifers are required per 100 cows £5,400 per 100 cows
*At a low milk price of 38p, this is 4,600 litres


Functioning

Ms Newman reminds farmers that a calf is born as a pre-ruminant and has to become a functioning ruminant by the time it is weaned. She adds: "Essentially, it’s up to the farmer to develop the rumen to achieve the Daily Live Weight Gain (DLWG) and the correct AFC. A developed rumen acts as a fermentation vat where microorganisms digest complex carbohydrates and high fibre feedstuffs. The rumen wall is covered in finger like projections called papillae which greatly increase the surface area which nutrients can be absorbed through.

When a calf consumes water and starter concentrates, bacterial fermentation is initiated in the rumen. This generates large amounts of Volatile Fatty Acids (VFAs) in the forms of acetate, butyrate and propionate. This production of VFAs (particularly butyrate) is responsible for rapid rumen development. The earlier we start to introduce  starter to the calf the better. Calves can start developing a rumen as early as three weeks old if they have had access to quality starter feed and water. Regardless of when a calf begins to eat starter feed, it takes 2 – 3 weeks for microbial population to grow to a size where it can efficiently digest grain, allowing energy to be gained from solid feeds, and increasing the chance of a successful weaning without detriment to health and growth rates.

Whatever the weaning age, choice of milk powder and environment is like, you won’t achieve the DLWG you need at the point of breeding if you haven’t developed a rumen. Poor rumen development in the milk feeding phase of rearing means that once weaned, calves are less able digest and utilise feed, causing a reduction in health and growth rates, increasing the AFC, which has a financial impact.

Calves will grow well on a high milk only diet, they will also grow well on a balanced milk and starter diet, but only one will develop a rumen. Picture A is the rumen of a milk only fed calf and picture B has been fed both milk and starter".

(Image: Penn State University)

Financial Impact

Calving at 26 months rather than 24 months could cost up to £2048 per heifer. This cost comes from extra youngstock needed on farm, longer rearing costs per heifer, reduced lifetime milk yield (based on the lowest current milk price of 38p/l).

How to encourage rumen development

Essential to rumen development are starter feed and water intakes.

Top tips to encourage starter intakes

  • Offer small amounts of starter feed fresh everyday
  • Feed should be in troughs or buckets they can reach easily
  • Lighter coloured buckets with wider openings are best
  • Offer a quality feed low in dust
  • Feed should be formulated with palatable ingredients, be correct balanced in terms of protein, energy etc
  • Overfeeding milk/milk replacer can reduce starter feed intakes
  • Ensure you have a controlled weaning programme
  • Paired or group housed calves generally have higher starter feed intakes
  • Calves in general poor health have lower feed intakes, so the calves environment and management should promote all round good health
  • Monitor starter feed intakes, if a 2 week old calf isn’t eating starter feed, you need to determine why

Ms Newman says, "Water should also be available to calves from birth. This should also be easily accessible, clean and fresh. In warm weather water should be out of direct sunlight."

"Roughage also has a place in rumen development. It provides a scratch factor which encourages muscle development and also fills the rumen to increase the size. Its main function is training the animal to chew and ruminate and produce saliva to maintain rumen pH. Chopped straw should be available separately to bedding."

Weaning Protocol

Calves should be consuming a minimum of 2kg of starter before they are weaned recommends Ms Newman. "If you’re feeding less than 2kg you need to review your milk program so that you don’t get stuck in between picture A and picture B.

Rumen development also doesn’t end at weaning, it is an ongoing process which continues (at a slower pace) until the heifer reaches maturity, therefore the rearing feed programme needs to continue to encourage rumen development.

When the dairy industry is looking towards health and welfare, longevity in the herd and improving efficiency and profitability, it’s important to realise the absolute essential and pivotal role of rumen development."

 


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