34 minute read
YOUNGSTOCK REARING
With large costs associated with heifer rearing, it is vital heifers are joining the main herd at the right time and in the right condition. Here we look at all aspects of this important stage.
40 COLOSTRUM
The early days of management 42 HYGIENE
Avoiding issues at housing 46 REPLACER
Research into feeding levels 48 SCOURS
Benefits of electrolytes 50 RUMEN
Impact on age of first calving
Heifers are a dairy herd’s future, which makes them the most valuable animals on-farm. And achieving an age at rst calving of 24 months for heifers is a good target for lifetime yield, longevity and individual lactation, says Jimmy Goldie, chief technical o cer at Carrs Billington.
Ge ing dry cow management right ensures the best colostrum for the calf.
He says: “ e rst 24 hours of a calf’s life determines the rest of its life. It should be fed the equivalent of 10% of its body weight in colostrum in the rst six hours.”
Get clean, good quality colostrum into the calf as quickly as possible, says Mr Goldie.
“Quality is important. Make sure to monitor the quality to ensure it is up to standard. It is not necessary to sample every batch, but knowing the general colostrum quality in the herd is important.”
A er colostrum, look into milk replacers or whole milk, he says. “Given that the price of milk replacer has gone up quite signi cantly, some farmers have been looking into giving whole milk instead.”
Mr Goldie suggests working out what o ers the best value between milk replacer and whole milk.
“Consider the consistency of quality given to calves on a daily basis.”
If using milk replacer, whether mixed by hand or machine, ensure the correct ratios are followed.
“Make sure the calves are ge ing the correct amount of milk powder.”
He also says producers should get hard feed or concentrates and water in front of the calves as soon as possible to aid with rumen development (see p50-51 for more on this).
Choose a pellet which o ers a balance between bre and protein, says Mr Goldie.
“Something too starchy will cause acidosis, but good nutrition is needed. About 18% protein is su cient.”
Straw
He recommends o ering straw to help develop the rumen.
“Although straw has the lowest nutrient value of forages, it is be er for the calf, as at that age it cannot digest haylage or silage.
“If they are o ered straw, they actually do not eat much of it, but it is su cient to allow the rumen to start developing.”
Ensuring access to water is also important, as the rumen needs water alongside forage to aid development.
Mr Goldie says: “Calves are fed milk and because of the oesophageal groove which by-passes the rumen and goes straight to the small intestine, but water goes into the rumen.”
Calves require a daily rate of 0.8kg for Holsteins and 0.65kg for Jerseys to hit body weight targets for bulling at 13-15 months. Rearing correctly is in the best interest of farmers, as it directly affects the future of the herd. So how can producers get it right? Ruth Wills reports.
Looking after the future of your herd
Costing
JCurrently, feeding concentrates, forage and straw to achieve growth rates of 0.8kg/day for a Holstein to calve at 24 months would cost about £2/calf/day at the rearing stage, says Mr Goldie.
He says: “The argument at
JIMMY GOLDIE
If aiming to calve at 22-24 months, heifers must reach their target body weight for bulling at about 13-15 months.
“ ey should reach 55-60% of their adult body weight by 13-15 months,” says Mr Goldie.
“To achieve this, they need a growth rate of 0.8kg/day for a Holstein and 0.65kg/day for a Jersey.” e rst stage of life is important in that process. “A healthy calf should be weaned at double its birth weight at eight to 10 weeks of age.”
It is important calves are weaned gradually. “ is will allow the animal to adapt: a 10- to 14-day weaning period is recommended. Increasing the intake of concentrates alongside access to water is key to ensuring their weight does not change.”
Producers should also ensure minimal exposure to health risks at weaning.
He says: “ is includes keeping the environment clean and dry with good ventilation. It also links back to having a good immune system from the colostrum.”
Also, avoid stresses at weaning, such as moving or dehorning, as this can cause a drop in weight.
Pellets
e next step is moving from a starter pellet to a rearing pellet.
Mr Goldie says: “Ensure these have su cient energy and protein balance to achieve required growth rates. Protein in the whole diet needs to be about 15% on a dry ma er basis to promote muscle and bone growth.”
Heifer rearing key points
rThe calf should be fed 10% of its body weight in colostrum in the first six hours rEvaluate whole milk versus milk replacer in terms of quality, cost and consistency rWater and straw will aid rumen development rCalves should reach 55% of their adult body weight by 13-15 months rTarget growth rates of 0.8kg/day for a Holstein and 0.65kg/day for a Jersey rA 10- to 14-day weaning period is recommended rRearing a Holstein to calve at 24 months costs £2/calf/day
the moment is that it would be cheaper to rear heifers for longer, so to 28 months of age, which is the national average for age at first calving.
“But in reality, saving 1kg/calf/ day of concentrate will only save 35p/calf/day, but the rearing has been extended by 100 days. So although feed is more expensive at the moment, it is not worth rearing heifers for longer than necessary. Also consider that more accommodation is needed because there are more animals on-farm.”
Supports animals during scouring, as an effective oral rehydration therapy.
It can also be used proactively to support calves and lambs to support calves and lambs that are potentially at risk of that are potentially at risk of stress or infection e.g. • if slow to suckle • weaning or feed change weaning or feed change • from handling and transportation • when in contact with when in contact with other scouring animals. other scouring animals.
What farmers tell us: “We have used Rehydion successfully for many years. successfully for many years. It is easy to administer as it It is easy to administer as it can be diluted in milk, which means there is no which means there is no interruption to milk feeding.” interruption to milk feeding.”
Rehydion is an oral rehydration therapy gel that provides sufficient essential electrolytes to correct acidosis and still allows continued milk feeding (when given at the recommended levels), as it does not disturb milk clot formation or delay abomasal emptying1 .
REFERENCE: 1. Constable 2009. Comparative effects of two oral rehydration solutions on milk clotting, abomasal luminal pH and abomasal emptying rate in suckling calves. J. Dairy Sci 92:296-312.
UK dairy farmers are making progress towards better calf colostrum management practices but still need to focus on improved performance monitoring. Katie Jones reports.
Steady improvements on colostrum management
Reporting on the results of an early 2022 survey of current colostrum management practices, conducted by MSD
Animal Health, the company’s youngstock category product manager Rob
Simpson says this latest feedback is particularly encouraging.
He says: “100 years on from the date [1922] that the crucial importance of colostrum was first formally recognised by science, it seems farmers are now making good strides forward in this crucial area and reaping the benefits of improved calf health as a result. That is great news.”
He reminds farmers that the importance of colostrum cannot be over-emphasised.
“In addition to providing immunity against key early life disease threats, fed correctly and in enough quantity, colostrum also helps kickstart sound organ development and a healthy metabolism.
“We also know that a good colostrum intake enables a greater response by the calf to important vaccines up to six to 10 months of age.
“Indeed, the additive impact of sound colostrum feeding protocols and vaccination is the cornerstone of immunity-led disease prevention.”
The survey results involved feedback from 248 UK dairy farmers representing both all year round and block calving herds.
Questions were designed to draw out current practices relating to the accepted five Qs of best practice colostrum management: Quality, Quantity, Quickly, sQueaky clean and Quantify.
Mr Simpson says: “Asked whether they check the quality of their cow colostrum before storing or feeding it, 49% of respondents said they always check its quality, 25% said sometimes and 26% never.
“Interestingly, when we asked this same question two years ago, 44% of farmers said they never test their colostrum.”
Timing
Newborn calves should be fed at least four litres (or 10% of bodyweight) of good quality colostrum within four hours of birth. A further two litres should be given within 12 hours of birth.
Mr Simpson says: “More than 70% of the 248 dairy farmers claimed to be feeding up to four litres, with a further 9% of respondents feeding more than four-and-a-half litres.
“Most seem to be getting it into the calf quickly; more than 75% giving it before the newborn calf is six hours of age and more than 15% within 12 hours of birth.”
He says it is also encouraging that farmers now appreciate the importance of hygiene. This is because the number of bacteria in the colostrum can double every 20 minutes if it is not stored in a fridge or frozen.
“More than 60% of farmers are feeding it within 30 minutes of harvest and another 23% within the hour.”
The final best practice Q relates to quantification and Mr Simpson stresses there is no point investing in better colostrum management and feeding practices if your progress cannot be monitored.
He says: “Failure of passive transfer of antibodies is nearly 14 times higher on farms which do not routinely monitor this goal compared with farms that do.
“However, this latest survey found that 40% of farms never check the transfer of antibodies from colostrum by calf blood analysis. And another 33% only do it in the event of a problem.”
Independent veterinary professional Owen Atkinson says farmers should be checking colostrum antibody absorption routinely.
He says: “Progess has been slow in this area, but now appears to be improving. In 2015, just 3% of farms were blood testing calves but this latest
The survey showed that nearly half of respondents always check the quality of colostrum.
survey suggests more than onequarter of the farms are now working with their vet in this area. That is really encouraging.”
Mr Atkinson says farmers may not be testing for passive transfer as it is perceived to come under the ‘important but less urgent’ category.
He says: “All the focus is on the crisis and there is less focus on less urgent issues. This is why the quantify colostrum management might drop off the radar.”
He adds the farm vet has a role to play in demonstrating the importance of this area as awareness of failure of passive transfer might be low onfarm, despite it requiring minimal time and cost to test for.
Mr Atkinson says best practice is to test 12 calves every three months to check for passive transfer, which he concedes is easier to do on larger farms where there are larger numbers of calves being born at any one time.
Improving hygiene at the calf rearing stage will help dairy farms reduce their cost of production and improve animal health and welfare. Debbie James reports.
Diseases in young calves are managed better with good hygiene protocols.
Good hygiene protocols in the rearing stage
Newborn calves have a very limited ability to defend themselves against pathogens in their environment; it is a key reason why a third of heifer replacements on UK dairy farms do not remain in the herd beyond their second lactation.
Consultant Jamie Robertson says even non-pathogenic bugs come at a cost to a calf’s metabolism since 8% of metabolisable energy (ME) in feed intakes will be used to ght pressure from these.
Mr Robertson says many diseases in young calves are managed be er with good hygiene protocols at this all important phase.
Yet research carried out in conjunction with the Agri-Food and Biosciences Institute (AFBI) on 66 farms in Northern Ireland has shown that many are failing at this.
Average cleaning frequency of feeding equipment was every two days but was as much as 84 days while on 18% of farms feed buckets are only cleaned when a calf is weaned.
It is a reason why so many milk-fed calves die in the rst four weeks of life as a result of scours caused by pathogens already present on a farm, says Mr Robertson.
“Many chronic animal health problems can be improved through be er management and design of systems and housing,’’ he says.
“A lot of facilities are extremely hard to clean so for me the answer is that we must make it simpler.’’
An initial intake of 10% of a calf’s bodyweight is recommended within the first two hours, followed by a second feed within six hours of birth.
Colostrum
JProviding calves with enough good-quality colostrum as quickly as possible after birth is a vital first step to reducing losses in the first month of life.
Becca Cavill, veterinary adviser at Boehringer Ingelheim, recommends an initial intake of 10% of a calf’s bodyweight, ideally in the first two hours, followed by a second feed within six hours of birth.
“Colostrum is key to good protection from parasitic diseases including cryptosporidiosis, caused by cryptosporidium infection and one of the most common reasons for calf scour,” she says.
A key area which farmers often overlooked is cleanliness in the calving pen, but this is a potentially major source of pathogens.
“It might take seven days for a calf to show signs of disease therefore farmers often fail to make the connection with the calving pen,” says Ms Cavill.
To minimise exposure to bacteria, ensure this environment is clean and dry.
BECCA CAVILL
OsmoFit is easy and key to maintaining health, performance and growth.”
Dr. Laura Tennant
Young Animal Feed Technical Adviser Trouw Nutrition GB
For more details about OsmoFit contact Laura at trouwnutrition.co.uk/osmofit
Jamie Robertson’s advice on best practice and areas to target
1Remove organic matter before disinfecting Dirt absorbs disinfectant so if a sufficient amount is not removed the chemical will not be as effective since it will be diluted by the presence of organic matter.
Mr Robertson says: “If you leave organic matter around the drinking area for example you are massively reducing the effectiveness of chemicals designed to kill pathogens.”
He advises removing all visible, loose material, physically cleaning with hand tools where needed and when washing out.
He adds: “Using a detergent before the disinfectant will also loosen the biofilm as water alone will not do this.”
2Use the appropriate product for the job Mr Robertson says the disinfectant needs to be the right one for the bacterial and viral flora specific to your farm: “If you have crypto or salmonella use a product formulated for tackling these organisms.
“Poultry units are already way ahead of the dairy industry on this. They will only have a couple of disinfectants they use because they will know which ones they need rather than buying a product that is on offer at their local agricultural supply merchant.”
He advises mixing the disinfectant to the right dilution by using a measuring jug and using the product as instructed on the label. “If the advice is that it needs to be left for two hours before washing on then leave it for two hours.
“Instead of sloshing disinfectant around in buckets invest in a dispenser for cleaning pens, they only cost about £25 and they will make the job easier and the easier a job is the more likely it is to get done correctly.”
And before restocking, Mr Robertson advises allowing pens time to fully dry. “Use a hydrated lime or similar low cost material or a squeegee to aid that process.”
3Adopt strategies for dealing with hard to clean equipment “Some facilities are not designed with cleaning in mind – a case in point is a teat feeder with internal divisions,” says Mr Robertson.
“To clean these, have two containers which can be filled with a detergent solution and fully submerge the feeders in these once a week before disinfection.”
4Pens must have drainage systems Mr Robertson says three quarters of all pens he sees on farms do not have adequate drains. “So when the pens are cleaned there is nowhere for the water to drain, and there never will be until the floor is changed.
“Establish a curb in between group pens so if one needs to be cleaned the moisture and dirt does not end up getting sloshed into the adjoining ones.”
JAMIE ROBERTSON
“Steam clean and consider using a gas weeder to clean along the joints between the walls and the floors.”
8Feed little and often Too many producers fill a bucket with dry feed and it slowly becomes unclean says Mr Robertson. “The massive benefit of a little fresh feed every day is that the producer can observe the feed intake of every animal.
5Allow space for emptying pens for cleaning A lack of space to empty pens for cleaning is a major intrinsic weakness of too many calf systems says Mr Robertson.
“There will be an inevitable build-up of bugs in the environment when buildings are constantly stocked.”
6Facilities must be cleanable Mr Robertson says the weakest point in many calf facilities are the ‘thousands of tiny cracks’ that provide a resilient home for bugs even after cleaning.
“The joints between walls and the floor are also a source of re-infection.
7Deep clean annually A deep clean is recommended by Mr Robertson once a year or after an outbreak of disease that may carry over to the next batch of calves, such as cryptosporidium. 9 Do not under-estimate the need for a calf kitchen Mr Robertson says getting the facilities together to make what is an absolutely necessary job better by being slicker and more effective.
He adds: “It will pay for itself and more.”
10 Adopt protocols for cleaning milk machines and feed utensils He advises having clean brushes for cleaning utensils, a measuring jug, detergent and, if needed, disinfectant.
“Rinse with cold water before soaking in a warm detergent solution at 55degC.
Rinse after brushing and wash with a disinfectant at 50degC. Rinse and dry.”
He also says to discard buckets and teats that have too many small fissures and cracks.
A dedicated kitchen area in a calf shed will more than pay for itself, says Jamie Robertson.
Efficient heifer rearing and elements of longevity have their foundations in early life nutrition, making this a crucial management stage, says Dr Leonel Leal, team leader calf and heifer research at Trouw
Nutrition.
In 2014, Trouw Nutrition launched
LifeStart, a science-based programme which focuses on the critical first few months of a dairy calf’s life.
He says that in pre-weaned calves, early life nutrition is a major stimulus and the initial stage of the LifeStart programme was to understand the effects of elevated feeding of milk replacer on calf development, feeding a typical 600g/day of milk replacer compared to an elevated rate of 1.3kg/day of milk replacer.
“This showed calves fed more milk replacer had higher growth rates.
At 54 days old, calves fed more milk replacer weighed 83kg, gaining at double the rate of the traditionally fed calves, which weighed 61kg at the same age.”
As calves were meeting more of their appetite requirements from milk, intakes of starter feed were marginally reduced, but starter intakes were still adequate at weaning.
Water intakes were the same in both groups as milk is a feed, not a drink, and calves need water for hydration. Ensuring faster calf growth, exploiting better feed efficiency in pre-weaned animals and getting them off to a good start is a vital first step in heifer rearing.
Previous LifeStart research had shown that calves fed elevated levels of milk replacer had improved development of key organs including mammary tissue. So researchers wanted to see if these benefits were carried forward.
In the second stage of the trial, groups of calves fed on the two different levels of milk replacer were amalgamated and fed exactly the same diet with no differences in management.
They have been followed through into the milking herd to understand how improved pre-weaning nutrition influences productivity, longevity and resilience.
Calves which received more milk replacer retained the weight advantage they had shown at weaning. Heifers were inseminated based on weight, not age, and were served when they had reached 390kg, equivalent to 60% of mature bodyweight.
Dr Leal says: “Heifers which had been fed elevated levels of milk replacer were four days younger at first service, had a 10% higher conception rate and conceived 10 days sooner. They required fewer services per conception. These heifers were on target to enter the milking herd younger, helping save on total rearing costs. They continued to perform better when they entered the milking herd. This is the most important data as this is when we can start to see a return on the investment in youngstock rearing.”
Heifers which were fed more milk replacer before weaning produced more fat and protein corrected milk and had higher dry matter intakes. They also had better fertility performance with higher conception rates.
Survivability
In addition to being better producers, there was a significant effect on survivability through the lactations.
More of the heifers fed increased milk replacer survived in the herd longer. While 76% of these heifers completed lactation two, only 65% of traditionally fed heifers completed their second lactation.
The survival rate of the enhanced fed calves until their fourth calving was significantly improved. While less than 25% of traditionally fed heifers entered a fourth lactation, the figure for heifers fed elevated milk replacer was 40%.
Moving to elevated levels of milk replacer has the potential to reduce rearing costs.
The latest assessment of the cost of rearing a heifer is £1,891. Heifers must complete close to two lactations to cover rearing costs, meaning longevity is key to maximising return on heifer rearing. Dairy Farmer reports.
Calves fed more milk replacer stay in herd longer
Effect of milk replacer feed levels on performance
Lactation one Lactation two Normal milk Elevated milk Normal milk Elevated milk replacer replacer replacer replacer
Dry matter intake (kg) 19.0 19.7 23.0 23.3
Yield (kg) 29.1 29.1 33.3 34.7
Fat and protein 29.9 30.8 35.5 36.8 corrected milk yield (kg)
Conception rate to 40% 47% 13% 41% first service
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As scour is the largest cause of mortality in young calves, it is important that the problem is managed as effectively as possible. Katie Fallon looks at the role electrolytes could play in this.
Role of electrolytes in scour management
Scour accounts for 50% of all calf deaths and, while calves can recover, they may experience reduced growth, delayed calving and reduced lifetime production as a result, says Dr Graham Shepherd, of G. Shepherd Farm Animal Health.
Both infection and nutritional issues can cause calf scour, says Dr Shepherd, with diseases such as rotavirus and cryptosporidium being common causes.
However, changes to milk consumption in terms of quantity and quality can be a nutritional cause.
“When calves scour their gut lining is damaged, which results in less food being digested,” says Dr Shepherd.
Toxins
He explains it also causes toxins which drive water and salt loss from the calf and, as a result, directs them into the bowel causing a large amount of watery diarrhoea. This results in the calf becoming dehydrated.
Blood and tissue fluids also become too acidic for the calf to handle, causing acidosis. Dr Shepherd says: “Acidosis is a powerful depressant and is usually what will kill the calf.”
Because of this, he advises always using an electrolyte with an alkalinising agent.
The two main electrolytes for calves in the UK are either a sachet or a liquid, says Dr Shepherd.
He says: “Sachets containing an accurate amount of well mixed powder formulation are usually for mixing with water not milk.”
Water mixed formulations can be fed by a stomach tube to calves which will not drink but can stand and have a suck reflex.
Liquid electrolytes are formulated for mixing with milk or a milk replacer, says Dr Shepherd.
He says: “These can be used when the calf is drinking voluntarily, but should not be fed by a feeding tube.”
An advantage of liquid electrolytes is their simple feeding, says Dr Shepherd.
He says: “By adding them to the milk or feeding alongside milk, the calf can still benefit from the milk’s feed value, which is important as starvation starts to affect the gut adversely after two days.”
In terms of what is in a good electrolyte, Dr Shepherd says labels can be ‘complicated’ and the units ‘complex’ and, while you might think you need to be a chemist to work them out, most reputable formulations fit into the recommendations.
Water is vital and Dr Shepherd advises that in addition to electrolyte feeds, calves should always have access to water.
He says: “Calves are 75% water and need 10% of their body weight in water per day.”
Water
He says that diarrhoea can increase a calf’s water requirement between one and four litres per day.
Dr Shepherd says salt levels in electrolytes, including sodium, potassium and chloride levels are well researched.
“Products which are too low in sodium will not adequately restore hydration in the calf, but products which are too high may increase the risk of sodium poisoning, if access to water is not available.”
Dr Shepherd advises checking the label of liquid electrolytes when using them with milk powder, as wheybased powders can be high in salt.
“Dextrose and glycine are components of electrolytes which help to drive water and salt back into the cells and the body, however, too much dextrose can be detrimental.”
He also says dextrose is included within formulations to help rehydration, but it is not a food source, so calves benefit from milk as well. Whereas glycine is not required with milk products as the milk provides enough amino acid on its own.
Bicarbonate or similar alkalinising agents are used in electrolytes to neutralise excess acid in the calf’s blood and tissues, says Dr Shepherd. He says bicarbonate and citrate are good, but should not be fed with milk or within a four-hour window after being fed milk. He says that acetate is a better alkaliniser.
In terms of scour management, Dr Shepherd advises to always suspect scour if a calf looks dull or is slow to feed.
Dr Shepherd says: “Sometimes if the calf is just starting to scour, diarrhoea can be watery and is not seen on the bedding.”
He advises taking the calf’s rectal temperature to stimulate the flow of scour.
Method
JDr Graham Shepherd advises feeding electrolytes early, with the simplest method of feed being to add a liquid electrolyte into the milk for two to three days, with clean bedding and access to water.
He advises oral rehydration therapy as the standard nutritional support for scouring calves with a good suck reflex, which can stand and only show mild depression signs.
Suck reflex
If the calf is standing, but has a weak suck reflex, Dr Shepherd advises being ‘aggressive’ with water-based oral fluids, fed by a stomach tube.
“If the calf is unable to stand or has no suck reflex, you need veterinary advice, as it will need intravenous fluids.
“If scour is common or severe then you need to involve your vet to diagnose the cause. Reaching the true cause can often be less than straightforward and is often a mixture of issues.”
DR GRAHAM SHEPHERD
Rumen development has a huge impact on age of first calving, and ultimately on the financial performance of a farm business. Dairy Farmer reports.
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 overall 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 at 22-24 months is rumen development.”
She says that through her work she has seen the improvements in milk powders and starter feeds.
However, she adds that while these can have a big impact on how we rear our heifers, if rumen development is not optimised these products are not going to do their job.
She says: “When I am 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 [being developed] early enough to reach the age of first calving we are aiming for?”
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 is up to the farmer to develop the rumen to achieve the daily liveweight gain (DLWG) and the correct age of first calving.”
She says a developed rumen acts as a fermentation vat where microorganisms digest complex carbohydrates and high fibre feed-
Financial impact
JCalving 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 in past 24 months which would include additional heifers required and their rearing costs.”
Example of financial 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 £2048 per heifer
In addition, if calving at 26 months £5,400 per an extra three heifers are required 100 cows per 100 cows
Liz Newman says by far the biggest influence on achieving an age of first calving at 22-24 months is rumen development.
stuffs. The rumen wall is covered in finger like projections called papillae which greatly increase the surface area which nutrients can be absorbed through.
She adds: “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.”
Ms Newman says the earlier starter feed is introduced, the better with it being possible for calves to start developing a rumen as early as three weeks old if they have had access to quality starter feed and water.
She says: “Regardless of when a calf begins to eat starter feed, it takes two to three 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.”
According to Ms Newman, whatever the weaning age, choice
Weaning protocol
JCalves should be consuming a minimum of 2kg of starter before they are weaned, recommends Ms Newman and she adds that rumen development does not end at weaning.
She says: “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.”
of milk powder and environment, it is not possible to achieve the DLWG needed at the point of breeding if the rumen is not properly developed.
She says: “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 age of rst calving, which has a nancial impact.”
She says calves will grow well on a high milk only diet, and they will also grow well on a balanced milk and starter diet, but only one will develop the desired rumen (see rumen pictures , above right).
PICTURE : Penn State Extension
Picture A is the rumen of a milk-only fed calf and B is a rumen which has been fed both milk and starter.
How to encourage rumen development
JMs Newman says starter feed and water intakes are essential for rumen development. Top tips to encourage starter intakes: rOffer small amounts of starter feed fresh everyday. rFeed should be in troughs or buckets they can reach easily. rLighter coloured buckets with wider openings are best. rOffer a quality feed low in dust. rFeed should be formulated with palatable ingredients, be correct balanced in terms of protein and energy. rOverfeeding milk/milk replacer can reduce starter feed intakes. rEnsure you have a controlled weaning programme. rPaired or group housed calves generally have higher starter feed intakes. rCalves in general poor health have lower feed intakes, so the calves environment and management should promote all round good health. r Monitor starter feed intakes, if a two-week-old calf is not 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.”
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