Rehydration: The Unsung Hero Of Calf Rearing

Reducing the incidence and consequences of dehydration in calves is vital to ensure optimum growth rates and calf performance

Early life nutrition

Calf dehydration, mainly as a result of diarrhoea, is a major drain on dairy farm performance and is the biggest single cause of calf losses, according to Dr Laura Tennant, Young Animal Feed Technical Advisor with Trouw Nutrition GB.  She says the benefits of reducing the impact of dehydration can be considerable as it has a range of consequences which affect profitability.



The effects of dehydration

“Firstly, dehydration affects animal welfare with more unfit and sick calves which is associated with emotional distress in the animal.  Secondly, dehydration increases including the direct costs of treatment and intervention, as well as the extra time spent looking after these calves.  Then there are the indirect costs of compromised development and reduced growth rates and the lost investment whenever a calf dies due to dehydration.

“Finally, there is the disruption to daily routines from intensive monitoring, changed feeding routines, cleaning additional pens and so on.  But by understanding how dehydration affects calves it is possible to take action to reduce the consequences.”

She explains calves are at greater risk of dehydration than older animals due to their body composition and increased metabolic rate.  They also lose fluids more easily than older animals because a higher proportion of body fluids are outside body cells which means they are less well protected and will be lost more easily and quickly.

“Dehydration disturbs many of the key pathways in the animal, reducing blood sugar, causing malnutrition and increasing the risk of hypothermia.  It can also affect the absorptive capacity of the intestines, leading to poorer use of feed, reduced growth rates and poor feed conversion.

“Also calves with diarrhoea are losing much more sodium in their faeces.  This is important as the bigger the loss of sodium, the harder it is to maintain an electrolyte balance and consequently the more challenging it is to reduce the extent and duration of dehydration.

“Our increased understanding of the issues means we can develop more effective ways to help farmers manage the problem on farm, in particular using hypotonic oral rehydration solutions.”

Goborne Hall Farm

Ensuring calves get off to a good start is a high priority for Mary Ankers, the third generation of the family to farm at Golborne Hall near Chester.  Mary runs the farm with her father Hugh where the principal enterprise is the 110 strong Goldbourne herd of pedigree Holsteins.

Mary originally studied Rural Estate and Land Management at Harper Adams and worked as a Land Agent with Strutt and Parker from 2010.  In 2014 she went part time and undertook a degree in Dairy Herd Management at Reaseheath College while working part time on the farm.  In 2016 she joined in partnership with her father and in 2017 went full time on the farm. 

The cows average 9700 litres, calving predominantly between August and November.  The herd is Johnes free and cows are currently vaccinated against rotavirus which is the most common cause of neonatal scours.  The cows are run and housed in one milking group and are TMR fed in the winter. 

The farm has recently invested in a Lely Juno feed pusher and a robot slurry cleaning system along with Auto ID for feeding in the parlour.  They are in the process of upgrading the fertility and rumination collars. 

Cows are mainly served to sexed black and white semen.  A small number of cows are served to Angus with calves sold to Buitelaar at 2-3 weeks old weighing 55kg.  Heifers are served to sexed Jersey bulls as Mary wants an easy calving.  These calves are sold privately at 2-3 weeks old.

“We are moving towards calving down at 24 months,” Mary explains.  “We had been closer to 28 months but have a batch of 30 on target to calve at two years now.  Getting calves growing well pre-weaning and avoiding any complications is vital to keeping them on track.

“We are trying to build up the sale of surplus heifers, Golborne Holsteins and the key is getting the rearing right if we are to get a good name for ourselves.”

Dry cows are fed a DCAB diet and calve in a pen close to the parlour to allow colostrum to be collected post calving.  Mary operates a just in time calving system, moving cows into the pen just prior to calving.

Calves will stay with the cow for 24 –48 hours before moving into individual hutches.  Calf jackets are used as soon as the temperature drops below 10C.  They are then moved into pens of evenly matched calves at around eight weeks old.

All colostrum is tested and calves each receive around four litres, or 10% of bodyweight within six hours of birth.  It will either be fed via a teat or by tube depending on the time available.  Mary’s preference is to give colostrum using a teat.

Calves are fed unpasteurised fresh milk for the first two weeks, with milk collected and fed immediately to eliminate the risk of bacterial contamination.  They then move onto an Energized Calf Milk replacer, mixed at a rate of 135g/litre with two feeds a day of four litres each.  At eight weeks old the feed rate is stepped down ahead of weaning. 

Solid feed is offered from day one and after weaning they are fed concentrates and haylage.  Calves are housed for the first summer, grazing in their second year.

Using OsmoFit

“If we see scours it is typically in days 8-14,” Mary continues.  “This is the time when the source of immunity switches over in the calve.  Earlier scours is apparently associated with poor quality colostrum which we avoid by colostrum testing.

“As soon as we see signs of dehydration we intervene because we want to get the calf right as soon as possible.  We have tried several rehydration products which were mixed with milk but have changed to Osmofit from Trouw Nutrition which is mixed with water.   We replace one feed of milk with Osmofit and the calves take it enthusiastically as it is very palatable.  We routinely give a dose of Metacam when we rehydrate them.”

Dr Tennant says an early indicator that calves are dehydrated is changes in drinking behaviour and drinking speed.  Pre-weaned calves are driven to consume milk so if they are not doing so, it is time to act quickly.

“Rehydration strategies based on oral rehydration solutions (ORS) aren’t new,” she acknowledges.  “They have been and remain an essential weapon in the battle against dehydration.

“It is important to understand the role of an ORS.  The key to effective rehydration is the delivery of a careful nutrient balance to form a hypotonic solution, combined with high palatability to support voluntary intakes.  Rehydration solutions do not prevent diarrhoea but can offer an important nutritional solution to support recovery from the consequences of diarrhoea.

“Many solutions include high amounts of glucose as they are fed at a time when milk has been removed and so were formulated to provide sick calves with an energy source.  At the same time they commonly have a high sodium concentration.  This combination can actually reduce the effectiveness of the product due to relative concentration compared to the blood, which is measured as osmolality.”

Blood and bodily fluids have an osmolality of around 300mOsm/kg.  Anything higher is called hypertonic and can have the effect of pulling more water from the body.  A liquid lower than 300mOsm/kg is called hypotonic and has the reverse effect, supporting absorption and movement of water from the gut into the body.

“Many oral rehydration solutions are hypertonic which can reduce absorption and can therefore be less effective in controlling dehydration.  Our research shows that the combination of a hypotonic rehydration supplement, fed alongside highly digestible milk maximises the recovery from dehydration. 

OsmoFit is an oral rehydration solution designed for use alongside continued feeding of milk or milk replacer.  A hypotonic solution containing lower levels of sodium and glucose than other rehydration solutions, it helps stabilise the water and electrolyte balance.  It can be used during periods of, and recovery from diarrhoea.

“By continuing to feed milk you are providing the energy the calf needs and in so doing helping to regenerate the gut wall.  The milk feeding also allows you to maximise the total fluids you can feed by feeding a hypotonic oral rehydration supplement between milk meals through a teated bucket or bottle.  It is still essential to ensure plenty of clean fresh water is available to all calves.

“Never be tempted to save time by mixing an ORS with milk as they are formulated to be mixed with water.  Mixing with milk increases the osmolality of the mixed solution resulting in less effective rehydration.  Replace a feed of milk with a ORS to address the consequences of dehydration and then return to feeding milk to provide the energy they need.  One feed with no milk will not harm the calf but will actually help them recover quicker.”

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