Impact On Productivity Of Feeding Pre Weaned Calves Biology Essay

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The dairy farmer has a range of options to feed pre-weaned heifer replacement calves. Beef-cross calves and dairy bull calves are typically sold at 10-40 days of age at the local livestock market. These animals also need feeding in a cost-effective manner, both to save feed costs and to produce a healthy, saleable young animal.

Replacement rearing costs are a significant cost of a diary farm, and feed costs are a significant proportion of the rearing costs. Also, other factors such as management time, achieving a good growth rate for target weight gains required for entry into the milking herd at 24 months (this aspect is particularly important for block calving) and the additional management and vetinary/medicine costs incurred by ill health are important factors. Further, once the animal is in the dairy herd she needs to be healthy and live a long life to be profitable.

The natural feed for pre-weaned calves is their mother's milk but calves are typically separated from their dams 1-4 days after birth. Weaning occurs early (typically 6-8 weeks) because liquid feeds tend to be more expensive than solid feeds. So, there is a period of 38-55 days when a calf requires liquid feed. It would be possible to use tank milk but this is relatively expensive and 'loss of production' would occur since a proportion of the yield would need to be used to feed the calves. Commonly, dairy farms use powdered milk or dump (antibiotic) milk which are cheaper. Another option is to use a 'suckler cow', which is lactating but whose milk is unsuitable for sale. This may be due to her being on antibiotics or another drug with a milk withdrawal period; or other reasons.

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Any situation where milk is pooled, or a calf receives fresh (unpasteurised) milk from a cow other than her dam, carries a risk of disease spread via the milk. The main concern is Johne's disease.

Also there is a concern that antibiotic milk leads to a build up of antibiotic resistance in the calf, which might affect her treatment and prognosis during rearing or later on in her productive lifetime.

The different options of feeding pre-weaned calves carry widely different management requirements. For example, once-a-day feeding is popular and if large numbers of calves are reared together, automated/computerised feeding offers time savings.

Common aspects - quantity of feed

In nature, milk is available to calves (almost) ad-lib - from their dams. In modern farming, in the first few days of life, this is the case, so long as problems such as mismothering or weak calf syndrome (Dewell et al., 2010) do not occur. This is a critical phase due to the requirement of colostrum intake, so if the calf does not intake enough, it is necessary to intervene.

In a modern dairy farming system, calves and their dams are separated between 1-4 days after calving. From this time to weaning, the quantity of feed intake is a management factor.

The natural option is to try to emulate the dam by offering milk (or a substitute) ad-lib. Ad-lib feeding has been shown to increase liveweight gain no matter if the calf is consuming by suckling a cow (Fröberg, 2008), drinking milk from a nipple (Jasper and Weary, 2002) or drinking milk replacer (from a nipple on an automated feeder) (Borderas, 2009). Additionally, there are behavioural benefits such as a reduction in cross suckling (Fröberg, 2008). Fears of a reduction in solid feeds intake post-weaning and a subsequent growth check (Passillé et al., 2011; Hepola, 2003) are unproven:

"Ad libitum nipple feeding of milk to dairy calves can allow for increased milk intake and weight gain with no detrimental effects on intake of solid food after weaning."

(Jasper and Weary, 2002)

However this is expensive. So, restricted feeding is the norm, and is perceived as the most economically efficient system. Over recent years, a 'traditional' system has been established where calves are fed approximately 5 litres milk (substitute) per day (Dairyco, 2008).

Liquid feeds (pre-weaning) are traditionally relatively expensive. However, in some situations, ad-lib feeding is an option (or recommendation) for a variety of reasons:

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The calf may be left on the dam. This should be done for organic calf rearing:

"11.5.2

You should allow calves to wean naturally.

11.5.3

When natural weaning is not possible you should only wean calves when they are taking enough solid food to satisfy their full nutritional needs.

11.5.4

Your calves' diet should consist of:

• colostrum, preferably suckled within six hours of birth

• organic whole milk, suckled from the dam or nurse cow until weaning, and

• suckled milk once or twice a day, beyond 12 weeks."

(Soil Association, 2010)

High growth rate may be desired to fit the particular system (eg veal)

Excess milk is available at cheap/no cost (eg dump milk, a sick cow is available to foster calves onto).

Traditional suckler herds also effectively feed pre-weaned calves ad-lib, although the cow will typically yield milk in reasonable quantities (eg 10 litres per day, a suitable amount for a calf to consume) whereas a modern high genetic merit Holstein cow might yield up to 60 litres per day.

Common aspects - weaning age

In traditional systems, milk or milk powder is much more expensive per unit of nutritional benefit than solid feeds, so there is an economic incentive to wean calves as soon as possible. Weaning age should not be the criteria - it should be adequate rumen development, as determined by amount of starter (solid feed) consumed per day (Quigley, 1997). This typically equates to 6-8 weeks for Holstein dairy calves. However if feed cheaper than solids is available, extending the weaning age makes economic sense.

There is some variation in opinions of the ideal weaning age. In a study by Passillé et al. (2011) the later weaned calves did better on qualitative measures:

"Delaying the age at which calves are weaned off milk reduces the drop in energy intake and behavioral signs of hunger that result from weaning."

When performance measures (liveweight gain, heart girth, hip height, withers height, and health measures such as faecal score and respiratory score) were taken into account:

"Management abilities, calf health and labor determine the best method to use for raising young calves on individual operations. Many management combinations are possible for producers; however, weaning calves as early as 4 weeks and once daily feeding can be used to save time and money by way of reduced labor with no apparent negative effects on calves through 8 weeks of age."

(Kehoe et al., 2007)

Experiments have been done where weaning has been done as early as 3 weeks with no detrimental effect (Kehoe et al., 2007) and it was noted that feed costs and labour requirement was less, the earlier they are weaned.

Weaning is a critical time so it is important to address any problems at this time.

"Cross-sucking may be intensified during gradual weaning".

"Furthermore, there appear to be problems with cross-sucking around weaning, especially in calves fed large amounts of milk, and there is a lack of knowledge of the effect of different weaning methods on cross-sucking."

(Jensen, 2003)

Organic calf rearing imposes extra obligations at weaning, including her being at least 12 weeks of age. (Soil Association, 2010).

Common aspects - health risks/benefits

Johne's disease

Johne's disease is caused by an infection with the MAP (mycobacterium avium subspecies paratuberculosis) bacterium (XLVets, date unknown). It is a disease which shows few symptoms in early life but later on (typically 3-6 years of age), causes scouring and weight loss despite normal feed intakes. Later on its clinical signs are bottle-jaw, emaciation and death. It is essentially irreversible. Even before death, it has a production impact and the reduced longevity is typically half the breeding lifespan of an unaffected animal. So from a production point of view, it is an important disease.

It is spread from drinking contaminated colostrum/milk from the dam, ingesting dung which may be present on the teats; contaminated feed and contaminated environment. While older animals remain susceptible, calves within the first 2 months of life are most at-risk (DEFRA, 2004). In rare cases it can be spread from the cow to the unborn calf.

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It is wise to have a health plan in place for Johne's disease:

Know your health status. Isolate and test any animals showing clinical signs

If Johne's is in the herd, follow precautions such as culling affected animals, not retaining their offspring, hygiene during calving, and maintaining biosecurity measures to limit the spread (including not pooling colostrum or milk from affected or suspect animals)

If the herd is Johne's free, then the biosecurity measures should be approached from a slightly different angle, by monitoring and ensuring the herd remains disease-free. Measures such as maintaining a closed herd or buying known-status (disease free) animals in are vital. Pooling colostrum or feeding dump milk has no impact if the herd is disease free.

Antibiotics

Background

"The presence of drug or antibiotic residues in milk and meat is illegal."

(Jones, 1999)

There are several reasons why antibiotics are not allowed in milk. Firstly, there is a concern that antibacterial resistance will develop in humans, if antibiotics are consumed. Secondly, some people are highly allergic to beta-lactam antibiotics and would suffer a reaction to antibiotic milk (NaturalCheck, 2008). And thirdly, it is known to interfere with the production of dairy products such as cheese, butter and yogurt (Jones, 1999).

When a cow is treated with antibiotics, it is necessary to observe the withdrawal period which is detailed for each drug. This is determined after considerable research (RUMA, 2005).

A common misunderstanding is that organic milk is free of antibiotics, while non-organic milk is likely to be contaminated. This is untrue, but often used as an argument for organic.

Dump milk

The regulations give rise to milk being collected (separately from tank milk) which, apart from having a risk of higher than MRL (maximum residue limit) antibiotics is otherwise normal. Milk is dumped for other reasons too, for example other health concerns of the cow might increase the somatic cell count, bactoscan amounts or it may be visually defective. For a large herd (ie where variations over time are smoothed out due to large numbers of cows/calves) and depending on the amount of disease or antibiotic use, there is usually enough dump milk to adequately feed all the pre-weaned calves.

Antibiotic resistance

There is evidence that feeding calves antibiotic milk increases their resistance to antibiotics (Langford et al., 2003; Berge et al., 2005). In Langford et al.'s study, apart from the antibiotic resistance buildup, their performance (based on weight gain) was unaffected. Berge et al. (2009) disagreed, and concluded that weight gain is affected (albeit only slightly) by antibiotics, and also noted that their health (determined by cases of diarrhoea and fever) is poorer.

Benefits of antibiotics?

There is a school of thought that excess antibiotics (over and above a disease treatment level) has a beneficial therapeutic effect on calves, and it may be deliberately incorporated into milk powders (Alpharma, 2003). However Donovan et al. (2002) suggests that:

"antibiotics in milk replacers can be replaced with compounds such as fructooligosaccharides, probiotics, and allicin to obtain similar calf performance".

Composition of milk

Fat, Protein, Carbohydrate

Milk is an emulsion of water and fat, with other (non-fat) solids of mainly protein as casein and carbohydrate as lactose.

Typical composition is fat: 3.7%, protein 3.4%, carbohydrate 4.6%, ash 0.7% (Jensen, 1995). In the production of dairy products, fat is the most valuable component, followed by protein.

Fats

Milk fat is of complex composition. 98% are triacylglycerols (Varnam and Sutherland, 1994).

Protein

Over 80% of the protein in milk is casein, the remaining being whey proteins. There are 5 main classes of casein. Whey proteins are beta-lactoglobulins, alpha-lactalbumins, proteose-peptones and small quantities of blood-derived proteins, serum albumin, lactoferrin and immunoglobulins. Milk protein is of very high nutritional value and provide essential amino acids (Varnam and Sutherland, 1994; Jensen, 1995).

Carbohydrate

Lactose is the dominant carbohydrate in milk.

Other constituents

Ash consists of minerals including an important source of dietary calcium, and a large number of minor components including urea, approximately 50 enzymes including lysozyme, plasmin, lipoprotein lipase, catalase, lactoperoxidase and xanthine oxidase. These have important roles in oxidations of unsaturated fatty acids, taste, and antimicrobial action and also play a role in stability during storage. Pasteurisation inactivates most of these. Also present are vitamins A (as the precursor beta-caratine), B1, B2, B6, B12, C, D, E, panththenic acid, niacin, biotin and folic acid. Vitamin A and D are present in dietary significant amounts. The vitamin content of milk is strongly modified by losses during processing and storage (Varnam and Sutherland, 1994; Jensen, 1995).

Mention must also be made of contaminants which can enter milk, eg antibiotics, mycotoxins and radioactive material may be found when the cow is exposed or consumes these constituents.

How milk powder differs

Milk powder is not the same composition as milk (solids components). The production process would render it more expensive than bulk (tank) milk at its sellable price. If this occurred it would be very unmarketable. So it is manufactured to be cheaper, by substituting valuable components of milk with alternates.

Fat source

Since milk fat is a valuable constituent of milk, milk powders are made from by-products of the dairy food industry where the fat has been removed:

Skim milk by-product of milk when the fat is removed mechanically, from non-homogenised milk.

Buttermilk by-product of butter production (fat removed by churning)

Whey by-product of cheese production (fat removed by acidification then coagulation)

The fat in powdered milk is then made up with other, cheaper fats/oils such as animal oil (Thickett et al., 1988), vegetable oil or coconut oil (Webster, date unknown). Animal oils are now banned from inclusion in calf feed (Garnsworthy, 2005).

Protein source

Skim milk powder (or those based on buttermilk) are rich in milk protein (mainly casein), having approximately 35% protein. However due to the denaturation of casein during heat treatment (pasteurisation) they do not clot as much as raw milk's protein, the effect depending on the severity of heat treatment. Whey based powders contain far less milk protein (12-13%) (but higher in sugar) and need to be supplemented with protein from other sources. Examples include soluble wheat gluten (Garnsworthy, 2005) soya, fish, single-cell synthetic protein and high-protein wheys (Thickett et al., 1988).

The amount of casein is important because it is able to coagulate in the stomach of a calf, due to the action of chymosin, which is an enzyme secreted by the abomasum of the calf , making the liquid feed more able to be fully digested over time. This is important for products designed to be fed once-a-day.

Preparation for conventional or automated feeding

Many milk powder manufacturers produce a range of powders with versions designed/optimised for "instant mixing' or computerised/automated feeding, the difference being the latter is designed to be a free flowing powder. This is typically achieved by using a different process of adding fat (homogenised, then added to liquid skim before spray drying) and is slightly more expensive to do. Non-machine mix powders have their fat added by blending after drying, but this tends to lump in store.

Also powders can be made easier to mix by 'instantisation', which is a process of retaining an agglomerated form in fluidiser beds and coating with lecithin during manufacture (Thickett et al., 1988).

Shine Compumate, distributed by Richard Webster Nutrition Ltd, claims to be the only milk powder specifically formulated (as distinct from free flowing physical property) for computerised feeding, in an attempt to address some of the health issues:

"Shine Compumate contains anti bacterial agents such as Lactoperoxidase, Lactoferrin and organic acids to ensure disease levels are minimised especially around the teat and feed station. Compumate contains high levels of Vitamin C, E and organic selenium to increase calf immunity."

(Webster, undated)

Acidification

Acidified milk powders were introduced in 1978 and are designed for a cold ad-lib system. Mild organic acids are added to prolong the keeping time before cleaning out is necessary (management time saving). However the level of acidity is important. At too high a level, casein precipitation occurs. The level of acidity is generally mild enough not to affect taste to the calf and affect intake levels. For non-casein milk powders (whey based) the level of acidity may be higher although this can be less acceptable to the calf (Thickett et al., 1988).

Other additives (fortification)

There is a broad range of constituents which may be added to milk powder by the manufacturer:

Constituent added

Notes

Source

Flavouring

unspecified

Massey Feeds

Calcium

GP Feeds

Phosphorous

GP Feeds

Selenium

(GP Feeds, xx) (Webster, undated)

Lactoferrin

(Robblee, 2003) (Webster, undated)

Lactoperoxidase

(Webster, undated)

Vitamin C

(Webster, undated)

Vitamin E

(GP Feeds, xx) (Webster, undated)

Antibiotics:

(oxytetracycline and neomycin)

(Donovan et al. 2002)

Antibiotic

Aureomycin® (chlortetracycline).

(Alpharma, 2003)

Enteroguard

a blend of fructooligosaccharides, allicin, and gut-active microbes

Allicin is an organosulphur compound with questionable antibiotic and antifungal properties)

(Donovan et al. 2002)

(Amagase, 2001)

Deccox

An anticoccidal

(Massey Feeds) (Alpharma, 2003)

Rumensin

an ionophore:

a chemical compound capable of forming a complex with an ion and transporting it through a biological membrane

(Elanco, 2011)

(Collins English Dictionary, 2011)

.

Management issues

Feeding calves milk (either tank milk or dump milk) is best suited to feeding just after milking, to preserve the freshness of the milk. Also if properly coordinated, almost no reheating (which is often done by adding hot water) will be necessary, if its 'straight out of the cow'. With twice-a-day milking, the calves would therefore be fed twice a day.

Once-a-day feeding

Once-a-day feeding of calves offers significant time and labour savings (Kehoe et al., 2007) with no detrimental effect on growth rate or health. Many others (Ackerman et al. 1969) have looked at this over time and no detrimental effects have been found.

It is worth mentioning that the regulations require that calves are checked at least twice-a-day (The Welfare of Farmed Animals (England) Regulations 2000).

Automated feeding

Milk powder offers the opportunity to mix the powder and water on demand, to supply 'fresh' milk (powder) to calves at any time of the day. This could be set to offer ad-lib, or up to a maximum amount per day or maximum number of visits to the feeding machine after which visits are unrewarded. This has the potential to offer further time/labour savings. Hepola (2003) noted that automated fed calves needed less medication, but higher incidence of pneumonia and diahorroea. However this may be related to being housed in larger groups.

Grouping calves together

Many labour saving management strategies rely on grouping calves together into larger and larger groups, to realise the labour savings. Their potential cost savings also rely on being able to feed large numbers of animals, to spread the fixed costs.

Calves should be grouped in similar size/age ranges to minimise competition during feeding and other times which are likely to stress the younger/smaller animals. Also, the greater the number of animals in each group, the more susceptible they are to cross-infection of a wide range of diseases. So it is important when evaluating feeds to determine if it is the feed itself, or the way in which it is fed, which is a co-factor in the relative merit of that feed (Hepola, 2003).

Evaluation of available feeds

Milk

Cow's milk is the obvious choice for feeding calves, so it should be included in an evaluation. A calf (or any pre-weaned mammal) needs nothing more than her mother's milk. However, it is expensive compared to others, its price being the saleable price of the milk. This is currently (March 2011) 26.34p (Dairyco, 2011).

"In reality it makes no economic sense on most farms to feed whole milk to calves"

(Webster, undated)

Also, if a once-a-day regime is desired, milk is unsuitable because to optimise solids intake, the solid percentage of the liquid feed needs to be around 20% (Webster, undated). Milk powders can be mixed to 20-25% solids (ie 'double strength').

In some cases this high price can be justified, for example in organic milk production, the standards require that at least 51% of a calf's feed is milk:

"11.5.7 Revised

The milk you feed to your calves must be:

• at least 51% fresh, whole, organic milk (preferably maternal milk), for at least 12 weeks, and

• no more than 49% organic dried milk, skimmed milk powder or milk replacer which must be free from additives such as antibiotics, growth promoters or ingredients of animal origin (except milk derivatives)."

(Soil Association, 2010)

It makes sense that milk should be used as a baseline for other feeds, even if it is not ultimately selected on cost grounds.

Milk Powder

Fat

Animal fat is easily digestible for young calves, and was used for milk powders in the past. This is no longer available (as regulations now prohibit it) so milk powder manufacturers are obliged to use vegetable fat.

"The choice of vegetable fat greatly affects the growth of young preweaned calves."

(Huuskonen et al. 2005)

Research suggests that coconut oil is the best, rapeseed oil is good and cottonseed, corn, and soybean oils give poor performance. Once animals get older (eg veal calves) the source of oil is less important (Xu et al., 1999).

Protein

Manufacturers make bold claims about their particular blend of milk and non-milk proteins:

"Protimax® is rich in specific proteins to help protect calves from the main challenges of early life.

• Rotavirus

• Coronavirus

• Salmonella

• E. Coli

• Clostridium"

(NWF, date unknown)

Comparison between milk and non-milk proteins shows that (milk based) casein performs better, however not statistically significantly so (Yuangklang et al., 2004).

"Generally the higher the level of milk products in the replacer the better."

(Webster, date unknown)

The frequency of feeding is important. When fed once-a-day, the coagulation of milk in the calves stomach is important, and this is strongly related to the amount of casein protein. So, whey-based powders will be unsuitable where skim-based perform well.

Other constituents/fortification

Many of the additives are already present in milk, eg calcium, vitamins, etc. Without details of amounts of constituents in the milk used in manufacturing the powder; and the final product, it is not known whether it is merely monitored, assumed or added to the product, the product labels of each milk powder product would need to be interpreted carefully.

The actual benefits of many of these additives is difficult to establish because there is a lack of independent research - while information is available, many of the studies are sponsored by feed companies and are published to appear like scientific papers. Also it is not clear whether each compound added would show a benefit in isolation, or if it interacts with others. Additionally, a medicated additive may be effective only on calves under disease pressure. For example Deccox is available as an additive and marketed as helping with subclinical coccidiosis (Alpharma, 2003) But if calf management were kept at high standards the disease would be controlled anyway.

One of the few scientific studies shows lacroferrin is a benefit (Robblee et al, 2003).

Prices and variations

An evaluation of milk powders reveals that there is a wide variation in types and prices of milk powder. Price information is generally not published, but email correspondence with NWF Agriculture obtained these prices:

Product

Based on

Price

Price expressed as ppl, mixed to 12% DM content

Ultra Milk Yellow

Skim

£1860/t

22.32p

Ultra Milk Blue

High quality whey

£1395/t

16.74p

Ultra Milk Red

Whey

£1350/t

16.2p

Note that all milk powders cost less than saleable milk (average 26.34p).

Milk powders vary greatly in their composition when fat and protein are considered in detail. Also there are different products for machine or bucket feeding. So is it important to specify the milk powder requirement for a given scenario accurately, in any comparison.

In conclusion, the best milk powders are only marginally worse than real milk, and offer extra advantages (such as possible to feed once-a-day, storage, ease of use etc). Cheaper milk powders don't perform so well but are significantly cheaper.

Dump milk

Dump milk (a superset of antibiotic milk) is essentially, a £0 feed since it would otherwise be disposed of. For this reason, any evaluation should take into account that even if it performs less well compared to other feeds, so long as basic nutritional needs are met and other issues can be worked around, it is still worth using.

Consistency of supply

Three factors are important:

Number of cows whose milk is not saleable

The yield from these cows

The number of calves which need feeding

It is expected the first factor varies considerably from farm-to-farm depending on the 'healthiness' of the herd and the amount of use of antibiotics or other drugs which have a milk withdrawal period. Anecdotally, there is normally an excess of dump milk so over time, there is little likelihood of not enough dump milk being available to feed calves, even if there is an exceptional number needing fed. On the rare occasions when there is not enough milk, then tank milk could be used (which should be easier to manage than switching to milk powder) but this only occurs a handful of days per year.

In herds with good health, it is expected that calf feed needs might exceed dump milk availability more frequently - it could still be incorporated as a partial fulfilment of the feeding of preweaned calves though. Equally, if dump milk is available in surplus, then weaning age can be extended to save solid feed costs with no detrimental effects.

Risks - Johne's disease, other

Using dump milk (or tank milk) increases the risks of Johne's disease spreading uncontrolled, but only if one or more cows in the herd suffer from it. For this reason, it is essential that a health plan is in place to deal with it. If not, then it would be sensible not to feed dump (or tank) milk at all. Colostrum would need to be managed carefully too.

Using a sick cow as a suckler cow

A system is proposed where a cow which, for various reasons cannot join the main herd and be milked in the parlour, may be housed with pre-weaned calves which are expected to suckle from her. The calves may/may not be her own offspring, and there may be more than one calf per cow (it would also be possible to house more than one cow and a group of calves together). This simultaneously solves many management issues:

the feeding of the calf

the milk let-down of the cow (if she is left unmilked, she will suffer discomfort through milk back-pressure and dry off)

saves a trip to the parlour, eg if the cow is lame

saves milk being gathered and dumped, eg if antibiotics used

It is difficult to accurately determine milk intake, so research has measured other variables such as growth rate (Roth et al., 2009), visits to the cow, proportion of unrewarded suckling attempts (Jensen, 2003), etc. One study presents results including intake of suckled milk (colostrum) but does not mention how these results were obtained (Franklin et al., 2003).

There are a few problems with the system

There is no accurate way to know the intake of milk from cow to calf. So it could be possible that a calf is not receiving sufficient feed. This might be exacerbated with >1 calf or larger groups with >1 cow.

The system imposes that a calf is housed with a cow - so disease risks compared to calf housing (where it is exclusively calves housed) are present.

Evidence shows that feed intakes are, in fact, much greater (Wagenaar and Langhout, 2007); Franklin et al. 2003) so this is not a serious issue (regulations still require calves are checked twice a day, so this should pick up issues with non-suckling calves). One side effect of greater feed intake might be scouring, although it is not clear whether this is caused by greater feed intake directly, or is a consequence of the housing arrangements:

"This can be explained by the enormous milk amounts the calves consumed, which caused a high incidence of diarrhoea."

(Roth et al., 2009)

But large intakes of feed in itself might not cause scouring:

"No increased incidence of disease was found for high-fed calves (ad-lib and high volume milk groups)."

(Borderas et al., 2009)

There are more qualitative benefits such as more natural behaviour (Wagenaar and Langhout, 2007; Roth et al., 2009) including less cross suckling (Fröberg and Lidfors, 2007). However disadvantages include stress at weaning (Wagenaar, and Langhout, 2007). If the system has calves suckling from healthy cows (eg organic might do this, for standards compliance), then there is a loss of marketable milk. Many of the advantages and disadvantages of dump milk also apply to this system, eg risk of Johne's disease spreading and consistency of supply.

Variations

It is possible to combine robotic milking and (partial - part of the day) access to the cows by calves (Fröberg and Lidfors, 2009); or to combine regular parlour milking with partial access.

Experiment Design

Choice of feeds to evaluate

While it is noted that tank milk is the obvious choice of feed for preweaned calves, its high relative cost probably means that it would not be chosen. A suckler cow is an interesting management strategy, but difficulties in quantifying feed intake and other influencing factors such as housing, consistency of supply, etc mean it is impractical to measure and give a meaningful comparison. Milk powders vary greatly, so it is important to ensure its specification is suitable for the use.

Milk powder and dump milk will be evaluated.

Method and management

It is proposed that pairs of heifer calves on an all-year-round calving dairy farm are selected according to the following criteria:

Any chronically ill calves are excluded

Any resulting from difficult calvings are excluded

Underweight or overweight (<30kg or >50kg) calves are excluded.

In the first 4 days of life, the calves suckle colostrum from their dam then separated and fed bottle fed colostrum. The pairs of calves are then housed in the same shed but in separate pens. They are bottle fed, then trained to feed from a teat bucket (for ease of management).

Each calf is (restricted) fed either 2l twice daily dump milk, or 2l twice daily powder milk (a suitable specification and brand chosen for twice-a-day feeding from a bucket) prepared to the same DM content as dump milk. In addition to liquid feed, each calf will be offered fresh barley straw and starter solid feed. Weaning will occur at 6 weeks or once adequate intake of solid feed is ensured, whichever occurs later.

Measurements

Solid feed intake will be measured daily.

The following parameters will be measured at 4d (start of experiment), 7d, 14d, 21d, 28d, 35d, 42d, 49d and at weaning:

Live weight

Height at withers

Chest girth

Episodes of scouring, other illness or any necessary vetinary intervention will be recorded, alongside any treatments given and mortality.

Area of future study

Heifer

The potential outcome would be…..

Equipment

Materials/methods

Area for future study - effect of weaning age?

Number of calves - how to select, exclusion criteria (chronically ill, difficult calving, weight range)

Management - restricted feeding, group housed

Measurements - weight at 7d, 14d, 21d, 28d, etc etc

height/girth

episodes of scouring

treaetments needed (eg vet/med used)

Appendix A - ppl calculation of milk powders

Price per ton £1860

Solids content of mix 12%

Amount to add to 880g water to make 12% mix to 1000g 120g

(density of mix is assumed to be 1000g/litre)

£1860 per ton  1860/1000000 per gram

1860/1000000 x 120 per 120 grams powder

710 words at Thu 19/5/11

1496 words at ??????

2305 words at 26/5/11 2pm

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3389 words at 28/5/11 8pm

3612 words at 30/5/11 5:35pm

3899 words at 30/5/11 6:05pm

4432 words at 31/5/11 9pm

4613 words at 1/6/11 1:50pm

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