RWN News Digest

Rumen Buffers, Acidosis, 
Cow Health and Feed Efficiency

Cow Health - Many of the health problems with modern dairy cows are primarily triggered by, associated with or are directly caused by acidosis. These cow health issues include lameness, mastitis, high somatic cell counts (SCC), left side displaced abomasum (LDA), impaired liver function, loss of body condition,  negative energy balance, infertility, milk yield below potential and high culling rates. 

Most cows at some point in their lactation suffer from acidosis

First and foremost acidosis can only be controlled by well designed diets with emphasis on efficient rumen function. Good quality high D-Value forage is essential. Over feeding of fast fermentable starch and excessive concentrate to forage ratios should be avoided. Equally all diets must contain sufficient floaty, scratchy, mature long fibre in order to form a rumen mat and to stimulate cudding and rumen mixing. Providing straw as the long fibre is only really effective where the straw is cleanly chopped to between 1" and 2"  long to avoid sorting and rejection by the cow. 

Rapid diet changes involving sudden increases in concentrates must also be avoided especially post calving. This is all fine in theory, but in practice cows are usually group fed with a single total mixed ration (TMR), and cows do usually have to be moved directly from dry cow diets to high energy peak lactation diets involving sudden diet changes at a critical time often with long lasting consequences. 

There are also limitations with forages, wet acid silages, high starch forage maize, and grazed grass. Yes, cows do suffer from acidosis at grass. Ever considered why cows scour at turnout? Rumen pH on grazed grass can be as low as 5.4 pH.

Good diet formulation is essential. But even if we do everything right it isn't enough! 
There are considerable benefits to be gained from feeding an effective Live Yeast Supplement together with a Rumen Buffer

Feeding for Rumen Efficiency - More than anything else performance of high yielding dairy cows depends on the rumen functioning efficiently. Feeding systems that maximise microbial growth and production will maintain high milk yields, safeguard herd health and maximise profitability. Rumen microbes are essential to digest the forage, which makes up a large part of the cows diet. These rumen microbes produce volatile fatty acids and microbial protein and in doing so can provide up to 75% of the energy and up to 60% of the amino acids required by the high yielding cow. For the rumen to work efficiently and effectively the rumen microbes need a steady supply of fermentable energy and degradable protein and most importantly they need a stable rumen pH between 6.0 and 7.0 pH. Within this pH range the rumen is at its most efficient. 

The rumen microbes ferment starches and sugars to form organic acids, propionate and other  volatile fatty acids (VFA). This is not a problem if the rumen stays above 6.0 pH. If on the other hand these acids build up in the rumen then the pH of the rumen drops. The fall in pH has two effects. Firstly, the rumen stops moving, becoming atonic. This depresses appetite and production. Secondly, the change in acidity changes the rumen flora, with lactic acid-producing bacteria taking over. They produce more acid, making the acidosis worse. The increased acid is then absorbed through the rumen wall, causing metabolic acidosis. 

When acidosis occurs the rumen microbes use additional energy to get rid of excess hydrogen ions. This in turn results in fewer less active microbes being available to ferment the cows diet. 

High yielding cows often experience a few hours of high rumen acidity during the day. If this situation is corrected, milk production can be increased. 

Sub Acute Rumen Acidosis (SARA) - is a very common and much under rated metabolic disorder which has a significant effect on milk production and herd health. SARA occurs when the pH of the cow’s rumen drops below 5.8. The cow’s dry matter intake declines, fibre digestibility and rumen microbial protein production is reduced, butterfat % declines, and milk production suffers. 

All too often farmers and nutritionists assume that there is no acidosis problem unless intakes severely decline, butterfat (%) declines, and laminitis is apparent.  This is not the case. 

Diagnosing sub clinical acidosis in the field is a challenge. The following signs can be useful in identifying SARA, but can vary and may be caused by other factors:

• Cow experiencing laminitis and foot problems, especially first lactation and fresh cows

• Moving dry cows to a high concentrate TMR after calving without a transition diet

• Increasing concentrate intake after calving faster than 0.75kg per day

• High concentrate : forage ratio 

• Cows fed more than 4.5kg of concentrate per feed

• Overall concentrate feed rates higher than 0.38kg/litre

• Low levels of scratchy structural forage fibre greater than 1" long in the diet

• Less than half of the cows chewing their cuds

• Average cudding rate less than 60 chews per cud

• Starch levels greater than 15% or combined sugar and starch greater than 23% in the diet

• Dung appears loose, foamy and bubbly and inconsistent across the herd

• Poor rumen fill and with variable feed intakes

• Individual cows off feed for no apparent reason

• Negative energy balance, excessive weight loss and loss of body condition score

• Dull, rough, stary damp coats

• Tail swishing and dirty backs

• Individual cows with low butterfat % and high milk protein %

• Cows selectively consume coarse long forage (straw or hay)

• Hyper ventilation or rapid breathing

• Excessive intakes of free access salt or minerals or cows lick urine or soil

• Increased incidence of left side displaced abomasums, ketosis, sick cows, general ill health 

• High cell counts, mastitis, reduced immune response, poor reproductive performance and infertility

• Lameness and laminitis - haemorrhages or red discolouration in the hoof

• Hoof surfaces have horizontal ridges or lines

Efficient Rumen Function = Healthy Cows = High Feed Efficiency = High Yields = Profitability

Transition Management and Acidosis - 
Early lactation is where acidosis is most common, most severe and most damaging to cow health, and this is where acidosis can have the most profound effect on future fertility and milk output. 30 years ago when most cows were fed parlour cake and silage, few farmers would ever consider feeding a new calved cow more than 10kgs of concentrates the day after calving. Now with modern total mixed rations (TMR) it is common practice on many farms to move cows from a low energy high forage diet to the high yield group TMR with little thought to the dire consequences for the cow. 

The transition cow undergoes massive physiological changes to the rumen, intestines and liver during the 3 - 6 weeks pre and post calving. The diet that we feed to the cow following digestion all has to be absorbed through the rumen and intestinal wall and processed by the liver. The rumen wall is covered in papillae which provide the massive surface area necessary to absorb sufficient nutrients to meet the requirements of the high yielding cow. These papillae regress on high forage diets during the dry period. Sudden introduction of excess starchy concentrates post calving usually results in acidosis as a result of excess acid production and can slough off the rumen papillae reducing the surface area for absorption of nutrients. The result is reduced dry matter intake, often resulting in more severe acidosis, metabolic disorders, ketosis, loss of body condition, infertility, reduced yields, lameness, mastitis high cell counts. 

Acidosis is a disaster for the fresh calved cow

Prevention of Acidosis (SARA) - Transition diets should be designed to introduce concentrates at least 3 - 4 weeks before calving and where possible to increase concentrates by no more than 0.75kg per day after calving.  Where possible a 3 week post calving group is very beneficial. Avoid high concentrate to forage ratios and avoid feeding excessive levels of  starch and sugars. Always feed sufficient long scratchy fibre in the diet. Where cows in early lactation are under performing with excessive weight loss as a result of SARA feeding more concentrates will make matters worse.

In all herds showing any acidosis there needs to be a full assessment of the diet 
by an experienced nutritionist

Most cows at some point in early lactation suffer from a degree of sub-acute rumen acidosis. The effects on the lactation performance and the health and fertility of the cow are such that we now recommend feeding Biocell yeast from 3-4 weeks pre-calving through lactation and feeding a rumen buffer from calving onwards. Rumen buffers and live yeast supplements have completely different modes of action but are complimentary. 

Yeast metabolises lactate, lifts rumen pH and stimulates growth and activity of rumen microbes increasing rumen fermentation rates and improving feed efficiency. Rumen buffers directly neutralize acids in the rumen and buffer to provide a stable pH for rumen microbes to thrive. 

The combined cost of using a rumen buffer in addition to yeast as standard in dairy diets is less that of 0.5 litre of milk but the benefits are massive. Buffers are beneficial even at grass where the rumen can be as low as 5.4 pH. With this in mind there is good reason to include rumen buffers in all dairy diets. 

We now recommend using a Rumen Buffer as well as Biocell Yeast in all our Dairy Diets

RUMEN BUFFERS

Traditionally rumen buffers have been used in the main where a specific acidosis problem has been identified, often as a short term measure. It has now become widely recognized that the inclusion of rumen buffers as standard in TMR's particularly in early lactation and high yielding dairy diets have a valuable and cost effective role to play. 

Chopped Straw - Whilst straw is not a rumen buffer it has been widely used to provide long scratch fibre and encourage cows to cud and to produce more saliva and saliva contains bicarbonate which acts as a buffer. Sufficient long scratch fibre should always be included in the diet in order to maintain an adequate rumen mat. However straw alone will not cope with sudden increases in concentrates after calving, with excessively high concentrate feed rates, or with very high starch diets. 

With very high D-value forages which have insufficient structural fibre to form a rumen mat and to encourage cudding , chopped straw fed at up to 1kg is very beneficial. Straw is only really effective if is cleanly chopped to between 2cm and 6cm to prevent sorting. Shredded straw is much less effective than cleanly chopped straw. Weathered straw stored outside should be avoided as it can be a source of mycotoxins. 

Where forages are relatively mature with low to average digestibility and with adequate chop length, adding straw simply makes acidosis worse. The reason for this is that low digestibility forages take longer to digest and are lower in energy value, consequently the rumen remains full for longer, dry matter intakes are lower and energy intakes are reduced. The cow under performs and loses body condition and is invariably then fed higher levels of starchier concentrates in order to maintain milk yields.  

The resulting acidosis is due to the high concentrate to forage ratio rather than to a lack of structural fibre. Adding more indigestible straw simply further reduces intakes making the acidosis  even worse.

In these situations, replacing the straw with an effective rumen buffer increases the digestibility of the TMR, reverses the acidosis and lifts intakes allowing the high concentrate level to be eased back. 100 - 150 gms of an effective rumen buffer costs less than 1kg chopped straw, does not reduce the energy density of the diet and generally proves much more effective. 

BENEFITS OF OSTREA OVER OTHER RUMEN BUFFERS

Limestone Flour - Mistakenly ground limestone flour has often been recommended as a rumen buffer fed at 100gms - 200gms per cow on the grounds of price. Whilst limestone flour is an excellent source of calcium, well absorbed at the very low pH seen in the true stomach, it is in fact largely insoluble above about 5.5 pH. It is therefore totally unsuitable as a rumen buffer and should not be used as such. Inappropriate use of ground limestone flour can also interfere with a range of other nutrients including phosphorous, zinc, copper, iodine, selenium and manganese resulting in trace element deficiency which has on occasions resulted in problems with lameness, high somatic cell counts and mastitis. When using any buffer, diets need to be checked by a competent nutritionist who can advise on mineral, trace element interactions.

Sodium Bicarbonate - Traditionally Sodium bicarbonate (NaHCO₃) has been used to buffer dairy diets. However results have been mixed. It is only effective with very low rumen pH or for neutralising low pH silages. Also sodium bicarbonate only works for a limited time and is unable to provide any long term stabilising effect. 

Sodium bicarbonate is highly soluble and as with some other rumen buffers can result in very rapid rumen pH rises which can adversely affect the rumen environment. To be effective sodium bicarbonate requires a relatively high feed rate of up to 200gms - 250gms which can result in a higher cost per cow than other rumen buffers. 

The high sodium level in sodium bicarbonate can however, restrict its use in many diets. since feeding 250gms of sodium bicarbonate is equivalent to feeding 170gms of salt. 

Acid Buf -  Acid Buf is a natural product, derived from calcified seaweed with a very fine particle size.  Acid Buf provides calcium, magnesium and a range of important trace minerals. It is normally fed at 100gms - 125gms / cow and has proven effective in reducing the acid load of wet, low pH silages as well as in raising rumen pH. Some care is needed since Acid Buf has the potential to give very rapid and large pH rises beyond the optimum range for rumen pH.

Proprietary Rumen Buffers - There are a number of proprietary rumen buffers available in the UK, produced by various mineral manufacturers. These usually contain a combination of buffer and neutralizing ingredients such as sodium bicarbonate, sodium carbonate, ground limestone, magnesium oxide, calcified seaweed  and sometimes a token amount of yeast. These are designed to have a spread of ingredients which may buffer over a long time period however since they carry additional manufacturing costs are generally more costly than individual straight buffers.

Ostrea Oyster Shell Flour - Ostrea Crushed Oyster Shell flour is a source of chalk derived from natural shell banks in the North Sea. The shells are dried and then ground to a powder. Sea-shell chalk is a rich source of calcium carbonate (96.1 %). The dry matter percentage is 99.5 %. 

Ostrea Oyster Shell Flour is held in high regard by dairy farmers in Holland, Belgium and France who have used the product as a rumen buffer for many years.

It is often claimed that Sodium Bicarbonate (NaHCO₃) is better than Calcium Carbonate (CaCO₃) for neutralising rumen acidosis. We consider this claim to be incorrect!

So how does Ostrea actually work in the rumen of the cow?  The main cause of acidosis is due to volatile fatty acids (VFA’s) in the rumen. Research shows that 1 mol of calcium carbonate efficiently binds with 2 mols of VFA’s. This is twice the capacity of sodium bicarbonate which only binds to 1 mol of VFA. Because the molecular weight of calcium carbonate is higher than that of sodium bicarbonate the amount of calcium carbonate required to obtain the neutralising effect in the rumen is less. Ostrea is capable of neutralising over 150% more acid than sodium bicarbonate. 

Unlike sodium bicarbonate, sodium carbonate and many proprietary rumen buffers Ostrea Oyster Shell Flour does not supply excess sodium, which at high levels can lead to excessive water intakes, softened hooves and damage to the cows kidneys. 

Neutralising acids in the rumen is not the only benefit when feeding Ostrea. The calcium in Ostrea is highly available and fulfils the calcium requirements of the animal. 

The calcium is absorbed by the animal over a period of time which contributes to overall animal health. In addition Ostrea contains a wide range of other highly available mineral and trace nutrients of benefit to the animal.

Digestion in the rumen is most efficient within a stable pH range between 6.0 and 7.0

We consider Ostrea to have clear advantages over other rumen buffers available to farmers in the UK. Many commercially available rumen buffers based on sodium bicarbonate, sodium carbonate or calcified seaweed, are capable of buffering the rumen pH to a level well above the optimum range for efficient fermentation. These buffers can also result in very rapid pH rises within the rumen fluid resulting in an alkaline shock which can adversely affect the rumen microbial population and rumen fermentation rates. Excessively high rumen pH value can reduce cudding and saliva production, and disrupt the whole rumen environment. Effective rumen function can rapidly decline to the detriment of production and health of the animals. 

Ostrea Oyster Shell Flour on the other hand has a natural ability to minimise wide fluctuations in rumen pH and to maintain the rumen within the optimum range. In addition Ostrea has the important advantage of slow release, avoiding rapid fluctuations in rumen pH and resulting in a much more stable rumen pH over time. 

In practice Ostrea cannot over buffer the cows rumen. If the rumen pH is OK,  Ostrea will not lift the pH further but will instead dissolve at the very low pH in the abomasum allowing the minerals and trace elements in Ostrea to be absorbed.

In our experience feeding Ostrea as standard in dairy diets has resulted in improvements in both herd health and in feed efficiency far in excess of the 3.5 - 5.0 pence per cow per day cost of the product. 

Feeding Ostrea to cows at grass increases rumen efficiency helping to reduce lameness, maintain body condition, improve fertility and lift milk yields.

Benefits of Feeding Ostrea Oyster Shell Flour -

Specific qualities of Ostrea Oyster Shell Flour

• Ostrea is a natural source of essential mineral and trace nutrients for animal husbandry

• Stabilises the rumen within the optimum pH range of between 6.0 and 7.0 pH

• Reduced risk of rumen acidosis results in improved performance and feed efficiency

• Improves the general health of high yielding cows

• Healthier hoofs and reduced lameness

• Rich in calcium with good absorption

• Improved Calcium : Phosphorous balance in feeding-stuffs

Ostrea Oyster Shell Flour Dosage

• Lactating cows (Fully Housed)    - 100g per day

• Lactating cows (Grazing)           -   80g per day

• Calves and Youngstock              -   50g per day

• Beef Cattle                              -   50g per day

Contact Richard Webster for further information on using rumen buffers, feed efficiency, milk output, health and fertility.

Full nutritional support package free of charge to customers along with the most extensive range of high quality feed inputs available

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