NEB, Immunity and the Domino Effect
There is a direct correlation between Negative Energy Balance (NEB) and Immunity, and individual imbalances, around calving. Imbalance in both energy and immune system are inevitable at calving; the degree of severity will determine the domino effect this has; being the cascade of metabolic and infectious diseases that can be precipitated from these two crucial functions of our calving cow.
As stated in earlier articles, my definition of transition extends from dry-off to pregnancy. From dry-off, the nutritional issues will determine our success in timely pregnancy. Dry-off BCS has been reducing over the last ten years as research correlates higher BCS with poor post-calving feed intakes, especially rate of increase. Hormonally driven milk increase, not being met by feed (energy) intake, and the gap widens in overconditioned dry cows in the first few weeks.
Negative energy balance and immune imbalance are intimately related, and our goal as manages is to minimise the severity and duration of both. Failure to meet energy post-calving leads to sub-optimal immunity and the dominos start falling. Immune function is an energy-hungry machine. If cows are quietly fighting sub-infection while dry, then energy becomes a scarce resource immediately at calving due a massive increase demanded by the mamary system, we’ll have a ‘health’ implosion. This scenario will only amplify the NEB crisis by reducing feed intake at the most critical time. It is well documented, sick cows, either clinical or sub-clinical, lose appetite.
To understand the magnitude of the increase in energy demand at the point of calving, researches have quantified this shift from 680 gm of glucose precalving to 1.8 kgs immediately post-calving. It almost trebles! The liver works overtime converting substrate from rumination to glucose, plus some help from body fat and protein. This is the tripping point: how much from rumination (feed intake), and how much comes from body reserves. As above, the lighter cow at calving will increase feed intake more rapidly than the heavier cow and hence reduce her reliance on conversion of body fat and protein to meet the mamary system’s demand as milk production escalates.
The immune system is already under pressure simply from the physical stress of calving. Any other physical stress factors will only multiply the demand on the immune system. Management can play a significant role here in preparitory minimisation of external stressors to our calving cow. Once energy supply becomes an issue, immunity will not cope with normal bacterial exposure at calving, let alone any preconditions, like mastitis. Retained membrane followed by metritis send the immune system into overload and inability to meet infection outbreaks. Again, all this only multiplies the energy issue by reducing feed intake. Here go the dominos!
We have two lines of health issues from here: infection due to compromised immune function, and metabolic disease due to excessive fat mobilisation, trying to meet the glucose deficiency, creating fatty liver syndrome and soon after, ketosis. Managing energy is the key.

There is a crisis where normal negative energy balance passes the point of no return. The mediators sent out by the immune system to fight infection also cause inflamation. Inflamation is good to a point. Inflamation is crucial in controlling intial bacterial invasion recruiting immune cells to the site of infection. However, imbalance in the immune system will cause excessive inflamation and incomplete killing of bacteria, pain and swelling for the cow, either external or internal.
Inflamation is also very counter to conception. The inflamation in the uterus from a clinical mastitis case will devistate conception or holding of early pregnancies due to physical and chemical changes in uterine mucus. Immune mediators travel via the blood system, so inflamation is systemic.
How do we manage it?
Dry-off in lower BCS than has been customary. Keeping cows milking well up to dry off will enable this. Cows dried off in summer/early autumn can be a problem due to low protein diet at that time of year. It is imperative the dry cow has no weight gain or loss while dry. Either will precipate the reduced feed intake post-claving. Controlling the dry cow diet is easy during late summer early autumn when pasture intake is not a problem. Good quality adlib silage will do the job nicely.
As discussed in a previous article, 30% to 40% clover must be our pasture goal to meet cows calcium need on top of supplementation in bale feed. Silage made from this pasture mix will also meet the dry cow’s calcium need with significant benefits to immunity, milk protein production and fertility. Controlling energy intake in dry cows once pasture is available requires more monitoring. Adlib hay rings and strip grazing calculating pasture energy intake by monitoring hay consumption and adjusting strip width, is as close as we can get in a grazing system.
The springer cow diet is, as above, plus 3 or 4 kgs of a good lead feed grain mix including anionic salts. Again, it is imperative we monitor/calculate energy intake. DCAD (Dietary Cation/Anion Difference) is critical to springer cows. This is easily done by checking urine pH several times each week. A pH of 5.5 to 6.5 with Jerseys at the lower end and holsteins toward the other end. Drenching cows at calving with propylene glycol is very successful in mitigating ketosis. We have several clients with computer rotary dairys who administer small doses of propylene glycol to fresh cows for 20 days via the computer.
Ketosis status is easily measured with a Milk Keto Test Strip. We encourage all cows be checked at day three for ketosis. Any cow with a reading above 100, treat with propylene glycol: 200 to 400 ml dependant on the severity of the reading. Recheck three days later and retreat as above.
If we’ve been successful with both dry cow and springer cow nutrition, including mineral supplementation, both trace and macro, we’ll avoid most of the problems, metabolic and infection. Our cow is now capable of reaching her genetic potential for milk production, and, contrary to popular belief, most likely to become pregnant in a timely manner. The highest producing cows in the USA (15,000 lts in 305 days), have the highest MP%’s, and the highest fertility.

Digestive Tract Development in Newborn Calves

Most newborn calves are separated from their mother soon after birth on modern dairy farms. In the first few weeks of life they then consume less milk solids daily than if they were nursed by their mothers. We then expect rapid growth and development of the GI tract to accommodate digestion of solids feeds and early weaning. Natural weaning takes up to ten months. We expect our calf to achieve this in two months.

Enormous research has gone into calf rearing systems to minimise cost and labour rather than focusing on development of the GI tract to digest solid feeds. Right or wrong, our new born calf is certainly “put to the test” during its first few weeks of life. Despite history telling us through ever increasing productivity of our cows we’re doing a better job, however, USDA data highlights mortality rate is still around 10% and morbidity (depressed) near 50%.

There are two challenges a newborn must overcome: 1) they must overcome attacks on their immune systems, 2) transition from a monogastric to a ruminant. Weaning at two months is determined by surviving a pathogen attack in the first few weeks. Digestive disease is number one threat. Gut ailments or infections either end in mortality or expensive antibiotic treatment costs and retard development. Calves are born with little immunity and we have twelve hours to administer colostrum for it to be effective to passive immune transfer.

Even the switch to whole milk or milk replacer immediately after administration of colostrum, robs our calf of hormones, prebiotics and immune stimulants that may aid in development of the GI tract, and are found in fresh cow’s milk for up to a week after calving. There is a strong argument for collecting fresh cow milk for a week post-calving for feeding calves. It is also higher in fats and protein than milk past the first week. If you are using milk replacers, ensure they contain milk fats and proteins avoiding products containing fats and proteins of vegetable origin; they are poorly digested.

A calf should be drinking milk with 12% to 13% solids and at a minimum rate of 10% of their body weight. Calves fed up to 20% of their body weight have been shown to have higher lifetime milk production, but requires multiple daily feedings to avoid gut disease/infection (refer last month’s ‘Rumen Drinking’ article). While being fed as a monogastric on milk, the rumen is rapidly developing. At birth the calf rumen is only 25% of the forestomach. It must reach 70% to enable sound growth on solid feeds. Coarse calf grain mix is most effective for developing the rumen, enabling transformation of our calf’s diet from calories and energy from milk to Volatile Fatty Acids (VFA) from ruminal fermentation. Allowing 4 or 5 kgs of grain consumption post-weaning will accommodate the calf’s need for VFA’s for sustained growth, health and further development of the rumen to allow for digestion of forage which is very limited before six months of age. They will not get acidosis.

Newborn calves that survive pathogenic challenges will naturally develop a functioning rumen and should double their birth weight in sixty days. There is as much art in this as science, as any successful calf rearing person knows.

CALF SCOURS & Misconceptions

Misconception #1 Nutritional scours is a common problem in calves

A generation or two ago, nutritional scours was an issue, but today’s high quality/low cell count milk and calf powdered milks no longer carry scour causing organisms common in the past. Nutritional scours were diagnosed on the basis calves passing high amounts of manure. A calf consuming 0.8 kgs (6 lts x 13% solids) of milk solids daily will pass significant amounts of manure. Nutritional scours can occur through stress. Milk changes, environmental, transport, vaccination, weather, dehorning etc. However, these stress induced scours usually pass in a couple of days.

Misconception #2 Liquid manure is scours

As above, high milk intakes common today will produce liquid manure. Calves that are healthy, active and showing no signs of dehydration are unlikely to have scours.

Misconception #3 Electrolytes don’t work

There are electrolytes on the market that are very light-on in minerals and glucose. Perhaps veterinary advice is warranted here. Quality electrolytes are very effective in rehydration and mineral support when used correctly. They must be fed in between milk feedings as the water content is as important as the minerals.

Misconception #4 Type of scour can be identified by colour

Rotavirus, coronavirus and even increased milk can produce a white scour. Several bacterial strains can produce the same colour scour. Fecal culture is the only way to identify the type of scour.

Misconception #5 Scour type can be identified by calf age

It is true some diseases can occur based on days from birth (eg salmonella, e. coli etc). However, if the calf has a true scour, and not just high volume manure from a high plain of nutrition, then that can happen at any age.

Misconception #6 Reduce feed intake for sick calves

Many years ago the rule was ‘No milk while using electrolyte’. Most calves still died. Why? Starvation! Their energy requirement increases to support an energy-hungry immune system under challenge. Possibly, what had been said, was not to feed milk and electrolytes together.

Environmental hygiene goes without saying. There are a number of products on the market for disinfecting calf sheds. However, the most effective product we have witnessed is Vibrex. (Available from Roy Watson 0428 526 581 )

Ensuring calf nutrition is optimal, that is, timely administration of quality colostrum, that they are receiving adequate milk solids daily (fresh milk can vary – it pays to check – see Feb 20th article on refractometers), add to this CALFMAX containing essential minerals, vitamins, Bovatec, MOS, glucans and galactosamine, and disease and scours can largely be avoided.

Limestone and Salt

Perhaps the two most abundant compounds on the face of the earth, yet our cows are deficient in both, with significant implications to health, fertility and milk production. Why, perhaps due to their commonness, and we tend to take little notice of things that are very common.

Salt is an essential compound in a cow’s diet for a number of metabolic functions, but also for buffering capacity of saliva in the rumination process. Apart from these important functions, salt will make cows drink water, and there is a direct correlation between water intake and dry matter intake; which naturally drives milk production. Salt should be in the dairy grain mix, but also offered free choice as the cows’ needs can vary daily.

The subject I really want to address is calcium in our cow’s diet. Limestone dressing on pastures is another subject that requires urgent attention. No, or low, calcium in soils will seriously retard plant growth and mineral content of plants. Calcium is the transport system of other minerals in both our soil and our cows’ rumens.

Gary Oetzel, DVM, professor of dairy science at the University of Wisconsin, during a seminar stated: “You ought to respect hypocalcemia, you ought to be afraid of it, and you ought to do everything you can to minimise it”. Hypocalcemia is low blood calcium. Milk Fever in clinical form, but we’ve made massive inroads on milk fever with anionic lead feeds and good transition management reducing incident rates to 2% – 3% of the herd. Despite this, sub-clinical milk fever is reported to run around 60% of all second-plus lactation cows. Heifers are not immune either.

The clinical milk fever cow can be recognised, treated, and back in production relatively easily. The consequences of sub-clinical hypocalcaemia have far more serious effects than we realise, and far more reaching into lactation production, health and fertility. Blood tests are the only real indicator of the degree of hypocalcaemia. Initially, at calving, there are big benefits in oral calcium supplements (drenches or boluses) to help cows cope with “lactational osteoporosis”. This is virtually unavoidable to meet the 300% increase in calcium that fresh cows require. Oetzel estimates sub-clinical hypocalcaemia at four times the cost of clinical milk fever. When research has identified up to 60% of mature cows suffer sub-clinical hypocalcaemia, at four times the cost of clinical milk fever, then this is a very significant cost to farm profit.

Sub-clinical hypocalcaemia is well documented as the prerequisite to a numerous diseases common around calving: obviously clinical milk fever, but add to that, retained membrane, metritis, mastitis, ketosis, and a major industry problem, fertility. Productive life as milking cows can be unnecessarily cut short as a result of sub-optimal calcium nutrition. Our clients that have been proactive in calcium nutrition have seen major decreases in fresh cow mastitis, metritis, and very significant improvements in fertility.

My concern is, in our low calcium ryegrass pastures, this hypocalcemic disorder goes on well past early lactation. A cow producing 30 litres of milk is exporting 36 gm of calcium daily in milk. That’s the calcium content of 100+ gms of limestone. Then there are urinary loses, reabsorption of calcium into bones and metabolic functions requiring calcium. The immune system alone has a high calcium demand.

Dietary calcium deficiencies are common in ryegrass pastures which frequently have little or no clover content these days. Milk protein production is also limited by calcium deficient diets. Ryegrass contains typically around 0.3% calcium. Clover is around 1.4% and Lucerne 1.7%. A recent article in the Australian Dairyfarmer highlighted the need for a return to 30% to 40% clover content in grazing pastures. This article was more about pasture production and soil health and their need for clover, rather than cow nutrition.

Soils have a high need for calcium to function well (transport other nutrients). Obviously, legumes have a high need for soil calcium availability for growth, and their high calcium content. The author of the Dairyfarmer article stated “we’ve lost our way” in pasture production with the neglect of clover. Losing our way is correct. When I started share farming in the 1970’s, applying lime was an annual autumn event. Where I live in SW Victoria we sit on top of a limestone mountain, yet I see very little spreading of lime on pastures. Certainly SW Vic would benefit immensely from gypsum applications. Gypsum will supply sulphur as well as calcium, another element lacking in our soils as a legacy of high analysis fertilisers and urea. Gypsum will restore soil structure allowing for better water and air penetration.

I think the massive uptake of urea use, the demise of super applications, the spraying of broadleaf weeds have all contributed to clover’s departure from our pastures. These are all reversible including broadleaf sprays that are now available and harmless to clover. A return to lime applications must precede sowing of clover. It is not just a soil pH issue, but a locking up of other nutrients that only calcium can undo that needs to happen to ensure good clover establishment and perseverance.

Reestablishment of clover in our pastures will not just increase calcium in the diet of our cows with major benefits to production, health and fertility, but increase pasture harvested per hectare, improve soil nutrient availability to plants, improve soil structure and reduce soil compaction problems prevalent on most dairy farms.

I profess no expertise in agronomy and strongly advise consultation with sound agronomists. Calcium is not a stand-alone cure-all. It is intimately involved with numerous other elements in both soil and animal nutrition. However, calcium is called a macro element, meaning, it is required in large amounts and our capacity to meet this need through grain mixes alone is limited. Increasing calcium in our forages through good pasture clover content will go a long way in improving both pasture and cow health and production. As the Dairyfarmer article said; “we’ve lost our way”. This is not rocket science, but was standard, good-farming practice of 50 years ago.

Leafy summer fodder crops like sorghum have a high need for calcium and respond in yield very significantly when calcium is not a limitation. As one of my clients says; lime is a fertiliser.