Transition

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.

John Lyne

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