All dairy cows go through a state of negative energy balance (NEB) right after calving. When a cow breaks down too much of her body fat to cover this energy gap in such a short period, accumulation of fat in the liver or fatty liver syndrome results and is detrimental to her health and milk performance. The risk can be greatly reduced with a good preventive feeding program implemented before these cows enter the milk line.
I am currently working with a dairy producer who milks a herd of about 200 cows in which fatty liver syndrome caused several recent deaths. So on my latest visit, I conducted an investigation. It started by going outside and looking at the cows in both the faraway dry-cow and then close-up dry-cow pens. Then I went inside the free-stall barn and got an overall impression of the lactation cows. Finally, I took out a plastic bag and grabbed a handful of total mixed ration (TMR) in the feed bunk.
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A list of clues
Here is a list of fatty liver clues that I collected:
- Dry cows in both the faraway and especially the close-up pens were over-conditioned. Many had a body condition score (BCS) of four and higher ( one equals emaciated to five fat.) In the lactation barn, many cows that were ready to be dried off had a BCS of more than 3.5.
- Many lactating dairy cows were producing over 100 -120 lbs. of milk in the first 30 days of lactation. It crossed all parities.
- TMR samples had adequate moisture and lots of effective fibre. DMI of this lactation diet was 24.5 kg. The producer had removed all bypass fat in the diet three weeks earlier.
- The veterinarian took several blood samples because he suspected the presence of sub-clinical ketosis in the herd.
- I also reviewed these barn-walk findings with the producer.
Recommendations
Regardless of what we figured out, preventing future fatty liver (as well as ketosis) is a much better option than controlling it amongst the cows.
I recommended proper faraway and close-up dry cow diets to promote optimum body condition and good dry matter intake in susceptible dairy cows. For example, by feeding a well-balanced feed of bulky grass-type forages, an optimum BCS of 3.0 – 3.5 in faraway dry cows that also supports a healthy growth of their fetus.
This entire faraway dry cow diet should supply about 14 to 16 Mcal of dietary energy, 13-14 per cent crude protein, complemented by 0.50 per cent calcium, 0.30 per cent phosphorus, 0.5 per cent salt and trace-minerals and vitamins (A=100,000, D=3,000 and E=1,000 iu/head). Lastly, 10 g per head per day of commercial yeast should be included. This diet should dovetail into a new close-up dry cow diet, which is fed for three weeks before calving.
This new close-up dry cow diet is formulated to carry a modest amount of dietary energy, namely, 0.60–0.65 Mcal/lb. (dm basis) as well as 14-15 per cent protein. A balance of calcium and phosphorus in a 1.5:1.0-2.5:1.0 with potassium levels controlled to promote good calcium metabolism. It should have good mineral-vitamin micro-premix to supply essential levels of trace-minerals, Vitamin A and high levels of Vitamin E (500-1,000 iu/kg).
A fatty liver prevention diet also takes into account that there is a 30 per cent natural decline in dry matter intake from the start of the faraway dry period to calving. To keep the close-up diet palatable, it should contain moderate-energy forages such as mixed-grass hay (limiting alfalfa), which can be complemented with specific grain-based pellets and mixed with some lactation diet containing either barley or corn silage. These prepartum cows should be consuming 12 kg of this good feed, which helps them calve at an optimum BCS of 3.0-3.5.
Finally, I would re-introduce bypass fat into the lactation TMR to ensure it is more energy-dense for the early-lactation cows. We are also reintroducing drenching incoming fresh cows with propylene glycol as well as considering a fresh cow pellet with added choline and biotin, which helps steady body fat mobilization. Together, it should work out in preventing fatty liver syndrome in this herd and others.
