Low milk fat - podcast transcription
Low milk fat
Greg: Welcome to Dairy News. I am Greg Mills and today I have with me Tony Dowman. Tony, low milk fat percentage, quite often a problem in many herds. Should I be worried about it?
Tony: Well these days most farmers are paid on their composition in their milk with the butter fat and the protein concentration in milk. I guess you should be worried about it if you’re worried about your income. But the problem is the cost of remedial action may be greater than the return from your milk. So you really need to have a think about what’s causing this problem and how expensive it will be to rectify the problem before you jump in and just do it.
Greg: So what problems am I quite often looking for?
Tony: There’s some easy ones to cross off the list to start off with and the obvious ones is the breed of cow. It’s just a fact of life that the Holstein Friesians are low butter fat cows whereas your Channel Island breeds are going to be higher. Start looking at the age of the animal. They lose a small amount of test percent as they get older. When they freshly calve they have low test percent and the test percents get higher as they get later in lactation.
So if you’ve got a seasonal calving herd or a batched calving herd, that could be quite a legitimate reason why your fats are a little bit lower than you thought they should be. But the fundamental one obviously is what the cows are feeding and that’s the one that you’ve got the biggest control over.
Greg: So what sort of feeds influence that percentage in milk?
Tony: Historically we’ve always said that it’s the fibre content in the diet that causes the fat problem. So if you have a low fibre diet, in other words a high energy intake, high grain diet, that you’ll tend to see lower test percents in the bulk milk fat. But it’s a bit more complicated in that inside the cow. What is fundamentally happening is that as the cows go onto a high unsaturated fat diet, it’s unsaturated fats which are found in plants and in plant material, the cows actually convert some of this fat into what they call trans fat which actually then blocks the cow’s ability to produce butter fat in the udder. So the old cure of low fat testing to feed a higher fibre diet actually solved this problem inadvertently.
Greg: Is there any particular feeds that make this problem worse or maybe make it better?
Tony: If you’re seeing a lot of, as I said, unsaturated fat such as cooking oil for argument’s sake, people sometimes are putting cooking oil in the cow’s diet to increase the energy concentration of the diet. Adding unsaturated fats like that will most definitely cause low butter fat levels in the milk.
So you need to stay away from those energy dense feeds if it’s causing you a problem. But again you need to see am I losing lupus as well as I’m losing fat test percent because you get paid on the kilograms of component, not on the test percent. If your test percent drops but your litres increase, in actual fact the cows are probably producing more fat and therefore more milk.
Greg: High energy feeds like grain can then be a problem potentially. So is there any rules of thumb in terms of what’s a safe level of grain to feed?
Tony: A safe level of fibre to grain ratio is about 60% fibre which is grass, hay, silage and about 40% grain based product, and that is really a safe level that the cow’s rumen can handle. As you get higher and higher grain and lower and lower fibre in their diet you’ll start to see the butter fat test percent applied. The litres will stay up and probably go higher and the protein level will probably stay the same or go higher as well.
When you get to about probably 40% fibre and 60% grain you’re going to see quite a significant difference in the components and in the litres. If you keep going higher than that you’ll probably start causing things like acidosis, upset stomach for the cows and then you’re going to start seeing some animal health issues turning up.
Greg: Given fibres are such a key component and quite often dairy farmers are relying on their test results of feed that they’re sending off to a lab, what sort of things should you be looking for in those test results when they come back?
Tony: The fibre on the test report is normally expected NDF, neutral detergent fibre. The cow requires around about 30% neutral detergent fibre in her diet. Hay and silage and grass normally remains between about 45 and about 65% neutral detergent fibre where grain can be between 10 and 20% neutral detergent fibre. So you can see if you have a very high grain diet you end up running very, very close to that magic 30% number that the cows require for rumen function.
So in a high grain low fibre diet the rumen will be completely out of kilter, start wiping out the bugs in the stomach which digest fibre. You’ll start seeing acidosis occurring. You’ll have sick cows, downer cows and ultimately dead cows.
Greg: Tony, quite often you hear the term ectofibre. Is there a difference between effective fibre and fibre?
Tony: Yes there is. Effective fibre is what we call long fibre which basically causes the cow to chew her cud. You can get fibre which is very, very short and gets digested very quickly. The cows must chew their cud to produce saliva. Saliva is the natural buffer for the rumen and as the cows regurgitate their feed and chew their cud, they produce 60, 80, 100 litres of saliva a day which basically goes back into the rumen to control the rumen’s pH to keep it in control.
So, if they have a very, very low fibre or very ineffective fibre length, what will happen then is they’ll stop chewing their cud and you’ll start seeing acidosis.
Greg: So is there any better sources of this effective fibre?
Tony: Anything which will chew their cud is effective. But obviously what it needs to have in that fibre is high energy and high protein, things like straw and rice hull are very high in fibre but nutritionally they’re very, very poor. So the trick is to try and find a source of fibre which is also high in energy and high in protein. Things like rye grass, clover based hay, lucerne is another example, good quality feed of improved pastures whether it’s freshly grown or hay or silage, is by far the best fibre source because it’s also to find the nutrients that the cow requires.
Greg: Thank you Tony.
Disclaimer
Users rely on the information in this podcast at their own risk. The Department of Industry and Investment and the State of NSW do not warrant nor represent that the information is complete, current, reliable nor error free, and they disclaim all liability concerning the podcast to the extent permitted by law. Details about disclaimers, privacy and copyright are available on our website at www.dpi.nsw.gov.au/legal or by calling 02 6391 3552.
