DairyReporter spoke with Kevin Harvatine, associate professor of nutritional physiology at Penn State University’s College of Agricultural Sciences, about his work with feed rations and how they can improve levels of milk fat across herds.
This may be useful for not only higher quality milk, but cheese, ice cream and butter.
DairyReporter: Tell me a bit about what you’ve been researching.
Kevin Harvatine: The overview is that we study milk fat all the way from very applied feeding experiments to very basic microbiology. We’re testing different fat supplants and different feed supplements to see how they affect the cow … On the applied side, when I got to Penn State almost seven years ago, the first thing we did was a time courses. That was really important, as we experimentally need to know how to design experiments.
On farm, someone has to know: if I make a change and it’s going to work, long do I have to wait for it to work? If that change can work, they can make an additional change. When they see milk fat depression they need to know if it is something that happened yesterday, a week ago or a month ago.
Our latest work is working with [feed supplement] Alimet … It helps see a milk fat growth. We got really nice data when we had Alimet in the diet. It prevented cows from dropping into milk fat depression.
DR: Why is this work so important?
KH: Producers are paid for fat and protein … and not for water that you’re selling. Especially right now, milk fat price is sort of crazy relative to milk protein. When you look across farms, there’s a lot of variation in milk fat. We know a lot of that is due to [the cow’s] diet. There are some genetic differences between cows and their ability to make milk fat, but it’s highly driven by diet.
We’ve known for decades that high grain diets and diets high in saturated fat lead to the problem. What happens is they disrupt rumen fermentation and you get production of very specific type of trans fatty acids. We know the type of diets that are higher risk, but there are also the diets higher in energy that we’re feeding to meet energy demands of the cow and trying to get optimal milk yields.
We’re constantly running this risk that we’re trying to get energy intake and trying to high feed efficiently, but at the same time we run the risk of having lower milk fat. Our work is basically trying to figure out how we can control the risk factors and if there are other things we can do to alleviate that risk.
DR: What kind of response has your research received from the dairy industry?
KH: There’s been a lot of interest in how to improve milk fat for a long time. I know I get out and do a reasonable number of talks for diary nutrition conferences and symposiums that some of the nutrition companies are sponsoring … So I usually think of milk fat as being one of those top of mind issues for dairy products
There are two major issues. One is the economic value. The other is that we tend to associate higher milk fat with having the diet balanced right, that if we have good milk production and high milk fat, we know we’re feeding the cow [well] … But feeding cows is really complicated.
DR: With the high production and turnout of dairy products, is there a way to make milk fat more impactful?
KH: The one thing that caused some challenges a number of years ago was when we stared feeding more [refined] grains. The original distiller grain production that was used, they were really high in fat and also quite variable. That has really limited the amount of distiller grains that a lot of dairy nutritionists are willing to feed. That’s gotten a lot better in the last few years.
I think we have less challenges today than we had 10 years ago. Distiller grain sources have become more consistent and lower in fat. Just over 15 years ago, we had a major breakthrough of what was causing milk fat depression. Since then, the understanding of basic biology behind it has really helped focus what we do. I think we’re much more successful in combatting the problem. We understand a lot more of the fundamental biology.