Mentors are gifts. I have many in my professional and personal life and I hope you do as well. If you don’t, you should find some. We all need the advice, council, and the occasional wise word from those in our circles that have more experience than we do on a topic or two.
One of these mentors for me often sends me comments on my writing here in Hoard’s Dairyman. Every time this occurs, when I see the email come in, my heart rate goes up a little as I am concerned that perhaps I have misspoken or had some factual inaccuracy. I am truly glad for the input and occasional critique. Thin skin does not work well for writers.
So, who is this mentor? His name is Al Kertz. In my first dairy nutrition job in the early 1990s, Kertz was among my tech support team. At this early point in my career, I knew a lot about cows and felt well-trained in nutrition. But those had been beef cows, and my new job was in dairy nutrition. This created a steep learning curve. I needed teachers, and Kertz was among those who helped me. Now 34 years later, I am still looking for the same help.
This most recent email from Kertz was in response to my article in the January 10, 2025, edition of Hoard’s Dairyman titled, “Calculating shrink isn’t just for silage.” The main subject of the article was not on the most commonly discussed shrink risk, which is silage, but the less-discussed topic of differential shrink among grain and by-product ingredients. Differential shrink is a term I coined that combines physical form-based shrink risk, ingredient cost per ton, and feed rate. In the article, I described some different examples to make the point.
As I prepared for writing that article, I looked around the literature and had a hard time finding much detail on reported shrink on specific ingredients. So, I made some educated estimates of shrink values for various grains, by-products, and commercial mineral blends. I used these shrink estimates to convert shrink to a cost per cow. I think my concept was sound, but I admit that the educated guesses I made for each ingredient was a shortcoming in my overall argument.
What I received as a comment from Kertz was a copy of an older paper, on which he was an author, in the journal called, The Professional Animal Scientist from 1994. Frank Standaert, another early mentor of mine, was the lead author. In the paper was the information I had looked for but not found. There was a table included that showcased ranges of shrink risk for a plethora of different ingredients. The table also included risk levels for three different storage approaches open, covered three-sided bays, and upright bins.
I have included that table here. The middle column shows the normal storage approach in a modern dairy feed storage area. In my differential shrink calculation model described in my article, I used values ranging from 5% to 10% that fits the table. So, I was reasonably close.
Of interest in the table is the high shrink risk of wet ingredients such as distillers grains and brewers grains. I am curious about this, knowing that this loss could stem from leaching liquid resulting in nutrient loss or a simple loss of moisture resulting in potential feeding errors. I would also note that the 4% to 10% range for soybean hulls or wheat midds may represent a loose versus pelleted form. In these low-density by-products, pelleting is almost necessary in an on-farm application, even in enclosed feeding centers. Even if the wind is blocked reducing loss risk, the extreme dust from these by-products can result in loss of visibility for loader operators, and even an explosion risk.
As I look at these numbers, the changes in the feeding style since the date of this paper will keep me on the hunt for better shrink data. My guess is that there are commercial farms that made big investments in enclosed feed storage and mixing facilities that have before and after shrink information that could be helpful. I expect many lending proposals for new feed centers include shrink differentials to calculate a return on investment. In general, I feel like a number of around 10% in an open facility could perhaps be cut in half with an enclosed mixing area. Remember that a good feed mill with enclosed storage, augers, belt drags, and enclosed mixers may have 2% to 3% shrink. So, any system on-farm that hopes for anything less than 5% should be cautious.
In this situation, I am truly grateful for mentors that have been making me a better nutritionist now for more than 30 years. These are relationships I value. And one last note, if you are like me and are getting a little gray hair, be on the lookout for younger colleagues that could grow from you by sharing some of your valuable experience.
