There’s not much I like better than mulberry season. Mulberries are the first great harvest of fruit for the year, and the trees don’t hold back their bounty. A good tree will produce many gallons of sweet, juicy berries. Our little acreage will soon have no shortage of mulberries, given that I’ve planted over a dozen for home use, and so far several hundred for propagation (more on that later). Yet more important than being a tasty treat, mulberries are perfectly suited as a means of dramatically reducing feed costs for farmers raising hogs, poultry and other livestock.

This simple and humble fruit, grown on the most resilient of trees, will play a major role in creating regenerative pig and poultry agroecosystems.

When it comes to mulberry, I know of no accounts more inspiring and informative than those found in Tree Crops, by J Russell Smith, a classic first published in 1929. The book transports readers back to a time before industrialized, chemical, input-intensive agriculture, back to a day when integrating trees, forages and livestock was much more commonplace. It is packed full of everyday wisdom now mostly forgotten and in real need of reclamation. It is knowledge and wisdom that will serve us well today as we look to recreate agriculture in nature’s image, creating low-input, perennial and resilient systems. Of all the tree crops available to produce feed for hogs and poultry, mulberries will likely prove to be the most valuable. Below are quotes from the book which illustrate just how commonly mulberries were used, and just how valuable they were. 

“All through the Southern States, mulberries are commonly used as feed for pigs and poultry. In North and South Carolina and Georgia nearly every pig lot is planted with these trees, and the mulberries form a very important addition to the pig’s diet. 

I find a very general belief in the Cotton Belt that one “everbearing” mulberry tree is enough to support one pig (presumably a spring pig) during the fruiting season of two months or more. Professor J. C. C. Price, Horticulturist, Agricultural and Mechanical College, Mississippi, says, “The everbearing varieties will continue to bear from early May to late July, a period of nearly three months. I believe that a single tree would support two hogs weighing 100 pounds each and keep them in a thrifty condition for the time that they are producing fruit. They could be planted about 35 trees to the acre.”

Mr. James C. Moore, farmer of Auburn, Alabama, writes, “I never weighed my pigs at the beginning and close of the mulberry season, but think I can safely say that a pig weighing 100 pounds at the start would weigh 200 pounds at the close. Three-fourths to the mulberries is safe calculation of the gain. I have had the patch about 18 years bearing. I planted my trees just 32 feet apart, and now the branches are meeting, and I have about 40 trees. I have carried 30 head of hogs through from May 1 to August 1, with no food but the gleanings of the barn and what slops came from the kitchen of a small family.”

“We have talked this matter over thoroughly here in the office and believe that one mulberry tree 10 years old ought to support a pig 4 to 6 months old during the tree’s fruit season. As the tree gets older, 15 to 20 years old, if it has had good attention and has grown well, then it ought to support two or three pigs at the same age as mentioned above.” (O. J. Howard, J. Van Lindley Nursery Company, Pomona, North Carolina, August 11, 1912.)

What gets really interesting is when we crunch the numbers and figure out just how valuable these trees are. Feed costs are after all the largest variable expense for raising hogs. According to research in North Carolina, feed costs made up 45-63% of the cost to raise a hog, depending on the cost of feed. So, anything that can be done to reduce feed costs should be seriously considered. Let’s run the numbers and find out just how valuable mulberries can be. Here are the assumptions for my calculations:

  • The hogs eating mulberries are 100 pounds at the beginning. That’s the assumption made by two folks quoted in Tree Crops, so we’ll go with those numbers
  • We’ll give versions for both 60 and 90 days of mulberry yield. The farther south you are, the longer mulberries tend to yield. It also seems that the more nutrients (like, hog or chicken manure) trees have access to, the longer they’ll yield. 60 days is likely the more realistic version for folks in USDA zone 7 or colder.
  • We’ll assume that mulberries will reduce feed bills by 66%, not the 75% or 100% that some mention, as a means of being more conservative with our assumptions. 
  • We’ll use the feed prices listed in the NC study cited above, broken down by organic, non-GMO and conventional. You can decide which best fits your production system. 
  • We’ll assume that hogs are eating on average 5 pounds per day over this period. 

The results are pretty impressive, as you can see from the chart. On the low end, with hogs on conventional feed supplementing their diet with mulberries over just 60 days, we get a total feed savings of $43.56 per hog per year. On the high end, with organically fed hogs supplementing their diet for 90 days, the savings can amount to $136.62 per year. 

These numbers sure look good to me, but I’m no economist. Thankfully, an actual economist read a previous article on honey locusts pods and sugars, then wrote to share the formula for how to determine the present-value of a future stream of income. Here’s what he wrote:

I just read your article on the value of the honey locust sugars. I am an economist by training so allow me to answer the question of the value of the sugars somewhat differently. 

We economists have a standard way of determining the value of a stream of income (we also see costs avoided as being the same as income– except you don’t pay taxes on the former!).  Suppose you had a bond that paid you $18.20 (i.e. the cost of replacing the sugar from the honey locust pods with molasses) a year every year forever. If you had a risk adjusted discount rate of 5% you should be willing to pay up to (18.20/0.05) or $364 today for the right to that stream of future income. But if the stream of income from the bond won’t start for another 10 years then you won’t want to pay $364 today but $364*(1-0.05)^10 or $217.94 which is quite a bit more than the $16 cost of the seedling plus tree shelter making the honey locust a good investment.

This calculation, applied to our mulberry scenario, is what is reflected in the column titled, “Upper Limit of Investment”. As you can see, paying up to $521 (in our lowest-value scenario) or $1,635 (in our highest-value scenario) to establish a high-yielding mulberry tree would be a good investment. And these figures were made with the assumption that there’s zero yield for the first 10 years, when in fact grafted mulberry trees (which run in the $15-40 ballpark) should start yielding within two or three years of planting. Hence, even on the conservative end, a field full of grafted mulberries would make a terrific investment to a hog operation.

Let’s break down the numbers another way for a second perspective. If a mature mulberry tree can offset ⅔ or 66% of the feed requirements for a hog who would otherwise eat 5 pounds of feed, that’s a difference of 3.3lbs/day. If that can be sustained over 60 days, as would likely be the case for high yielding cultivars, that’s offsetting 198 pounds of feed. Plantings at 30’x30’ spacing would result in 48.4 mulberry trees to the acre, which together would offset 9,583.20 pounds of feed per acre of trees. I’ll let you figure out how much that’s worth to you based on your cost of feed. Even in our lowest value scenario above, the value of offsetting feed was $2,090.88/acre/year (see far right column). 

Let’s put those 9,583.20 pounds of feed into perspective. A bushel of corn weighs 56 pounds, so  9,583.20 pounds is equivalent to 171.1 bushels. That’s higher than the 2021 state average corn yield in Pennsylvania, which at 169 bushels to the acre set a new state record. 171.1 bushels per acre might seem outrageously high, given that these trees would require a fraction of the massive inputs that corn receives, and they haven’t been backed by the Cargills, DuPonts and Monsantos of the world. But keep in mind that mulberries are one of the most generous and heavy yielding trees in existence, that they have the supreme benefit over corn of not having to start each year anew as little seed kernels, and have deep, tenacious root systems able to acquire vastly more water and nutrients than corn roots ever could.

Now let’s break down how much those 171.1 bushels would cost to produce. It’s a bit tougher than figuring out your cost to produce corn, because it’s a one-time cost spread out over potentially 100+ years, with yield increasing year after year. But here’s a shot. Assume the cost of establishing 48.4 trees per acre is $1,500, or $31/tree, which would include the tree itself, a tree shelter, labor and mulch. Let’s take out a loan for that investment, since we don’t want to be hit by the cash flow pinch that occurs because the trees won’t start bearing fruit and paying us back for several years. With a 20 year loan at a 5% interest rate, your annual costs of the loan would be $120 per acre. When you break that down to dollars per bushel, you get an astoundingly low $.70/bushel. Granted, you won’t see any return the first 2-3 years, but yield will steadily climb after that, and your per-acre yields would likely hit a nice plateau by year 15 if trees are well cared for with some initial mulch and some fertilizer, which could be in the form of hog or poultry manure naturally dropped in the course of feeding on mulberries. After the 20 year loan, your costs dwindle down to whatever your costs of maintenance are, like pruning or removing trees, costs which are then offset by the value of the dense fuel wood harvested. 

Anyone producing chickens, especially broilers, can use mulberries to slash their feed costs while producing a truly different product that’s been fattened on fruit. Mmm.

So far I’ve focused on mulberries for hog production, but there may be an even better use for mulberries: broilers. Now, any poultry will gladly eat mulberries and make great use of them, but layers need roughly the same amount of feed all year round, while mulberries drop their fruit only over a 2-3 month period. Conveniently, 2-3 months is about the lifespan of a broiler. With some forethought you could have a large chunk of the feed needs of a flock of broilers met by mulberries. How much? I wish I could say, but I have not been able to find a source of information on that. If broilers did similar to hogs, you could reduce feed costs by 50% or more.

Fun fact: mulberries are so easily digestible that even humans can eat them. Often they are used like stuffed grape leaves.

What one does find when searching the internet for information on mulberry and poultry is all sorts of articles and research on the use of mulberry leaf. The leaves of mulberry trees, unlike most other trees, are both high in protein and highly digestible, so much so that they are routinely used in both poultry and hog feed, as well as fed to ruminants. Whether the leaves are used to feed the hogs and poultry that also dine on the fruits, or used to feed herds of ruminants during a drought or summer slump, good mulberry trees more than earn their keep on a farm. 

Now, not all mulberries are created equal, and not all will perform in a stellar way on a farm. Half of all mulberry trees grown from seed will be male, half will be female, and only females yield fruit. Of the females, not all yield heavy, or over a long period of time, or have especially tasty fruit. The ideal is a tree that yields a lot of sweet fruit over a long period, say 3 months. Seedlings can of course be used, but I estimate that the per-tree yield of mulberry trees grafted or otherwise cloned from top-quality parent trees should be 4x or higher that of seedling orchards. Just by eliminating the 50% of male trees and having all females you double yields. Then, by taking a bunch of mediocre seedlings and grafting them to superior varieties, you’ll easily double production again.

These pigs, foraging through the famous Spanish dehesa, are picking up their own feed through fallen acorns. We can do the same, and not just with acorns. Mulberries in the early summer, followed by apples, pears, persimmons, acorns, chestnuts and much, much more.

Those superior varieties are currently available through nurseries, but not in nearly the quantity needed for the scale of application mulberry trees deserve. There should be high-yielding mulberry varieties on farms from New England into the Deep South, out to the Great Plains and along the West Coast. Dozens, hundreds or even thousands per farm, offering shade to livestock, reducing feed costs and putting more cash in farmer’s wallets. In order to do that, millions of quality mulberry trees should get churned out and planted over the coming decades. 

As part of our mission to serve regenerative livestock producers, Trees For Graziers is working to make high-quality mulberry trees (as well as other silvopasture trees) available at scale, and at good prices. Join the email list to be informed as that stock develops. If you’re interested in mulberries at scale for your own silvopasture application, send us an email, we would love to work with you towards that goal. 

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