I grew up on a farm, or more properly, what was left of the farm - Grandmother had sold off 80 acres to the Tulsa County Parks Department to make Haikey Creek Park, but kept 10 acres for the family, which included the water catchment, irrigation ponds, House, Barn, and about six and a half acres of fields. When we took up residence in the old farmhouse in 1976 or 77, most of the fields had become overgrown, but we had them whipped into shape and mended the fences by 1979, which is when the first goats arrived. "We'll just have a few goats for milk, and a few chickens for eggs" the parents said .. That is how it always starts, you know.
By 1985 "Fine Fiddler" Farm had over 144 head of dairy goats, at least twice that many chickens, unenumerable 'racing' pigeons, somewhere between 40-50 'Emperor' pigeons, half a dozen turkeys, a dozen geese, two score ducks of various pedigrees, and at least 8 purebred Chinese wardogs called "chows" One acre was reserved for the annual vegetable garden, and one and a half acres was generally kept in some sort of fodder that never did quite equate to the amount of food that that many goats required; it was necessary to constantly import feed and hay and straw for bedding - this was definitely NOT a permaculture operation, and it constantly operated at a loss up until the parental units decided to sell off the livestock, pack up, and relocate to a mountaintop in Taney County, Missouri.
People get the idea in their heads that they can enhance their self sufficiency by raising animals .. and although the living space requirements for livestock can be met in small spaces, those animals require additional resources, and those resources have to come from somewhere. Lets start with grass. Assuming that one has a good pasture full of grass for fodder, with an average height of a foot, and an expected amount of grazing down to 2 inches, there is about 2000 pounds of feed per acre. The formula is Height in inches x 200 lbs/acre. Now, let's compare feed requirements for different animals:
A cow will eat about 25 pounds per day when freely grazing, meaning an acre that is well planted in forage will support one cow for 80 days, 160 days with a 3-month on/3 month off rotation. In temperate climates, close to 90 days of the year will require supplemental feeding with hay and/or other fodder, meaning that one cow will need 1.5 acres PLUS the space needed to grow their winter feed - about an extra acre of hay. That is 2.5 acres/cow.
Sheep require less feed per animal, but at a higher ratio of body weight/feed. Sheep consume about %4 of their body weight per day, with an average weight for adults of around 150 lbs, expect to need 6 lbs/day. With the same 3 month rotation, 2.7 adult sheep can be maintained/acre, plus winter feed .. all together, about half an acre/sheep. Goats, with their lighter frames, on average can get by on 1/3 acre/goat, presuming that one is raising any goat worth having - Nubians on flat land, Saanens on flat land/light hills, or Toggenburgs on hilly land. If someone tries to give you a pygmy, Nigerian dwarf, Boer, or Kiko goat, they are not your friend, and turning the dogs loose on them is appropriate.
Pigs need about 6 pounds of feed/day, and amazingly, they can get it from pasture grass just like a sheep can, although pigs can also eat .. well, just about anything. Half an acre/pig is just about right, but for giving a porker extra butcher weight, you might want to get your hands on some extra fodder, about 1/6 acre/pig being raised up for the butcher - which should take about 6 months to go from suckling piglet to 240-250 lb bacon factory.
Chickens need about 1/4 lb of feed per day, or 113,398 milligrams. A conservative estimate of biomass in the organic horizon and boundary between organic and soil surface horizon is 400 million specimens, according to the Smithsonian Institute. With an average weight per insect of 3 milligrams, the final mass/acre of potential chicken feed is approximately 1.2 million kilograms, or enough insects to provide 10,582 days of chicken feed .. enough feed in bugs alone to keep 28 birds fat and sassy. That is about 1,500 square feet per bird, with a forage rate of 4 square feet per bird per day. A chicken tractor measuring four feet across and a dozen feet long could have a dozen birds in it, and would need to be moved once per day in order to keep them well fed - but Laying hens require more space to feel comfy, up to ten square feet. Doubling the size of the enclosure, and moving every other day would keep the birds happy and well fed.
Whether one is planning on raising livestock or not, water is going to be a necessity - and in most places, that means storing water, in swales, ponds, and so forth. This presents the opportunity to do some aquaculture - raising fish! There are many varieties of acceptable pond fish depending on location, but if one is considering growing fish specifically for food, I have a couple suggestions: In warmer climates, where the water is not going to get cooler than 55F on most days, Tilapia makes a great fish to farm. Extracting the fish and placing them in a holding tank for a week prior to processing allows them to 'purge' their systems of waste that might make the flesh taste 'off'. If you have ever had tilapia that didn't taste good, chances are this processing step was skipped. there are other good choices, obviously, but I mention these in particular because of their dietary requirements: They are omnivorous, but can live on a purely vegetarian diet.
OK, time for some fish math. The basic rule is one pound of food and one pound of air makes one pound of fish in ten gallons of water. It takes 240 days to grow from fingerling size to a harvest weight of 1 - 1 1/2 pounds, and the fish will consume up to %5 of their weight in food per day. Lets take the example of 20 fingerlings in a 300 gallon tank (you can scale up to any size pool or pond from there). The first ten days, they will consume 1 ounce of food/day, totaling 10 ounces. The second ten days, they will consume 2 ounces of food/day for 20 ounces, 30 ounces total, and so forth. Over 240 days, those 20 fish will have consumed 187.5 pounds of food. Now the question is: would you like to feed those fish for free? Of course you would! Let me tell you about duckweed.
Lemna Gibba is an aquatic perennial that grows from USDA zones 4-11 at a fast rate - it can double every 24 hours under the right conditions .. up to 1 ounce per square foot of pond surface area. Remember our hypothetical 20 tilapia? at 24 ounces each, they would have a combined mass of 480 ounces, and consume 1 and 1/2 pounds of food per day .. the amount produced by a 6 ' x 8' pond full of duckweed, doubling itself every day. One foot of depth in that pond is a little over 300 gallons. Alright, maybe you live in a place where you can't maintain 55F water for at least 240 days out of the year. Don't worry, we have you covered!
The system that I am about to describe is well suited to cooler climates, ideal for situations where multiple water catchments will overflow into each other as they proceed down a slope, and is the system that my grandfather established on the old farm. At the top pond or swale, stock nothing but minnows, preferably herbivores, but a few predator fish wouldn't be amiss, particularly for keeping things like mosquito larva under control, so long as they will never reach a size to eat adult minnows. Set up the drainage overflow from this catchment to flow downslope, wide enough at its entrance to funnel in the feeder fish, and narrow at its exit.
The second tier of catchment areas should be stocked with things like sunfish and bluegills. Just like the first pond, this one should have a funneled overflow to direct the feeder fish down the slope to the third pond, which is where the big boys live: Bass and Crappie. The primary product fish from this system is crappie for the table, but the occasional bass can be taken if they are large enough; the purpose of the bass is to keep the numbers of crappie within reason, as they will overpopulate in record time without a predator to control them. Irrigation lines can be laid in to any of the catchments to send excess water to thirsty plants, just make sure that the intakes are screened to prevent accidently 'watering with fish' .. the fish manure will fertilize your plants as you water them.
Gorillas are a lot like us in several ways .. the little one in the photo above, for example will spend 1/3 of his life resting, a good deal of time commuting from one place to another, and not nearly enough time socializing with his peers, but there are some huge differences. Gorillas spend half of their time eating - no wonder they don't have time to develop language, art, physics, chemistry, philosophy, space travel or engage in warfare! The reason is simple enough: Just like cattle, sheep and goats, there is a broad variety of edible vegetation on the menu for the gorilla, but very little of it is nutritionally dense food .. so they make up for the deficit by consuming in volume.
The practice of grazing livestock in and amongst trees is called silvopasture, and it is a good deal, both for the trees, and the livestock: The trees get the benefit of pruning from browsing animals (although care must be taken to prevent the destruction of young seedlings) and the beneficial fertilizer in the form of manure. The animals gain the benefit of a constant supply of shade, and, if the landscape is managed to include long swales and water catchments - readily available water resources. The use of perennial species to form the fodder for the grazing animals fits neatly into the plan: Clovers for groundcover, and Rye Grass, Alfalfa, and Perennial Buckwheat for the rest of the forage. The resulting fodder is nutrient dense, and high in protein - and while your livestock might not develop complex reasoning skills, they will definitely enjoy a life of lower stress, greater health, and better butcher weights.
Alfalfa, Clover, and Buckwheat all also have another property in common, and it is one that has great benefits for a polyculture: They all are pollinated by insects. While this does not mean that one must keep beehives (solitary bees do a fine job on their own) it does mean that any bees that one does decide to raise will have a ready supply of nectar close at hand, and this keeps the pollinators close by for other jobs, like pollinating the trees in your orchards - orchards that help to shelter the hives. Clover and buckwheat honey is just another potential yield derived as a byproduct of building a healthy, integrated system.
Since we're on the topic of integrating systems, lets take a minute to see how everything ties together: The selection of what trees you want to grow will have an effect on what animals you may use, if any. Acorns are acceptable feed for pigs, and goats can have some so long as they are not permitted to over indulge, but cattle and sheep need to be kept away from acorn mast. Aside from that, I want to remind you of the concept of stacking layers and functions, where it pertains to animal feeding habits.
Goats like to browse, just taking the top 2 or 3 inches off of everything. The forage that they can take before needing to be moved on is thus 600 pounds/acre (72 square feet/lb) .. beyond that, they will continue to browse, and even eat everything down to the ground, but there is more benefit to having the goats cause a little disruption, then rest the grazing area for a week or two before bringing in the sheep. Once the sheep are done mowing everything down a bit - but not to the point of killing off your perennial fodder - it will be time to move them along, too, rest the area for another couple of weeks, and follow up with the poultry.
By managing stocking numbers and grazing your livestock in succession, the space between your trees is kept healthy, the livestock is kept healthy, and yields will reflect your wise land management practices. A good rule of thumb for managing livestock is to not think of the potential yield - that is the trap that growers fall into, and it leads to an imbalanced system. Instead, think of the animals as a means of accomplishing work: The browsers prune, the grazers weed and fertilize, the poultry does pest control. As long as the numbers and time on each plot remain in line with this thinking, the yields will come - individually lower than the intensive grower's, but in the aggregate, in greater abundance.