High-density grazing helped Angus McIntosh restore soil health, eliminate pests and diseases and double the feed conversion ratio of his chickens.
Before Angus McIntosh started farming at Spier Biodynamic Farm just outside Stellenbosch in the Western Cape, somebody warned him that the soil there was very poor. “That person won’t believe his eyes if he saw the quality of the ‘poor’ soil today,” he said proudly.
McIntosh ascribes his success to ultra-high-density grazing – where a large herd of animals graze a confined area for a short period. The system mimics the way large herds of game used to move from one area to another and only return to a specific area after a long time.
The “high density” part of the system results in manure being concentrated in these areas, and in effect enhances pasture fertility; the nomad movement gives the soil enough time to recover fully from the grazing. These ideas are described in detail in Michael Pollan’s book, The Omnivore’s Dilemma.
At the time of original publication, McIntosh used the system on 30 ha of his 270 ha farm. The pasture in the system is under irrigation and consists of mixed grasses and legumes, and perennial grasses and legumes. The system supports 900 broiler chickens per week, 250 head of cattle and 750 laying hens.
BROILERS TAKE FRONT ROW
McIntosh buys day-old chickens before they are debeaked – as battery chickens often are – to prevent their grazing ability from being hampered. All the chicks are kept in a temperature-regulated brooder house where they receive normal rations and water.
Effective Micro-organisms (EM) are mixed into the water to improve the health of the chicks and strengthen their bones. EM consists of a variety of beneficial anaerobic organisms that help to destroy harmful bacteria. Soothing classical music is played in the brooder house to improve chick health.
After 3 weeks, the broiler chicks are transferred to the broiler cages, which measure 1 2m² (4m by 3m). Each cage houses up to 80 chickens. The chickens receive normal rations, free from antibiotics, synthetic vitamins, hormones and growth stimulants. They roam freely and eat insects, almost like free-range chickens, but inside their cages.
The 34 cages are moved by one length (4 m) at 10 am every day, to ensure that the entire veld is fertilised. McIntosh has found that one day is long enough for 80 chickens to eat sufficient grass and seed to stimulate pasture growth, but short enough that there won’t be a parasite build up. The quantity of manure spread over the small space is also sufficient to build up soil nutrient levels, but not so excessive that it will burn plants.
The broilers stay on the land until they are ready for slaughter at 42 days when their average weight is about 1.4 kg. The broilers have an excellent feed to weight conversion ratio. In conventional systems, the average is about 3 kg of feed for every 1kg of bird. In McIntosh’s system it’s 3 kg feed for every 2 kg of bird.
McIntosh ascribes the good feed conversion ratio to the following:
- The chickens get sufficient rest. They sleep at night and aren’t exposed to 24 hours of light, as battery chickens are.
- They get natural exercise because they can roam.
- They eat grass, their diet doesn’t consist solely of grain.
- They eat other organisms, such as insects, larvae and caterpillars.
CATTLE ARE NEXT IN LINE
McIntosh has 250 head of cattle (Ngunis and a Bonsmara x Nguni cross breed) that graze areas after the broiler cages had finished with it. An electrified fence is used to contain cattle movement to a 0.5 ha area for 24 hours. The cattle are moved from one area to another every day at 4 pm, when the sugar content (Brix count) of the grass is at its highest.
Left to themselves, cattle in an open paddock will only eat the most palatable grazing, and these plants will ultimately be eliminated. In an ultra-high-density system, however, movement is restricted to a small area so cattle are forced to eat some of the less palatable plants. The cattle help to prevent the pasture from growing out of control and their manure improve the nutrient status of the soil.
In addition to pasture, the cattle receive a special lick consisting of 3 parts salt, 3 parts kelp and 1 part bokashi – bran mixed with EM and fermented in molasses.
McIntosh wanted to expand his herd to 400, but was still conducting trials to decide whether the Ngunis or the Bonsmara type are best suited to his farming system. The Bonsmara type is heavier, but because the Ngunis have a smaller frame, more animals can be used per hectare. So far, the Ngunis are also producing 33% more meat/ha/year than the Bonsmara type.
Also read: Healthy soil ensures healthy cattle
LAYERS ARE AT THE BACK
Layer chicks are only taken to the veld at the age of 5 weeks, when their feathers are well-developed. They follow the cattle in egg-mobiles. McIntosh has five such trailers or egg-mobiles, which house the water, nests and food for the layer chickens.
The trailers are moved 300 m to 400 m every 3 days on the grazed pastures. Keeping the layers at the same spot for a longer period will result in hens making their nests in the grass, which will make it difficult to collect eggs.
About 750 hens and a few cocks (about one for every 25 hens) scratch and roam in the grazed pasture and peck at any parasite larvae in the cattle dung. In the process they eliminate the build-up of parasites.
McIntosh wanted to expand the layers in the system to 2 000. He has Rhode Island Red, Plymouth Rock, New Hampshire, Boschvelder and Lohman Brown chickens. He’s especially impressed by the Lohman Browns and New Hampshires and will probably use only these breeds in future.
He points out that there’s a good demand for fresh eggs from hens on pasture. At the time of publication, all the eggs were sold directly to restaurants in Stellenbosch.
- This article was written by Johan Coetsee, originally appeared in Landbouweekblad, and was adapted for Farming SA.