Thursday, July 7, 2016
Managing the Dry Season
Sheep are ruminant animals, which means they have multiple compartments to their digestive tract. Micro-organisms in the rumen (and to a lesser extent, in the omasum, abomasum and reticulum) allow ruminant animals to break down cellulose (plant fiber) into essential fatty acids. In other words, the bugs in a sheep's gut allow the animal to make a living on grass!
To facilitate the digestion of cellulose, these micro-organisms require the animal to consume forages or other feeds with at least 8 percent protein - the bugs need the protein to survive. On our annual rangelands, green forage typically contains 15-25 percent protein. During the growing season (fall, if we get rain, and especially springtime), the standing forage contains more than enough protein - indeed, this is why we lamb in late winter and early spring. But during the dry months (mid-June through October or November, typically), our dry annual grasses and broad-leaf plants are very low in protein (as low as 3-4 percent). Despite the decline in quantity, we typically have more than enough quantity of forage during these months. The trick for us, then, is to get enough protein to the sheep to allow their "bugs" to digest this dry forage.
The most important part of our grazing/nutritional strategy is timing. We time our production cycle to take advantage of the usually sufficient quantity of high quality forage in the spring time - we match demand with supply. The greatest nutritional demand for a ewe is during her last month of pregnancy and her first six weeks of lactation. By overlaying this 10-week period of high demand with the period of rapid grass growth in the spring, we eliminate the need for supplemental feeding during this critical time. Equally as important, this schedule allows us to match our period of lowest demand (post-weaning and pre-breeding) with the period of lowest forage quality.
After we wean the lambs and before we start preparing the ewes for the next breeding season (a technique called "flushing" - more on this below), we simply want the ewes to maintain their condition. Actually, for the 7-10 days after we wean the lambs, we like to have the ewes on low quality forage to dry up their milk production as quickly as possible (which reduces the chance of mastitis). During this maintenance phase, we put our "dry" ewes (dry, as in no longer producing milk) on our dry annual grass. To make sure they can digest this dry forage, we also provide supplemental protein. Over the years, we've tried a variety of supplements - from alfalfa hay to molasses-based protein tubs. Currently, we've provided tubs with 18 percent protein to the ewes; next week, we're going to try a small quantity of barley screenings (12 percent protein) fed by hand every other day instead of the tubs. The grain won't replace the dry grass in our ewes' diets; rather, it will provide their gut micro-organisms with enough protein to digest the grass they'll will be grazing. If it works, it will be a much lower cost alternative to the protein tubs.
The lower quality dry forage we're currently grazing also makes the effect of flushing more pronounced. In early September, we'll move the ewes back to our irrigated pastures (which will have been ungrazed for 50-75 days at that point). We'll also hand-feed the sheep with a high-protein, high-energy feed (this year, we'll use pelleted canola meal). The shift from low-quality dry grass to higher-quality green grass and supplemental feed will increase ovulation in the ewes - and give us more lambs next spring!
In the meantime, our summer days are spent moving water on our irrigated pastures and building fence on our hard, dry annual rangelands. We check the dogs (guardian dogs and border collies alike) and our socks for stickers and burs. We watch the horizon for smoke and the sky for fire planes (wildfire is a constant worry during our summer grazing season). We lug 125-pound protein tubs or buckets of grain to the ewes. And we look forward to the first rains of autumn!