What factors affect palatability of forage for pastured poultry?

Answer: The term “palatability” refers to how “tasty” a bird finds a particular plant to eat at a particular time. Whether or not a plant is palatable is one of the most critical factors for birds on pasture: if the bird won’t eat a plant, the benefits of the plant—no matter how nutritious—are worthless. Several factors directly affect palatability:

Plant Species/Variety. Like people, poultry find some plants highly palatable, while others are completely unappealing and will not be eaten. Some plants have strong flavorings that poultry love, like the tart taste of yellow wood sorrel or clover seed pods, or despise, like the bitter fluid from milkweed. Generally, legumes and young, soft grasses are appreciated, while forbs and shrubs can be hit or miss. Clovers and alfalfa have long been considered among the best forages for a variety of reasons: high protein content (legumes), lush leaves, perennial growth, and, importantly, because these legumes mature slower and stay palatable much longer than grasses. Grass leaves on average contain twice the fiber of legume leaves. Fiber content in alfalfa and crimson clover leaves at the mid-blooming stage is around 25%, compared to fescue and orchardgrass leaves that have fiber contents near 50% and up to 70% in big bluestem and bermudagrass as the plants go to seed. Given their structural purpose of supporting seeds, it comes as no surprise that stems are typically much higher in fiber than leaves (Buxton and Redfearn, 1997).

The specific variety of a plant can affect the amount of grazing a bird does on pasture. For instance, alfalfa varieties high in bitter tannins or saponins are less palatable than varieties with little of these compounds. The tannins can also depress protein digestibility and reduce overall feed intake, which can reduce feed conversion. Therefore, in the case of alfalfa, variety can play a significant role in the amount of vegetation consumed.

Feeding Poultry, a poultry nutritional text from 1955, makes the following suggestion on desirable species for poultry production:

“For poultry pastures, plants capable of forming a dense, hard-wearing, and lawnlike turf are desirable. Wild white clover and ladino clover are suitable legumes. Grasses suitable for poultry turf are perennial rye grass, meadow grasses, the fescues, creeping bent, and crested dog’s tail. However, poultry does not like the plants after they have become aged and woody and will then only eat them as a last resort. Turkeys prefer ladino clover, but other grasses can be satisfactorily used for grazing.” (Heuser, 1955)

Stage of growth. As pasture forage plants near maturity, they will direct energy and nutrients away from producing nutrient-dense leaf mass and into producing the next generation of seeds. Funneling nutrients into the seeds, which includes pulling nutrients from existing leaf mass, greatly decreases the livestock feed value of the forage. Additionally, the lignin content (roughly, the “woodiness”) of the plant increases as the plant gets closer to producing fruit or seeds, especially in the stems (resulting in higher fiber content). As an example, alfalfa’s nutritive qualities plummet after the blooming stage. It makes sense that the younger the forage, the more tender and palatable it will be. Plant stems become lignified faster than leaves, and rapidly become indigestible and unattractive to poultry.

Although grasses can be higher in several nutritive qualities, other plants may be preferred as forages because they stay palatable for a longer time during the growing season. It was noted in the 1950s that “clover and alfalfa ranges are preferred [for poultry], primarily because the green stuff is available over a longer period of the year. They do not grow up and become tough and unavailable, as grass does. Frequent mowing of grass, either with ruminants or machinery, however, will help keep it tender” (Heuser, 1955).

Ready to learn more? Check out the ATTRA publication Pastured Poultry Nutrition and Forages. This publication explores the important role that forages play in pastured poultry production for either meat or egg production. Research on the effects of raising poultry on pasture has increased greatly in recent times, with an ever-growing body of scientific work. This publication pays special attention to the nutritional benefits of poultry foraging on pasture: regarding both the birds’ health and the impact that forages have on the nutritional and flavor qualities of the meat and eggs.

References:

Heuser, G. 1955. Feeding Poultry: The Classic Guide to Poultry Nutrition for Chickens, Turkeys, Ducks, Geese, Gamebirds, and Pigeons. Norton Creek Press, Blodgett, OR. Reprinted 2003.

Buxton, D., and D. Redfearn. 1997. Plant limitations to fiber digestion and limitation. Journal of Nutrition. Vol. 127, No. 5. p. 814S-818S.