Tropical grasses such as Bermudagrass, bahia grass, African star grass and Pangola grass are well adapted and are the main forages for much of the southern U.S.
These C4 grasses are able to produce higher amounts of dry matter per unit of water than C3, or cool-season grasses. They also produce more dry matter than C3 grasses.
However, this comes at a cost in the way of higher fiber content and lower energy than most cool-season grasses.
It is because of this higher fiber content that animal performance is much lower in mid-summer when temperatures are higher. The ruminant animal has to deal with the high outside temperatures and the higher inside temperatures caused by the high fiber being digested.
There is also the fact that fiber slows the passage of feed through the digestive tract, leading to the animal to eat less when it needs to eat more due to lower nutrient concentration.
It is this lower nutrient concentration and lower intake that leads to lower animal performance in the summer months on tropical perennials.
To avoid this slump in animal performance we have several options:
-Use adapted genetics that maintain a higher relative intake on low-quality (sometimes called low-octane grasses ) and can handle the digestion heat and the outside heat.
- Use grass management that allows for lower fiber via less mature grass and more nutrient-dense grass. This may involve correct grazing management for this type of grasses, mowing when necessary, and ultra-high-density grazing when applicable.
- Supplement to lower the fiber content of the diet and increase nutrient intake, which is the least desirable option.
When we do some of this we will find we have excess grass in the summer and deficiency of grass in the winter.
What we can do is defer some of the grass for the winter, to be able to not feed hay, and then manage for the winter. I will describe that in my next post.