What happens when you feed cattle poorly?

By Gary Sliworsky
OMAFRA Rep.

Can cattle survive on poor quality forage? How bad is too bad? What problems does feeding low quality forage present? When feed is in short supply and that old field of mature grass is baled up, sometimes these questions arise. Following are some considerations from Barry Potter, OMAFRA.
Poor quality forages do not digest very quickly. They take longer to go through the digestive system. So the first problem posed is that intake is lower than normal when cattle are eating very low quality forage.
For example, a 600 lb. feeder should consume 2 % of its body weight, on a dry matter basis. This works out to about 14 lbs. of hay, on an as fed basis. But using % of body weight as an indicator does not account for the quality of the forage. A better thumb rule is that cattle can eat about 0.9 % of their body weight in Neutral Detergent Fiber. Therefore a 600 lb. stocker could actually eat 5.4 lbs. of NDF fiber.
NDF indicates the amount of digestible fibre in the ration. The more fibre, the less intake of feed by an animal. Looking at two different types of forage will show why this rule works better. If we have an average quality hay with 42 % NDF, the stocker will consume about 15 lbs. of hay (5.4 / 0.42 / 0.85 {hay being 15 % moisture}). However, if we feed a poor quality hay of 62 % NDF, then that same stocker can only eat 10 lbs. of hay (5.4/ 0.62 / 0.85).
Not knowing the difference in quality of feed, and the intake of the animal could mean that the stocker starves to death or does very poorly, even though full of feed. Step one for a farmer should be to test his forages for protein, total digestible nutrients (TDN), acid detergent fibre (ADF), and neutral detergent fibre (NDF), as well as major minerals. NDF will give an indication of digestible fibre, while ADF provides an indication of the energy in the feed. The higher the ADF, the lower the energy. When you have high fiber, low energy feeds the intake and energy consumption problem is compounded.
Feeding poorer quality feed will decrease an animal’s performance as the animal can not maintain itself or grow. Other symptoms may manifest themselves with breeding females (especially heifers) through reduced growth, weak calves born, lower quality colostrum, and a tendency to slow re-breeding.
Since poor feed also tends to have more dust or molds, more of it is usually wasted. Chopping the hay can reduce sorting, reduce feed refusal, and increase digestion of the feed.
Sometimes we are forced to feed very low quality feed. Make sure you know how much the livestock are eating, and then combine this information with feed analysis to ensure they are meeting nutrient and performance requirements.
Dates to Remember
Nov.2 – RR Federation of Agriculture Annual Fall Dinner Meeting, Emo Legion