Ways for Determining Range Forage Quality


Several earlier articles here on Cattle Management provided steps for estimating the amount of forage present in a pasture. A forage inventory is not complete, however, until plant quality is determined. Forage quality is easily measured on improved pastures or areas where only a few plant species are distributed uniformly across the acreage. Representative samples of the forage are collected and sent to a laboratory for nutrient analysis.
Determining forage quality on rangeland is more difficult because of the number of different plant species and their uneven distribution. Another complicating factor is that cattle are selective in what they choose to eat when given a choice. Because of range plant variability and livestock grazing habits, determining forage quality through plant sampling is very time-consuming. The quickest and best way to determine if cattle are receiving their required nutrition is to observe their feces.
A Forage Quality Photo Guide has been assembled by Lyons, et. al. and is available through the Texas AgriLife Extension Bookstore. Photographs of four different appearances of cow fecal pads are presented in the guide with the following descriptions of how they relate to a cow’s nutrition.
1) “Forage contains greater than 20 percent crude protein with a digestibility of 70 to 80 percent, if the dropping forms around grass stems or whatever is beneath it. The feces is a dark green color and has little shape of its own. Protein and energy availability exceeds the cattle’s requirements for maintenance, growth or lactation.
2) A slight crater-like appearance in the surface of a fecal pad indicates a forage crude protein level between 10 percent and about 17 percent and a digestibility of 61 to 67 percent. In the 10 to 13 percent crude protein range, small folds may be present in the dropping. At these nutritional levels, supplementation or the addition of protein and energy to the diet is not required for mature cows. Forage, that creates droppings like this, should support one pound to 1.5 pounds average daily gain on heifers and steers.
3) When a dropping exhibits flat folds, forage crude protein level is between six and nine percent and digestibility is from 58 to 63 percent. As forage quality increases within these ranges, the folds become smaller. Droppings with folds indicate forage quality is adequate to supply maintenance requirements for mature cows. Minimal weight gain in replacement heifers and stocker cattle should be expected.
4) Forage crude protein level of five percent or less and digestibility at or below 56 percent is depicted by cow feces pads resembling stacks of hard dry rings. These droppings indicate that forage is below the maintenance requirements for all classes of beef cattle. Forage digestibility and intake may increase with protein supplementation.
Increased levels of cattle activity can result in loose droppings. To obtain good forage quality estimates, evaluate cattle dropping consistency only after they have undergone a rest period.”
These evaluations allow a producer to determine if range forage has a nutritional deficit. If a deficit does exist, the evaluations are accurate enough for determining the type and amount of needed nutrient supplement. Feces pad observations provide prompt indications of nutritional deficits and allows the problem to be corrected within a 48- to 72-hour period.
Fuente: TCB

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