Stocking rate influences the amount of grain, husk, and leaf available per animal. The amount of grain and husk available affect diet quality because both are highly digestible. The rate of decline in digestibility is affected by stocking rate, trampling, residue components available, and environmental factors. Previous comparisons have shown that gains increase as stocking rate decreases. Stocking rate influences the quality of the diet consumed and, consequently, the animal performance.

Residue (leaf and husk) yield is related to grain yield, but hybrids obviously vary in this relationship. With high producing corn (irrigated or with ample rainfall) there will be about 16 lb dry leaf and husk per bushel corn yield. Some residue disappears by trampling and other factors. We estimate 50% utilization of the leaf and husk. Therefore, 150 bu corn produces 2400 lb (16 lb of leaf and husk dry matter per bu of corn x 150 bu/acre) leaf and husk per acre on a dry matter basis and 1200 lb (50% of the total 2,400 lb) of husk and leaf on a dry matter basis available for the animal to consume. This is equivalent to about 1.76 AUM (1200 lb of husk and leaf per acre at 50% use/680 lb of feed per AUM). One Animal Unit Month (AUM) is the amount of forage required to sustain a 1,000 pound cow or equivalent for one month and it has been determined that a 1,000 pound cow will consume 680 pounds of dry matter monthly. A 1200 lb cow is 1.2 AU and would consume 816 (680 lb x 1.2AU) pounds of forage dry matter per month. If the corn yield was 150 bu per acre and that yield produces 2400 lb of husk and leaf per acre on a dry matter basis and 50% of the husk and leaf are consumed, then this residue field would provide 1.5 AUM’s (1200 lb of husk and leaf on a dry matter basis per acre/816 lb of forage per month for a 1200 lb cow = 1.47 AUM’s) per acre for a 1200 lb cow or 44 days of grazing (30 days per month x 1.5 AUM’s = 44 days of grazing). If one acre would feed a 1200 lb cow for 44 days then it would feed a 600 lb calf for 88 days. Higher grain yields provide more AUM and lower yields less. One acre of irrigated corn stalks or grain sorghum stubble will provide approximately 1.5 to 2 AUM of grazing. This number depends, though, on factors such as harvest conditions and subsequent weather conditions.