Diet Selection by Cattle Under High-Intensity Low-Frequency, Short Duration, and Merrill Grazing Systems

Abstract

A study was conducted to evaluate standing crop of forage and cattle diets for a 7-pasture high-intensity low-frequency (HILF) grazing system, and a 7-pasture short-duration grazing (SDG) system on the same area. A 4-pasture, 3-herd (Merrill) deferred rotation grazing system was sampled as a standard for comparison. Standing crop of forage was highest for the HILF grazing system compared to the SDG and Merrill grazing systems. The Merrill system with brush control (Pasture 10) had a greater standing crop than the Merrill system without brush control (Pasture 16) or the SDG system. Standing crop in Pasture 16 was comparable to the SDG system. Cattle diets from the HILF system varied significantly between collections at the beginning and end of each grazing period. A significantly higher percentage of forbs were consumed at the beginning of each grazing period (Period A) compared to the end (Period B). Cattle selected the greatest amounts of pricklypear at the end of each collection period during fall and spring, but not during the winter. Greater amounts of pricklypear were selected when mature grasses and oak and juniper browse were the primary alternatives. Crude protein (CP) levels of diets from the HILF system decreased with shifts in forage selection from Texas wintergrass and forbs (Period A) to pricklypear and dry grass (Period B). Diets from the SDG system were characterized by higher percentages of grass and less forbs and pricklypear compared to the HILF grazing system. Also, there were no major shifts in forage selection between collection period A and B for the SDG system. This resulted in a non-significant difference in CP values for diets collected in period A compared to period B. However, a significant decline was recorded for digestibility of diets between the two collection periods. CP and digestibility were higher for diets from the SDG system compared to the HILF grazing system. Botanical composition and diet quality were comparable for the SDG and Merrill grazing systems. Competition between different kinds of animals may be reduced by changing management from a HILF to a SDG system. This would be important where combinations of animals such as cattle, sheep, goats, and deer utilize a common range. Based on diet quality, livestock production from a SDG system should be equivalent to a Merrill system.