Evaluation of Rotation Grazed Pastures from Esophageal and Hand Gathered Forage Samples¹

Abstract

A study was conducted to determine changes in certain characteristics of rotation grazed irrigated orchardgrass‐alfalfa pastures. Samples for botanical composition and selected proximate components were taken from esophageal fistulated animals and by hand collection. Botanical composition at the beginning of each rotation from the esophageal samples was similar to that of the hand samples. However, at the end of the rotations the esophageal samples had a grass‐alfalfa ratio of 6:1 while the hand samples had a ratio of 3:2. Dry matter digestibility was similar each year but first‐day samples were more highly digestible than last‐day samples. for a given date there was no difference between dry matter digestibilities of hand and esophageal samples. First‐day samples had higher protein levels than last‐day samples. There was more protein in the esophageal samples than in the hand samples but it was not as digestible. The net effect was that by both methods the estimate of digestible protein intake per unit weight of dry matter was approximately equal. Crude fiber was higher at the end of a rotation than at the beginning and the esophageal samples contained less crude fiber than the hand samples. Crude fiber digestibility declined in both kinds of samples from the first to last day of grazing a rotation. Total digestible crude fiber intake per unit weight of dry matter intake was not the same for the two methods.

Cattle Preferentially Select Birdsfoot Trefoil from Mixtures of Tall Fescue and Birdsfoot Trefoil

“…These results are supported by research in Washington and Kansas in the USA as well as Saskatchewan and Manitoba in Canada that shows grazing cattle select forage with lower fiber and higher crude protein concentrations when compared to the forage‐on‐offer (5,8,12). This tends to occur in both monocultures as well as in mixed pastures, but the differences are often larger for mixed pastures than for monocultures (5).…”

Selection and Dietary Quality of Beef Cattle Grazing Smooth Bromegrass, Switchgrass, and Big Bluestem

“…Animal performance on warm-season grass pastures is often better than predicted from IVDMD, CP, or fiber fractions (Forwood, 1986). Grazing animals select diets greater in CP and lower in fiber compared with forage-on-offer (Galt et al, 1969;Heinemann and Russell, 1969) in mixed pastures and rangeland. Grazing animals on mixed pastures or rangeland are allowed to select from different forage species to augment the diet throughout the grazing season.…”