HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Fernandez-Rivera, S. Articles by Thompson, T. L. Search for Related Content PubMed PubMed Citation Articles by Fernandez-Rivera, S. Articles by Thompson, T. L.

A Simulation Model of Forage Yield, Quality and Intake and Growth of Growing Cattle Grazing Cornstalks¹

University of Nebraska, Lincoln 68583

Abstract

A simulation model was developed to predict corn crop residue yield and quality and intake and performance of growing cattle grazing cornstalks. The model is wholly deterministic and integrates the effects of weather, residue supply and animal components. Low temperatures increase animal energy requirements, whereas snow cover decreases residue available. Residual grain and leaf are calculated from grain yield. Residue quantity and quality are reduced daily by environmental losses and animal consumption. Daily performance is predicted based on the nutrients obtained from residue and supplemental feed. Under unlimited roughage supply, leaf, husk and grain are primary diet components. Grain consumption decreases as the supply diminishes and forage quality decreases with time. Intake is calculated based on digestibility and fecal output = .0365 W^.75. Forage availability affects intake in a curvilinear fashion. Energy gain is predicted by NRC equations and protein gain from metabolizable protein supply. The model underestimated intake of calves measured with chromic oxide and in vitro DM disappearance. Simulated daily gain (y, kg) of calves grazing at several stocking rates was related to observed daily gain (x, kg) by the equation y = .012 + .853x (R² = .71, Sy·x = .077). The model overestimated response to protein supplementation. Severe cold weather was predicted to reduce gains or cause weight loss due to increased energy requirements for maintenance. The model can be used as an aid in both research planning and cattle management.

¹ Published with the approval of the Director as Paper No. 8548, Journal Ser., Nebraska Agric. Exp. Sta.

² Present address: Universidad Autonoma Chapingo, Departamento de Zootecnia, Chapingo, Mexico 56230.

³ Dept. of Anim. Sci.

⁴ Dept. of Agric. Eng.