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Correlation of Steer Average Daily Gain with Diet Quality and Forage Phenology in an Improved Annual Grassland

1989; University of Arizona; Volume: 42; Issue: 5 Linguagem: Inglês

10.2307/3899552

2162-2728

C. A. Raguse, James G. Morris, Virginia N. Landry,

Agronomic Practices and Intercropping Systems

Management of legume-improved ammaI range forage is made difficult by the rapid decIiner in nutritive quaIity and animaI gains as tbe pIants mature.An improved abiIity to predict occurrence of tbe critIcaI spring graxing period (CSGP) when these declines begin would belp in making livestock management decisions.Objectives of tbis study were to construct a model to describe seasonal changes in steer average daily gain (ADG); to observe changes in nitrogen concentration ([ND and in vitro organic matter digestibiiity (IVOMD) related to time of season and ADG; and to relate the phenological progress of maturation of rose clover (Trifolium hi&m L.) to ADG, IN], and IVOMD.Data from 5 years of a grazing experiment were used to construct the ADG model, wbicb consisted of 3 season-reiated zones which were described by a series of linear and quadratic functions.Data for [N] and IVOMD from 2 spring seasons of sampling with esophageally II&dated steers, and from 1 seeson of hand-cut sampiing of roee clover and other plant species from annurrl range were reiated to the CSGP.Nitrogen content of the forage was a more useful predictor of rapid ADG change during the CSGP than was IVOMD.Tbe CSGP midpoint coincided with an approximately 0.5:0.5 mixture of 2 well-defined maturation stages of rose clover.