Cattle preferences for a hybrid grass: chemical and morphological relationships

Abstract

Forty-six clonal lines of a hybrid cross between Pseudoroegneria spicata [Pursh.] Scribn. and Smith × Elytrigia repens [L.] Beauv. were used to evaluate the influence of various chemical and morphological characteristics on cattle preference. Variables examined included total carbohydrates as well as several individual sugars, silica, nitrogen, moisture, leaf and growth form, phenology and plant height. In 3 of 4 trials, over 60% of the variation in preference as measured by bite counts was accounted for in the analyses. However, dominant factors controlling preference varied from trial to trial. Predictive equations developed for each trial (N=46) produced R2 values which ranged from 0.53 to 0.81. Common variables that influenced predictions included basal area, phenology, nitrogen, leaf score, and digestibility. Basal area was the most important single variable positively related to preference with an R2 value of 0.70 over all trials. Individual sugar analyses were not significantly (P>0.05) related to bites for most trials but became important from mid-June to mid-July. Equations which included sugar analyses (n=20), accounted for 73 to 87% of the variation in bites. However, basal area and phenology were the dominant variables in these equations. Therefore no single equation could be used to accurately predict preferences.