Relation of Ration Sucrose Level and Grain Content to Lactation Performance and Rumen Fermentation

Abstract

Sixteen cows were used in a 4 × 2 factorial experiment in which sucrose replaced corn at 0, 3, 6, and 9% (dry basis) of total dry matter in rations of 30 and 70% grain. Solids-corrected milk yield increased linearly (P<5%) with increments of sucrose. Solids-corrected milk (SCM) yield and yield per megacalorie of estimated net energy were significantly lower for the 70%-grain than for the 30%-grain rations. Solids-corrected milk/estimated net energy (ENE) increased with increments of sucrose in the 30%-grain ration, but decreased with added sucrose in the 70% grain. Milk fat and solids-not-fat were not significantly altered by sucrose or grain levels. Raising the sucrose levels in the ration produced linear decreases of the molar percentages of propionate (24.2 to 19.2 molar per cent) and isovalerate (3.5 to 1.0 molar per cent) and a linear increase in butyrate (15.9 to 22.4 molar per cent) in rumen fluid. Inclusion of sucrose in the ration resulted in a high proportion of ketogenic acids (acetate plus butyrate) relative to propionate in the rumen fluid. Rumen pH and the ratio of acetate to propionate were not significantly different among treatments. © 1969, American Dairy Science Association. All rights reserved.