Sunflower Seed as a Protein Supplement for Cows Grazing Winter Range

Abstract

Seventy-four crossbred cows (538 kg) were used in a completely randomized design to evaluate the performance of gestating and/or lactating cows individually fed different protein supplements while grazing winter pasture in northeastern Colorado. Cows were fed one of the following supplements: 1) sunflower meal, negative control, (−SFM), 2) sunflower meal, positive control, (+SFM), 3) an equal combination of nitrogen from SFM and whole sunflower seeds (SFM:WS), and 4) whole sunflower seeds (WS). Supplements provided 273g CP per head per d, and the negative control provided 136g CP per head per d. Cows fed SFM:WS had higher (P=0.01) body condition scores during gestation and at calving than the other treatments. Over the duration of the trial, cows fed SFM:WS or WS had higher (P=0.06) body condition scores than those fed −SFM. Experiment 2 used four mature, cannulated cattle (618 kg) in a 4 x 4 Latin square arrangement of treatments to determine the effect of sunflower meal and whole seeds on intake and digestibility of brome grass hay (9.9%CP). Treatments were identical to those in experiment 1. Digestible DM intake was lowest (P<0.05) for −SFM. Dry matter digestibility was higher (P<0.05) for +SFM and WS than SFM:WS, all of which had higher (P<0.05) DM digestibilities than −SFM. The nylon bag technique was used to evaluate forage and supplement DM disappearance. Treatments were identical to those in experiment 1 and were not different as measured using the nylon bag technique to measure forage and supplement dry matter disappearance. These studies suggest that sunflower meal and whole seeds improved dry matter digestibility of low quality forage and have potential for minimizing cow body condition loss while grazing winter range.