Pelleted Maize Plants as a Forage Extender for Dairy Heifers on Improved Pastures in Puerto Rico

Abstract

A study to determine the effects of a high quality roughage supplement on heifer groth rate was conducted at the Corozal Substation. Sixteen dairy heifers, averaging 190 kg, were subjected to a 43-day adjustment period to grazing of heavily fertilized Pangola grass (Digitaria decumbens). They were then assigned in equal number to either grazing of Pangola grass alone or grazing supplemented with 2.27 kg per day of dehidrated wholeplant maize (Zea mays) pellets. Grazing was at the rate of five head per ha, each treatment being rotated among four assigned pastures of 0.40 ha each. Both groups were rotated to new pastures simultaneously and weighed at 5- to 7-day intervals. The trial was terminated when body weights averaged 320 kg. During the early weeks, supplementation of pasture with maize pellets proved detrimental to weight gains as heifers grazing alone gained more rapidly than heifers on grass supplemented with maize pellets. This discrepancy was due primarily to maturation of herbage in the pastures grazed by the latter heifers. later in the trial the pellets were advantageous when pasture growth was inhibited by drought. Mean daily gain at 302 days was .29 and .44 kg for heifers on grazing only and on grazing and maize forage pellets, respectively. Pastures were sampled before and after grazing by clipping six quadrats of 0.84 m² 
each. Differences between before and after yields were significant. Treatments, sampling before and after grazing, cycles, and pastures within treatments showed significant differences. Cycle x sampling before and after grazing was the only interaction of significance, indicating the effect of the drought on intake of forage. The study showed that high-quality maize pellets are advantageous as feed for heifers on pasture, except when pastures are lush, plentiful and high in nutritive value.