Mineral composition and nutritive value of fresh and supplemented rice straws preserved in manual stacking, balling, and wrapping storage methods

Rice straws are underutilized as feed due to cattle’s preference for fresh straw. Rice straws have low nutritional value and are easily susceptible to microbial spoilage during traditional storage of loose stacking or manual open-air balling. Supplementing fresh rice straws with some minerals, energy, and protein could improve the nutritional value and storage stability under different preservation methods. The present study aimed to determine the effect of supplementing fresh rice straws with minerals, molasses, and urea, stored under three manual treatments: loose stacking, open-air balling, and airtight wrapping. Fresh rice straws were treated with 1% calcite-based mineral mixture, 0.6% molasses, and 0.05% urea and stored for 60 days. The supplemented rice straws were chopped and mixed with a basal diet composed of 55% elephant grass and 20% concentrate. Four experimental diets were then developed from the composite. That is the basal diet + fresh rice straw (FRS), basal diet+stacking supplemented rice straw (SSRS), basal diet+balling supplemented rice straw (BSSR), and basal diet+wrapping supplemented rice straw (WSRS). The experimental diets were fed to young Pesisir bulls using a 4x4 Latin Square design for eleven days. Fresh and supplemented rice straws were analyzed for dry matter, mineral content, blood hematology profile and protein content. The fresh rice straw had a relatively high potassium, iron, and manganese content but was low in calcium, sodium, phosphorus, copper, and selenium. Supplementation significantly increased the concentration of calcium, phosphorus, potassium, sodium, copper, and selenium in the preserved rice straw. Rice straw preserved in the wrapping way had the highest copper, cobalt, and selenium content. Feeding cattle with supplemented rice straw preserved in the wrapping method, decreased the blood monocyte value equivalent to that of the fresh straw. Supplementation of fresh rice straws with calcite-based minerals, molasses, and urea has the potential to increase some essential mineral content and maintained the nutritional value of rice straw preserved in an air-tied wrapping method. Key words: Calcites, Hematology, Mineral, Pesisir cattle, Rice straw, Storage, Supplementation