Cecal dilatation in cattle ingesting Megathyrsus maximus (syn. Panicum maximum) cv. Mombasa and cv. Tanzania

Nine outbreaks of cecal dilatation are reported in cattle in rotationally-grazed pastures of Megathyrsus maximus during the rainy season with one day grazing and rest intervals of 23-28 days. Clinical signs, observed 6-24 h after entering the pasture, were inappetence, long periods in sternal recumbency, rough hair coat, arched back, tenesmus with difficult defecation, dry stools, reduced ruminal movements, intestinal tympany with right abdominal distention, and decreased milk production. The animals recovered 8-12 h after their removal from the pastures. All pastures were fertilized at 80-120 kg/ha of urea/year. In six farms, in addition to urea, chicken litter (CL) was also added. Water-soluble carbohydrates (WSC), non-fiber carbohydrates (NCF) and starch concentrations in the pastures causing tympany were higher (P < 0.05) than in control pastures. To demonstrate the relationship of the disease with fertilization of the pastures, a pasture of M. maximus was divided into five blocks of 16 m(2) and each block subdivided into four plots each, totaling 20 plots. One plot of each block was randomly chosen for 1 of 4 different treatments: 1. fertilized with 8 t/ha of CL; 2. fertilized with 16 t/ha of CL; 3. fertilized with 180 kg/ha urea; 4. control without fertilization. In general, plots fertilized with urea or with CL had higher NFC and starch concentrations (p < 0,05) than the control plots. In another experiment a pasture of M. maximus was divided into 23 paddocks and rotationally grazed. Ten paddocks were fertilized with 180 kg/ha of urea and five fertilized with 8 t/ha of CL. The concentration of NFC and starch were significantly higher (p < 0.05) in the pastures fertilized with urea and with urea plus CL. These results suggest that cecal dilatation may be caused by the high concentrations of NFC and starch in the pastures fertilized with urea and/or poultry litter.