The effect of harvest date on the yield and forage quality of ensiling safflower biomass

Safflower (Carthamus tinctorius L:) usually grown as a source of oil can be also used as fodder either for hay or ensiling purposes, particularly in semiarid regions. In 2002-2003 a research project was carried out in Southern Italy to evaluate the production and forage quality of safflower biomass cv Centennial (high oleic), harvested at three different stage: May 14 (at complete appearance of primary buds, PB), May 26 (at complete appereance of secondary and tertiary buds, STB), June 11 (at 25% of flowering stage, FS). For each stage of growth, 50% of the biomass was ensiled in 4-L glass jars without and with inoculation (Lactobacillus plantarum); the other 50% was field wilted for 24 hours before ensiling. DMY ranged from 4,5 t ha (PB harvesting) to 11, 6 t ha (FS harvesting). DM content varied from 129 g kg (PB not wilted) to 630 g kg (FS wilted). The following chemical parameters have been evaluated: pH, buffering capacity (BC), lactic acid, acetic acid, NH3-N, crude protein content (CP), water soluble carbohydrates (WSC), NDF, ADF, ADL, ash and fat. The WSC concentration in the forage before ensiling without wilting ranged from 128 (PB stage) to 105 and 100 g kg DM at STB and FS stage, respectively. The wilted safflower forage showed on the average a lower WSC (95.8 g kg DM) than for forage which was not wilted (111.4 g kg DM). The high sugar substrate allowed lactic acid fermentation and a good conservation quality in all the harvesting stages. Silages quality was strongly influenced by the treatment performed. Wilting practice as averaged effect increased DM, pH and NDF contents but reduced lactic acid, acetic acid and NH3-N values. Inoculation reduced, on the average, DM, pH and NDF contents but increased lactic acid, acetic acid, CP and ash values. Wilting the forage for one day is very effective on early stage of harvesting because this practice will greatly increase DM, reducing at the same time the intensive fermentation and proteolysis processes of the silage. When harvesting is performed at the beginning of flowering stage wilting is not necessary.