Evaluation of cattle feeding preferences using short-term trials

Eight Podolian (mean LW: 400 kg) and eight Italian Friesian (mean LW: 500 kg.) non-lactating cows were used in this experiment. They aged 4 years and had the same range experience, having grazed on natural pasture of Pignola (Potenza, Italy). Two grasses (Lolium perenne – ryegrass, DM 31.8 % and Avena sativa – oat, DM 42.8%) and two legumes (Trifolium squarrosum – clover, DM 28.8% and Onobychis viciaefolia – sainfoin, DM 33.5%) were tested. Plants, harvested just before their utilisation, were chopped into 4-6 cm pieces. Each group was exposed to a one-week training period into its home straw bedded pen: cows were moved once a day to the manger where they received approximately 4 kg of a mixture containing the four experimental plants in two plastic baskets. Subsequently, each plant was separately tested with each other. Each comparison was performed on separate days. All the animals on each day received the same treatment (plant comparison). Therefore, the experimental design was series of six consecutive trials, one conducted every 24 h. Two minutes before the beginning of the trial each animal was moved to the manger. Trials consisted of a double-choice presentation where the animal was offered the two plants to be simultaneously tested. Cows were allowed to eat for 5 min. or take a maximum of 30 bites. In this latter case the two baskets were removed. Herbage was weighed before and after each presentation in order to determine the total intake using an electronic digital scale. A control basket was used to measure evaporative weight losses. During each double choice presentation an observer recorded the plant which was ingested first, number of bites and feeding time (prehension time + mastication time). These data were used to calculate bite mass (dry matter ingested per number of bites), bite rate (number of bites per feeding time) and intake rate (dry matter ingested per feeding time). Preferences of the animals were determined as a proportion of the first 30 bites, proportion of total feeding time and proportion of total intake. Plant species did not affect intake rate of Friesian cows. Conversely, Podolian cows had higher grasses intake rates (P<0.05) compared to legumes. In particular, they showed a higher intake rate for oat than for the other plant species. Both breeds showed a preference for legumes than grasses. In addition, Friesian cows ingested a higher proportion of clover, whereas Podolian subjects preferred sainfoin (P