Effects of dietary sainfoin on feeding, rumination, and faecal particle composition in dairy cows

Summary

An experiment was conducted to test whether dietary sainfoin (Onobrychis viciifolia), a plant containing condensed tannins, affects feeding and rumination behaviour of dairy cows fed different roughage-only diets. Out of a herd of sixty lactating Swiss Fleckvieh cows, twenty-nine were chosen for a 6-week experiment. Cows were fed pasture, fresh cut grass and hay. During week 1 (baseline) and weeks 2-4, they had access to pasture for 4 hours during day, and received approximately 6 kg DM/day fresh grass and 4 kg DM/day hay in barn. In week 5 and 6, daily pasture allowance was 2 h; hay offer was doubled. In week 2-6, each cow individually received respectively 1 kg of pelleted feed in the morning and in the evening. Ten cows received ryegrass pellets in week 2, 3 and 5, and sainfoin pellets in week 4 and 6 (sainfoin short term; SST). Nine cows were fed sainfoin (Sainfoin long term; SLT) and another ten ryegrass pellets (Control; C) during the whole term. Rumination and feeding behaviour was measured with RumiWatch® sensor halters during week 1, 4, and 6. Individual faeces samples (4 per cow/week in week 1, 4 and 6) were analysed for particle fractions (wet sieving at 4.0, 2.0, 1.0, and 0.3 mm). Data was evaluated with a general linear model using group and week as fixed factors; baseline data served as covariate. Compared to week 4, all cows showed an increased duration of feeding (15.5% ) and a decreased ruminating activity (14.2% ) in week 6 (p<0.001). Feeding sainfoin pellets (SLT and SST) led to decreased feeding time (2.0-4.6%) and increased rumination time (4.4-6.5%) compared to C (p<0.05) in both weeks. Total particle proportion in faecal DM was lower in SST and SLT by 11.7% compared to C (p<0.05). Also the proportion of the 1.0 - 0.3 mm fraction was lower in faeces of SST and SLC (p<0.05). Milk yields, fat and protein contents were not affected. Results indicate effects of sainfoin supplements on eating behaviour and digestion even when roughage composition varies. This approach could be further used to develop targeted feeding aimed at improving digestion and feed efficiency in low-input dairy systems.