Effect of non-forage roughage replacement on feeding behaviour and milk production in dairy cows

The objective of this study was to determine whether the partial replacement of roughage from forage with non-forage fiber sources, in a total mixed ration (TMR), could reduce feed sorting by dairy cows without modifying behaviour and milk production. Twelve Holstein cows were fed two TMR maize silage based diets in a cross-over experiment. Compared to the control diet (C-diet), experimental diet (Ediet) was formulated by replacing 8% neutral detergent fibre (NDF) from straw and alfalfa hay with soybean hulls and wheat bran. E-diet had a lower physical effectiveness factor (pef) (0.37 vs 0.34; P<0.001) and physical effective NDF (peNDF) (15.5 vs 14.6%; P<0.01). Feeding and sorting behaviour, ruminal activity, milk yield and composition and blood metabolites were measured. The results indicated that dry matter intake was not affected by diet. Cows fed the experimental TMR spent less time eating (192 vs 178 min/d; P<0.05) but showed the same number of meals per day. C-diet fed cows sorted against peNDF in a greater extent (98.3 vs 100.9%; P<0.05). Treatments did not affect cows time budget of general behaviours, with particular regard to ruminating activity. Despite different forage sources in TMR, no significant differences in milk yield and quality were detected.