Dry matter intake and feeding behaviour of grazing dairy cows offered a mixed ration with or without canola meal

Abstract

Dry matter intake and feeding behaviour were measured in grazing dairy cows fed partial mixed rations with (PMR+C) and without (PMR–C) canola meal. In spring (early lactation), 32 Holstein–Friesian dairy cows were offered two amounts of the two supplement treatments in a two × two factorial arrangement of treatments for 24 days. Amounts of supplement were low (8 kg DM/cow.day) versus high (14 kg DM/cow.day). The PMR–C ration comprised wheat grain (59.5%, DM basis), maize grain (18.9%) and lucerne hay (21.6%). The PMR+C ration was the same, except some wheat grain was substituted with canola meal (21.6%). Both rations were isoenergetic, with a grain to forage ratio of 78 : 22 (DM basis). All cows were offered a low pasture allowance of 10 kg DM/cow.day to ground level. Replacing some wheat in a ration with canola meal increased pasture and total eating time. Dry matter intake did not differ between PMR–C and PMR+C cows. The present experiment also demonstrated that altering the amount of supplement did not influence the increase in eating time that occurred as a result of the inclusion of canola meal. Increasing the amount of supplement reduced pasture intake as a result of a reduction in grazing time and grazing intensity.