Feeding behaviour and intake of heifers fed on hays of various quality, offered alone or in a choice situation

Abstract

We studied the feeding behaviour of cattle offered unconstrained choices between two hays of either different or similar nutritive values, and linked these choices to their behaviour when the same forages were offered alone. Over successive 10-day periods, six 15-month-old Aubrac heif- ers received three hays (a leafy one, G, and two late cut ones, C1 and C2, of very similar nutritive value), ad libitum, alternately alone and associated two by two. As expected, the heifers ate more G than C1 or C2 when the hay was offered alone, and preferred G in choice trials. They displayed a simi- lar behaviour towards C1 and C2 when they were given alone, and also when they were independently associated with G (C1 and C2 making up 18% and 17% of the total intake and 21% and 17% of total feeding time, respectively) or when they were offered together (each accounting for nearly 50% of the total intake or feeding time). The choices could be related to the daily intakes of the forages given alone, which could thus be a good predictor of relative daily intakes under choice conditions. Heifers always showed partial choices, which could be seen as the research of the maintenance of optimal ruminal conditions, the result of sampling behaviour and/or the pleasure associated with the diversity of the diet. Their tendency to diversify the diet was also supported by the reaction to the recent diet by temporarily increasing their preference for the hay that had not been offered during the previous no- choice sub-period. Finally, all the choice situations raised the daily dry matter intake, which could be seen as the result of their motivation to eat due to the diversity of the offer. feeding choice / intake / cattle / hay