title: Chopped or long roughage: what do calves prefer? Using cross point analysis of double demand functions.
abstract: The present study aimed to quantify calves' (Bos taurus) preference for long versus chopped hay and straw, and hay versus straw, using cross point analysis of double demand functions, in a context where energy intake was not a limiting factor. Nine calves, fed milk replacer and concentrate, were trained to work for roughage rewards from two simultaneously available panels. The cost (number of muzzle presses) required on the panels varied in each session (left panel/right panel): 7/35, 14/28, 21/21, 28/14, 35/7. Demand functions were estimated from the proportion of rewards achieved on one panel relative to the total number of rewards achieved in one session. Cross points (cp) were calculated as the cost at which an equal number of rewards was achieved from both panels. The deviation of the cp from the midpoint (here 21) indicates the strength of the preference. Calves showed a preference for long versus chopped hay (cp = 14.5; P = 0.004), and for hay versus straw (cp = 38.9; P = 0.004), both of which improve rumen function. Long hay may stimulate chewing more than chopped hay, and the preference for hay versus straw could be related to hedonic characteristics. No preference was found for chopped versus long straw (cp = 20.8; P = 0.910). These results could be used to improve the welfare of calves in production systems; for example, in systems where calves are fed hay along with high energy concentrate, providing long hay instead of chopped could promote roughage intake, rumen development, and rumination.
authors.affiliation: Animal Production Systems Group, Wageningen University, Wageningen, Netherlands.
authors.forename: Laura E
authors.initials: LE
authors.lastname: Webb
authors.affiliation: Department of Animal Sciences, Aarhus University, Tjele, Denmark.
authors.forename: Margit Bak
authors.initials: MB
authors.lastname: Jensen
authors.affiliation: Biometris, Wageningen University, Wageningen, Netherlands.
authors.forename: Bas
authors.initials: B
authors.lastname: Engel
authors.affiliation: Livestock Research, Wageningen University and Research Centre, Lelystad, Netherlands.
authors.forename: Cornelis G
authors.initials: CG
authors.lastname: van Reenen
authors.affiliation: Animal Nutrition Group, Wageningen University, Wageningen, Netherlands.
authors.forename: Walter J J
authors.initials: WJ
authors.lastname: Gerrits
authors.affiliation: Animal Production Systems Group, Wageningen University, Wageningen, Netherlands.
authors.forename: Imke J M
authors.initials: IJ
authors.lastname: de Boer
authors.affiliation: Animal Production Systems Group, Wageningen University, Wageningen, Netherlands.
authors.forename: Eddie A M
authors.initials: EA
authors.lastname: Bokkers
mesh_terms: D000818:Animals; D002417:Cattle / Q000378:metabolism*; D003196:Computer Graphics; D004043:Dietary Fiber; D002149:Energy Intake; D005518:Food Preferences; D008297:Male