title: Short communication: Effect of straw inclusion rate in a dry total mixed ration on the behavior of weaned dairy calves.
abstract: The primary objective of this study was to determine the effect of straw inclusion levels on the feeding behavior of young, weaned calves adapted to a dry total mixed ration (TMR) composed of a multitextured concentrate and chopped straw. A secondary objective was to determine how developed feeding patterns persist after calves were switched to a conventional silage-based diet. Ten Holstein bull calves (91 ± 2.4d of age, weighing 136 ± 12.3 kg) were assigned to 1 of 2 treatments: a TMR containing [dry matter (DM) basis] either (1) 85% concentrate and 15% chopped straw for 10 wk (wk 1 to 10) or (2) 85% concentrate and 15% chopped straw for 5 wk (wk 1 to 5), then 70% concentrate and 30% chopped straw for 5 wk (wk 6 to 10). After 10 wk, all animals were transitioned to a TMR containing (DM basis) 42.3% corn silage and 57.7% haylage for 2 wk (wk 11 to 12). During wk 1 to 5, all calves had similar DMI (5.5 kg/d), average daily gain (1.7 kg/d), feed efficiency (3.5 kg of DM/kg of gain), and eating time (151.9 min/d). During wk 6 to 10, calves transitioned to the 70% diet ate less DM (5.5 vs. 7.4 kg/d), grew more slowly (1.3 vs. 1.6 kg/d), sorted more against long forage particles (62.8 vs. 103.8%), and had greater feeding times (194.9 vs. 102.6 min/d). The difference in feeding time occurred only during the first 8 h after feed delivery. Despite similar DMI (5.2 kg/d) and average daily gain (1.1 kg/d) in wk 11 to 12, differences in behavior were observed resulting from previous diets. In wk 11 to 12, calves previously fed the 70% diet continued to have a longer meal immediately after feed delivery. Overall, the results indicate that diluting a dry TMR containing a multitextured concentrate and chopped straw with more straw resulted in calves spending more time feeding and having longer meals immediately after feed delivery; this feeding pattern carried over after calves were transitioned to a silage-based ration.
authors.affiliation: Department of Animal and Poultry Science, University of Guelph, Kemptville Campus, 830 Prescott Street, Kemptville, ON, K0G 1J0 Canada; Animal Nutrition Group, Wageningen University, PO Box 338, 6700 AH Wageningen, the Netherlands.
authors.forename: M J
authors.initials: MJ
authors.lastname: Groen
authors.affiliation: Nutreco Canada, 150 Research Lane, Guelph, ON, N1G 4T2 Canada.
authors.forename: M A
authors.initials: MA
authors.lastname: Steele
authors.affiliation: Department of Animal and Poultry Science, University of Guelph, Kemptville Campus, 830 Prescott Street, Kemptville, ON, K0G 1J0 Canada. Electronic address: tdevries@uoguelph.ca.
authors.forename: T J
authors.initials: TJ
authors.lastname: DeVries
mesh_terms: D000821:Animal Feed / Q000032:analysis*; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D002417:Cattle / Q000502:physiology*; D004032:Diet / Q000662:veterinary; D004435:Eating; D005247:Feeding Behavior / Q000502:physiology*; D008297:Male; D018547:Plant Stems; D012820:Silage
keywords: dairy calf; feeding behavior; straw; total mixed ration