title: The effects of physical form of feed, carbohydrate source, and inclusion of sodium bicarbonate on the diet selections of sheep.
abstract: We proposed an hypothesis that ruminants attempt to select a diet that promotes high levels of feed intake by maintaining optimal ruminal conditions. Three tests of the hypothesis considered whether the diet selection of sheep given either a choice of two high energy density (ED) feeds or a choice between a high and a low ED feed is affected by 1) sodium bicarbonate inclusion (NaHCO3; 1, 2, and 4% [wt/wt]) in the high [ED] feed); 2) dietary carbohydrate source (barley-based, B and sugar beet/ barley, S) of the high ED feed; or 3) physical form (alfalfa: pelleted, ALFP and long chop, ALFL) of the low ED feed. To conduct these, 42 lambs were used in seven 6 x 6 Latin squares, which were either foods ALFL and ALFP offered alone and paired with feed B or S and their NaHCO3 derivatives as a choice, or foods B and S offered alone and paired with their NaHCO3 derivatives as a choice. Each Latin square period lasted for 3 wk. For the choices between a NaHCO3-supplemented high ED feed and either a high or a low ED one, the inclusion of NaHCO3 increased feed intake. Its level of inclusion had a marked effect on the proportion of unsupplemented high ED feed selected (P < .05) but not on the proportion of low ED feed (alfalfa) selected. More alfalfa was selected when the high ED feed was based on barley (B) rather than sugar beet/barley (S) (P < .05). The physical form of the alfalfa affected diet selection because its selection was greater (P < .001) when ALFP (pelleted) was offered in the feed choice rather than ALFL (long-chop). The significant effects of NaHCO3 level, dietary carbohydrate, and physical form on the diet selection and feed intake of the sheep are consistent with the proposed experimental hypothesis.
authors.affiliation: Genetics and Behavioural Sciences Department, Scottish Agricultural College, Edinburgh, Scotland, United Kingdom.
authors.forename: S D
authors.initials: SD
authors.lastname: Cooper
authors.forename: I
authors.initials: I
authors.lastname: Kyriazakis
authors.forename: J D
authors.initials: JD
authors.lastname: Oldham
mesh_terms: D000821:Animal Feed / Q000592:standards*; D000818:Animals; D001835:Body Weight / Q000502:physiology; D004040:Dietary Carbohydrates / Q000008:administration & dosage / Q000494:pharmacology*; D004063:Digestion / Q000502:physiology; D004435:Eating / Q000502:physiology; D004734:Energy Metabolism / Q000502:physiology; D005260:Female; D005511:Food Handling; D005518:Food Preferences / Q000502:physiology*; D001467:Hordeum / Q000592:standards; D000455:Medicago sativa / Q000592:standards; D012417:Rumen / Q000502:physiology; D012756:Sheep / Q000254:growth & development / Q000502:physiology*; D017693:Sodium Bicarbonate / Q000008:administration & dosage / Q000494:pharmacology*
chemical_list: D004040:Dietary Carbohydrates; D017693:Sodium Bicarbonate