title: Growth, feed intake, carcass characteristics, and eating behavior of feedlot lambs fed high-concentrate diets containing soybean hulls.
abstract: The objectives of this experiment were to determine the effects of replacing ground corn with soybean hulls (SH) in high-concentrate diets on the growth (56-d period), carcass characteristics, and eating behavior of feedlot lambs. Sixty-four Santa Inês ram lambs (18.3 ± 2.8 kg of BW and 69 ± 5 d of age) were assigned to a randomized complete block design experiment with 8 blocks and 4 diets. The control diet contained 10% coastcross (Cynodon sp.) hay, 70% corn, and no SH (SH0) in the dietary DM. In the remaining diets, SH replaced corn at the rate of 15 (SH15), 30 (SH30), or 45% (SH45) of the original corn concentration, resulting in 0, 10.5, 21.0, or 31.4% SH in the dietary DM. Dry matter intake increased linearly (P < 0.01) when SH replaced ground corn (1.0, 1.0, 1.1, and 1.1 kg/d for SH0, SH15, SH30, and SH45, respectively). There was no effect on ADG of lambs, with values of 276, 278, 282, and 287 g for SH0, SH15, SH30, and SH45, respectively. Feed efficiency decreased linearly (P < 0.01) with SH inclusion. Carcass measures were not affected by SH as a replacement for ground corn. Eating time, expressed as minutes per day and minutes per gram of NDF, showed a quadratic effect (P < 0.05), whereas no effect was observed when expressed as minutes per gram of DM. Rumination, in minutes per day, was not influenced by dietary SH inclusion, but a linear decrease (P < 0.01) was observed when this variable was expressed as minutes per gram of NDF. Soybean hulls can replace up to 45% of the ground corn (31.4% of SH in the dietary DM) in high-concentrate diets fed to feedlot lambs without negative effects on ADG and carcass measures. The linear decrease in feed efficiency (11.6% reduction from SH0 to SH45) suggests that optimal dietary SH inclusion rates should be dictated by the relative costs of SH and corn.
authors.affiliation: Departamento de Zootecnia, Escola Superior de Agricultura Luiz de Queiroz, Universidade de São Paulo, Piracicaba, São Paulo, Brazil.
authors.forename: E M
authors.initials: EM
authors.lastname: Ferreira
authors.forename: A V
authors.initials: AV
authors.lastname: Pires
authors.forename: I
authors.initials: I
authors.lastname: Susin
authors.forename: C Q
authors.initials: CQ
authors.lastname: Mendes
authors.forename: R S
authors.initials: RS
authors.lastname: Gentil
authors.forename: R C
authors.initials: RC
authors.lastname: Araujo
authors.forename: R C
authors.initials: RC
authors.lastname: Amaral
authors.forename: S C
authors.initials: SC
authors.lastname: Loerch
mesh_terms: D000821:Animal Feed / Q000032:analysis*; D000822:Animal Husbandry; D000818:Animals; D001823:Body Composition; D031744:Cynodon; D004032:Diet / Q000662:veterinary*; D004435:Eating / Q000187:drug effects*; D005247:Feeding Behavior; D008297:Male; D012756:Sheep / Q000254:growth & development* / Q000502:physiology*; D013025:Glycine max / Q000737:chemistry*