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Instituto de Ganadería de Montaña (CSIC-Universidad de León). Finca Marzanas, E-24346 Grulleros, León (Spain)
Abstract
Three experiments were performed in order to study the nutritional characteristics of sugar beet pulp (SBP) according to the level of vinasse (condensed molasses solubles) added. Eighteen Merino ewes were used to study preference in Exp. 1, and 18 Merino ewes were used in Exp. 2 to study voluntary intake of SBP with different levels of vinasse inclusion (0, 7, and 13% on SM basis, SBP0, SBP7, and SPB13, respectively). Sheep showed a marked preference for SBP with vinasse regardless the level of addition, whereas voluntary feed intake was not affected (P > 0.34). Eight ruminally cannulated Merino ewes were used in Exp. 3 to study rumen fermentation of SBP0 and SBP13. Regardless of the diet fed to the animals (SBP0 or SBP13), disappearance rates of DM, NDF, and CP were greater when SBP13 than when SBP0 was incubated in sacco (P < 0.05), and NDF and CP disappearance rates were particularly high when animals were fed SBP13 diet. No significant differences were observed for pH, ammonia concentration, or total or individual VFA in the ruminal liquor of sheep at different sampling times after feeding (P > 0.23) in response to vinasse addition. Experiment 4 was designed to study digestibility, solid passage rate, and excretion of purine derivatives from 12 Merino ewes fed SBP0 and SBP13. Digestibility of NDF tended to be higher (P < 0.10) for the SBP13 group compared to the SBP0 group; digestibilities of DM, OM, CP, and ADF were not affected (P > 0.11). Digesta flow kinetics and urinary excretion of purine derivatives were not significantly affected by the presence (SBP13) or absence of vinasse (SBP0) in the diet (P > 0.21). In conclusion, sheep showed a clear preference for SBP with vinasse. However, the lack of significant differences in most of the in vivo variables measured indicates that ewes can be satisfactorily fed with any of the levels of vinasse inclusion studied.
Key Words: digestibility preference rate of passage rumen fermentation sugar beet pulp vinasse
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