Simultaneous substitution of forage and grain with sugar beet pulp in finishing lambs: impacts on feed efficiency, ruminal fermentation, and chewing behavior

Articles in Press

Document Type : Research Article (Regular Paper)

Authors

Department of Animal Science, College of Agriculture, Isfahan University of ‎Technology, Isfahan 84156-83111, I. R. Iran

Abstract

Sugar beet pulp (BP) is a by-product rich in both non-fibrous carbohydrates and highly digestible neutral detergent fiber. This study evaluated the effects of simultaneously substituting forage (alfalfa hay) and grains (corn and barley) with increasing levels of BP on growth performance, digestibility, chewing behavior, ruminal fermentation, and blood metabolites in fattening lambs. Twenty-six male Lori lambs (body weight= 28.2±3.6 kg) were randomly assigned to one of four iso-nitrogenous and iso-energetic diets in a completely randomized design. Diets included 0% (BP0), 10% (BP10), 20% (BP20), or 30% (BP30) BP, with BP replacing equal proportions of both forage and grains. As BP inclusion increased, the forage-to-concentrate ratio declined from 25:75 to 10:90, dietary neutral detergent fiber (NDF) increased (28.8% to 31.3%), and starch (43.5% to 32.6%) and forage NDF (14.2% to 6.9%) decreased. Increasing BP levels linearly reduced dry matter (DM) intake, while NDF intake remained unchanged. Apparent digestibility of DM and NDF increased linearly, but crude protein digestibility was unaffected. Average daily gain (ADG) tended to decline linearly, whereas feed efficiency showed a quadratic response, peaking at BP10 and BP20. Carcass traits (dressing percentage, tail fat, offal weights), blood metabolites (glucose, urea nitrogen, cholesterol, triglycerides, total protein, β-hydroxybutyrate), urine pH, and ruminal pH were not influenced by treatment. However, ruminal acetate proportion and the acetate-to-propionate ratio increased linearly, while propionate decreased. Total rumination time and rumination per kilogram of DM or NDF intake declined linearly, with the lowest values observed in BP30-fed lambs. In conclusion, moderate inclusion of BP (10–20%) improved fiber digestibility and feed efficiency without compromising health or carcass characteristics, despite a slight reduction in DM intake. Inclusion at 30% may reduce intake and chewing activity, potentially limiting its practical utility at this level.

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References

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Available Online from 25 May 2026

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