Energy metabolites and glycemic curve of sheep fed with different fiber levels in extruded roughage

Objective: To evaluate the energy metabolites and the glycemic curve of sheep fed with corn silage or different fiber levels in extruded roughage. Material and Methods: The experiment was conducted at the Small Ruminants Sector of Federal University of Uberlândia, Minas Gerais, Brazil. Twenty Santa Inês were used, with body weight of 64 kg and 4 years old, allocated in metabolic cages. The animal was distributed in a randomized design and fed ad libitum with (1) corn silage, (2) extruded roughage Foragge® with 52.5% (including virginiamycin as an additive), and (3) 60%, (4) 65%, and (5) 70% Urochloa (no additives added) at 8:00 am and 4:00 pm, during five experimental period of 15 days (10 days of adaptation and 5 days of collection). Blood samples were collected before feeding by venipuncture of the jugular vein using Vacutainer® tubes on days 11, 13, and 15 of the experimental periods. The data were subjected to normality and homoscedasticity tests, followed by analysis of variance, contrast for (1) roughage source and (2) additive addition in extruded roughage, and regression for the levels of extruded roughage (P≤0.05). Results: There was no effect of roughage on cholesterol (57.7 mg dL⁻¹; P = 0.34). However, the corn silage increased the triglyceride (32.67 vs. 16.81 mg dL⁻¹, P<0.01) and reduced the glucose (49.00 vs. 63.62 mg dL⁻¹; P=0.03) compared to the forage as a source of roughage. The additive and levels of extruded roughage (60; 65 and 70%) did not affect blood metabolites (P>0.05). No significant differences were found between sampling times (08:00 am; 11:00 am; 02:00 pm; 05:00 pm e 08:00 pm; 59,78 mg dL⁻¹; P=0.59) or for the treatment vs. time interaction (P=0.95). Conclusion: The use of extruded forage results in higher triglyceride and glucose levels compared to corn silage, indicating a greater energy supply.