Rumen Metabolism and hematochemical profile in sheep as affected by linseed dietary supplementation

The supplementation of the diet with oilseeds is used to improve the nutritional value of meat and milk in ruminants, but may be associated with detrimental effects on ruminal fermentation in sheep. Seed processing is known to have an impact on fatty acids rumen metabolism, and only few data are available for linseed. The objective of this work was to study the effects of feeding raw or extruded linseed on ruminal fermentation characteristics, metabolic and lipidic profiles, and oxidative status in sheep. Six ruminally cannulated sheep were used. Animals were divided in 3 groups and received 3 diets according to a replicated Latin square design. Dietary treatments consisted of 1) a control (CTR) diet with no linseed added, 2) a raw linseed (RL) diet and 3) an extruded linseed (EL) diet. All diets were based on mixed hay (1500 g/d) and maize grains (200 g/d); RL and ER diets were supplemented with 130 g of linseed per day. After a 15-d adaptation period, ruminal pH, NH3-N and volatile fatty acids concentrations were analyzed. Blood was sampled before the morning feeding for analysis of alkaline phosphatase, aspartate aminotransferase, urea, total protein, creatinin, albumin, glucose, cholesterol, triglycerides, beta-hydroxybutyrate, not esterified fatty acids, total antioxidative status and glutathione peroxidase. Rumen pH was not altered by the dietary treatment. Ruminal ammonia (mg/dl) concentration was significantly (P<0.05) increased by the RL diet (CTR: 9.40; RL: 11.50; EL: 9.59). Total production of volatile fatty acids (mmol/l) was significantly (P<0.05) increased when EL was added to the diet (CTR: 0.64; RL: 0.77; EL: 0.82), but no differences in individual fatty acid proportions among treatments were observed. As for the metabolic profile, both linseed supplementations were shown to increase (P<0.05) alkaline phosphatase values (U/l) (CTR: 210.83; RL: 378.83; EL: 383.50). When RL was added to the diet, serum triglycerides (mg/dl) concentration (CTR: 24.86; RL: 38.26; EL: 36.34) was increased and cholesterol (mmol/l) level (CTR: 2.07; RL: 1.67; EL 1.78) was decreased (P<0.05). Feeding raw or extruded linseed, at a supplementation level of 130 g/d, did not affect main biochemical indicators of rumen metabolism in sheep. Hematochemical parameters were shown to be slightly influenced by the dietary treatment.