Francisco Leonardo Costa de Oliveira

Effects of sudden melon intake on ruminal parameters of non-adapted sheep

This study evaluated the effects of varying amounts of melon with high sugar content offered to sheep without prior melon experience and that were not adapted to consuming it. We used 12 eight-month-old, rumen-cannulated crossbred sheep weighing 25 kg each. The animals received a base diet of roughage, and then half were randomly selected to have 25% of their diet replaced with melon (G25%) and the other half had 75% of their diet replaced with melon (75%). Ruminal fluid was collected before administration of melon and at 0, 3, 6, 12, 18, and 24 h after the administration of the fruit. Sheep from the G25% group presented volatile fatty acid ruminal acidosis (sub-acute) between 3 and 6 h after consumption. This acidosis was characterized by a rumen pH slightly lower than 5.6, increased discrete L-lactic acid content, and increased redox potential (RP) and methylene blue redox (MBR) time of the ruminal fluid. The G75% group presented lactic ruminal acidosis at T6h, characterized by a rumen pH lower than 5.0, high lactate-L content, increased RP and MBR time, and increased ruminal fluid osmolarity. Therefore, offering large amounts of melon (75% of dry matter (DM)) is not recommended but 25% of DM of this fruit can be used safely.

Potential prophylactic effect of recombinant bovine somatotropin (rbST) in sheep with experimentally induced hyperketonemia

Hyperketonemia in sheep is associated with a disease known as pregnancy toxemia. The purposes of this study were to (1) induce hyperketonemia by infusion with D-beta-hydroxybutyrate (D-BHB) in eighteen healthy, non-pregnant, non-lactating ewes, (2) to evaluate the metabolic pathways in which recombinant bovine somatotropin (rbST) may be involved, and (3) to evaluate the possible benefits of preventive rbST therapy on the metabolic profiles of the sheep. The sheep were intravenously infused with a D-BHB solution over 2 h. Three days prior to the infusion, one group (n = 9) was injected with a single dose of 160 mg rbST, and the other group (n = 9) was injected with saline as a control. Blood samples were collected and metabolic profiles were analyzed every 20 min during the infusion and at 15, 30, 60, 120, 180, and 240 min post-infusion. Hyperketonemia was successfully achieved, demonstrated by serum BHB concentrations of 3.9 and 3.0 mmol/L in the rbST and control groups, respectively, without the presence of clinical signs. An increase in peripheral insulin resistance was observed after infusion but not during the infusion, in the rbST group. Higher glucose concentrations were observed in the rbST group post-infusion, suggesting a positive impact of D-BHB on gluconeogenesis. Our data suggest that prophylactic treatment with rbST may be useful in sheep to reduce the risk of PT.