Plasma profile of cimicoxib in sheep after oral administration at two different rates.

Sheep are often subjected to painful procedures and thus they need to be treated with analgesics. Nevertheless, knowledges about pharmacokinetic features of these drugs in this species are poor. The aim of this study was to evaluate plasma behaviour of cimicoxib in sheep after a single oral administration at two different dose rates (4 and 6 mg/kg). Maximum plasma concentrations of cimicoxib were equal to 273.78 (median value; range 189.00-567.32) and 565.01 (range 308.27-822.59) ng/mL after treatment with 4 and 6 mg/kg, respectively. The time of maximum concentration (Tmax) was achieved between 4 and 10 hours following treatment at the lower dose, and between 6 and 10 hours after the administration of the higher dose, with one sheep achieving the concentration peak at 0.75 hours. The slow absorption and the great individual variability in plasma concentration, probably due to ruminal effects, suggest that cimicoxib is not suitable for oral treatment in sheep.

Milk fatty acid composition, rumen microbial population, and animal performances in response to diets rich in linoleic acid supplemented with chestnut or quebracho tannins in dairy ewes.

The aim of the study was to evaluate milk fatty acid (FA) profile, animal performance, and rumen microbial population in response to diets containing soybean oil supplemented or not with chestnut and quebracho tannins in dairy ewes. Eighteen Comisana ewes at 122±6 d in milking were allotted into 3 experimental groups. Diets were characterized by chopped grass hay administered ad libitum and by 800 g/head and day of 3 experimental concentrates containing 84.5 g of soybean oil/kg of dry matter (DM) and 52.8 g/kg of DM of bentonite (control diet), chestnut tannin extract (CHT diet), or quebracho tannin extract (QUE diet). The trial lasted 4 wk. Milk yield was recorded daily, and milk composition and blood parameters were analyzed weekly. At the end of the experiment, samples of rumen fluid were collected to analyze pH, volatile fatty acid profile, and the relative proportions of Butyrivibrio fibrisolvens and Butyrivibrio proteoclasticus in the rumen microbial population. Hepatic functionality, milk yield, and gross composition were not affected by tannin extracts, whereas milk FA composition was characterized by significant changes in the concentration of linoleic acid (CHT +2.77% and QUE +9.23%), vaccenic acid (CHT +7.07% and QUE +13.88%), rumenic acid (CHT -1.88% and QUE +24.24%), stearic acid (CHT + 8.71% and QUE -11.45%), and saturated fatty acids (CHT -0.47% and QUE -3.38%). These differences were probably due to the ability of condensed versus hydrolyzable tannins to interfere with rumen microbial metabolism, as indirectly confirmed by changes in the relative proportions of B. fibrisolvens and B. proteoclasticus populations and by changes in the molar proportions of volatile fatty acids. The effect of the CHT diet on the milk FA profile and microbial species considered in this trial was intermediate between that of QUE and the control diet, suggesting a differential effect of condensed and hydrolyzable tannins on rumen microbes. Compared with control animals, the presence of B. fibrisolvens increased about 3 times in ewes fed CHT and about 5 times in animals fed QUE. In contrast, the abundance of B. proteoclasticus decreased about 5- and 15-fold in rumen liquor of ewes fed CHT and QUE diets, respectively. The use of soybean oil and a practical dose of QUE or CHT extract in the diet of dairy ewes can be an efficient strategy to improve the nutritional quality of milk.