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.

A study was carried out to determine the quality characteristics, antioxidant capacity, oxidative status, and consumer acceptability of chicken meat after dietary administration of a semi-solid olive cake, known as “paté” (pOC), in broilers. pOC is an olive oil industry waste rich in bioactive compounds, such as polyphenols, obtained by mechanical extraction from destoned olives. Two hundred and ninety-seven 22-day-old fast growing (Ross 308) female chicks were randomly assigned to three experimental grower-finisher diets. Each dietary group consisted of three replicates, each with 33 birds. The experimental treatments were: (1) basal control diet (C); (2) C diet supplemented with a low dose of pOC (82.5 g/Kg, L-pOC); and (3) C diet supplemented with a high dose of pOC (165.0 g/Kg, H-pOC). Chicken growth rate increased with increasing pOC concentration in the diet. Polyphenol analyses were performed through liquid-chromatography coupled to tandem mass spectrometry technique (LC-MS/MS). In meat of animals belonging to L-pOC and H-pOC groups, tyrosol and sulphate metabolites of hydroxytyrosol were detected. Meat quality parameters and proximate composition were not affected by the dietary treatment, whereas the antioxidant status and the oxidative stability of meat were positively affected, especially when the highest level of pOC was applied. These results demonstrate that pOC can be recommended in chicken diets to improve performance and meat oxidative status.