Effect of milk thistle (Sylibum marianum L.) endosperm in the diet for cows on milk yield and fatty acid profiles

The experiment was carried out an 30 multiparous Black-and-White Lowland co ws from 45 to 70 days of lactation, divided into three groups according to calving date and milk yield, and fed a basic ration consisting of maize, gr ass and sugar beet pulp silages with concentrate for the control group. In both of experimental groups, 20% of concentrate was substituted with endosp erm from milk thistle (Sylibum marianum L.) and 3% of calcium carbonate, bu t in one of the experimental groups, 1.5% of buffering sodium carbonate was additionally added to the concentrate mixture. Endosperm of milk thistle c ontained 23% fat with a high proportion of unsaturated fatty acids. The mean fat content in the milk of the experimental groups was similar (4. 83 and 4.61%, respectively) but significantly higher (P <0.05) compared wit h the control group (4.27%). A decline in the percentage of short-chain (C- 8:0 C-10:0, C-12:0) and medium-chain (C-14:0 C-16:0) fatty acids was observ ed along with a simultaneous advantageous, from the dietary point of view, increase in the percentage of unsaturated fatty acids (C-18:0 Delta -6-cis- C-18:1 Delta -9-12-cis-C-18:2) in the milk of cows of the experimental grou ps.