Intake, Digestibility and Ruminal Parameters in Cattle Fed with Oil, Selenium and Vitamin E

This study aimed to evaluate intake, ruminal parameters and digestibility of nutrients in the diets with 6% soybean oil (SO) and with or without supplementation of organic selenium (Se) and vitamin E (E). Five steers cannulated with average initial BW of 398 ± 28.7 kg were subjected to a 5 x 5 Latin Square with 21d periods. Diets consisted of 65% concentrate and 35% corn silage. Steers were assigned to treatments: without additional oil (WAO); SO; SO+E; SO+Se; SO+E+Se. The additives were daily supplemented with 1500 IU vitamin E and 5 g selenium per animal. Rumen contents were collected every two hours after morning feeding to measure SCFA and ammonia nitrogen. Total collection of feces was completed for three days in each period to measure digestibility of nutrients. The data were analyzed using PROC MIXED of SAS. The diet with SO had lower intake (kg) of DM (9.82 and 10.6; P = 0.02), DMBW (21.05 g/kg BW and 23.1 g/kg BW; P < 0.01), OM (9.96 and 10.8; P = 0.05), CP (1.25 and 1.36; P = 0.02), NDF (3.20 and 3.52; P = 0.01), and NFC ( 4.22 and 5.11; P < 0.01), total protozoa (45 and 380 10³/mL; P < 0.01), total digestibility (g/kg) of DM (726 and 760; P = 0.05), OM (725 and 759; P = 0.05), NFC (814 and 845; P = 0.04) and NDF ( 567 and 639; P < 0.01), ruminal digestibility (g/kg) of CP (426.50 and 511; P = 0.05) and NDF (505.75 and 587; P < 0.01), and excretion of N microbial (202 and 156.2 g/day; P = 0.01). However, SO had a greater intake (0.85 and 0.33; P < 0.01) and total digestibility of EE (897.25 and 826; P < 0.01) than WAO. Se reduced ruminal digestibility of DM (475 and 508.5; P = 0.05) and OM (475 and 509; P = 0.05) and had greater molar proportion (mMol) of acetate (35.6 and 30.45; P = 0.04), propionate (19.1 and 16.0; P = 0.04), butyrate (9.53 and 8.37; P = 0.05) than diet without Se. The diet with SO+E+Se had lower ruminal digestibility of CP (417 and 511; P = 0.04) and greater EE (-56.5 and 159; P = 0.05). Overall, the study showed that supplementation with soybean oil reduce DM intake and fiber digestibility, while the use of E/Se does not change the total digestibility of nutrients.