Free ferulic acid uptake in ram lambs

The objective of this research was to investigate the fate of free ferulic acid (FA) in sheep. Ferulic acid is normally present in plants, bound to the indigestible cell wall. If the FA present in a ruminant diet is released from the cell wall with feed pretreatment methods, FA may be released into the rumen for digestion or absorption into the bloodstream or both. Eight male Dorset x Finn lambs were randomly assigned to 1 of 4 treatment (trt) concentrations, 0 (control), 3, 6, or 9 g/d free FA as part of a replicated 4 x 4 Latin square design. Lambs were housed individually and consumed chopped alfalfa hay (Medicago sativa; 22.8% CP, 39.3% NDF, 0.73 Mcal/kg NEg) ad libitum and 350 g corn grain (Zea mays L.; 9.1% CP, 11.2% NDF, 1.52 Mcal/kg NEg) once daily at 0800 h. Basal concentrations of FA in hay, grain, blood, feces, and urine were established following a 14-d adjustment to diet and housing. An oral dose of free FA was administered for 5 d via bolus after each morning feeding, after which hay, grain, blood, feces, and urine were sampled. Body weights were recorded at the beginning and end of each trt, and DMI was measured daily during trt periods. In addition to trt, each lamb ingested a daily average of 3.78 g FA in its bound form via the offered hay (2.67 mg/g FA; 1.0 kg/d DMI) and corn (3.17 mg/g FA; 0.35 kg/d DMI). The FA administered had a quadratic effect on average hay DMI (1.25, 1.41, 1.41, and 1.29 kg/d for 0, 3, 6, or 9 g/d FA trt; P < 0.01; SE = 58.9 g), but lamb BW did not change as a result of FA trt (P = 0.28). The NDF content and amount of FA in refusals were not affected by trt, (P = 0.30; P = 0.82, respectively). Fecal FA did not differ among trt or when compared with basal FA (P = 0.53), while urine FA increased as FA dose increased (P < 0.01), indicating that free FA was absorbed and transferred into urine. No free FA was found in the plasma analyzed, suggesting that disappearance from the blood of absorbed free FA occurred within the 5 h that passed between bolus dosage and blood collection. An in vitro analysis was conducted to assess the degree of inhibition of microbial NDF digestion caused by FA supplementation. In vitro, NDF disappearance was not inhibited as a result of FA treatment (P = 0.80). These data in combination with the results of the lamb study indicate that free FA as 0.24, 0.43, and 0.70% of DMI in lambs is absorbed and excreted in the urine as opposed to the feces with no apparent effects on rumen microbial NDF digestion.