PSII-26 - Feeding behavior and feed conversion in roughage-lacking diets containing ionized amino acids as antibiotic alternative

Abstract: In order to improve animal performance there has been an increase of starch amounts in the ruminant diets, however feeding high-grain diets can induce metabolic disturbs, needs to include antibiotics in the diet to avoid acidosis and control the growth of acid latic producing microorganism. In this study was used ionized amino acids to replace the monensin and withdraw all forage of diet. Twenty-four Nellore young bulls were alloted into two groups. The first group was fed with high-grain diet containing Brachiaria brizantha hay (15% of DM) and sodium monensim (120 mg/d). The second group was fed with high-grain diet without forage and without antibiotics, containing 82 mg/kg of ionized amino acids (no-forage diet, MJ Nutricao Animal). The feedlot lasted 100 d before slaughter, at the end of period the liquid ruminal was collected to VFAs and latic acid measurements. The Penn State Particle Separator has been used to monitor feeding sorting, the dry matter intake (DMI) was monitored daily in GrowSafe system and body weight (BW) was measured monthly. A completely randomized design was used. In the forage plus monensin diet the animals sorted larger particle (7.8 to 19 and > 19 mm), the proportion of larger particles decrease after feeding, the proportion of particles from 1.7 to 7.8 mm increased and there was no effect on smaller particles (< 1.7 mm). The animals feeding with no-forage diet avoided the whole cottonseed, the proportion of particles from 1.7 to 7.8 mm decreased and smaller particles (< 1.7 mm) did not change, before or after feeding. The feeding behavior had been changed, there was smaller number of visits in the Growsafe feeder, the visits were faster and there was higher amount of consumption per visit, in no-forage diet. However, there were higher concentration of propionic acid (50.9 vs 16.0 mM), smaller acetic:propionic ratio (1.1 vs 3.4), a trend to increased latic acid (0.3 vs 0.2 mM), and the pH decreased in no-forage diet (6.29 vs 6.68), reducing the DMI (2 vs 2.5% of BW). There was a trend to reduce the BWG (1.7 vs 2.0 kg/d) in no-forage diet. There was no difference in feed conversion (6.43 in forage diet vs 6.08 no forage diet). In conclusion, the faster starch consumption of no-forage diet can induce higher propionic acid concentration reducing DMI, on the other hand, the no-forage diet representing advantage to become the management of feedlot diets easier, allowing supply concentrate with less frequency, reducing dependence of forage production on farm, with the same feed conversion, without use of antibiotics. We hypothesize that fast passage rate reducing the hind gut starch digestibility, thus, further investigation can include supplies to improve alfa-amylase, in order to achieve even better feed conversion.