Efecto de la fuente energética y el nivel de energía sobre la longitud de vellosidades intestinales, la respuesta inmune y el rendimiento productivo en pollos de engorda

the objective of this study was to evaluate, during the whole productive cycle, the use of three energy sources with different unsaturated (ufa) and saturated (sfa) fatty acid profiles with two levels of metabolizable energy (me), in diets for broilers, vaccinated or not against infectious bursal disease (ibd). two experiments were conducted evaluating the three energy sources with different ufa and sfa profiles corresponding to soybean crude oil (sco), a mixture of 46.8% pig fat with 53.2% bovine fat (pbf), and a mixture of 39.2% animal fat with 60.8% of vegetable oil (avf). in the first trial, diets contained two levels of me (3 000 and 3 200 kcal/kg) for vaccinated and non vaccinated broilers against ibd. the second trial used sco, pbf, avf, sco/pbf and sco/avf in the diets, substituting sco with pbf and avf in the last two treatments on day 22. in trial 1, sco group showed higher growth and iga concentration than pbf and avf (p < 0.05), the broilers fed with 3 200 kcal/kg me (p < 0.05) were heavier and had higher titers of antibodies against ibd. at 21 days of age, vaccinated birds had a higher productive performance along with highest iga and igg concentrations, and larger length of villi in duodenum and jejunum (p < 0.05). in trial 2, higher concentration of unsaturated fatty acids in sco enhanced feed conversion the first 21 days of age (p > 0.05); later on, during growing and finishing there were no differences among energy sources. as a conclusion, it can be said that in broilers, during the growing stage, there is a positive effect on performance and immune protection according to the source and concentration of energy.