Efecto del nivel de aceite de soja sobre el consumo y la digestión de novillos alimentados con ensilaje de sorgo

In order to evaluate the changes that may occur on voluntary intake and nutrient digestion when Soybean Sludge (SLU) is supplemented, a study was conducted offering different levels (TR) of SLU to confined cattle fed a sorghum silage basal diet. The experiment was a Latin square design, with 4 experimental periods (EP) using Aberdeen Angus steers fitted with ruminal and duodenal cannulas. The diet consisted of whole plant sorghum silage (SS), soybean expeller (SE), ground corn grain (GC), and a mineral salt block. Each EP lasted 14 days, the last 4 days being used to collect samples and measurements to estimate intake (I), to evaluate in vivo apparent ruminal and total tract digestibility (ARD and ATD) with the use of chromic oxide (Cr2O3) as an external marker, and to characterize the chemical composition of the ingested diet on a dry matter (DM) basis, and so as to characterize ruminal fermentation by pH, ruminal ammonia (N-NH3) and volatile fatty acid (VFA) concentrations, and the proportions of the major VFA: acetic (A), propionic (P), butyric (B), iso-butyric (iso-B), iso-valeric (iso-V) and, valeric acids (V). In feed, orts, fecal (F) and duodenal (D) samples, composited by Animal and EP; analytical determinations were made to estimate the organic matter (OM) content, ash corrected neutral detergent fiber with amylase (aNDFmo) and acid detergent fiber (ADFmo), total nitrogen (TN) and starch (S); only feed samples were analyzed for ether extract (EE). Once discarded the potential residual effect of previous treatment, data were analyzed as standard LSD using a mixed model by REML for a LSD for I, the ARD and ATD, with TR and EP as fixed effects, and animal random. Differences between means were compared using PDIFF. It’s concluded that SLU supplementation at the levels used in this study and with a diet based on sorghum silage does not affect OM intake, neither the other nutrients studied, although it induces a negative effect on apparent ruminal and total tract ADF digestion, but not in its sites of digestion. It also produces a decrease in the total tract digestion of the NDF, but not ruminal, without being able to specify the site of the hind-gut digestive tract which affects digestion of this fiber component. The digestibility of OM, S and TN were not affected by including sludge of soybean. The ruminal fermentation pattern presented typical characteristics of forage diets, whose values were within physiological ranges. The behaviour of pH in ruminal fluid is related to the daily amount of OM, ADF, NDF and S apparently digested in rumen; these quantities decrease markedly with SLU supplementation from a biologically point of view, although the differences were not statistically significant for all variables. If it is confirmed that through soybean SLU supplementation the nutritional value of meat is enhanced, it would be necessary to assess whether the observed decrease in the amounts of nutrients apparently digested are offset by the higher energy density of the diet when studying animal performance variables.