Fornecimento de flushing com silagem de milho moído e reidratado a cabras da raça Saanen

Abstract

The objective was to evaluate the impact of replacing ground corn (GC) with rehydrated ground corn silage (RGCS) in flushing diets on productive performance, feeding behavior, metabolites, follicular development, and ovulations in Saanen goats. Thirty-six non-lactating goats were blocked by body condition score (BCS) and randomly assigned to one of three treatments: maintenance diet (control, n=12), GC flushing (n=12), or RGCS flushing (n=12) for 24 days. The estrus synchronization protocol began on the 12th day. Goats were weighed, and BCS and subcutaneous backfat thickness (SFT; mm) were measured on the day before feeding the diets (d-0; covariate) and on days 7, 14, and 21. Blood samples (days 0, 7, 14, and 21) were analyzed for glucose and urea. Feeding behavior was assessed (days 13-14) using 24-h scans at fiveminute intervals. Digestibility was evaluated via total fecal collection over five days, and apparent digestibility coefficients for dry matter (DM) and nutrients were calculated. Ovaries were assessed daily by ultrasonography from day 20 until ovulation. After 10 days, the corpora lutea was assessed. Analyses were performed in SAS software, with generalized models for intake, digestibility, feeding behavior, and reproductive data. Mixed models were used for metabolite concentrations. Treatment effects were compared using orthogonal contrasts: 1) control diet vs. flushing, and 2) GC vs. RGCS, with significance set at 5%. All nutrients, except NDF and ash, showed higher intake in flushing diets (GC and RGCS) compared to the maintenance diet (CON). Flushing diets with GC and RGCS did not differ (P>0.05) in terms of intake of DM, protein, ether extract, non-fibrous carbohydrates, and starch, indicating that both sources are equivalent. Final body weight was higher in the RGCS group (P<0.05). Plasma glucose concentrations did not differ between treatments (P>0.05). Plasma urea nitrogen (PUN) concentrations were lower (P<0.05) in goats fed flushing diets, suggesting better nitrogen utilization. On day 21, concentrations differed between goats fed GC and RGCS (13.0±1.26 mg and 8.3±1.24 mg dL⁻¹, respectively). Follicular growth was more pronounced in the flushing groups (P<0.05), but the total number of ovulations did not significantly differ between treatments (P>0.05). The number and diameter of follicles did not differ (P>0.05) between treatments, but a higher follicular growth rate (P<0.01) was observed in animals fed flushing diets. The number of ovulations was 1.47 in the control group, 1.18 in animals fed GC, and 1.94 in those fed RGCS (P>0.05). Total luteal area differed between flushing treatments and was greater in animals in the RGCS group (2.76 vs. 1.56; P<0.05). Goats fed flushing diets required less time for feeding, rumination, and total chewing activity. The feeding efficiency of DM and NDF was greater in animals fed RGCS, and a higher number of chews per ruminal bolus was observed in these animals. It was concluded that replacing GC with RGCS in flushing diets does not impair feeding behavior and improves DM and NDF efficiency, resulting in higher weight gain. Flushing diets resulted in a higher follicular growth rate, with a greater total luteal area observed in the RGCS diet.