Ingestive behavior of sheep fed Brazil nut cake in the diet

Abstract

This study evaluated the ingestive behavior of sheep when fed a corn-silage-based diet with varying levels (0%, 15%, 30%, and 60%) of Brazil nut cake (NC) (Bertholletia excelsa Bonpl.). Sixteen mongrel sheep with an average weight of 33 ± 6.04 kg were randomly distributed between four treatments. Data were tested for assumptions of normality, subjected to an analysis of variance, and adjusted in regression equations and by Williams’ test, to estimate the W point. The voluntary intake of dry matter (DM) and insoluble neutral detergent fiber (NDF) decreased linearly (P = 0.013 and P = 0.002) by 5.0 g and 2.41 g d-1, respectively, for every 1% of NC added to the diet. The time the animals spent feeding (288.75 min d-1) was not significantly affected; time spent idle increased linearly (P= 0.0002) by 3.10 min, and time spent during rumination decreased linearly by 2.62 min (P = 0.001) for each 1% addition of the co-product. The number of ruminated boluses (NRB) displayed a decreasing effect (P = 0.004) of 4.61 d-1 for each 1% of NC. For ruminating chews, the time spent per bolus (37.5 sec) and the number per bolus (56.14) did not differ (P > 0.05) between treatments. However, the total chewing time (TCT) decreased linearly (P = 0.002) by 0.05 h d-1 and the number of chews per day displayed a quadratic effect (P = 0.008), with a maximum value estimated at 17.5% of NC in the diet. Rumination efficiency did not differ between the treatments (101.95 g DM h-1 and 36.76 g NDF h-1). The feeding efficiency (FE) had a linear reduction (P = 0.045) of 0.42 g NDF h-1, but was similar for g DM h-1 (172.5). The daily intake of DM and NDF showed W points estimated at 51.96% and 30.67% NC, respectively. The variables NRB, TCT, and FE (g NDF h-1) had W points estimated at 56.64%, 56.19%, and 56.33% NC, respectively. The Brazil nut cake, when present at levels greater than 56% of the diet’s DM, affects the ingestive behavior of the animals, particularly rumination-related variables, and at levels of 30.67%, it begins to affect the consumption of NDF, primarily due to the ether extract content and the diet’s fiber source.