The goal of this study was to evaluate different levels of crambe meal (0, 330, 670 and 1,000 g kg-1 dry matter [DM]) as a replacement for soybean meal in diets supplied to feedlot lambs, and their effects on performance, carcass traits and non-carcass components. Twenty-four castrated lambs weighing 18.2 kg at the beginning of the experiment were allocated in a completely randomized design. Diets were formulated to meet the requirements of the lamb for an average daily gain of 0.200 kg. The roughage:concentrate ratio was 60:40, using Brachiaria dyctioneura hay as roughage. Dry matter intake, feed conversion, average daily gain, carcass traits and non-carcass components were evaluated. There was no effect of different levels of crambe meal replacing soybean meal on performance, carcass traits and non-carcass components, except heart weight. Replacement 1,000 g kg-1 DM of soybean meal protein by crambe meal protein does not affect the performance, carcass traits, or non-carcass components.

The objective of this study was to evaluate ingredients and diets containing increasing levels of crambe cake protein replacing soybean meal protein, with in vitro ruminal fermentation parameters using a gas production technique. Diets were formulated for feedlot lambs and contained different levels of crambe cake protein (0, 250, 500, 750, and 1000 g kg-1) replacing soybean meal protein. Corn silage was used as roughage. Carbohydrate digestion rates were estimated using the in vitro gas production technique and the cumulative gas production kinetics were analyzed using the bicompartmental logistic model. The parameters values of ruminal degradation kinetics were generated using the R statistical program with the Gauss-Newton algorithm and then subjected to analysis of variance and regression (when necessary) according to a completely randomized experimental design with five treatments and five replications. Upon carbohydrate fractionation of ingredients and experimental diets, it was observed that corn grain and corn silage presented the highest levels of total carbohydrates (TC), with values of 128.3 and 464.8 g kg-1 dry matter (DM) in fraction B2, respectively. Lower TC content was found for soybean meal and crambe cake (CC). There was a predominance of fractions A + B1 in the ingredients and experimental diets. The B2 fraction decreased in the diets with the inclusion of the CC protein, and CC presented the highest C fraction. Protein fractionation (g kg-1 DM and g kg-1 crude protein - CP), the ingredients and diets showed a higher proportion of fractions A and B1 + B2. In in vitro degradation, the diet without CC (0 g kg-1 DM) showed the highest final cumulative gas production (365.04 mL g-1 of incubated DM), while the CC presented the lowest volume (166.68 mL g-1 of incubated DM). The gas volume of non-fibrous carbohydrate fermentation and fibrous carbohydrate degradation rate exhibited a quadratic effect according increasing levels of CC (Pmax = 265.8 g kg-1 DM and Pmin = 376.3 g kg-1 DM, respectively). The lag time and final gas volume showed a decreasing linear effect with increasing levels of CC protein. The degradation rate of non-fibrous carbohydrates and the final volume of fibrous carbohydrates did not differ. Replacing soybean meal protein with CC protein at the level of 250 g kg-1 of dry matter in diets formulated for feedlot lambs leads to good profiles of ruminal fermentation kinetics with respect to the degradation of fibrous and non-fibrous carbohydrates.

The aim of this trial was to evaluate the ruminal degradation kinetics of carbohydrates in diets with different roughage:concentrate ratios and dosages of garlic and rosemary essential oils, in order to find the most suitable dosage to supply feedlot lambs. Three roughage:concentrate ratios (50:50, 40:60, and 20:80) and six dosages of garlic and rosemary essential oils (0.0, 0.10, 0.25, 1.0, 1.50, and 2.0 g L−1) were tested. Kinetic parameters for carbohydrate breakdown were estimated using a semi-automated in vitro gas production technique. Ruminal degradation parameters were subjected to variance analysis and then regression analysis at a 5% significance level. There was no interaction between the roughage:concentrate ratios and the dosage of rosemary essential oil. The roughage:concentrate ratios in diets with rosemary oil affected the non-fiber carbohydrate degradation rate (Kdnfc), colonization time (L), gas volume and breakdown rate from the degradation of fiber carbohydrates (Vfc and Kdfc, respectively), and final gas volume of both fiber and non-fiber carbohydrates (Vfinal). Rosemary dosages affected Vnfc and Vfc, which presented a quadratic response with a peak at 0.71 g L−1 and a nip at 1.17 g L−1, respectively. Bacterial colonization time was quadratic, reaching a maximum value at 1.18 g L−1. Vfinal showed a decreasing linear trend, such that each gram of rosemary essential oil added to the diet could reduce gas production by 30.312 mL. Therefore, rosemary essential oil has an effect on carbohydrate degradation kinetics. There was no interaction between roughage:concentrate ratios and different garlic oil dosages, except for colonization time. Roughage:concentrate ratios with garlic oil had affected the Vnfc, Kdnfc, and L. Garlic oil dosages affected Vfc and Vfinal in a quadratic manner, with the lowest values of gas production at 1.35 and 1.54 g L−1, respectively. L was affected by the garlic oil dosage and roughage:concentrate ratios in a decreasing linear trend for a 50:50 ratio and quadratic response for a 40:60 ratio, peaking at 0.14 g L−1. Based on these in vitro results, a ruminal content of 1.0 g L−1 is recommended for both rosemary and garlic essential oils.