Scielo RSS <![CDATA[Revista Brasileira de Zootecnia]]> vol. 44 num. 7 lang. en <![CDATA[SciELO Logo]]> <![CDATA[Replacement of aruana grass by gliricidia (Gliricidia sepium) on silage quality]]> Our objective was to investigate the effect of the replacement of aruana grass by gliricidia on the fermentative losses, chemical composition, and aerobic stability of silages. For ensiling, whole-crop aruana grass (75 d of growth) was chopped (275 g kg-1 dry matter - DM) and ensiled alone or associated with gliricidia (270 g kg-1 DM; 150 d of growth). For gliricidia, we used only the leaves and stalks to ensile. The evaluated treatments were different ratios of aruana grass to gliricidia (100:0, 75:25, 50:50, 25:75, and 0:100), with four replicates (mini-silos). The silage composed only of gliricidia exhibited a lower pH than the other silages. Dry matter recovery was not affected by the treatments, although effluent losses were affected. The replacement of aruana grass by gliricidia 50% at ensiling resulted in a higher lactic acid bacteria count. The aruana grass silages displayed lower protein contents and a higher neutral detergent fiber content than the gliricidia silages after 40 d of fermentation. Consequently, the silage consisting of 100% gliricidia showed higher in vitro DM digestibility, presenting an increase of 8.13% after 40 d of fermentation compared with 100% of aruana grass silage. After silo opening, the gliricidia silage was very stable (&gt;72 h). The low quality of aruana grass silage is improved by replacing this grass with significant amounts of gliricidia (approximately 75%). <![CDATA[Reproductive success or failure in four breed groups of beef bulls]]> The objective of this study was to determine the main causes of failure in bull breeding using a soundness evaluation in Rio Grande do Sul State/Brazil. We evaluated 19,836 bulls from 15 different breeds with ages ranging from two to eight years. The failures of bulls in each step were analyzed by logistic regression. The binary logistic regression was applied because the response variable had only two responses: Success (1) and Failure (0). Older bulls are more likely to be rejected than are younger bulls, regardless of their genetic group. Depending on the step of the assessment, one or another group is rejected. All steps of bull breeding soundness evaluation (BBSE) are important, with special attention to the failures of the behavioral evaluation (libido and physical ability). A BBSE performed before the breeding season reduces the risk of sub-fertile bulls in the herd. <![CDATA[Physicochemical characteristics and fatty acid profile of meat from lambs with different genotypes and diets]]> The objective of this study was to evaluate the chemical composition and fatty acid profile of meat from Santa Inês, Dorper × Santa Inês, and undefined-breed lambs finished in a feedlot system according to two forage:concentrate ratios (50:50 and 20:80) in the diet. Overall, 54 non-castrated animals were used (with an average initial weight of 23±1.5 kg at 150 days old) and were slaughtered when they reached 36 kg of live weight or 63 days of confinement. Diets with high concentrate levels favored meat production with higher protein content. Among the saturated fatty acids, only heptadecanoic (C17:0) and arachidic acids (C20:0) differed among the treatments. The amount of oleic acid detected in the meat ranged from 49.2 to 51.9 g/100 g, making this one the most representative fatty acids. Regardless of the diet and genotype, the unsaturated fatty acid and desirable fatty acid levels in the lamb meat characterize it as of satisfactory quality for the consumer market. <![CDATA[Relationship between residual feed intake and enteric methane emission in Nellore cattle]]> Feed intake and average daily gain (ADG) in Nellore cattle were determined to calculate residual feed intake in two performance tests: first during the growth phase (RFIgrowth) and then during a measurement of the methane emission phase (RFImet). During the RFIgrowth test, 62 males and 56 females were classified as low-, medium-, and high-RFI. Enteric methane emission was measured in 46 animals; 23 males used for RFImet measurement plus 23 females (22 low-RFIgrowth and 24 high-RFIgrowth). Diet consisted of Brachiaria brizantha cv. Marandu hay (445 g/kg DM) and concentrate (555 g/kg DM). During the RFIgrowth and RFImet phases, DMI was lower in the animals with low RFI, with no difference in ADG. Residual feed intake was -0.359 and 0.367 kg DM/d for low- and high-RFI animals. Enteric methane emission (g/d, g/kg BW0.75 and g/kg ADG) did not differ between RFIgrowth classes. Enteric methane emission (g/d) was higher in high RFImet and lower in low RFImet males. Spearman correlations among traits obtained during both tests, which were high between metabolic BW (r = 0.959) and between DMI (r = 0.718), and zero between ADG (r = -0.062), resulted in moderate correlation between RFIgrowth and RFImet (r = 0.412). However, it is not possible to confirm that high-efficiency animals release less enteric methane, since different results were obtained when enteric methane was compared between the RFIgrowth and RFImet classes. <![CDATA[Fatty acid profile, chemical composition, and sensory effects of crude glycerin on the longissimus dorsi of crossbred Boer goat kids]]> The objectives of this trial were to evaluate the fatty acid profile, chemical composition, and sensory effects of crude glycerin on the longissimus dorsi muscle of crossbred Boer goat kids. Twenty crossbred Boer goat kids (20.8±2.9 kg of BW at slaughter) were used in a completely randomized block design to determine the effect of partial replacement of corn by crude glycerin on chemical composition, longissimus dorsi muscle fatty acid profile, and sensory characteristics of meat. Kids were penned individually for 51 d and fed an isonitrogenous (140.0±2.0 CP, DM basis) diet composed of 700 concentrate and 300 Tifton (Cynodon sp.) hay. Increasing levels of crude glycerin (80.0 g/100 g glycerol, DM basis) were 0, 40, 80 or 120 There was no effect on the moisture, protein, or total lipids in the longissimus dorsi; however, the ash content decreased linearly with glycerin addition. Linear decrease for linoleic acid (3.57, 2.84, 3.76, and 2.33) and ω6:ω3 ratio (10.61, 9.71, 7.26, and 7.18 for CG0, CG40, CG80 and CG120, respectively) was observed with crude glycerin inclusion. Saturated, monounsaturated, and polyunsaturated fatty acids were not affected by treatments. In the sensory assessment, crude glycerin changed the toughness, color intensity, and overall appreciation of the longissimus dorsi muscle. The partial replacement of corn by crude glycerin has a low impact on chemical composition and meat fatty acid profile. Based on the overall appreciation, it is recommended to include 80 crude glycerin in the diet.