The objectives of this study were to determine the emission of nitrous oxide (N₂O), methane (CH₄), and carbon dioxide (CO₂), as well as the isotopic composition of N₂O from excreta of beef steers fed ‘AU Grazer’ sericea lespedeza hay [SL; Lespedeza cuneata (Dum. Cours.) G. Don]. Fifteen Brahman × Angus crossbred steers were fed one of three experimental diets: 0, 50, or 100% inclusion of SL into ‘Tifton 85’ bermudagrass hay (Cynodon spp.). Gas sampling occurred on days 0, 1, 3, 5, 7, 14, 18, 25, and 32 after urine or feces application to static chambers for two experimental periods. Effect of the day after feces application (P < 0.001), while day × inclusion of SL interaction was observed in urine (P < 0.001) for all greenhouse gases (GHG) analyzed. Peaks of emission of all GHG in urine and feces occurred in the first days (P < 0.001), with days 3 and 5 being most depleted in ¹⁵N-N₂O in feces, and days 3, 5, and 7, in urine (P < 0.001). Feeding SL to beef steers was effective in mitigating the emission of GHG from the excreta, but further research is necessary to investigate the mechanisms behind the reductions.

An experiment was conducted to evaluate the effects of different proportions of ‘Au Grazer’ sericea lespedeza [SL, Lespedeza cuneata (Dum. Cours.) G. Don], a legume rich in condensed tannins (CT), on nutrient intake and digestibility, and to estimate methane (CH₄) emissions and ¹³C isotopic composition (δ¹³C_CH4) from beef steers consuming a forage-based diet. Twenty-five Angus-crossbred steers were distributed in a randomized complete block design (344 ± 48 kg initial BW), and randomly assigned to one of five treatments: 0SL, 25SL, 50SL, 75SL, and 100SL, diets containing 0%, 25%, 50%, 75%, and 100% of SL hay, respectively, mixed with ‘Tifton-85’ bermudagrass hay (Cynodon spp.). The study was carried out for two experimental periods of 21-d each. The statistical model included the fixed effect of treatment and random effects of block, experimental period, and their interaction. Apparent total tract digestibility of crude protein, neutral detergent fiber, and acid detergent fiber was linearly decreased (P < 0.001) by the inclusion of SL. No effects were observed for total CH₄ emissions per day, nor for CH₄ relative to organic matter intake or digestible organic matter with the inclusion of SL. However, emission of CH₄ in relation to intake of CT was affected by treatment (P < 0.001). A linear (P < 0.001) decrease and a quadratic effect (P < 0.001) were observed for δ¹³C of diets and gas, respectively, in which diets and enteric CH₄ with greater inclusion of SL were more depleted in ¹³C. Moreover, the difference in δ¹³C between diets and gas (Δδ¹³C) had a linear decrease (P = 0.001) with the inclusion of SL. The model developed to predict the C₃ proportions in the enteric CH₄ fitted to predicted values (P < 0.0001). Therefore, greater proportions of SL resulted in lesser CH₄ emission when CT intake was considered and the isotopic composition from enteric CH₄ was able to predict the contribution of SL in the emissions.

Objetivou-se neste trabalho avaliar o efeito da inclusão de 2 fontes lipídicas (óleo de soja e óleo de soja residual) na dieta de ovinos confinados sobre os parâmetros sanguíneos. Foram utilizados 24 borregos Santa Inês × Dorper, machos, não castrados, distribuídos em delineamento em blocos casualizados e submetidos a três dietas experimentais: C= dieta controle, volumoso: concentrado na proporção de 40:60; S= C com inclusão de 6 % de óleo de soja; e R= C com inclusão de 6 % de óleo de soja residual de fritura. Silagem de milho foi utilizada como volumoso e o concentrado era composto por milho grão inteiro, casca de soja, farelo de girassol, ureia, sal mineral, calcário e antioxidante. Os animais foram confinados por 105 dias, sendo que no dia 59 foram realizadas colheitas de sangue através de punção da veia jugular para quantificação de glicose, triglicérides, colesterol e proteínas totais, além das enzimas hepáticas aspartato aminotransferase (AST), gama glutamiltransferase (GGT) e fosfatase alcalina (FAL). A inclusão de 6 % de óleo de soja ou de óleo residual na dieta aumentou as concentrações sanguíneas de colesterol e da AST (p<0,01), e a FAL tendeu a aumentar (p= 0,06) quando óleo residual foi utilizado. Porém, tais alterações não foram suficientes para causarem prejuízos na saúde animal.

The feasibility of unconventional feed for ruminants must be analyzed for appropriate use as sources of energy or protein that contribute to a sustainable production system addressing concerns about climate change, greenhouse gas emissions, and food security. The objective of this study was to evaluate the nutritive value of by-products including bean residue (BR), bean straw (BS), cassava bagasse (CB), corn straw (CS), orange bagasse (OB), peanut shell (PS), sugarcane bagasse (SB), soybean hull (SH), and sugarcane straw (SS). Chemical composition, in vitro degradability, and fermentative parameters were analyzed and subjected to multivariate and principal component analyses. Crude protein content was highly variable among by-products with BR and SH presenting the highest values (p < 0.001). These values did not differ between BR and SH, while the lowest values were observed in OB, PS, SB, SS, CS, and CB. Neutral detergent fiber content was higher in SB, PS, CS, and SS (p < 0.001), while greater in vitro degradability was found for CB, BR, OB, BS, and SH (p < 0.001). However, the in vitro gas production (p < 0.001) and total short-chain fatty acid concentration (p < 0.001) were higher in CB, BR, BS, and OB. Multivariate cluster analysis showed three distinct groups with the most degradable in group 1 followed by group 2. These results demonstrate that the by-products used in this study did not impair in vitro fermentation, and thus have the potential to be used in the diets of ruminants and to improve the sustainability of the livestock production sector.

Two experiments were performed to evaluate the effects of (1) different levels of liquid supplementation (LS) based on molasses enriched with 32% (as fed; 45% on DM basis) crude protein (CP) on intake of Hemarthria altissima hay (LH), digestibility, and rumen fermentation, and (2) different levels of LS based on molasses enriched with 32% CP in the in vitro gas production in LH diets. In Exp. 1, twelve heifers and 12 adult male castrated and cannulated cattle were used. Treatments were allocated in a randomized block design, in four treatments: (CTL) access ad libitum to the LH; (SUP2) ad libitum access to LH and supplementation with 0.9 kg d⁻¹; (SUP4) ad libitum access to LH and supplementation with 1.8 kg d⁻¹ and; (SUP6) ad libitum access to LH with 2.7 kg d⁻¹. In Exp. 2, treatments were carried out in a randomized block design with four different proportions of LH diet: (CTL) 100 LH, (SUP2) 85 LH and 15 LS, (SUP4) 70 LH and 30 LS, (SUP6) 55 LH and 45% LS. In Exp. 1, liquid molasses-based supplementation did not affect LH intake (p > 0.05). Molasses intake improved as the supply increased, not reducing the intake of LH. In Exp. 2, the addition of LS to the LH caused a change in the VFA profile, with an increase in propionate production in vitro.

Pasture mowing at the beginning of deferment stimulates tillering and can be used in different ways. The aim of this study was to understand how the mowing of Urochloa brizantha cv. Marandu Syn. Brachiaria brizantha cv. Marandu (marandu palisade grass) prior to the deferment period modifies tillering activity and the characteristics of young, mature, and old tillers. Three mowing strategies were evaluated: canopies kept at a height of 15 cm for five months before deferment (15/15 cm); canopies kept at 30 cm (30/15 cm) or 45 cm (45/15 cm) for five months before deferment and posteriorly cut to 15 cm at the start of the deferment period. The structural characteristics of young, mature, and old tillers of marandu palisade grass were compared only at the end of the deferment period. The tiller appearance rate was greater before (16.0%) than during (6.4%) the deferment period, but a contrasting response pattern was observed for the tiller mortality rate. The defoliation strategies that resulted in greater numbers of tillers in the canopies were 30/15 cm (2,098 tillers m-²) and 45/15 cm (2,160 tillers m-2). The defoliation strategy that generated the greatest percentage of young tillers in the canopy was 45/15 cm (26.1%), while the percentage of old tillers was greater in the canopies submitted to the 15/15 cm (64.1%) and 30/15 cm (61.5%) strategies. Weight and percentage of live stems of mature and old tillers were greater in relation to young tillers. The percentage of live leaves was grater in young tillers (52.6%), intermediate in mature tillers (41.4%), and lower in old tillers (21.3%). Regarding the percentage of dead leaves, the opposite trend was observed, where the percentage was greater in the old than in young tillers. Leaf area was greater in mature tillers (55.3 cm²) than in old tillers (29.2 cm²). Mowing of the marandu palisade grass to 15 cm at the beginning of the deferment period increases the number of young tillers, which have a more favorable morphological composition than mature and old tillers.