The objectives of the present work were to evaluate the in vivo antimethanogenic effects of Cymbopogon citratus (CC), Matricaria chamomilla (MC) and Cosmos bipinnatus (CB) on beef cattle fed a high in concentrate diet (forage-to-concentrate ratio [F:C] of 19.4:80.6), and the effects of increasing levels of CC (0%, 2%, 3%, and 4% of the daily DM intake (DMI)) on enteric CH₄ emissions by beef cattle fed a ration low in concentrate (F:C ratio of 49.3:50.7). Two experiments were conducted to address the objectives. For the first experiment, eight Charolais × Brown Swiss steers distributed in a replicated 4 × 4 Latin square experimental design were used. Four treatments were evaluated: (1) control diet (CO), (2) CO + 365 g dry matter (DM)/d CB, (3) CO + 365 g DM/d MC, (4) CO + 100 g DM/d CC. For Experiment 2, four Charolais x Brown Swiss steers distributed in a single 4 × 4 Latin square design were used. It was concluded that 100 g DM per day CC and 365 g DM per day CB (Experiment 1) reduced CH₄ yield of beef cattle. In Experiment 2, CC supplementation levels exceeding 2% of DMI reduced daily CH₄ emissions but at the expense of decreasing digestibility of DM.

This paper aims to describe the construction and operation of a respiration chamber of the head-box type for methane (CH₄) measurements in bovines. The system consists of (1) a head box with a stainless steel frame and acrylic walls, floor, and ceiling; (2) a stainless steel feeder; (3) an automatic drinking water bowl; (4) a hood made from reinforced canvas; (5) an infrared (IR) CH₄ gas analyzer, a mass flow generator, a data-acquisition system; and (6) a steel metabolic box. Six assays were conducted to determine the pure CH₄ recovery rate of the whole system in order to validate it and comply with standards of chamber operation. The gravimetrical method was used for the recovery test and the recovery rate obtained was 1.04 ± 0.05. Once the system was calibrated, measurements of CH₄ were conducted using eight animals consisting of four Holstein cows with a live weight of 593.8 ± 51 kg and an average milk yield of 23.3 ± 1.8 kg d⁻¹ and four heifers with a live weight of 339 ± 28 kg. The CH₄ production values were 687 ± 123 and 248 ± 40 L CH₄ d⁻¹ for cows and heifers, respectively. The CH₄ yield was 19.7 ± 3.4 g and 17.1 ± 3.4 g CH₄ kg⁻¹ of dry matter consumed for cows and heifers, respectively. These results are consistent with those reported in the literature.

Coffee is one of the main traded commodities worldwide, unfortunately, it generates massive amounts of by-products like coffee pulp (CoP), which could be utilized as an alternative feedstuff for cattle contributing to mitigate coffee production environmental damage. The objective of this work was to evaluate the effect of increasing levels of CoP supplementation on milk production, milk composition, and grass dry matter intake (GDMI) by dual-purpose tropical cows. A 4 × 4 Latin square experimental design was conducted, where four multiparous dual-purpose Holstein x Cebu cows with an average live weight of 477 ± 7 kg and milk yield of 12.1 ± 2.7 kg/d were used. The cows grazed 10 h/d on a Cynodon plectostachius sward with a stocking rate of three cows/ha. All cows received 6 kg/d DM of an experimental concentrate (EC), and the treatments consisted of four supplementation levels of CoP: T1 = 0, T2 = 0.6, T3 = 0.9, and T4 = 1.2 kg DM/d, which was provided on top of the concentrate and mixed with the EC. Grass intake was determined by the n-alkanes technique. A significant difference was observed for the average total daily DM intake (p < 0.02). No significant differences (p > 0.05) were observed for milk yield, milk composition, body weight, and GDMI for all the inclusion levels of CoP. It was concluded that CoP can be included at levels of 0.6 to 0.9 kg DM/d in the diets of cows without compromising milk yield or GDMI.

Methane production is a waste of energy for ruminants and contributes to greenhouse gas emissions. The objective of the present study was to evaluate the anti-methanogenic effect of increasing the supplementation levels of Cymbopogon citratus (CC) on the dry matter intake (DMI), digestibility, methane (CH₄) production, and partitioning of the gross energy intake in growing beef heifers fed with a diet high in forage (68.6% forage: 31.4% concentrate). An experiment was conducted using Holstein × Charolais heifers distributed in a 4 × 4 Latin square design. The experimental treatments were: (1) control diet (CO), (2) CO + 30 g CC DM/d, (3) CO + 60 g CC DM/d CC, and (4) CO + 90 g CC DM/d. A reduction of 22.4% in methane yield (CH₄ g/kg DMI) and a reduction of 21.2% in the Ym factor was observed with the 30 CC treatment (p ≤ 0.05). However, no significant differences (p > 0.05) were observed for the total daily CH₄ production, DMI, nutrient digestibility, and gross energy intake partitioning in the heifers. Therefore, we concluded that the supplementation of 30 g CC DM/d reduced the CH₄ yield without affecting the animal performance. However, the anti-methanogenic properties of Cymbopogon citratus deserve more investigation.

Methane (CH₄) produced by enteric fermentation in cattle is of utmost importance as it contributes to greenhouse gas emissions. This gas is a product of the fermentation that feed undergoes in the rumen, resulting in an energy loss for the animal. So, reducing CH₄ production would lead to a more efficient use of the gross energy ingested, which could be used to transform it into meat or milk and would also reduce CH₄ emissions into the environment. There are several CH₄ mitigation strategies, such as the addition of plants with a high concentration of secondary metabolites, like Cymbopogon citratus (CC). Therefore, the present study aimed to evaluate increasing levels of CC on dry matter intake (DM), nutrient digestibility (DIG), CH₄ production and partition of gross energy intake in growing cattle fed a high forage diet (68.6% forage: 31.4% concentrate). Four heifers (¾ Holstein × ¼ Charolais) with an average initial live weight of 225 ± 64 kg distributed in a 4×4 Latin square design was used. The experimental treatments were: 1) control diet (CO); 2) CO + 30 g CC DM/d; 3) CO + 60 g CC DM/d and 4) CO + 90 g CC DM/d. A 22.4 % and 21.2 % reduction in CH₄ yield (CH₄ g/kg DMI) and Ym factor respectively was observed with the 30 CC treatment compared to CO (P ≤ 0.05). No statistically significant differences were observed for means related with DMI, DIG and partition of gross energy intake (P > 0.05). It is concluded that supplementation with 30 g CC DM/d reduces CH₄ yield without affecting animal performance.