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.