The present study aims to establish the relationship between chemical composition and in vitro methane (CH₄) production of high Andean grasses. For this purpose, eight species were collected in dry and rainy seasons: Alchemilla pinnata, Distichia muscoides, Carex ecuadorica, Hipochoeris taraxacoides, Mulhenbergia fastigiata, Mulhenbergia peruviana, Stipa brachiphylla and Stipa mucronata. They were chemically analyzed and incubated under an in vitro system. Species such as A. pinnata and H. taraxacoides were characterized by high crude protein (CP. 124 g/kg DM) and low neutral detergent fiber (NDF. 293 g/kg DM) contents in both seasons, contrary to Stipa grasses. This same pattern was obtained for H. taraxacoides, which presented the highest values of gas production, organic matter digestibility (DOM), metabolizable energy (ME) and CH₄ production (241 mL/g DM, 59% DOM, 8.4 MJ ME/kg DM and 37.7 mL CH₄/g DM, on average). For most species, the content of CP, acid detergent fiber (FDA) and ME was higher in the rainy season than in the dry season, which was the opposite for CH₄ production (p ≥ 0.05). In general, the nutritional content that most explained the behavior of CH₄ production was the NDF content (R² = 0.69). Grasses characterized by high NDF content produced less CH₄ (R = −0.85).

• Three management strategies (open corral, semi-open shed, cria body vest) were investigated in the Andes mountains of Perú for their impact on alpaca cria survival and body weight gain. • The use of a cria body vest as a protection strategy for alpaca neonates improved survival to 12 weeks of age (100%) and improved cria body weight gain (0.17 kg / d) compared with a semi-open shed (76% survival; 0.14 kg/d) or an open corral (64% survival; 0.13 kd/d). Sex of the cria did not influence cria survival or body weight gain. • Results of this study are useful because the use of a cria body vest can be implemented and semi-open sheds can be redesigned to improve survival and growth rate of crias reared in harsh environments.

A study was carried out to determine the metabolizable energy (ME) and net energy (NE) of corn, wheat by-product, soybean meal, fishmeal, and soybean oil in poultry. 190 male chickens were used, distributed in six experimental diets (basal (B), B + corn (40%), B + wheat by-product (40%), B + soybean meal (30%), B + fish meal (30%), B + soybean oil (10%) with three feeding levels (ad libitum (AL), 85% AL and 70% AL). ME was determined by the total collection method of excreta and NE by the comparative slaughter method, the chickens received the experimental diets from 7 to 21 days of age, the excreta were collected every 24 hours (day 19 to 21). For NE, the energy retained and heat production were determined (7 and 21 days) The ME and NE of corn, wheat by-product, soybean meal, fishmeal and soybean oil was 3734, 2197, 2477, 3289, 8767 kcal / kg DM and 2527, 1598, 1417, 1837, 7550 kcal / kg DM respectively, the NE: ME ratio was higher with soybean oil compared to other feed ingredients.

El objetivo del estudio fue determinar la producción de metano en vacunos al pastoreo en el altiplano peruano en un pastizal de Festuca dolichophylla - Muhlenbergia fastigiata (Chilliguar), suplementados con ensilado y concentrado o taninos durante la época seca (agosto). El estudio se realizó en el Centro Experimental «La Raya», Cusco, Perú, ubicado a una altitud de 4200 msnm. Se plantearon tres tratamientos (T1: pastos naturales + ensilado de avena; T2: como en T1 + taninos; T3: como en T1 + concentrado). Cada tratamiento contenía cuatro repeticiones distribuidos en un diseño jerárquico. La determinación de metano se realizó con la técnica del marcador con hexafluoruro de azufre (SF6), siendo la frecuencia de medición por animal de 24 h por 7 d. El contenido de energía promedio en el pastizal fue de 4.1 Mcal EB/g, materia orgánica 91.8%, proteína cruda 10.3% y materia seca 91.1%. La producción de metano (g/d) para T1 fue de 421.7 ± 43.4, para T2 de 330.6 ± 66.7 y para T3 de 367.7 ± 116.5. La utilización de taninos redujo significativamente (p<0.05) las emisiones de metano frente al uso o no de concentrado.