The objective of this study was to determine the enteric methane (CH₄) emission factor (EF) at the national level for Peruvian dairy cattle following the IPCC Tier II (2006, 2019) methodology. Data were collected from seven regions of Peru and classified according to the type of feeding as intensive, semi-intensive or extensive. It included farm information (geolocation) and livestock information for two seasons of the year. At the national level, lactating cows obtained the highest EF with 117 kg CH₄/head/year, followed by heifers from 15 to 24 months of age (91 kg), non-lactating cows (74 kg), heifers from 12 to 15 months of age (67 kg), calves (62 kg) and pre-weaned calves (16 kg). Additionally, the highest EF was reported for lactating cows in the intensive system (151.8 kg CH₄/head), which is 46.8 kg CH₄/head more per year than that reported in the semi-intensive and extensive systems in the same animal category. The combined uncertainty in all animal categories was low to very low (between 9.4 and 18.72%), except for that of lactating cows, which was low to medium (22.24 and 26.72%). These results allowed us to find the EF that exerts the most pressure according to the level of intensity in Peruvian dairy farming.

La avena es un cereal de alto valor nutritivo para humanos y animales. El objetivo del estudio fue caracterizar agronómicamente ocho genotipos de avena en respuesta a la restricción de lluvia. Se realizó en los Andes centrales del Perú mediante un diseño completamente al azar con arreglo factorial ocho genotipos de avena forrajera (INIA901 Mantaro15, INIA902 Africana, INIA903 Tayco, Junín-Jauja blanca, Centenario, Junín-Tarma negra, Junín-Jauja negra y Cayuse) con 0 % y 60 % de restricción de lluvia y tres repeticiones. Se tuvieron 48 unidades experimentales (parcelas de 4,8 metros cuadrados), donde la restricción de lluvia se logró a través de interceptores de lluvia. Se encontró a una confianza del 95 % que no existe interacción entre los genotipos de avena y la restricción de lluvia. La restricción de lluvia afectó al rendimiento (ton MS/ha) disminuyéndolo de 4,3 ± 0,7 a 3,0 ± 1,0, y al porcentaje de proteína cruda aumentándolo de 12,7 ± 3,1 a 17,0 ± 2,7. No se encontró efecto significativo de la restricción de lluvia sobre la fibra detergente neutro, la cual fue de 41,1 ± 1,8 % para el nivel sin restricción y 41,3 ± 3,2 % para el nivel con restricción; ni sobre la digestibilidad in vitro aparente de la materia orgánica que fue de 71,5 ± 15,3 % para el nivel sin restricción y de 67,8 ± 15,4 % para el nivel con restricción. Los genotipos que mejor resisten la sequía son Junín-Jauja negra y Centenario.

The aim of this research was to evaluate the effect of supplementation with two barley forage genotypes on milk production and quality in grazing cows. The genotypes evaluated were a local barley (Hordeum vulgare L.) and UNALM 96 M6h-326 barley in the district of Sincos, Junín (Peru). The experiment was conducted with 16 Brown Swiss - creole crossbred cows in second lactation and body weight of 385 ± 17 kg. Under a simple change design, the animals were divided into two groups for supplementation with 4 kg/day with one of the two barley forages. Supplementation was carried out in two stages of 13 days each, the first 8 days being for adaptation and the following 5 days for evaluation of milk production and composition. Milk production per cow/day was increased with UNALM 96 M6h-326 barley forage compared to the local variety (4.0 vs. 3.57 kg. p<0.05). Likewise, higher urea content in milk was obtained, but the fat content was lower (p<0.05).