Se evaluó el comportamiento productivo de bovinos doble propósito en un sistema silvopastoril intensivo (SSPi) en Apatzingán, Michoacán. La actividad se llevó a cabo mediante seguimiento técnico-económico. Asimismo, se monitorearon variables productivas y económicas (consumo de forraje, producción de leche, peso, ingresos y egresos) de 60 vacas de la raza Gyr analizadas mediante estadística descriptiva y presupuestos por actividad. La carga animal empleada fue de 2.06 UA ha-1 y la producción de leche obtenida fue 9.15 kg vaca-1 día-1. El manejo de vacas Gyr en un SSPi favorece la producción de leche y carne y el ingreso económico a la unidad de producción (UP).

Dual purpose farms southwest of the State of Mexico produce milk and calves under subtropical agrosilvopastoral systems (ASPS). During the dry season, farmers supplement their cattle due to the low availability and quality of grasses, without considering, besides grasses, the contribution of woody species to dry matter intake, metabolizable energy (ME), and crude protein (CP) requirements of cows. The aim of this study was to determine milk produced from forage energy (MFe) and protein (MFp) of grazing cow with three types of supplement. First supplement consisted of cracked maize and commercial concentrate resulting on 14 % of CP (S14).  To the S14 mixture 7 % of soybean meal was added to increase CP to 16 % (S16), and commercial concentrate of 16 % CP was used as a third supplement (SC16). Six lactating cows were allocated in a 3x3 replicated Latin Square (three cows per square), three experimental periods (EP) (three weeks per EP). There were no significant effects of supplements (P=0.80) on performance variables. Mean milk yield was 6.8 kg/cow/d. Milk from forage energy and protein were 0.8 and 6.1 kg/cow/day, respectively. Mean milk urea nitrogen (MUN) was high regardless of supplement; but nitrogen in urine (44.1 mg/dL) and feces (1.4 mg/g) were higher for SC16 (P=0.001 and 0.04, respectively). Cows obtained 90 and 10 % of their CP and metabolizable energy requirements for maintenance and production from the agrosilvopastoral system.

<p><strong>Background.</strong> An alternative in animal nutrition, to replace the use of synthetic additives, are essential oils, considered additives of vegetable origin. They are bioactive compounds, that have been shown to improve ruminal fermentation, nutrient digestibility, productivity and animal welfare. <strong>Objective.</strong> To review the current knowledge on the benefits of essential oils and their active compounds on ruminal fermentation, as well as the results obtained when using them in small ruminant production. <strong>Methodology</strong>. A search for bibliographic information was carried out using key terms in publications in scientific databases on the Web and electronic journals available on the Internet. <strong>Main findings.</strong> This paper presents the main essential oils used in animal production, their chemical structure and the results obtained from their use in small ruminants. Emphasis is made on the need to know the specific mode of action of each bioactive compound of essential oils, to optimize a dose without causing adverse effects. <strong>Implications.</strong> The limited information from <em>in vivo</em> studies on the biokinetics of essential oils in the rumen make it necessary to evaluate the specific mode of action of each bioactive compound, the biokinetics in the animal, as well as the optimal dose. This would provide scientific basis for the prudent and planned management of essential oils as additives commonly used in the feeding of small ruminants. <strong>Conclusions.</strong> Plant-derived essential oils can be useful in improving animal health and welfare, as well as meat and milk quality, and have potential environmental benefits such as mitigating enteric methane and ammonia nitrogen.</p>