Electrochemical ammonia sensors were used to analyse the existing relationship between the ammonia concentration and ambient levels of both temperature and relative humidity in commercial lamb fattening housing equipped with mechanical ventilation and straw-bedded pens. In the first stage of the experiment, sensors were placed over straw beds covered in lamb urine and analysed under laboratory conditions in order to determine ammonia emission evolution over time; three control temperatures (25, 35, and 50°C) were used. A HOBO H8 temperature and relative humidity logger and a Dräger NH 3 LC-6809680 electrochemical ammonia sensor placed in a Dräger Polytron 7000 gas detector were utilized as sensors. A positive correlation was established between both ammonia emission time and emitted amount with temperature. Additionally, tests were performed in a commercial lamb housing to determine ammonia concentration variation with respect to height from the ground; three ammonia sensors placed at 50, 90, and 135 cm above the ground were used simultaneously. The ammonia concentration significantly decreased as height increased. A 90 cm height was selected, and three ammonia probes were placed in three different pens inside the livestock housing, along with temperature and relative humidity sensors; four different housing ventilation rates were then tested under real conditions over a time period of 4 months. An adjustment polynomial equation between the housing ambient temperature and the ammonia concentration was obtained with R 2 = 0.632. In conclusion, a relationship can be established between temperature and ammonia concentration in commercial lamb housing under certain handling conditions, which in turn allows for estimating the ammonia concentration adequately based on the ambient internal temperature.

Sheep farming makes an important socio-economic contribution to Spain’s rural areas by sustaining farming and employment in less favored regions, but it is a low-profit sector because of high operating and regulatory costs. One possible solution would be to raise for slaughter lambs from dairy sheep that are not required as replacements. However, the early weaning of these lambs and their artificial rearing generally lead to reduced growth rates and high mortalities. In the work presented herein, three housing systems (slat + heating plate, slat + infrared lamp, and deep-litter + infrared lamp) were tested on 763 lambs over an eight-month period in a farm located in Ejea de los Caballeros (Zaragoza, Spain), with a view to reducing mortality during the period of artificial lactation. The effect of the environmental parameters of the lamb housing on the development of the lambs was evaluated by monitoring environmental (temperature, relative humidity, CO2 and NH3) and productive parameters (weight, average daily gain, and deaths). The results suggested that the combination of deep litter with straw bedding and infrared lamp heating would be the most favorable option, as it led to the highest average daily gain and the lowest percentage of deaths. From the study of the relationship of the initial weight with deaths, a prediction curve was obtained, defining the maximum prices to be paid per lamb as a function of their initial weight to guarantee the profitability of the raising process. This may be regarded as a valuable guidance for Spanish sheep farmers, as it can reduce their economic uncertainty.

Resumen: Dada la difícil situación que está atravesando el sector ovino de carne, se hace necesaria la búsqueda de estrategias para mejorarla. Una posible solución sería introducir en el mercado cárnico corderos procedentes de ovejas lecheras, pero esta opción se ve afectada por una alta mortalidad durante la etapa de lactancia artificial. En el presente trabajo se estudia un nuevo sistema de explotación de corderos de razas lecheras que reduce dicha mortalidad y facilita su crecimiento hasta pesos elevados, sin engrasar. El trabajo se ha desarrollado en un cebadero de corderos, situado en Ejea de los Caballeros (Zaragoza), trabajando con 763 corderos, divididos en seis periodos, desde septiembre de 2016 a abril de 2017. Se han empleado tres sistemas de manejo diferentes (slat + placa calefactora, slat + lámpara infrarroja, y paja + lámpara infrarroja) y se ha evaluado el efecto de los parámetros ambientales del alojamiento ganadero sobre el desarrollo de los corderos en el periodo de lactancia artificial. Este proceso ha requerido una monitorización en continuo de los parámetros ambientales (temperatura, humedad relativa, CO2 y NH3) y un seguimiento de los parámetros productivos (peso de entrada de cada cordero, peso al cabo de 15 días y al cabo de un mes, ganancia media diaria, y bajas para cada tipo de manejo en cada periodo). También se han ensayado tres tipos de lacto-reemplazantes con diferentes composiciones al objeto de evaluar su efecto. Los resultados obtenidos sugieren que el sistema de manejo basado en suelo de paja con calefacción con lámpara infrarroja es la opción más deseable, tanto desde un punto de vista ambiental como por su influencia positiva en los factores productivos. Del estudio de la relación del peso de entrada con las bajas, se ha obtenido una curva de predicción de las mismas, de utilidad para la determinación del precio máximo a pagar por cordero en función de su peso de entrada que garantice la rentabilidad del proceso.