[ES]En los sistemas de producción animal intensivos actuales, el manejo y otras condiciones del ambiente, pueden inducir el incremento de la frecuencia cardíaca, presión sanguínea u otro conjunto de ajustes, que finalmente, promueven la ruptura del equilibrio existente entre la producción de especies reactivas del oxígeno y los mecanismos antioxidantes del propio animal, dando lugar a estrés oxidativo. El estrés oxidativo en el animal también puede ser promovido por el consumo de altos niveles de ácidos grasos poliinsaturados, o debido a una deficiencia de los nutrientes implicados en el sistema de defensa antioxidante. De cualquier manera, el estrés oxidativo en altos niveles influencia negativamente parámetros relacionados con el bienestar animal y el rendimiento productivo de los animales en los sistemas de producción intensivos. Por otro lado, la calidad de la carne también puede verse afectada por el estrés oxidativo. La oxidación lipídica es la principal causante del deterioro de la carne tanto de corderos de cebo como lechales, afectando directamente sobre características del producto como: el flavor, el color, la textura, el valor nutritivo y la seguridad alimentaria. La oxidación lipídica en el músculo se inicia en el animal vivo, tal y como ya hemos comentado anteriormente, pero la oxidación lipídica es particularmente acentuada por el manejo, el procesado y el almacenado, promoviendo por tanto la reducción de su vida útil. Algunos compuestos procedentes de la dieta, como es el caso de la vitamina E, contribuyen a la defensa del sistema antioxidante del animal protegiendo las membranas celulares frente a la oxidación lipídica, y por tanto preservando el bienestar animal y la calidad del producto. Existen muchos otros compuestos naturales (proceden de plantas) con propiedades antioxidantes que podrían utilizarse incluidos en el propio alimento de los animales para mejorar la resistencia de los animales al estrés oxidativo. En este contexto, se ha sugerido que la suplementación de compuestos fenólicos en la alimentación, podría mostrar efectos beneficiosos sobre algunos parámetros relacionados con la respuesta inmune e inflamatoria, especialmente bajo condiciones de estrés oxidativo. Además, algunas plantas con altos contenidos en compuestos fenólicos incluidas en la dieta de los animales han mostrado actividad antimicrobiana y la capacidad de retrasar la oxidación lipídica de la carne. Con este objetivo se ha puesto especial atención en el Romero (Rosmarinus officinalis L.), una planta comúnmente utilizada como especia. Las propiedades bioactivas de dicha planta son atribuidas principalmente a su alta concentración en compuestos fenólicos y en especial al diterpeno fenólico denominado ácido carnósico. No obstante, la concentración de compuestos fenólicos en las la plantas varía, dependiendo del estado de de madurez o de las condiciones climatológicas, por lo tanto sería aconsejable la utilización de extractos de romero con cantidades conocidas de ácido carnósico, en lugar de la utilización de la planta completa para permitir establecer recomendaciones sobre las cantidades de romero que deben ser administradas a los animales en función de sus niveles de ácido carnósico.

El artículo titulado: “Antioxidants included in the diet of fattening lambs: Effects on immune response, stress, welfare and distal gut microbiota” describe el efecto de las diferentes dosis de ácido carnósico en todos los parámetros descritos y los compara con el antioxidante más frecuentemente utilizado en alimentación animal, la vitamina E. Tras 7 semanas con la dieta experimental se extrajeron muestras de sangre permitiendo la medida de las subpoblaciones linfocitarias mediante citometría de flujo, así como la producción de interferón-gamma (IFN-γ). Tras la toma de muestras de sangre los corderos fueron sometidos a estrés por transporte durante un periodo de 4 horas con intención de estudiar la evolución de los parámetros tanto hematológicos como biológicos durante el transporte. Finalmente, para realizar un estudio de la diversidad microbiana se recogieron muestras de líquido ruminal y heces. Con respecto a los resultados obtenidos, la suplementación de corderos de cebo con vitamina E incrementa la producción de IFN-γ, aunque el significado biológico de este efecto queda todavía por determinar. A su vez, la suplementación con vitamina E tiende a reducir el incremento producido durante el transporte en los indicadores de daño tisular en sangre (creatina fosfoquinasa), por tanto preserva la salud de los animales sometidos a condiciones de estrés. Finalmente, el ácido carnósico únicamente generó cambios a nivel de la comunidad bacteriana en heces, pudiendo estar relacionado con diferencias en la digestión del alimento a nivel de intestino grueso. El artículo titulado: “Metabolic acidosis corrected by including antioxidants in diets of fattening lambs” describe el efecto de los antioxidantes (diferentes dosis de ácido carnósico y vitamina E) incluidos en la dieta de los animales sobre la acidosis promovida por dietas acidogénicas a nivel ruminal y metabólico. Para ello, tras 7 semanas de alimentación con la dieta experimental se tomaron muestras de sangre para la medición de: pH, bicarbonato (HCO3-), presión de CO2 (pCO2), anión gap, CO2 total (tCO2), así como las concentraciones de Na+, K+ y Cl−. Tras el sacrificio (a los 25 kg de peso vivo) se tomó líquido ruminal para la determinación inmediata del pH. Así mismo se conservaron dos muestras de la pared ruminal para el posterior estudio anatómico. Los resultados mostraron que el pH sanguíneo era menor en los corderos CONTROL comparado con los grupos alimentados con antioxidantes, siendo también el resto de los parámetros sanguíneos indicativos de acidosis metabólicas. Por el contrario, no se encontraron diferencias entre los grupos a nivel ruminal. Por tanto, la acidosis metabólica en corderos de cebo se corrigió con ambos antioxidantes (ácido carnósico y vitamina E), pero no se observaron efectos sobre la acidosis ruminal.

The article entitled “Antioxidants included in the diet of fattening lambs: Effects on immune response, stress, welfare and distal gut microbiota” describes the effects of different doses of carnosic acid on all these parameters and compares them with the most frequently used antioxidant in animal nutrition, vitamin E. Thus, after 7 weeks of being fed the experimental diets, blood samples were taken to measure blood lymphocyte subpopulations by flow cytometry and interferon-gamma (IFN-γ) production; then, all lambs were subjected to a 4-h transportation stress period to study the evolution of haematological and biological parameters during road transport. Finally, rumen fluid and faeces samples were collected to study microbial diversity. With regards to the results obtained, vitamin E supplemented to fattening lambs enhanced IFN-γ production, although the biological significance of these effects remains to be determined. Additionally, vitamin E supplementation tended to reduce the increments of blood tissue damage indicators (creatine phosphokinase) during road transport, thus preserving the health of the animal under stress conditions. Finally, carnosic acid only promoted changes in the faecal bacterial community that might be related to differences in feed digestion in the large intestines. The article entitled: “Metabolic acidosis corrected by including antioxidants in diets of fattening lambs” describes the effects of the antioxidants (different doses of carnosic acid and vitamin E) included in the diet of animals on the ruminal and metabolic acidosis promoted by acidogenic diets. Thus, after 7 week of being fed the experimental diets blood samples were collected to measure pH, bicarbonate (HCO3−), CO2 pressure (pCO2), anion gap, total CO2 (tCO2), and Na+, K+ and Cl− concentrations. After slaughter (25 kg of intended body weight) rumen fluid was also obtained and ruminal pH determined immediately. Two pieces of the rumen wall were conserved for further anatomical study. Regarding the results, the pH of blood samples was lower for the CONTROL lambs when compared to the groups fed antioxidants, being also the rest of blood parameters indicative of metabolic acidosis. On the contrary, no differences between groups were detected at the ruminal level. Therefore, metabolic acidosis in fattening lambs was corrected by both antioxidants (carnosic acid and vitamin E), but no detectable effects were observed on ruminal acidosis.

The final part of this study was designed to determine the influence of the dietary inclusion of carnosic acid on meat quality parameters. Accordingly, the animals were slaughtered at 25 kg of intended body weight and the pH of the meat was measured after 0, 45 min and 24 h post-mortem in longissimus thoracis muscle. Then, the experimental muscles were removed from the cold carcass, longissimus thoracis being used to determine chemical composition and fatty acids profile, whereas the other quality parameters were analyzed on sliced stored (4ºC with 12 h of daily illumination) muscles [longissimus lumborum (LL) and gluteus medius (GM)] packaged in modified atmosphere (MAP) (35% CO2, 35% O2 and 30% N2). Finally the left hind leg was removed and stored at −30 °C until sensory evaluation. On the article entitled “Carnosic acid dietary supplementation at 0.12% rates slows down meat discoloration in gluteus medius of fattening lambs” the effect of carnosic acid supplementation on the color, water holding capacity, microbial spoilage, and sensorial characteristics of the meat is described. No statistical differences were found on water holding capacity, sensorial characteristics or microbial spoilage of meat. Nevertheless dietary carnosic acid seemed to be useful to protect meat from discoloration after a long period of time under MAP at refrigerated storage, particularly in medium stable muscles such as gluteus medius. However, its effectiveness was lower than that observed for vitamin E. On the article entitled “Meat texture and antioxidant status are improved when carnosic acid is included in the diet of fattening lambs” the effect of carnosic acid supplementation on oxidative stability of lipids (lipid peroxidation and cholesterol oxidation products) and proteins and the related quality parameter -texture- is described. The results show that carnosic acid dietary supplementation reduces lipid peroxidation in meat samples after a long period of time under MAP at refrigerated storage, particularly in medium stable muscles such as gluteus medius. Texture and protection against cholesterol oxidation were also improved either by carnosic acid or vitamin E, being the effectiveness of the last one better once again.

The manuscript entitled: “Effect of carnosic acid dietary supplementation on meat quality from suckling lambs”, describes the influence of dietary carnosic acid on the meat quality of artificially fed suckling-lambs. Animals were slaughtered at the intended body weight (11-12 kg LW). Longissimus thoracis muscles were used to determine the proximate composition of meat, whereas different muscles (longissimus lumborum and gluteus medius) were sliced and kept under refrigerated during 0, 7, and 14 days to determine water holding capacity, thiobarbituric acid reactive substances (TBARS), and cholesterol oxidation products (COPs) in cooked meat samples. Biceps femoris muscles were used for the analysis of volatile compounds on precooked meat after 1 and 7 days of storage. The results indicate that carnosic acid dietary supplementation in artificially fed suckling lambs might reduce the levels of lipid peroxidation and COPs in meat whilst volatile compounds levels would not be affected. However, the results are not conclusive at the dose of carnosic acid used in the present study. To sum up, metabolic acidosis was corrected by the inclusion of carnosic acid in the diet of fattening lambs. This compound also promoted changes in the faecal bacterial community that might be related to differences in feed digestion in the large intestine. Regarding meat attributes, carnosic acid added on the diet of fattening lambs improved some important quality parameters such as color or texture and seemed to delay lipid peroxidation. However, the effect of carnosic acid was not conclusive when included in the diet of artificially fed suckling lambs at the rate of 0.096 g carnosic acid kg-1 of LW.

Dietary factors such as vitamin E contribute to the antioxidant defence system of the animal and protect biological membranes of the cells against lipid oxidation, also preserving the welfare and food quality. There are many other natural compounds (plant origin) with antioxidant properties which also might be included in animal feedstuff to improve the resistance of animals against oxidative stress. In this context it has been suggested that supplementation with phenolic compounds may have beneficial effects on certain inflammatory and immune parameters, particularly under oxidative stress conditions. Additionally, some plants with high content in phenolic compounds have demonstrated antimicrobial activity and delayed lipid oxidation of meat when they are included in the diet of the animal. With this regard, especial attention has been paid to rosemary (Rosmarinus officinalis L.), an herb commonly used as a flavouring agent. The bioactive properties of this plant have been attributed to the high quantity of phenolic compounds, and chiefly to the diterpenic phenolic compound carnosic acid. However, the concentration of phenolic compounds in the plants varies depending on the maturity stage or climatic conditions, so feeding rosemary extracts with a known richness of carnosic acid instead of intact plants will allow recommendations to be established about the amount of rosemary which should be fed to the animals according to its levels of carnosic acid.

Para la determinación del efecto producido por la inclusión de diferentes dosis de ácido carnósico en la dieta de corderos de cebo sobre parámetros relacionados con el bienestar y la calidad de carne, se utilizaron 32 corderos Merinos machos. Tras su estratificación en función del peso vivo (Promedio del peso vivo = 15.2 ± 0.749 kg), los corderos fueron alojados al azar de manera individual y asignados a uno de los cuatro grupos experimentales existentes (ocho corderos por tratamiento): un grupo control alimentado con paja de cebada (BS) y concentrado únicamente (CONTROL); un segundo grupo alimentado con BS y concentrado suplementado con una dosis básica de ácido carnósico (CAR006: 0,6 g ácido carnósico kg-1 concentrado); el tercer grupo se alimentó con BS y concentrado suplementado con una dosis doble de ácido carnósico (1,2 g ácido carnósico kg-1 concentrado); y por último el cuarto grupo se alimentó con BS y concentrado suplementado con vitamina E (50% α-tocoferol acetato) a razón de 0,6 g kg-1 concentrado (VITE006, equivale a 900 UI de vitamina E kg-1 concentrado). Diariamente el concentrado (35 g kg-1 peso vivo al día) y el forraje (200 g paja de cebada día-1) se pesaban y administraban en comederos separados a las 9:00. El agua de bebida fresca estaba disponible en todo momento. Así mismo los restos se pesaron diariamente, y se recogía una muestra del alimento para la determinación de la composición química y del perfil de ácidos grasos (FAs).

In order to determinate the effect of different doses of carnosic acid included in the diet of fattening lambs on some parameters related to welfare and meat quality, 32 male Merino lambs were used. After stratification on the basis of body weight (average BW = 15.2 ± 0.749 kg), lambs were penned individually and allocated randomly to one of four different groups (eight lambs per treatment): a control group was fed barley straw (BS) and concentrate alone (CONTROL); a second group was fed BS and concentrate with a single dose of carnosic acid (CARN006: 0.6 g carnosic acid kg-1 concentrate); a third group was fed BS and concentrate with a double dose of carnosic acid (CARN012: 1.2 g carnosic acid kg-1 concentrate); and a fourth group was fed BS and concentrate with vitamin E (50% α-tocopheryl acetate) at a rate of 0.6 g kg-1 concentrate (VITE006, equivalent to 900 IU vitamin E kg-1 concentrate). Concentrate (35 g kg-1 BW per day) and forage (200 g barley straw day-1) were weighed and supplied in separate feeding troughs at 9:00 a.m. each day. Fresh drinking water was always available. The orts were also weighed daily, and feed samples were collected for chemical and fatty acids (FAs) composition analysis.

[EN] Management or environmental conditions of the current intensive animal production systems may induce acceleration of heart rate, blood flow and a set of metabolic adjustments which, at the end, may promote an imbalance between the production of reactive oxygen species and the animal's antioxidant defense mechanisms, resulting in oxidative stress. The oxidative stress in the living animal also is promoted by a high intake of polyunsaturated fatty acids, or by a deficiency of nutrients involved in the antioxidant defense system. In any case, high levels of oxidative stress might influence negatively the animal welfare, and hence the animal performance in intensive production systems. Moreover, the meat quality may also be affected by oxidative stress. Thus, oxidation of lipids is a major cause of deterioration in the meat from fattening and suckling lambs affecting directly meat characteristics such as flavor, color, texture, nutritive value and safety of the product. Lipid oxidation in muscle food is initiated in the living animal, as explained before, but damage to lipids is accentuated, in particular, during handling, processing and storage, thus promoting the reduction of shelf life of meat.

The article entitled: “Effect of dietary carnosic acid on the fatty acid profile and flavour stability of meat from fattening lambs” reveals that dietary supplementation of carnosic acid or vitamin E did not modify the fatty acid profile, but the volatile compounds production was clearly affected by the addition of carnosic acid to the diet of fattening lambs in a dose dependent manner. A second experiment was carried out to elucidate the effects of dietary carnosic acid on the welfare and meat quality attributes of artificially fed suckling lambs. Thus, 24 suckling lambs were stratified on the basis of body weight (average BW, 5.95±0.766 kg), and allocated randomly to one of three different groups (n=8 per treatment); a control group (CTRL), a second group fed a dose (0.096 g carnosic acid kg-1 of LW; CARN) of carnosic acid, and a third group fed a dose of vitamin E (α-tocopheryl acetate 50%) at a rate of 0.024 g kg-1 LW (VITE).