Nitrogen isotopic characterisation of macroalgae blooms from different sites within a subtropical bay in the Gulf of California.

In La Paz Bay conspicuous macroalgal blooms of Ulva spp. are recurrent in the waterfront of the city; studies relate its growth to seasonality and nutrient enrichment but their relative influence is not known. We use the δ15N to discern amongst nitrogen sources at three sites with different substratum and anthropogenic activities. Ulva blooms were monitored monthly at San Juan de la Costa (SJC), Casa del Marino (CM) and El Tecolote (TE). Species presence varied between sites and months. At SJC Ulva displayed the highest signal of δ15N associated with fishing products and local mining wastewaters (19.5‰). CM showed isotopic values related to sewage waters (13‰). The δ15N of species at TE were the lowest. We found higher isotopic signatures than in other tropical/subtropical regions, associated with nutrient rich water masses. Ulva species can be used to trace and discern amongst different sources of nitrogen from natural or anthropogenic sources.

The marine algae Sargassum spp. (Sargassaceae) as feed for sheep in tropical and subtropical regions

The objective of this study was to evaluate Sargassum meal as feed for sheep through the measures of in vivo digestibility, dry matter degradability, pH, ammonia and volatile fatty acids in rumen. The Sargassum algae used in this experiment were collected at the end of spring, when they are more abundant, bigger, and have completed their reproductive cycle. Four tons (wet weigth) were collected manually from the intertidal zone of La Paz bay, Baja California Sur, Mexico. These algae were sun-dried and ground in a hammer mill to obtain the Sargassum meal. Four fistulated Pelibuey sheep, were fed daily with diets containing the marine algae (MA) at different levels (0, 10, 20 and 30 %), using a 4 x 4 Latin-square design experiment. Feed intake was not affected (p>0.05). Water consumption and urine excretion increased with MA (p<0.05; r²=0.54 and r²=0.74, respectively). In all treatments dry matter digestibility was of 74%-79%, and crude protein digestibility was of 85%-88%. Acid detergent fiber (59%-65%) and neutral detergent fiber (55%-66%) digestibility were greater in all treatments with MA. Ruminal pH was greater in all groups fed with MA (p<0.05). Ammonium concentration was not influenced (p>0.05) by MA. Ruminal volatile fatty acids decreased in all MA groups (p<0.05). The marine algae Sargassum spp. can be used as a feed supplement for sheep, especially in tropical and subtropical regions where these marine algae are available. Rev. Biol. Trop. 57 (4): 1271-1281. Epub 2009 December 01.

El objetivo de este estudio fue evaluar la harina del alga marina Sargassum como alimento para ovejas, midiendo la digestibilidad in vivo, la degradabilidad de la materia seca, así como el pH y los ácidos grasos volátiles en rumen. El alga Sargassum utilizada en este experimento, fue recolectada a finales de la primavera, cuando esta alga es más abundante, alcanza su mayor talla y ha completado su ciclo reproductivo. Se recolectaron manualmente, cuatro toneladas (peso húmedo) de la zona intermareal en la Bahía de La Paz, Baja California Sur, México. Estas algas fueron secadas directamente al sol y molidas en un molino de martillos, para obtener la harina. Se utilizaron cuatro borregos Pelibuey fistulados, distribuidos en un arreglo factorial de 4 x 4. Los animales fueron alimentados diariamente con dietas que contenían el alga marina (AM) Sargassum a diferentes niveles (0, 10, 20 y 30%). El consumo de alimento no se vio afectado con la inclusión del alga (p> 0.05). El consumo de agua y la excreción de orina se incrementaron conforme aumentó la concentración de AM en las dietas (p<0.05; r²=0.54 and r²=0.74, respectivamente). En todos los tratamientos la digestibilidad de la materia seca fue de 74% a 79%, la digestibilidad de la proteína cruda fue de 85% a 88%. La digestibilidad de la fibra ácido detergente (59%-65%) y de la neutro detergente (55%-66%) fue mayor en todos los tratamientos con AM, lo mismo ocurrió con el pH en rumen (p<0.05). La concentración de amonio en rumen no se vio afectada por AM (p>0.05). La concentración de ácidos grasos volátiles se redujo en todos los tratamientos con AM (p<0.05). El alga marina Sargassum spp. puede ser usada como complemento alimenticio para ovejas, especialmente en las regiones tropicales y subtropicales donde está disponible.

The kelp macrocystis pyrifera as nutritional supplement for goats

The present study was aimed to evaluate Macrocystis pyrifera (MP) meal as a nutritional supplement for goats. There is an increasing interest to look at nutritional alternatives to guarantee a continuous supply of good quality forage for goats, in many communities around the world. Given its abundance and chemical composition, the algae M. pyrifera is an important potential resource as animal feed. Three diets with 10, 20, and 30% of MP meal concentrations and a control diet, with no algae, were evaluated. Four rumen cannulated goats, housed individually in metabolism cages, were used. The experimental design was a 4 x 4 Latin-Square. Feed and water intake, excreted urine and faeces, were measured. Digestibility in vivo, dry matter (DM) disappearance, and the metabolic variables of pH and ammoniacal nitrogen in the rumen, were determined. There was no significant difference in the feed intake but there was in water intake and urine excreted. No significant difference in digestibility in vivo among diets (P>0.05) was found. A significant difference (P<0.05) for degradability in situ was found for the algae diets containing 10 and 30 percent MP concentrations at 96 hours of sampling (78.3 and 82.2 percent). The raw algae in situ digestibility was 77 percent. A potential degradability of 87.3 percent was obtained with 30 percent MP diet. The highest effective degradation was obtained at an estimated rate of 0.02 h-1. Ruminal pH was higher (P<0.05) in all MP treatments (10 percent MP: 6.83, 20 percent MP: 6.85, 30 percent MP: 6.91). As suggested by the results, M. pyrifera represents a good unconventional feeding as a nutritional supplement for goats.

El objetivo de este trabajo fue evaluar Macrocystis pyrifera (MP) como suplemento alimenticio para cabras. Hay un interés creciente en buscar alternativas alimenticias para garantizar el suministro continuo de forraje de buena calidad para cabras en muchas comunidades del mundo. Dada su abundancia y composición química, el alga M. pyrifera es un recurso potencial importante como pienso para ganado. Se evaluaron tres dietas con concentraciones de 10, 20, y 30 por ciento de harina de MP, y una dieta control, sin las algas. Se utilizaron cuatro cabras canuladas dispuestas individualmente en jaulas metabólicas. El diseño experimental fue un Cuadrado Latino 4 x 4. El alimento y agua consumidos, la orina y las heces excretadas fueron medidas. Se determinaron la digestibilidad in vivo, la desaparición in situ de la materia seca y las variables metabólicas pH y nitrógeno amoniacal en rumen. No se encontró diferencia significativa en el alimento consumido, ni en la digestibilidad in vivo entre las dietas (P>0,05), pero si hubo diferencia significativa en el consumo de agua y la orina excretada (P<0,05). Se encontró diferencia significativa (P<0,05) para la digestibilidad in situ en las dietas que contenían el 10 y 30% del alga a la hora 96 del muestreo (78,3 y el 82,2 por ciento). La digestibilidad in situ del alga fue de 77 por ciento. Se obtuvo una degradabilidad potencial de 87,3 por ciento con la dieta que contiene 30 por ciento de MP. La mayor degradación efectiva se obtuvo a una tasa estimada de 0,02 h-1. El pH ruminal fue más alto (P<0,05) en todos los tratamientos con MP (10 por ciento de MP: 6,83, 20 por ciento de MP: 6,85, 30 por ciento de MP: 6,91). Los resultados obtenidos sugieren que M. pyrifera representa un buen suplemento nutricional no convencional para cabras.

The marine algae Sargassum spp. (Sargassaceae) as feed for sheep in tropical and subtropical regions.

The objective of this study was to evaluate Sargassum meal as feed for sheep through the measures of in vivo digestibility, dry matter degradability, pH, ammonia and volatile fatty acids in rumen. The Sargassum algae used in this experiment were collected at the end of spring, when they are more abundant, bigger, and have completed their reproductive cycle. Four tons (wet weigth) were collected manually from the intertidal zone of La Paz bay, Baja California Sur, Mexico. These algae were sun-dried and ground in a hammer mill to obtain the Sargassum meal. Four fistulated Pelibuey sheep, were fed daily with diets containing the marine algae (MA) at different levels (0, 10, 20 and 30 %), using a 4 x 4 Latin-square design experiment. Feed intake was not affected (p>0.05). Water consumption and urine excretion increased with MA (p<0.05; r2=0.54 and r2=0.74, respectively). In all treatments dry matter digestibility was of 74%-79%, and crude protein digestibility was of 85%-88%. Acid detergent fiber (59%-65%) and neutral detergent fiber (55%-66%) digestibility were greater in all treatments with MA. Ruminal pH was greater in all groups fed with MA (p<0.05). Ammonium concentration was not influenced (p>0.05) by MA. Ruminal volatile fatty acids decreased in all MA groups (p<0.05). The marine algae Sargassum spp. can be used as a feed supplement for sheep, especially in tropical and subtropical regions where these marine algae are available.

[Marine algae of Baja California Sur, Mexico: nutritional value]. / Algas marinas de Baja California Sur, México: valor nutrimental.

The Baja California Peninsula is one of the richest regions of seaweed resources in México. The objective of this study was to determine the chemical composition of some marine algae species of Baja California Sur, with an economical potential due to their abundance and distribution, and to promote their use as food for human consumption and animal feeding. The algae studied were Green (Ulva spp., Enteromorpha intestinalis, Caulerpa sertularoides, Bryopsis hypnoides), Red (Laurencia johnstonii, Spyridia filamentosa, Hypnea valentiae) and Brown (Sargassum herporizum, S. sinicola, Padina durvillaei, Hydroclathrus clathrathus, Colpomenia sinuosa). The algae were dried and ground before analysis. In general, the results showed that algae had a protein level less than 11%, except L. johnstonii with 18% and low energy content. The ether extract content was lower than 1%. However, the algae were a good source of carbohydrates and inorganic matter.