Miguel A. Olvera-Novoa

Diets containing sea cucumber (Isostichopus badionotus) meals are hypocholesterolemic in young rats

Sea cucumber is widely consumed as a putative functional food. It contains many biologically-active substances, but only limited research on its properties in vivo has been done. The effects of different meals containing Isostichopus badionotus, a sea cucumber from southeast Mexico, on growth performance and body lipid profile in young rats were analyzed. Sea cucumber body wall was either lyophilized, cooked (100 °C, 1 h in water) and lyophilized, or oven-dried (70 °C for 12 h). It was then ground and incorporated into cholesterol-containing diets. I. badionotus meals supported growth and improved lipid profile in rats. In particular, serum cholesterol, low density lipoproteins, triglycerides concentration and atherogenic index values were greatly reduced by some I. badionotus containing diets. Liver total lipids, triglycerides and cholesterol were also reduced. Cooking or heat-treatment of the meals lowered but did not abolish their hypolipidemic potency. Gene expression analysis of several key genes involved in cholesterol and lipid metabolism in liver showed that diets containing I. badionotus repressed the induction of key genes associated with dyslipidemia exerted by cholesterol supplementation. Consumption of I. badionotus from the Yucatan Peninsula is beneficial for dyslipidemia, although biological effect is clearly dependent on preparation method.

Evaluation of Artemia biomass production in San Crisanto, Yucatán, México, with the use of poultry manure as organic fertilizer

Abstract The main objective of aquaculture is to obtain high yields to improve the cost–benefit relationship. Organic fertilizers are considered cheap inputs that may contribute to improving crop yields; however, responses to these fertilizers can vary not only due to their own characteristics, but also to environmental conditions at the location, salinity and handling given to these wastes. In the present work, we evaluated nitrogen and phosphorus levels resulting from 24, 48 and 72 h decomposition of five doses of poultry manure (2.67, 5.33, 10.67, 16 and 20 g l−1, equivalent to 100, 200, 400, 600 and 750 kg ha−1 (kg/107 l), respectively) in seawater (experiment 1). The highest quantity of nitrogen in the water was obtained with 2.67 g of fertilizer at 24 h of decomposition. The highest amounts of phosphorus were obtained with 5.33 g of fertilizer at 24 and 48 h. Based on these results, it was decided to evaluate the 2.67 and 5.33g concentrations of poultry manure in the production of Artemia spp. biomass in earthen ponds (experiment 2). The highest biomass quantities (457.0 and 467.33 g 4000 l−1) were obtained with both concentrations of fertilizer (2.67 and 5.33 g, respectively) at 55 days of the trial. Biomass production in control ponds was always lower than that obtained in fertilized experimental units. The mean biomass production of the 11 evaluations recorded was not statistically different between the two doses of fertilizer (P>0.05), but these were significantly different from the control. The lowest apparent feed conversion ratio (AFCR=0.88) was obtained with the lowest concentration of fertilizer (2.67 g). Therefore, the best amount of fertilizer for Artemia biomass production under proposed experimental conditions is 2.67 g of fertilizer, equivalent to 100 kg ha−1. The use of poultry manure as fertilizer in Artemia culture could contribute to diversifying productive activities in the coastal zone of Yucatan and to partially satisfying the demand for this source in the region.

Producción de tilapia nilótica (Oreochromis niloticus L.) utilizando hojas de chaya (Cnidoscolus chayamansa McVaugh) como sustituto parcial del alimento balanceado

Aquaculture is an alternative for the production of high-quality, low-cost protein, particularly in developing countries with a limited food supply. In rural areas, the availability of alternative inputs is key to improving fish farming production, especially if these inputs are unprocessed. The leaves of tree spinach (Cnidoscolus chayamansa), a bush that grows in Mexico and Central and South America, are one such option. In this work, juvenile tilapia (7-14.5 g) survival, growth rates, and food conversion rates were studied during two seasons (warm and cold), substituting 25 and 50% of the balanced feed rations with raw tree spinach leaves (ad libitum). The experimental design was completely random, with two treatments and one control (100% of the balanced feed ration); three replicates were done in each season. The densities were 36 fish m per replica in the cold season and 44 fish m per replica in the warm season. The weight gain in the treatments with 50 and 75% balanced feed and tree spinach leaves was similar to that of the control group in both seasons. The cold season adversely affected survival, weight gain, and feed conversion rates in all treatments, but the warm season did not. When tree spinach leaves were included in the tilapia diet, the feed conversion rate for the balanced feed was reduced from 9.17 to 33.62% in the cold season and from 15.38 to 40.23% in 835 Producción de tilapia nilótica utilizando hojas de chaya the warm season. The results show that the use of locally available complementary inputs such as tree spinach leaves may favor the development of small-scale tilapia cultures in the tropics.

Nile tilapia production (Oreochromis niloticus L.) using tree spinach leaves (Cnidoscolus chayamansa McVaugh) as a partial substitute for balanced feed

Aquaculture is an alternative for the production of high-quality, low-cost protein, particularly in developing countries with a limited food supply. In rural areas, the availability of alternative inputs is key to improving fish farming production, especially if these inputs are unprocessed. The leaves of tree spinach (Cnidoscolus chayamansa), a bush that grows in Mexico and Central and South America, are one such option. In this work, juvenile tilapia (7-14.5 g) survival, growth rates, and food conversion rates were studied during two seasons (warm and cold), substituting 25 and 50% of the balanced feed rations with raw tree spinach leaves (ad libitum). The experimental design was completely random, with two treatments and one control (100% of the balanced feed ration); three replicates were done in each season. The densities were 36 fish m per replica in the cold season and 44 fish m per replica in the warm season. The weight gain in the treatments with 50 and 75% balanced feed and tree spinach leaves was similar to that of the control group in both seasons. The cold season adversely affected survival, weight gain, and feed conversion rates in all treatments, but the warm season did not. When tree spinach leaves were included in the tilapia diet, the feed conversion rate for the balanced feed was reduced from 9.17 to 33.62% in the cold season and from 15.38 to 40.23% in 835 Producción de tilapia nilótica utilizando hojas de chaya the warm season. The results show that the use of locally available complementary inputs such as tree spinach leaves may favor the development of small-scale tilapia cultures in the tropics.