Efecto del nivel de proteína en el crecimiento de Goodea atripinnis (Pisces: Goodeidae)

Background. Goodea atripinnis is an omnivorous fish that is only found in the state of Aguascalientes. Its population is being drastically reduced and its survival is considered to be threatened. To avoid its extinction, ex situ breeding programs are being implemented. To implement these programs, however, it is necessary to have feeding plans that allow the nutritional needs of this species to be met. Goals. To evaluate the effects of different protein levels in the diet (25, 30, 35, 40 and 45 % PC) on the growth of G. atripinnis. Methods. A randomized complete-block design with five treatments (protein levels) and 3 aquariums per treatment was used, each aquarium containing 20 fish. The experiment lasted 150 days. Daily feed intake and changes in weight and length of each fish were recorded every 15 days. Results. We found differences in final weight and total weight gain (p <0.05) depended on protein levels. Both the growth rate and the total food intake increased with higher levels of protein. As a result, the feed conversion rate, protein efficiency, and Fulton (K) body condition factor improved. The Gompertz model showed that high protein levels increased standard weight and that the inflection point occurred at the same weight. Conclusions. With higher protein levels, the standard weight is reached at an earlier age, leading to greater development of the fish.  Antecedentes. Goodea atripinnis es un pez omnívoro que sólo se localiza en el estado de Aguascalientes y su población se encuentra en estatus de amenaza. Para evitar su extinción se están implementando programas de reproducción ex situ; sin embargo, para lograrlo es necesario contar con planes de alimentación que permitan satisfacer las necesidades nutricionales de la especie. Objetivos. Evaluar los efectos de 5 niveles de proteína (25, 30, 35, 40 y 45% PC) en la dieta, velocidad de crecimiento y parámetros productivos de G. atripinnis. Métodos. Se utilizó un diseño de bloques al azar con 5 tratamientos (niveles de proteína) y 3 acuarios por tratamiento, cada uno contenía 20 peces (peso medio: 0.47 ± 0.02 g). El experimento duró 150 días, durante los cuales se registraron el consumo de alimento diariamente y los cambios en peso y longitud de cada pez cada 15 días. Resultados. Se encontraron diferencias en peso final y ganancia de peso total (p <0.05) entre los niveles de proteína. Tanto la tasa de crecimiento como la ingesta total de alimento aumentaron con el nivel alto de proteína. La tasa de conversión de alimento, la eficiencia proteínica y el factor de condición corporal de Fulton (K) mejoraron. El modelo de Gompertz mostró que los altos niveles de proteína aumentaron el peso estándar y que el punto de inflexión se produce en el mismo peso. Conclusiones. Con los niveles altos de proteína el peso estándar se alcanza a una edad más temprana y permite un mayor desarrollo de los peces

Effects of increasing dietary concentrations of fish oil on lamb performance, ruminal fermentation, and leptin gene expression in perirenal fat

ABSTRACT The objective of this study was to evaluate the effects of four levels of fish oil on lamb performance, carcass yield, ruminal fermentation, and leptin gene expression in perirenal fat. Thirty-two lambs (24.10±2.15 kg, Katahdin × Pelibuey) were used in a completely randomized experimental design. The lambs were assigned to one of four dietary treatments (n = 8 lambs/treatment), expressed as g/kg DM basis: 0 fish oil and 300 corn; 10 fish oil and 250 corn; 20 fish oil and 205 corn; and 30 fish oil and 170 corn. The lambs were weighed on consecutive days at the beginning (days 0 and 1) and at the end (days 55 and 56) of the trial. Ruminal fluid samples were collected on day 56 to evaluate the ruminal fermentation pattern. The lambs were slaughtered on day 56; perirenal adipose tissue samples were collected and the carcass yields were recorded. Volatile fatty acids, ammonia N, and leptin mRNA expression were not affected by the dietary treatments. However, the dry matter intake, average daily gain, final body weight, and the hot carcass yield showed either increased linear or quadratic responses as the proportion of fish oil increased in the ration; the estimated optimal level obtained of fish oil levels for average daily gain was 11.2±0.21 g/kg and 12.8±4.67 g/kg for feed conversion. Additionally, feed efficiency and backfat thickness had an increment, showing quadratic response as the proportion of fish oil increased in the diet. Increasing the fish oil concentration in the diet does not affect leptin messenger ribonucleic acid expression. The lamb performance can be improved with 12 g/kg fish oil in diets of finishing lambs

Evaluación de vainas y hojas de árboles forrajeros por la técnica de producción de gas in vitro

The kinetics of in vitro gas production to achnowledge the nutritional potential of tree leaves and pods that grow in a dry tropical area of Mexico using bovine faeces as inoculum, compared with guinea grass ( Panicum maximum ) as reference was studied. Leaves and pods were collected from: Prosopis laevigata , Pithecellobium dulce and Pithecellobium acatlense ; and only leaves from: Amelanchier denticulata , Verbesiana crocata , Haemotoxylum brasiletto , Acacia bilimekii , Acacia pennatula , Acacia constricta and Lantana velutina . The inoculums were prepared with fresh bovine faeces dissolved in water in 1:3 ratio. Parameters estimated were the maximum gas production (v), the production rate (s) and the lag phase (l). Three species showed low gas values (8,34-11,4 ml) while most were close to those of guinea grass (29 ml) with a similar production rate (0,03 h-1). In the pods, with exception of Pithecellobium acatlense, the others presented a higher gas production (33,8-46,3 ml) than guinea grass (25,6 ml) with a rate of production similar o greater (0,03 a 0,06 h-1). The results indicate that the pods of Prosopis laevigata and Pithecellobium dulce have nutritional value superior to that of guinea grass while leaves from Haemotoxylum brasiletto and Prosopis laevigata have a similar value. The gas production technique in vitro allows the estimation of the potential value of non-conventional feed resources.Se estudió la cinética de producción de gas in vitro para conocer el potencial nutricional de hojas de arbóreas y vainas que crecen en una zona tropical seca de México usando heces bovinas como inóculo, comparadas con el pasto guinea como referencia ( Panicum maximum ). Se colectaron hojas y vainas de: Prosopis laevigata , Pithecellobium dulce y Pithecellobium acatlense ; y sólo hojas de: Amelanchier denticulata , Verbesiana crocata , Haemotoxylum brasiletto , Acacia bilimekii , Acacia pennatula , Acacia constricta y Lantana velutina . El inóculo se preparó con heces bovinas recién depuestas disueltas en agua en proporción 1:3. Se estimaron los parámetros de la velocidad máxima de producción de gas (v), la tasa de producción (s) y la fase lag (l). Tres especies mostraron bajos valores de gas (8,34-11,4 ml), mientras que la mayoría fueron cercanos a los del pasto guinea (29 ml) con una tasa de producción similar (0,03 h-1). Con excepción de la vaina de Pithecellobium acatlense, el resto tuvo mayor producción de gas (33,8-46,3 ml) que el pasto guinea (25,6 ml) con una tasa de producción igual o mayor (0,03 a 0,06 h-1). Los resultados indican que las vainas de Prosopis laevigata y Pithecellobium dulce tienen un valor nutricional superior al del pasto guinea mientras que las hojas de Haemotoxylum brasiletto y Prosopis laevigata presentaron un valor similar. La técnica de producción de gas in vitro permite estimar el valor potencial de recursos forrajeros no convencionales