The effect of weaning diet type on grey mullet (Mugil cephalus) juvenile performance during the trophic shift from carnivory to omnivory

In captive grey mullet (Mugil cephalus) juveniles, the weaning stage overlaps the period where there are changes in the ontogeny of digestive enzymes as the fry transit from carnivory to omnivory. The aim of this study was to evaluate growth, survival, weight distribution and the activity of pancreatic and brush border digestive enzymes when fry are fed a carnivorous, herbivorous or omnivorous weaning diet. Fifteen 17-L aquaria in a flow through system with 40‰, UV treated, temperature (24.5 ± 0.5 °C) controlled seawater were stocked with eighty-five 23 dph grey mullet larvae per aquarium. This allowed the testing of three weaning dietary treatments, differing in their protein and carbohydrate content, in 5 replicate aquaria per treatment from 24 to 53 dph. Diet 1 was the dried macroalgal species Ulva lactuca and was designated as a low protein: high carbohydrate herbivorous diet. Diet 2 was a commercial microencapsulated starter feed designated as a high protein: low carbohydrate carnivorous diet. Diet 3 was a 1:1 ww mixture of diets 1 and diet 2 representing an omnivorous feeding regime. The average final weight of the omnivorous feeding fish was significantly (P .05). The activity levels of brush border alkaline phosphatase and intracellular leucine alanine peptidase were similar in grey mullet fry fed the carnivorous and omnivorous diets, but were higher than those in fish fed the herbivorous diet (P < .05). The intestinal maturation index exhibited the highest and lowest values in mullet fry fed the carnivorous and herbivorous diets, respectively, whereas those from the omnivorous group showed intermediate values (P = .03). This study broadly suggests that aquaculture feeds for juvenile grey mullet should be designed for omnivorous feeding habits.info:eu-repo/semantics/acceptedVersio

Circadian cycle of digestive enzyme production at fasting and feeding conditions in Nile tilapia, Oreochromis niloticus (Actinopterygii: Perciformes: Cichlidae)

Background. Fish have photoperiod-dependent rhythms (circadian cycle of about 24 h), including the enzymatic secretion cycles, and this information has not been available for Nile tilapia, Oreochromis niloticus (Linnaeus, 1758). The knowledge on the digestive enzymes in Nile tilapia may have practical implications in fish nutrition. The aim of the presently reported study was to determine the circadian cycle of digestive enzyme production of Nile tilapia, in fasting and feeding regimes, in hope to receive information that might improve feeding schedules of this fish in aquaculture. Materials and methods. In juvenile Nile tilapia the circadian cycle of concentrations of total soluble protein, protease, pepsin-like, trypsin, chymotrypsin, amylase, and lipase were determined. The baseline (fasting) and feeding conditions (ad libitum) were sampled and monitoring every hour for 24 h. Results. The basal peak of enzyme activity in the intestine occurred at 18:44 h for amylase, at 19:57 h for proteases, and 20:29 for trypsin. The minimal activity for most enzymes, appeared between 4:51 h (amylase) and 10:13 h (lipases). In the feeding treatment (ad libitum), stomach activity (pepsin-like) had maximal activity at 20:06 h and minimal activity 05:46 h. Intestinal amylase activity covered an extended period of low enzymatic activity beginning at the 05:46 h and ending at 12:59 h. The peak of digestive enzyme activity occurred within 18:44–20:29 h. In general, secretion of digestive enzymes was positively stimulated by food, for all enzymes assayed. Conclusion. Nile tilapia has a higher digestive enzyme activity at night than during the day. Knowledge of the circadian cycle of digestive enzymes, and modifications initiated by food, is useful to establish feeding times. If feeding schedules are adjusted to coincide with maximum natural peaks, feed efficiency will increase, which will be reflected in weight gain of the fish and provide more profitable yields for aquaculture

The seaweeds Sargassum spp. and Macrocystis pyrifera: An alternative for cattle forage in the Baja California peninsula?

The nutritional quality of dried seaweed Macrocystis pyrifera and a group of Sargassum species were compared with desert plants, cereals and animal meals commonly used as a feed for livestock in the Baja California peninsula during the dry season. The associated digestive enzymatic activity and the presence of digestive enzymatic inhibitors and lectins were evaluated and their general chemical analysis was also considered. The protein concentration of seaweeds was low, compared to other plants. The presence of lectins and enzyme inhibitors was negligible, compared to desert legumes. The use of seaweeds as a supplementary forage for herded cattle is apparently a good strategy, despite their low protein concentration. High carbohydrate, mineral and lipid concentrations can help meet maintenance requirements, especially when grasses are not available

The effect of weaning diet type on grey mullet (Mugil cephalus) juvenile performance during the trophic shift from carnivory to omnivory

In captive grey mullet (Mugil cephalus) juveniles, the weaning stage overlaps the period where there are changes in the ontogeny of digestive enzymes as the fry transit from carnivory to omnivory. The aim of this study was to evaluate growth, survival, weight distribution and the activity of pancreatic and brush border digestive enzymes when fry are fed a carnivorous, herbivorous or omnivorous weaning diet

Effect of feed frequency on growth and survival of Oreochromis aureus in experimental cultures [Efecto de la frecuencia de alimentación sobre el crecimiento y supervivencia de Oreochromis aureus en cultivos experimentales]

In semi-intensive systems Tilapia feed represents 50 to 75% of production costs. Knowledge of optimum ration for any species means providing the necessary food to achieve greater efficiency and maximize the growth of organisms and the reduction of overfeeding. The goal of the present study deals with the effect of feeding frequency on growth and survival of tilapia Oreochromis aureus, with the intention of providing information that can be applied in aquaculture. The results obtained show no significant differences in the growth of organisms, or survival, total weight gain, specific growth rate, total feed intake, daily intake, feed conversion rate and protein efficiency ratio. Provide feed in a single dose or divided into portions for up to seven frequencies has not a significant effect on growth and survival of tilapia Oreochromis aureus

Effect of feed frequency on growth and survival of Oreochromis aureus in experimental cultures [Efecto de la frecuencia de alimentación sobre el crecimiento y supervivencia de Oreochromis aureus en cultivos experimentales]

In semi-intensive systems Tilapia feed represents 50 to 75% of production costs. Knowledge of optimum ration for any species means providing the necessary food to achieve greater efficiency and maximize the growth of organisms and the reduction of overfeeding. The goal of the present study deals with the effect of feeding frequency on growth and survival of tilapia Oreochromis aureus, with the intention of providing information that can be applied in aquaculture. The results obtained show no significant differences in the growth of organisms, or survival, total weight gain, specific growth rate, total feed intake, daily intake, feed conversion rate and protein efficiency ratio. Provide feed in a single dose or divided into portions for up to seven frequencies has not a significant effect on growth and survival of tilapia Oreochromis aureus

Muscle amino acid profile of Macrobrachium tenellum and chemical score of used protein in its feeding [Perfil de aminoácidos del másculo de Macrobrachium tenellum y cZapotitlánmputo químico de proteínas usadas en su alimentación]

Freshwater prawns Macrobrachium tenellum were used to determine the content of amino acids (aa) of the muscle, and the chemical score of the main ingredients used in feeds for the species was determined. The separation and identification of aa is carried out by high performance liquid chromatography (HPLC) with fluorescence detection. The calculation of chemical score was obtained by dividing the value of essential aa between aa of the reference protein. The most abundant aa in muscle were glutamic acid (16.14%), lysine (9.60%) and aspartic acid (9.06%) and the lowest were methionine (2.88%), histidine (2.52%) and the tryptophan (0.47%). The first limiting amino acid for fishmeal was threonine and histidine for squid meal; and as a second limiting aa arginine and threonine, respectively. In wheat flour first and second limiting amino acids were lysine and threonine, in soybean meal, methionine and lysine, respectively. For feed formulation for M. tenellum intends to use a combination of plant and animal proteins that approximates the amino acid profile of the species

Muscle amino acid profile of Macrobrachium tenellum and chemical score of used protein in its feeding [Perfil de aminoácidos del músculo de Macrobrachium tenellum y cómputo químico de proteínas usadas en su alimentación]

Freshwater prawns Macrobrachium tenellum were used to determine the content of amino acids (aa) of the muscle, and the chemical score of the main ingredients used in feeds for the species was determined. The separation and identification of aa is carried out by high performance liquid chromatography (HPLC) with fluorescence detection. The calculation of chemical score was obtained by dividing the value of essential aa between aa of the reference protein. The most abundant aa in muscle were glutamic acid (16.14%), lysine (9.60%) and aspartic acid (9.06%) and the lowest were methionine (2.88%), histidine (2.52%) and the tryptophan (0.47%). The first limiting amino acid for fishmeal was threonine and histidine for squid meal; and as a second limiting aa arginine and threonine, respectively. In wheat flour first and second limiting amino acids were lysine and threonine, in soybean meal, methionine and lysine, respectively. For feed formulation for M. tenellum intends to use a combination of plant and animal proteins that approximates the amino acid profile of the species