This study aimed to evaluate the growth performance, feed utilisation, digestive and metabolic enzyme activity, and liver histology in juveniles of hybrid red tilapia (Oreochromis mossambicus × Oreochromis niloticus) fed with the inclusion of chitosan in their diet. Six dietary chitosan levels (0 “control’’, 10, 20, 30, 40, and 50 g kg⁻¹) were used to feed juvenile fish (initial weight 7.50 ± 0.20 g) that were cultured for eight weeks in 18 tanks at a density of 15 fish/tank. The growth performance presented significant differences (p ˂ 0.05) for weight gain, specific growth rate, feed conversion ratio, hepatosomatic index, and survival rate. The digestive and metabolic enzyme activities were significantly (p < 0.05) influenced by the levels of chitosan in the administered diet. Histologically, no damage was found in the liver; however, morphometrically, a significant difference (p < 0.05) was found in the hepatocyte area and sinusoid area. Vacuolisation of hepatocytes was found in treatments with 40 and 50 g kg⁻¹ of chitosan in the diet. Treatments with doses of chitosan showed a better response (p < 0.05) compared to the control treatment in most of the different groups of variables analysed. The result of the principal component analysis suggests that a diet containing 40 g kg⁻¹ of chitosan is optimal for tilapia growth performance.

A comparative study of serum biochemical and hematological parameters from Andinoacara rivulatus and Ichthyoelephas humeralis in Los Ríos Province, Ecuador, was carried out. Two of the native species that are the most commercialized in Quevedo, Mocache and Fumisa, were identified; 60 specimens were captured in each area (180 total). A factorial design (3×2) was used: three habitat zones (Fumisa, Quevedo, and Mocache) and two species (A. rivulatus and I. humeralis). Sex, weight, length, serum biochemistry (total protein, albumin, globulin, albumin/globulin ratio, aspartate aminotransferase (AST), alanine aminotransferase (ALT), calcium, phosphorus, sodium, magnesium, and potassium), hematological parameters (hemoglobin, hematocrits, erythrocytes, mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), total leukocytes, granulocytes leukocytes, and agranulocytes leukocytes) in fishes were determined. There was zone-species interaction for all indicators except MCH and MCHC (P < 0.05). For total proteins, albumins and ALT were for I. humeralis in Fumisa and Mocache zones (2.81, 1.57, and 326.67 g dL-1, respectively). In comparison, A. rivulatus was higher in Fumisa and Quevedo in globulins and the albumins/globulins ratio with 2.28 g dL-1 and 2.14, respectively. Electrolytes were found in low concentrations in the two species. For the hematological parameters, all presented significant differences (P < 0.05) except MCH and MCHC. For I. humeralis, its highest values were presented in hemoglobin with 13.37 g dL-1 in Fumisa, for MCV and total leukocytes (93.11 fL-1 and 8.03×103 μL-1) respectively, in the Mocache area. This study will provide essential tools in monitoring the health status of these fish species in particular and fish species in general.

The aquaculture due to the high cost and continued shortage of animal protein sources, the development of alternative plant protein sources has been one of the main challenges to establish sustainable aquaculture as economically viable. Objective of this investigation was to determine the chemical composition and effect of Tithonia diversifolia on the growth performance, feed efficiency and metabolic biochemistry of juveniles of Oreochromis mossambicus × Oreochromis niloticus. Five treatments were used: 0% (control), 4, 8, 12 and 16% levels of inclusion of T. diversifolia flour in diet to feed juvenile fish cultured in 15 plastic aquariums at a density of 15 fish/aquarium. The assay lasted eight weeks. The T. diversifolia flour was characterized for showing adequate levels of crude protein (21%), with low crude fat (4.5%) levels, neutral detergent fiber levels: 43.03% and acid detergent fiber: 24.40%. The growth performance presented significant differences (p˂0.05), for weight gain, day average weight gain (DAW), length gain, day average length gain (DAL), specific growth rate (SGR), feed efficiency (FE), protein efficiency ratio (PER) and feed conversion ratio (FCR). In treatment with 16% of inclusion of T. diversifolia flour, values obtained for weight gain, DAW, SGR, FE and PER (15.88 g, 0.28 g. day-1, 2.03 %, 0.34 g.g-1 and 0.98, respectively), which did not differ with the control treatment, highlighting the benefits of T diversifolia flour. The metabolic biochemistry parameters experienced a decrease with the increase of T. diversifolia in diet, where the highest values of triglycerides, cholesterol, and glucose were for the control treatment (p <0.05), while the protein increased to 4% of the flour. T. diversifolia flour presents an adequate balance of nutrients for its chemical composition and amino acids, without causing negative effects on the growth performance, weight-length relationship, feed efficiency, survival and metabolic biochemistry.

This study was designed to determine the effect of a combination of propionic-acetic acid on body weight, the relative weight of some organs, lactic acid bacteria, and intestinal pH of neonatal broilers. A total of 60 1-day-old Ross 308® broiler chickens were randomly placed in metabolic cages to two treatments, three replicates, and ten birds per replicates. The treatments consisted of a control diet (CD) and CD + 0.03% of propionic acid and acetic acid in the drinking water at a rate of 4 ml/L of water. The combination of organic acids depressed the body weight in neonatal broilers (p<0.05) and increased the relative weight (p<0.05) of gizzard, proventriculus, small intestine, and liver; also acidified the cecum with a significant decrease (p<0.05) of the pH. Also, these organic acids increased (p<0.05) the count of green bacilli with a white halo in the small intestine and decreased (p0.05) between treatments. The combined use in the diet and drinking water of the propionic and acetic organic acids, respectively, reduced the bodyweight of neonatal broilers (10 days) and the cecal pH, as well as modified the relative weights of some digestive organs and the growth of some morphological groups of lactic acid bacteria.

To evaluate the chemical composition of the earthworm (Eisenia foetida) co-dried (EW) with vegetable meals (VM) as animal feed ingredient, the blends were mixed with wheat bran (WB), rice powder (RP), corn meal (CM) and soy cake meal (SCM) in proportions of 85:15; 75:25 and 65:35. The dry matter (DM), crude protein (CP), crude fat (CFA), crude fiber (CF), ashes and nitrogen-free extract (NFE) of the ingredients and final mixtures were determined. All the mixtures resulted with a high content of DM (≥90.00 %). No significant differences among the proportions were revealed (P>0.05). In addition, the higher inclusion of the earthworm in the proportions (85:15) increased (P<0.05) the CP (54.70 %), CFA (7.28 %), and ashes (10.20 %), mainly when mixed with SCM, CM, and RP, respectively. However, the use of vegetable meals proportionally increased the CF (7.31 %), and NFE (52.62 %), mainly with the proportion of 65:35 and with RP and CM, respectively (P<0.05). The results showed that the vegetable meals (WB, RP, CM, and SCM) are useful to co-dry the earthworm to be use for animal feed. It is concluded that the most appropriate proportion (VM:EW) will depend on the animal species, productive stage and market requirement.