We investigated the effects of environmental color on the reproduc- tive behavior of Nile tilapia, Oreochromis niloticus. Two environ- mental colors were tested by covering the aquarium (60 x 60 x 40 cm) with white (12 groups) or blue (13 groups) cellophane and observing reproductive behavior in groups of 2 males (10.27 ± 0.45 cm) and 3 females (10.78 ± 0.45 cm) each. After assignment to the respective environmental color (similar luminosity = 100 to 120 Lux), the animals were observed until reproduction (identified by eggs in the female’s mouth) or up to 10 days after the first nest building. Photope- riod was from 6:00 h to 18:00 h every day. Food was offered in excess once a day and water quality was similar among aquaria. Daily observations were made at 8:00, 11:00, 14:00 and 17:00 h regarding: a) latency to the first nest, b) number of nests, c) gravel weight removed (the male excavates the nest in the bottom of the aquarium), d) nest area, and e) mouthbrooding incubation (indication of repro- duction). The proportion of reproducing fish was significantly higher (6 of 13) in the group exposed to the blue color compared the group exposed to the white color (1 of 12; Goodman’s test of proportions). Moreover, males under blue light removed significantly larger masses of gravel (blue = 310.70 ± 343.50 g > white = 130.38 ± 102.70 g; P = 0.01) and constructed wider nests (blue = 207.93 ± 207.80 cm 2 > white
Although chemical communication did not affect Nile tilapia’s reproductive behavior, rank signaling has been reported to be mediated by chemical cues in this species (38,39). This suggests that cichlid visual and chemical information seems to be important at different moments of fish life. In fact, multimodal signs provide more reliable information for receiver fish, and could be an advantage for males and females to obtain more precise information about quality of the partners during mate choice (2). This multimodal role for vision and chemicals in Nile tilapiareproduction, however, needs further investigations.
The process of genetic improvement of Nile tilapia to increase growth rate may be adversely affecting fertility and production of tilapia fingerlings of the GIFT variety. Taylor et al. (2008) observed that the IGF-I levels accurately reflected growth rate prior to elevations in sex steroids, suggesting that IGF-I may provide an endocrine signal between the somatotropic and reproductive axes that growth rate and/or size are sufficient to initiate gonad development. This result corroborates the positive correlation observed between the greatest growth and early maturation (Longalong et al., 1999). The relative and absolute low fertilities of the GIFT variety tilapia were confirmed by Mair et al. (2004) who carried out studies to check the growth and reproduction of different varieties of Nile tilapia and the absence of males and females with developed gonads in the age at which was expected more than 50% of mature animals. This fact indicated that these animals were sexually late, disagreeing with Longalong et al. (1999). Animals with late sexual development may be one of the reasons for the better reproductive performance of older females, since the beginning of the breeding occurs at an older age. It is thus possible that the production peak also occurs later.
Sexually mature Mozambique tilapia were raised in captivity from a brood-stock maintained at the University of Algarve (Faro, Portugal). Males and females were kept together in large 500 l stock tanks until used in experiments. Social groups were created in 200 l tanks with five males and five females of similar standard length (SL in mm) and body weight (BW in g; coefficient of variation of BW less than 5 %) as previously described [S1]. Males were tagged (T-Bar anchor FD94, Floy Tag Inc., Seattle, WA, USA) and systematic focal observation of their behaviour carried out daily [S1]. The frequency of submissive displays during agonistic interactions or absence of dark coloration without social interaction and dominant behaviours such as aggression (biting, chasing, lateral displays, circling or mouth-to-mouth fights), nest digging, courtship towards females or dark coloration without social interaction was recorded over five min for each male. A dominance index (DI) ranging from zero to one was calculated for every male each day as the sum of all dominant behaviours and subsequent division by the sum of all dominant and subordinate behaviours. Accordingly, after five days of observation the mean DI was assessed for every male [S1, 2]. Subordinate males had a DI ≤ 0.16 and dominant males a DI ≥ 0.8, the others were intermediates. After each daily observation, urine was collected from each male by gently squeezing the area immediately above and anterior to the urogenital papilla and collecting the resultant stream of urine into a plastic tube, subsequently stored at -20 °C until further analysis.
lactate, that can be used by the cells, has proven bene ﬁcial [56,63,66,71], but this should be carefully considered since it can also stimulate bacterial growth . Indeed, the bacterial growth is proportional to the storage time [55,73], and bacteria compete with the spermatozoa for nutrients and oxygen, and degrade the extender media [66,73]. To reduce the fungal and bacterial growth during storage, besides the use of sterile media [55,73], different authors have tested extenders supplemented with antimycotics and antibiotics [60,65,66,72,74]. Usually there is an improvement in the sperm storability with the use of antibiotics, but the dosage needs to be adjusted for each species. Concentrations above 0.5 mg/ mL of gentamicin in the Nile tilapia Oreochromis niloticus reduced the sperm viability  and above 0.1 mg/mL reduced fertilization rate in piracanjuba . Finally, there are commercially available extenders that may be used (some examples in Table 1). These media are recommended for use in ﬁsh farms where preparation of media is more complicated, and standardization of procedures is required.
A pheromone present in urine from dominant tilapia males stimulates the release of 17,20bP in pre- and post-ovulated tilapia females. Considering the established role of 17,20bP as matura- tion-inducing steroid (Nagahama, 1997) and the suggested role in primary follicles (Zapater et al., 2012), the stimulation of 17,20bP production and release demonstrates a speciﬁc priming ef- fect for the male urine pheromone to accelerate reproduction. The involvement of urine in several communication processes conﬁrms that cichlids have evolved a sophisticated chemical signalling sys- tem together with their complex visual (Maruska et al., 2011), Fig. 1. Plasma and urine concentrations of steroids in pre-ovulated and post-spawn tilapia. Plasma (n = 6–8) and urine (n = 4–6) concentrations (mean ± standard error) of E 2 , testosterone and 17,20bP after 6 h of exposure of female tilapia to distilled
ble until reproduction starts. For this reason we age: mutations that appear early in life are not transmitted and disappear from the population, while those that become active late in life when we barely reproduce can accumulate, decreasing our survival probability but without risking the perpetuation of the species. One of the most striking examples of such a mech- anism is the catastrophic senescence of the pacific salmon and other species called semelparous: In these species all individuals reproduce only once in life, all at the same age. This can be easily imple- mented simply by setting a maximum reproduction age equal to R. After many generations, the inher- ited mutations have accumulated in such a way that as soon as reproduction occurs, individuals die. This explanation was given by Penna et al. (1995), using the Penna model (see also Penna & Moss de Oliveira 1995 and a remark from Tuljapurkar on page 70 in Wachter & Finch 1997).
Nitric oxide (NO) plays a crucial role in reproduction at every level in the organism. In the brain, it activates the release of luteinizing hormone-releasing hormone (LHRH). The axons of the LHRH neu- rons project to the mating centers in the brain stem and by afferent pathways evoke the lordosis reflex in female rats. In males, there is activation of NOergic terminals that release NO in the corpora cavernosa penis to induce erection by generation of cyclic guanosine monophos- phate (cGMP). NO also activates the release of LHRH which reaches the pituitary and activates the release of gonadotropins by activating neural NO synthase (nNOS) in the pituitary gland. In the gonad, NO plays an important role in inducing ovulation and in causing luteolysis, whereas in the reproductive tract, it relaxes uterine muscle via cGMP and constricts it via prostaglandins (PG).
Inflammation is a dual process, together mandatory at numerous steps of the reproduction process and deleterious for reproductive performances if excessive or persistent. Optimisation of insemination success rate depends not on the suppression of inflammation but on its fine regulation. The cow has to be able to mount intense inflammatory episodes and, more difficult, to control and shut them down rapidly, what is made complex by metabolic challenges post partum. Better regulation of the inflammation can be obtained through an appropriate dietary management during the transition period, targeting energy balance, Dietary Anions-Cations Difference, and anti oxidant reserves (LeBlanc 2012). Immunomodulators rather than anti-inflammatory drugs are an elegant strategy (such as pegbovigrastim, long acting-analog of bovine granulocyte colony-stimulating factor; Ruiz et al., 2017; Heiser et al., 2018). The genetic option is also promising, with the selection of females with high immune regulatory competences (Thompson-Crispy et
The amount of light projected to the eyes (luminance) is determined by factors such as: the illumination that strikes visible surfaces, the proportion of light reflected from the surface and the amount of light absorbed, reflected or deflected by the prevailing atmospheric conditions such as haze or other partially transparent media . An organism needs to know about meaningful world properties, such as color, size, shape, etc. These properties are not explicitly available in the retinal image and must be extracted by visual processing. In this paper we will deal with the reproduction of the image when the high dynamic range of the lightness causes distortions in the appearance and contrast of the image in certain regions e.g. because a part of the image is highly illuminated looking plain white or another is in darkness. High dynamic range (HDR) images enable to record a wider range of tonal detail than the cameras could capture in a single photo.
Abstract: Insects are a valuable source of nutrients for fish, but little is known about their nutritional value for Nile tilapia fingerlings. To evaluate the nutritional value and energy apparent digestibility coefficient (ADC) of five insects for Nile Tilapia male fingerlings, 900 fish were distributed in 18 fiberglass conic tanks, in a completely randomized design, with six dietary treatments (control, Nauphoeta cinerea meal (NCM) (Blattodea), Zophobas morio larvae meal (ZMM) (Coleptera), Gromphadorhina portentosa meal (GPM) (Blattodea), Gryllus assimilis meal (GAM) (Orthoptera) and Tenebrio molitor larvae meal (TMM) (Coleptera)) and three replicates (tanks), each containing 50 fish. The control diet had no insect meal included and the other five treatments comprised 80% commercial diet and 20% test ingredient with 0.1% chromic oxide as an inert marker. TMM presented a higher ADC for dry matter, protein, corrected protein and chitin than to other treatments (p < 0.01). GPM presented the highest ADC for lipids (p < 0.01). In general, the TMM presented better ADC of nutrients and energy and all the insect meals evaluated are potential feed for Nile tilapia fingerlings.
In this way the mazurka script is not, or at least is not simply, an element within a metrical hierarchy: it is a sign in its own right, and as such requires to be analysed in semiotic terms. In performance as in composition, then, a semiotically informed approach has the potential to shortcut conventional hierarchical conceptions, substi- tuting for a highly abstract theoretical model an analysis based on what is communicated by who to whom. But it does more than that. In contrast to the reproduction model of musical communication, it acknowledges that meaning is generated in the act of performance by virtue of decisions made voluntarily on the performer’s part (volun- tarily because, as Figure 6 makes clear, individual decisions are not prescribed by the composition). And because signs are by deinition socially conditioned, the semiotic approach also brings the audience into play in a way that the reproduction model does not: meaning arises through the construction of what the pianist does as mean- ingful by listeners. The analysis is accordingly displaced from the composer’s and even the performer’s intentions to the community within which signs are interpreted, a community that encompasses both performers and listeners, and that is always geographically and historically situated.
One third of the world’s fishing produce is not directly used for human consumption. Instead, it is used for making animal food or is wasted as residue. It would be ideal to use the raw material thoroughly and to recover by-products, preventing the generation of residues. With the objectives of increasing the income and the production of the industry, as well as minimizing environmental and health problems from fish residue, chemical silage from Tilapia (Oreochromis niloticus) processing residues was developed after homogenization and acidification of the biomass with 3% formic acid: propionic, 1:1, addition of antioxidant BHT and maintenance of pH at approximately 4.0. Analyses to determine the moisture, protein, lipids and ash were carried out. The amino acids were examined in an auto analyzer after acid hydrolysis, except for the tryptophan which was determined through colorimetry. The tilapia silage presented contents that were similar to or higher than the FAO standards for all essential amino acids, except for the tryptophan. The highest values found were for glutamic acid, lysine and leucine. The results indicate a potential use of the silage prepared from the Nile tilapia processing residue as a protein source in the manufacturing of fish food.
Chitosan foam can be used as a filter element for pollutants in Nile tilapia farming tanks to reduce the industrial chitin waste and value it. Another possibility is the inclusion of chitosan foam in fish feed. Therefore, this study aims at evaluating the apparent digestibility of nutrients and energy of chitosan foam for Nile tilapia. Apparent digestibility determination was carried out by the indirect fecal collection method, using chromic oxide as an inert indicator, a reference-diet and a test diet (70% reference-diet and 30% chitosan foam). Hence, 120 juveniles of Nile tilapia (50 ± 5 g) were used, divided into six replications. After the collection period, bromatological analyses of foam, diets and feces were carried out, as well as the determination of chromium concentration in feces. The coefficients of apparent digestibility concerning nutrients and energy were then calculated. Chitosan foam showed 83.7% digestible dry matter, 5.7% digestible protein, 7.9% digestible fat, 0.6% digestible ashes, 17.6% digestible crude fiber and 1021 kcal kg -1 digestible energy for juveniles of Nile tilapia. It can be concluded that chitosan foam is partially digestible for Nile tilapia and can be used mainly as a feed source of fiber and fat.
Fish (180 juveniles of Nile tilapia GIFT strain with an average weight of 32.65 ± 4.52 g) were kept in the fecal collection tanks during the entire trial and fed ad libitum every 2h from 8:30 to 17:00 by hand feeding. The collector tubes were installed and the feces were collected in the morning and kept frozen at -21°C until the end of the collection period, when the tanks were cleaned and all the water was replaced.
Oreochromis mossambicus is one of over 3,000 species of the Cichlidae family. Cichlids present a wide variation in social behaviour (e.g. ranging from territorial to shoaling and different parental styles). For all these reasons, it has been used as a model system in evolutionary studies (Seehausen et al., 2008; Simões et al., 2012). This species tolerates a wide range of diet requirements, ecological conditions and reproduces easily (Russell, Thuesen & Thomson, 2012). Furthermore, both biology and behaviour of this species is well known in aquaria and its ethogram has been described in detail (Oliveira, 1995). Mozambique tilapia is a very social mouthbrooder, leaving in shoals during the non-breeding period, and being the males very territorial/aggressive in the breeding season. During this season, these animals form leeks in shallow waters, where they build pits in the substrate for which they attract the females.
The field experiment consisted of two treatments, with three replicates each: 1. Treatment A (with fish) contained total phytoplankton, total zooplankton and fish (one adult Tilapia rendalli collected in the Lake Monte Alegre, ~ 30-31 cm of standard length); 2. Treatment B (no fish) contained phytoplankton + zooplankton < 60 µm, and was filled with the lake water filtered through a 60 µm mesh net (Arcifa and Guagnoni, 2003), which retained 80% of the zooplankton, but did not alter substantially the phytoplankton community. The largest and most efficient zooplankton was removed in treatment B to compare phytoplankton biomass without loss through herbivory.Thus, Treatment A contained total phytoplankton, total zooplankton and fish, and Treatment B (control group) contained phytoplankton and a few species of rotifers in low abundance (Figure 1).
SUMMARY: The objective of this work was to evaluate different microdiets for Nile tilapia (Oreochromis niloticus) sexual reversion phase. They were used 4000 tilapias larvae with 8.31 ± 0,14 mm total length. The experiment was conducted with five treatments and four repetitions as followed, FSH – powder diet without hormone (control); and diets with hormone (60 mg of 17 α methyl testosterone) FCH – powder diet, MAH – Microaglomerated diet, SSE – spray dried microencapsulated diet without wall material, SCE - spray dried microencapsulated diet with wall material (66.7% wall material and 33.3% of formulated diet). Weighing samples were conducted at the initiation of the experiment, at the 15 th and at the 30 th days. Larvae fed with SSE diet showed better weight and length means, condition factor sexual reversion ratio. On the other hand, treatment SCE showed worst growth performance with no compromise on sexual reversion ratio. The SSE resulted in better fish uniformity at the end of the sexual reversion phase. It can be concluded that the microdiets MAH and SSE were efficient and can be utilized for tilapia sexual reversion.