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Adjusting aquafeed to obtain sustainable growth and maximum profit margin of harvest is a worthy stride toward achieving the Sustainable Development Goals (SDGs) outlined by the United Nations. Therefore, this research aimed at modeling of nutritional behavior and harvest profit margin in fattening pacu (Piaractus mesopotamicus) fed on balanced digestible protein (BDP) contents and raised in an intensive recirculating aquaculture system (RAS). The feeding trial consisted of six treatments with three randomly arranged replicates (tanks) per treatment. A total of ten fattening pacus (490.60 ± 14.39 g, initial weight) were stocked per tank. Six experimental feeds containing the increasing contents (163, 201, 238, 272, 315, and 348 g kg-1 diet, dry matter) of BDP were manually fed to the fish for seven weeks three times a day until apparent satiation. The data obtained over the test diets were assessed through appropriate statistical procedures and mathematical models. Optimal levels of BDP were calculated for different nutritional and economic scenarios. Feed cost showed an ascending linear relationship with the BDP intake. Feed intake, feed efficiency, final body weight, weight gain, and specific growth rate (%) showed an inverted U-shaped quadratic behavior (P < 0.05). Feed conversion ratio showed a U-shaped quadratic behavior (P < 0.05). Protein efficiency ratio significantly (P < 0.05) decreased linearly in response to the increasing BDP contents. Final weights of the eviscerated and sliced fish showed an ascending linear behavior, but the overall effect was insignificant (P > 0.05) between the treatments. Whole body moisture and crude protein content increased (P < 0.05) linearly, while the whole body lipid content decreased (P < 0.05) linearly over the increasing BDP intake. Whole body ash content showed a U-shaped quadratic behavior (P < 0.05). The nutritionally optimal BDP content corresponding to the maximum gain in body weight of fattening pacu was calculated as 292 g kg-1 diet (dry matter). To obtain sustainable growth and maximum profit margin of harvest when it will be sold in the form of whole-body, eviscerated, and sliced fish the economically functional BDP intakes were calculated as 249, 256, and 260 g kg-1 diet (dry matter), respectively. This research revealed that the optimal BDP intake greatly improve the nutritional performance of fattening pacu. Moreover, harvest profit margin and eventually the economically sustainable BDP intakes were found dependent on the way the fish harvest is marketed and the changes in total feed cost. • Growth and economic performance was greatly influenced by dietary balanced protein. • Production characteristics of fattening pacu were mathematically modeled. • Harvest profit margin was subjected to marketing strategy and feed cost. • Sliced fish produced more profit margin than the eviscerated or whole fish. • Sustainable protein intakes were greatly affected by harvest profit margin. [ABSTRACT FROM AUTHOR]

• We simulated the response of broiler breeder hens in the function of lighting programmes during the growth period. • We used the stochastic model to simulate the population from 24 to 60 weeks of age. • Were estimated body compositions, age at from first egg and egg production in function of age. • Were observed differences in requirements between the lighting programmes until all the broiler breeders begin laying eggs. The aim of this study was to model the changes in the egg production and requirements of broiler breeder hens flock, in response to different lighting programmes during the rearing period. The growth of each individual in a population up to the time when its first egg is laid was simulated and then averaged to obtain the mean response of the population to different lighting programmes. The information about the age, body weight and body composition over the growth period are required in order to determine the amino acid requirements of broiler breeder hens until sexual maturity (egg-laying period), the age at first egg (AFE) and egg production. Were used equations to estimate body, feather, ovary, oviduct and compositions of these parts, as a function of age. Also was estimated AFE and EP according to the lighting programmes: Constant daylengths during rearing: 8, 10, 12, 14, 16, 18 h and Single increment from 8 to 16 h at 8, 10, 12, 14, 16, 18 and 20 weeks of age. It is important to point out the greater differences in the requirements until all the broiler breeders begin laying the egg. For 24 weeks of age, the requirements may vary 329–602 mg/bird/day of Lys, 258–550 mg/bird/day of Met + Cys and 180–392 mg/bird/day Thr. For 28 weeks of age, the requirements range 362–922 for Lys; 303–830 for Met + Cys and 213–599 for Thr. For 32 weeks of age, the requirements range 824–982; 711–888; 514–644 mg/bird/day for Lys, Met + Cys and Thr, respectively. Knowing the requirements helps to establish the best nutritional program, and optimize feeding without excesses and deficiencies. These results support the view that a modelling approach has the potential to help nutritionists to make decisions about feeding broiler breeder flocks more efficiently. [ABSTRACT FROM AUTHOR]

In diets based on corn and soybean meal valine is considered the fourth limiting amino acid. Despite that, there have been few studies to date on the response of broilers to dietary valine and most of them use empirical procedures leading to a great variation in the recommendations. Thus, the aim of this study was to quantify the performance and body composition of broiler chickens subjected to different intakes of digestible valine using the dilution technique. Three trials were conducted separately with Cobb 500 broilers in the starter (1–14 days), grower (14–28 days) and finisher phase (28–42 days). In the starter and grower phases, the birds were distributed in a completely randomized design with eight treatments (seven levels of valine and a control treatment), with seven replicates, each consisting of 12 birds for starter and grower phases while 10 birds were used in the finisher phase. Basal diets were formulated by dilution technique, being one summit diet with valine as the first limiting amino acid and diluted with a nitrogen-free diet to obtain the intermediary levels. Valine intake for maximum weight gain, valine deposition, and protein deposition in the defeathered body and feather were estimated with broken-line models. Body fat content was calculated with linear regressions. Results indicate that to maximize performance of broiler chickens across several parameters, the recommended requirement of digestible valine for the starter, grower and finisher diet is 226, 637 and 1231 mg/bird/day, respectively. These recommendations allow achieving optimum performance in the broiler production system but they can be different depending on way birds are sold (whole chicken or cut-up) and age of the birds at slaughter. [ABSTRACT FROM AUTHOR]