Tenebrio molitor is considered a sustainable protein source for diets in poultry. It has been investigated in regard to the performance, health status, and product quality in different poultry species. This study was designed to evaluate the effect of low-fat Tenebrio molitor meal (LFTM) included in the broilers’ diet on the growth performance and carcass composition of the birds. The trial was conducted at the Institute of Animal Science-Kostinbrod, Bulgaria. A total of 120 male one-day-old Ross 308 broilers were allocated to 5 groups. After an adaptation period of 14 days, the birds were fed a basal diet (C) and diets including LFTM in amounts of 2.5% (T2.5), 5% (T5), 7.5% (T7.5), and 10% (T10). The growth performance of the birds was measured during the trial. At 35 days of age, 8 birds per group were slaughtered, and their carcass quality was evaluated. We found a linear response of BWG and FCR towards the inclusion of Tenebrio molitor meal (TM) in the diet. For the whole period (14–35 d), the BWG decreased (p = 0.0002), while the values of FCR increased (p = 0.0001) with the increase in the levels of the insect meal. The doses of 7.5% and 10% of the insect meal were associated with lower carcass weight and also decreased the yield of the breast. The results of the study indicated that the incorporation of LFTM, especially in amounts of 7.5–10%, could not be appropriate for broilers due to adverse effects on the growth performance and carcass composition.

An experiment with male layer-type chickens of the Lohmann Brown Classic breed was carried out at the Institute of Animal Science-Kostinbrod, Bulgaria, aiming to investigate the effect of age at slaughter on the meat quality. The birds were reared in a controlled microclimate, with an initial stocking density of 22 birds/m². At five weeks of age, fragmentation of the stocking density was applied, decreasing the number to seven birds/m². Chickens were slaughtered at five and nine weeks of age at an average live weight of 329 g and 1096 g, respectively. After slaughter, 10 chickens from each age group were subjected to analysis to determine the quality of breast and thigh meat. The results of the study showed that the age affected the meat quality parameters of the male layer-type chickens and its effect differed between the breast and thigh. The chickens slaughtered at nine weeks of age displayed a lower pH but darker meat color (p < 0.001) than those slaughtered at five weeks. Furthermore, the older birds showed a significant decrease in the intramuscular fat content in thigh meat (p < 0.01) and a tendency for diminishing in breast meat. This decrease corresponded to the lower percentage of monounsaturated fatty acids (MUFA) in the meat of the nine-week-old chickens (p < 0.01). On the other hand, the meat of the older chickens displayed a higher content (p < 0.01) of polyunsaturated fatty acids (PUFA), especially n-6, leading to a considerably higher n-6/n-3 ratio.

A meta-analysis on the effect of gamma irradiation on lipid oxidation products in raw chicken meat subjected to different temperatures of storage and packageing was carried out. A total of 11 studies were examined in regard to the peroxide value (POV) and thiobarbituric acid reactive substances (TBARS). The high heterogeneity in the studies was decisive for the selection of the random effects model applied on the raw mean difference (effect size) for the analysis of the data. The results of the meta-analysis showed that gamma irradiation increased the contents of the primary (POV) and secondary products (TBARS) of lipid oxidation in the raw chicken meat (P<0.001). Further, meta-regression and the examined covariates indicated significant influence of the dose of radiation on the formation of POV (P<0.001), whereas TBARS contents tended to depend on the package of the meat. In most of the studies included in the meta-analysis, the contents of the lipid oxidation products remained in acceptable levels and the treatment with gamma rays did not affect negatively the high nutritive value of the meat.

This study aimed to assess the effect of the addition (2%) of soybean protein (SP) and insect flours derived from house crickets (Acheta domesticus, HCF) and yellow mealworm (Tenebrio molitor, YMF) in cooked sausages. The technological characteristics of the batter, the chemical composition of the sausages, their technological traits and lipid stability during refrigerated storage, as well as their sensory properties, were investigated. The SP, HCF and YMF batters displayed higher pH (p = 0.0025) and stability (p < 0.0001) but a darker colour (p < 0.0001) than the control samples. The addition of SP increased the plasticity of the batter (p = 0.0017), while YMF decreased its structural strength (p = 0.0274). Higher pH and darker colour were detected in SP-, HCF- and YMF-containing sausages; however, the effect of the alternative proteins depended on the duration of storage. The plasticity decreased in the insect-containing sausages (p = 0.0010) and increased over time (p = 0.0136), whereas the elasticity was lower in the YMF group (p < 0.0001). The protein and fat contents were higher (p < 0.0001) in the sausages containing alternative protein. TBARS content decreased over time in these groups. The HCF and YMF sausages received lower scores for their appearance, colour, texture, flavour and taste, suggesting the need for further technological interventions to make such products more attractive to consumers.

An experiment was carried out in the Institute of Animal Science—Kostinbrod, Bulgaria, to investigate the growth performance of male layer-type chickens (Lohmann Brown Classic), raised to 6 and 9 weeks of age, to evaluate the economic aspects of this rearing, as well as to present changes in the quality characteristics of the meat during frozen storage. The chickens were reared in a controlled microclimate with an initial stocking density of 9 birds/m². After 6 weeks of age, fragmentation of the stocking density was applied, and then it diminished to 3 birds/m². The chickens were slaughtered at 6 and 9 weeks of age. Ten 9-week-old chickens were subjected to carcass analysis. Meat quality parameters (pH, color), degree of proteolysis (free amino groups), and lipid oxidation (content of peroxides and TBARS) were assessed in fresh breast and thigh meat (0 d) and in samples stored for 60 and 120 days at −18 °C in chickens slaughtered at 6 and 9 weeks old. The mean live weight of the male layer-type chickens at 6 weeks was 608.81 g, while the 9-week-old chickens reached 1115.93 g. The feed conversion ratio (FCR) for the whole period of rearing was 2.75. There were no considerable deviations in the meat traits, indicating quality deterioration over the course of the frozen storage. There was a significant increase in the pH of the breast and thighs, reaching maximum values for 60 days of storage in the 6-week-old chicks, while in the 9-week-old birds, pH peaked in the samples stored for 120 days. The changes in the dynamics of pH corresponded to those of proteolysis. There was an increase in lightness (L*), allowing for higher values in the samples stored for 60 days to be reached regardless of the type of meat and age of the chickens. The content of the peroxides increased considerably for 60 days of frozen storage and decreased afterwards. During storage, there was a constant increase in the secondary products of lipid oxidation. Our results indicated that the application of practices such as the fragmentation of stocking density and finding the suitable age for slaughter have significant importance for the profitability of producing meat product from male layer-type chickens. We found that rearing this type of bird until 9 weeks of age resulted in lower costs and higher economic efficiency.

The valorisation of underutilized male layer-type chickens offers a sustainable and ethically aligned opportunity for the poultry industry. This study evaluated the feasibility of male layer-type chicken meat in the production of chicken pâtés and compared the effects of different meat sources—commercial broiler (CP), and 5 (5wP) and 9-week-old (9wP) male layer-type chickens—on product quality during refrigerated storage using the general linear model with the Tukey–Kramer post-hoc test. Pâtés made from 5wP meat exhibited the most favourable technological properties, including the lowest (p < 0.05) total expressible fluid (TEF), highest (p < 0.05) water retention (TEF_Water), and lowest (p < 0.05) fat content (TEF_Fat) than CP and 9wP indicating superior emulsion stability. The 5wP pâtés also presented the lowest (p < 0.05) TBARS values on day 1, along with reduced colour deterioration (ΔE) over 7 days of storage. CP samples demonstrated the greatest (p < 0.05) hardness, cohesiveness, and gumminess, but lower (p < 0.05) springiness and resilience compared to 5wP and 9wP, yielding softer and elastic pâtés. Overall, pâtés formulated with 5wP can be a promising option for the development of value-added poultry products. The incorporation of male layer-type chicken meat into commercial formulations will encourage further research of their market potential.