Embryonic development is one of the most sensitive and critical stages when maternal effects may influence the offspring’s phenotype. In birds and other oviparous species, embryonic development is confined to the eggs, therefore females must deposit resources into the eggs to prepare the offspring for the prevailing post-natal conditions. However, the mechanisms of such phenotypic adjustments remain poorly understood. We simulated a maternal nutritional transfer by injecting 1 mg of l-methionine solution into Japanese quail eggs before the onset of incubation. The increase in early methionine concentration in eggs activated the insulin/insulin-like signalling and mechanistic target of rapamycin (IIS/mTOR) signalling pathways and affected post-natal developmental trajectories. Chicks from methionine-supplemented eggs had higher expression of liver IGF1 and mTOR genes at hatching but were similar in size, and the phenotypic effects of increased growth became apparent only a week later and remained up to three weeks. Circulating levels of insulin-like growth factor-1 (IGF-1) and expression of ribosomal protein serine 6 kinase 1 (RPS6K1), the mTOR downstream effector, were elevated only three weeks after hatching. These results show that specific nutritional cues may have phenotypic programming effects by sequentially activating specific nutrient-sensing pathways and achieving transgenerational phenotypic plasticity.

Resources are needed for growth, reproduction and survival, and organisms must trade off limited resources among competing processes. Nutritional availability in organisms is sensed and monitored by nutrient-sensing pathways that can trigger physiological changes or alter gene expression. Previous studies have proposed that one such signalling pathway, the mechanistic target of rapamycin (mTOR), underpins a form of adaptive plasticity when individuals encounter constraints in their energy budget. Despite the fundamental importance of this process in evolutionary biology, how nutritional limitation is regulated through the expression of genes governing this pathway and its consequential effects on fitness remain understudied, particularly in birds. We used dietary restriction to simulate resource depletion and examined its effects on body mass, reproduction and gene expression in Japanese quails (Coturnix japonica). Quails were subjected to feeding at 20%, 30% and 40% restriction levels or ad libitum for 2 weeks. All restricted groups exhibited reduced body mass, whereas reductions in the number and mass of eggs were observed only under more severe restrictions. Additionally, dietary restriction led to decreased expression of mTOR and insulin-like growth factor 1 (IGF1), whereas the ribosomal protein S6 kinase 1 (RPS6K1) and autophagy-related genes (ATG9A and ATG5) were upregulated. The pattern in which mTOR responded to restriction was similar to that for body mass. Regardless of the treatment, proportionally higher reproductive investment was associated with individual variation in mTOR expression. These findings reveal the connection between dietary intake and the expression of mTOR and related genes in this pathway.

Methionine (Met) is an essential and first limiting amino acid in the poultry diet that plays a significant role in chicken embryonic development and growth. The present study examined the effect of in ovo injection of DL-Met and L-Met sources and genotypes on chicken embryonic-intestinal development and health. Fertilized eggs of the two genotypes, TETRA-SL layer hybrid (TSL) - commercial layer hybrid and Hungarian Partridge colored hen breed (HPC) - a native genotype, were randomly distributed into four treatments for each genotype. The treatment groups include the following: 1) control non-injected eggs (NoIn); 2) saline-injected (SaIn); 3) DL-Met injected (DLM); and 4) L-Met injected (LM). The in ovo injection was carried out on 17.5 d of embryonic development; after hatching, eight chicks per group were sacrificed, and the jejunum was extracted for analysis. The results showed that both DLM and LM groups had enhanced intestinal development as evidenced by increased villus width, villus height, and villus area (P < 0.05) compared to the control. The DLM group had significantly reduced crypt depth, glutathione content (GSH), glutathione S-transferase 3 alpha (GST3), occludin (OCLN) gene expression and increased villus height to crypt depth ratio in the TSL genotype than the LM group (P < 0.05). The HPC genotype has overexpressed insulin-like growth factor 1 (IGF1) gene, tricellulin (MD2), occludin (OCLN), superoxide dismutase 1 (SOD1), and GST3 genes than the TSL genotype (P < 0.05). In conclusion, these findings showed that in ovo injection of Met enhanced intestinal development, and function, with genotypes responding differently under normal conditions. Genotypes also influenced the expression of intestinal antioxidants, tight junction, and growth-related genes.

Nutritional cues during embryonic development can alter developmental trajectories and affect postnatal growth. However, the specific mechanisms by which nutrients influence avian growth remain largely unknown. Amino acids can directly interact with the nutrient-sensing pathways, such as the insulin-like growth factor 1 (IGF-1)/mechanistic target of rapamycin (mTOR) pathways, which are known to regulate growth. We examined the effects of embryonic leucine on gene expression and phenotypic growth in Japanese quails by injecting 2.5 mg leucine or saline (control) into Japanese quail eggs on the tenth day of incubation and incubating them under standard conditions. The treatment groups had similar hatching success and size at hatching. However, between 3 and 7 days post-hatching, quails treated with embryonic leucine showed increased growth in body mass and wing, tarsus, head, and intestinal lengths, lasting up to 21 days. The hepatic expression of IGF1, IGF1R, mTOR, and RPS6K1 was upregulated in leucine-treated quails, while the expression of FOXO1 remained unaffected. In conclusion, a subtle increase in embryonic leucine may induce developmental programming effects in Japanese quail by interacting with the IGF-1/mTOR nutrient-sensing pathway to promote growth. This study highlights the role of embryonic amino acids as crucial nutrients for enhancing growth. It provides valuable insight into nutrient intervention strategies during embryonic development to potentially improve poultry growth performance.

Indigenous chickens are well known for their dual-purpose function and palatable meat. However, the information on their hematology parameters is lacking and hence hampering the poultry industry production of local breeds. The main objective of this study was to examine the hematological parameters of Hungarian Partridge Coloured hen (HPC) and TETRA-SL (TSL) genotype and determine the hematological reference interval values. This trial was part of the larger experiment where a total of 200 chicks (HPC + TSL) were reared. For this trial the blood samples were obtained from brachial wing veins of 8 chicks of each genotype for blood hematological analysis. The results indicated that some of the hematological parameters such as red blood cells-RBC, white blood cells-WBC, hemoglobin-Hb, hematocrit-Ht, platelets-Plt, lymphocytes-LYM, and granulocytes-GRAN were significantly affected by the genotypes (p < 0.05). The genotype did not affect the mean corpuscular volume-MCV, mean corpuscular hemoglobin-MCH, mean corpuscular hemoglobin concentration-MCHC, and GRAN (p > 0.05). The hematological reference interval values were slightly higher in the TSL genotype compared to HPC chicks. It is concluded that genotype has a significant effect on the hematological parameters. The results from this trial will be help and design the baseline reference values for the HPC genotype which will be useful in assessing the health status of these indigenous chickens.

Introduction: Nutritional status influences developmental processes, including sexual maturation. While the effects of macronutrients on reproductive development are well studied, the role of specific amino acid composition in ovarian and follicular development in birds remains less explored. Here, we investigated the impact of dietary restriction and amino acid supplementation on growth and reproductive development of Japanese quail (Coturnix japonica).Methods: Birds were assigned to five dietary treatments: control (ad libitum), 20% dietary restriction (DR20), and DR20 supplemented with methionine (DR20+Met), leucine (DR20+Leu) or both (DR20+Leu+Met) at levels 20% above the recommended nutrient content.Results and discussion: Dietary restriction reduced body mass, ovary mass, ovary index, and total antioxidant capacity without affecting hierarchical follicle counts or size. However, supplementation with either amino acid improved these parameters from dietary restriction to the control levels. Furthermore, methionine supplementation alone or combination of methionine and leucine significantly increased follicle numbers, whereas leucine alone had no effect on hierarchical follicle numbers. Our findings underscore the importance of amino acids in mitigating the adverse effects of dietary restriction on growth, reproduction, and oxidative balance in birds at the onset of reproductive maturation.