Effects of maternal methionine supplementation on the response of Japanese quail (Coturnix coturnix japonica) chicks to heat stress.

This study investigated the hypothesis that methionine supplementation of Japanese quail (Coturnix coturnix japonica) hens can reduce the effects of oxidative stress and improve the performance of the offspring exposed to heat stress during growth. For that, the quail hens were fed with three diets related to the methionine supplementation: methionine-deficient diet (Md); diet supplemented with the recommended methionine level (Met1); and diet supplemented with methionine above the recommended level (Met2). Their chicks were identified, weighed, and housed according to the maternal diet group from 1 to 14 d of age. On 15 d of age, chicks were weighed and divided into two groups: thermoneutral ambient (constant temperature of 23 °C) and intermittent heat stress ambient (daily exposure to 34 °C for 6 h). Methionine-supplemented (Met1 and Met2) hens had higher egg production, better feed conversion ratio, higher hatchability of total and fertile eggs, and offspring with higher body weight. Supplemented (Met1 and Met2) hens showed greater expression of glutathione synthase (GSS) and methionine sulfoxide reductase A (MSRA) genes, greater total antioxidant capacity, and lower lipid peroxidation in the liver. The offspring of hens fed the Met2 diet had lower death rate (1 to 14 d), higher weight on 15 d of age, weight gain, and better feed conversion ratio from 1 to 14 d of age. Among chicks reared under heat stress, the progeny of methionine-supplemented hens had higher weight on 35 d, weight gain, expression of GSS, MSRA, and thermal shock protein 70 (HSP70) genes, and total antioxidant capacity in the liver, as well as lower heterophil/lymphocyte ratio. Positive correlations between expression of glutathione peroxidase 7 (GPX7) and MSRA genes in hens and offspring were observed. Our results show that maternal methionine supplementation contributes to offspring development and performance in early stages and that, under conditions of heat stress during growth, chicks from methionine-supplemented hens respond better to hot environmental conditions than chicks from nonsupplemented hens. Supplementation of quail hens diets with methionine promoted activation of different metabolic pathways in offspring subjected to stress conditions.

The deficiency of nutrients such as methionine in the diet of birds is affecting fertility rate, egg production, egg weight, and progeny weight. In addition, the maternal environment influences gene expression through epigenetic mechanisms, where the conditions experienced by the parental generation during embryonic development can produce effects on the progeny. This study investigates how methionine supplementation in the diet of quail hens can reduce the effects of oxidative stress and improve the performance of progeny subjected to heat stress during growth. For that, the quail hens were fed with diets containing three different levels of methionine; and their chicks were created (15 on 35 d of age) into thermoneutral and/or intermittent heat stress ambient. It was observed that methionine supplementation in the quail hens had a positive effect on mortality during the initial phase and greater weight gain in the progeny growth phase. In addition, genetic inheritance was observed through the positive correlation between the expression of genes (maternal and progeny) related to oxidative stress. The results show that methionine supplementation in the maternal diet contributes to the development and performance of the progeny when subjected to heat stress during the growth phase.

Liver transcriptome response to hyperthermic stress in three distinct chicken lines.

BACKGROUND: High ambient temperatures cause stress in poultry, especially for broiler lines, which are genetically selected for rapid muscle growth. RNA-seq technology provides powerful insights into environmental response from a highly metabolic tissue, the liver. We investigated the effects of acute (3 h, 35 °C) and chronic (7d of 35 °C for 7 h/d) heat stress on the liver transcriptome of 3-week-old chicks of a heat-susceptible broiler line, a heat-resistant Fayoumi line, and their advanced intercross line (AIL). RESULTS: Transcriptome sequencing of 48 male chickens using Illumina HiSeq 2500 technology yielded an average of 33.9 million, 100 base-pair, single-end reads per sample. There were 8 times more differentially expressed genes (DEGs) (FDR < 0.05) in broilers (n = 627) than Fayoumis (n = 78) when comparing the acute-heat samples to the control (25 °C) samples. Contrasting genetic lines under similar heat treatments, the highest number of DEGs appeared between Fayoumi and broiler lines. Principal component analysis of gene expression and analysis of the number of DEGs suggested that the AIL had a transcriptomic response more similar to the Fayoumi than the broiler line during acute heat stress. The number of DEGs also suggested that acute heat stress had greater impact on the broiler liver transcriptome than chronic heat stress. The angiopoietin-like 4 (ANGPTL4) gene was identified as differentially expressed among all 6 contrasts. Ingenuity Pathway Analysis (IPA) created a novel network that combines the heat shock protein family with immune response genes. CONCLUSIONS: This study extends our understanding of the liver transcriptome response to different heat exposure treatments in distinct genetic chicken lines and provides information necessary for breeding birds to be more resilient to the negative impacts of heat. The data strongly suggest ANGPTL4 as a candidate gene for improvement of heat tolerance in chickens.

Heterophil functional responses to dietary immunomodulators vary in genetically distinct chicken lines.

The effect of dietary supplementation of immunomodulators on in vitro chicken heterophil function was investigated using three diverse genetic lines of chickens (broiler, Fayoumi, and Leghorn). Dietary supplementation with ß-glucan, ascorbic acid, and corticosterone was fed from 8 to 11 weeks of age. Heterophil function was evaluated weekly during supplementation using phagocytosis, bacterial killing, and heterophil extracellular traps (HETs)-DNA release. Fayoumis fed the basal diet had significantly higher HETs-DNA release (P=0.002) than Leghorns and broilers. Both genetic line and immunomodulator diet supplementation had significant effects on bacterial killing (line and diet effect: P<0.001) and HETs-DNA release (line: P<0.001; diet: P=0.043). Dietary supplementation with immunomodulators, therefore, shows potential to affect and augment heterophil function in chickens. The current results also suggest the important role of genetics in innate immune responses.