Effect of in ovo feeding of γ-aminobutyric acid combined with embryonic thermal manipulation on hatchability, growth, and hepatic gene expression in broilers

In ovo sericin suppresses hepatic DNA demethylation in broilers at hatch

Over the years, the rearing period of the commercial broilers to attain the slaughter weight has reduced significantly. Hence, it emphasizes the importance of the period of embryonic development. It has been shown that inadequate nutritional supply to the embryo at the later phases can lead to various abnormalities. This adversely affects the hatchability and further the post-hatch performance of the chicks. This study attempted to study the effect of in ovo feeding of sericin on the developing Ross-308 embryos. Fertile eggs (n = 210) at 17.5 days of embryonic development (ED) were equally divided into five treatments based on the concentration of sericin fed. The treatments were: uninjected control (UCON), followed by different concentrations of sericin injected groups as 0SER (0 % sericin), 1.5SER (1.5 % sericin), 3.0SER (3.0 % sericin), and 4.5SER (4.5 % sericin). Hatch parameters across treatments did not differ significantly. Similarly, the organ (liver, yolk sac, gizzard, proventriculus and heart) indices and plasma antioxidant markers such as 2,2-Diphenyl-1-picrylhydrazyl - radical scavenging activity % (DPPH-RSA%) and malondialdehyde (MDA) content did not differ significantly across treatments. The hepatic mRNA expression of superoxide dismutase (SOD) was higher in 3.0SER treatment in comparison to 4.5SER. On the other hand, in ovo sericin downregulated the hepatic gene expression of DNA demethylation-related enzymes such as ten-eleven translocation methylcytosine dioxygenase 3 (TET3, p = 0.028) and methyl-CpG-binding domain protein 4 (MBD4, p = 0.007) compared to 0SER. Pearson's correlation analyses revealed a significant correlation between the hepatic gene expression of NADPH oxidase (NOX) related genes and DNA-demethylation-related genes (p < 0.01). Hence, in ovo sericin might not be potentially beneficial in improving the hatchability of broilers. Also, no notable effects on the antioxidant capacity of plasma was recorded. However, in ovo sericin downregulated the mRNA expression of some DNA demethylation-related genes which were significantly correlated with the expression of NOXs. Therefore, in ovo sericin feeding could suppress DNA demethylation which could in turn be beneficial to alleviate oxidative stress at hatch.

Neonatal α-Ketoglutaric Acid Gavage May Potentially Alleviate Acute Heat Stress by Modulating Hepatic Heat Shock Protein 90 and Improving Blood Antioxidant Status of Broilers

This study investigated the effect of neonatal α-ketoglutaric acid (AKG) gavage feeding on broilers. The first experiment was conducted to determine the effect of AKG on day-old broilers. A total of seventy-two-day-old Ross 308 broiler chicks were divided into four treatment groups: (i) Two groups of chicks with gavage feeding of 0.6 mL of distilled water (DDW) for four consecutive days (CON); (ii) chicks fed with 0.6 mL of 0.1% AKG dissolved in DDW on the day of hatch (AL) followed by 0.2%, 0.3%, and 0.4% for three consecutive days; and (iii) chicks fed with 0.6 mL of 0.2% AKG dissolved in DDW on the day of hatch (AH) followed by 0.4%, 0.6%, and 0.8% for three consecutive days. Twenty-four hours after the first gavage feeding, six birds per treatment were slaughtered to study the organ development. Chicks fed with AKG showed higher absolute (p = 0.015) and relative (p = 0.037) weights of the gizzard. The AH group had higher absolute (p = 0.012) and relative (p = 0.035) heart weights. The second experiment was carried out to determine the effect of AKG on 15-day-old broilers under acute heat stress (AHS) for 3.5 h at 33 ± 1 °C. Forty-eight birds (12 per treatment) were raised until 15 days of age, divided into four treatments with equal numbers (n = 12), and given one of the following four treatments: (i) CON group reared at standard temperature (25 ± 1 °C) (CON-NT); (ii) CON group subjected to AHS (33 ± 1 °C) for 3.5 h (CON-HT); (iii) AL group subjected to AHS (33 ± 1 °C) for 3.5 h (AL-HT); and (iv) AH group subjected to AHS (33 ± 1 °C) for 3.5 h (AH-HT). There was a significant reduction in the change in BW (ΔBW, p = 0.005), an increase in the final rectal temperature (RTf) (p = 0.001), and a decreased final body weight (BWf) for all the treatments under AHS. Further, AHS led to an increased expression of hepatic heat shock protein (HSP)70 (p = 0.009), nicotinamide adenine dinucleotide phosphate hydrogen oxidase (NOX)1 (p = 0.006), and NOX4 (p = 0.001), while nuclear factor erythroid 2-related factor (NRF2), superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase 1 (GPX1) remained significantly unaffected. Hepatic expression of HSP90 decreased in the AL-HT treatment as compared to CON-HT (p = 0.008). Plasma antioxidant status measured by malondialdehyde (MDA) concentration and antioxidant balance (AB) improved linearly (p = 0.001) as the concentration of AKG increased. Neonatal gavage feeding of AKG could potentially alleviate heat stress in broilers by enhancing plasma antioxidant levels and modulating HSP90 expression in the liver.

In ovo feeding of α-ketoglutaric acid improves hepatic antioxidant-gene expression, plasma antioxidant activities and decreases body temperature without affecting broiler body weight under cyclic heat stress

The broiler industry is adversely affected by the rise in global temperature. This study investigated the effects of in ovo feeding of α-ketoglutaric acid (AKG) on growth performance, organ weight, plasma metabolite, plasma oxidative stress, rectal temperature (RT), and hepatic mRNA expression of antioxidant-related genes in Arbor Acres broilers subjected to cyclic heat stress (HS). Three hundred fifty fertile eggs during incubation were divided into 5 groups according to AKG concentrations and temperature conditions. After dissolving AKG in distilled water at 0, 0.5, 1.0, and 1.5, 0% AKG was in ovo administered to 2 of the 5 groups whereas the remaining 3 groups received 0.5, 1.0, and 1.5%, respectively. From d 29 to 34 of age, 4 groups of birds received heat stress (HS) at 31°C ± 1°C for 6 h per day while the other group was kept at room temperature (21°C ± 1°C; NT). So, the 5 treatment groups were: 1) 0AKG-NT, where chicks hatched from eggs receiving 0% AKG were reared under thermoneutral conditions. 2) 0AKG-HS, where chicks hatched from eggs receiving 0% AKG were reared under cyclic HS conditions. 3) 0.5AKG-HS, where chicks hatched from eggs receiving 0.5% AKG were reared under cyclic HS conditions. 4) 1.0AKG-HS, where chicks hatched from eggs receiving 1.0% AKG were reared under cyclic HS conditions. 5) 1.5AKG-HS, where chicks hatched from eggs receiving 1.5% AKG were reared under cyclic HS conditions. HS significantly reduced body weight change (ΔBW %) and average daily gain (ADG) without affecting average daily feed intake (ADFI). Feed conversion ratio (FCR) was significantly increased (P = 0.003) in all HS-treated groups. A significant linear decrease in the final RT (P = 0.005) and a change in RT (P = 0.003) were detected with increasing AKG concentration. Total antioxidant capacity (P = 0.029) and antioxidant balance (P = 0.001) in plasma increased linearly with increasing AKG concentration whereas malondialdehyde concentrations were linearly decreased (P = 0.001). Hepatic gene expression of CAT (P = 0.026) and GPX1 (P = 0.001) were dose-dependently upregulated while nicotinamide adenine dinucleotide phosphate oxidase (NOX)1, NOX4, and heat shock protein (HSP)70 were linearly downregulated (P < 0.05). Hence, in ovo injection of AKG was effective in mitigating HS-induced oxidative stress without attenuating the adverse effects on broiler growth.

Dietary supplementation of solubles from shredded, steam-exploded pine particles modulates cecal microbiome composition in broiler chickens

This study evaluated the effects of supplementing solubles from shredded, steam-exploded pine particles (SSPP) on growth performances, plasma biochemicals, and microbial composition in broilers. The birds were reared for 28 days and fed basal diets with or without the inclusion of SSPP from 8 days old. There were a total of three dietary treatments supplemented with 0% (0% SSPP), 0.1% (0.1% SSPP) and 0.4% (0.4% SSPP) SSPP in basal diets. Supplementation of SSPP did not significantly affect growth or plasma biochemicals, but there was a clear indication of diet-induced microbial shifts. Beta-diversity analysis revealed SSPP supplementation-related clustering (ANOSIM: r = 0.31, p < 0.01), with an overall lower (PERMDISP: p < 0.05) individual dispersion in comparison to the control group. In addition, the proportions of the Bacteroides were increased, and the relative abundances of the families Vallitaleaceae, Defluviitaleaceae, Clostridiaceae, and the genera Butyricicoccus and Anaerofilum (p < 0.05) were significantly higher in the 0.4% SSPP group than in the control group. Furthermore, the linear discriminant analysis effect size (LEfSe) also showed that beneficial bacteria such as Ruminococcus albus and Butyricicoccus pullicaecorum were identified as microbial biomarkers of dietary SSPP inclusion (p < 0.05; | LDA effect size | > 2.0). Finally, network analysis showed that strong positive correlations were established among microbial species belonging to the class Clostridia, whereas Erysipelotrichia and Bacteroidia were mostly negatively correlated with Clostridia. Taken together, the results suggested that SSPP supplementation modulates the cecal microbial composition of broilers toward a "healthier" profile.

Impact of embryonic manipulations on core body temperature dynamics and survival in broilers exposed to cyclic heat stress

Ambient temperature-associated stress has been shown to affect the normal physiological functions of birds. The recent literature indicated that both, embryonic thermal manipulation (ETM) and in ovo feeding (IOF) of γ-aminobutyric acid (GABA) can mitigate the deleterious effects of heat stress (HS) in young broiler chicks. Therefore, this study intended to assess the effects of cyclic HS (32 ± 1 °C, 4 h/day from day 29 to 35) on rectal temperatures (RTs) and survival in broiler chickens after ETM and in IOF of GABA. A total of 275 RT data points and survival data were collected from chicks assigned to the following five treatments: chicks hatched from control eggs (CON); chicks hatched from control eggs but exposed to HS (CON + HS); chicks hatched from eggs injected at 17.5 days of incubation with 0.6 mL of 10% GABA and exposed to HS (G10 + HS); chicks hatched from thermally manipulated eggs (39.6 °C, 6 h/day from embryonic days 10 to 18) and exposed to HS (TM + HS); chicks hatched from eggs that received both previous treatments during incubation and exposed to HS (G10 + TM + HS). Under thermoneutral conditions, RTs increased quadratically from 39.9 ± 0.2 °C at hatching to 41.4 ± 0.1 °C at 8 days of age. When exposed to cyclic HS during the last week of rearing, the birds' RTs tended to decrease at the end of the heat stress challenge (from 43.0 ± 0.2 °C on day 29 to 42.4 ± 0.1 °C on day 35). A stepwise Cox regression indicated that treatment was predictive of birds' survival. Hazard ratios (HR) and their confidence intervals (CI) were calculated to assess the likelihood of death during the trial. The birds, belonging to the G10 + TM + HS group, were less likely to die under HS (HR 0.11, 95% CI 0.02 to 0.91, P = 0.041) compared to the CON + HS birds. Taken together, the combination of ETM and GABA IOF may help mitigate the drawbacks of cyclic HS by improving the survival of broilers.