A comparison of two sources of methionine supplemented at different levels on heat shock protein 70 expression and oxidative stress product of Peking ducks subjected to heat stress

High water temperature raised the requirements of methionine for spotted seabass (Lateolabrax maculatus)

This study evaluated the effects of dietary methionine level and rearing water temperature on growth, antioxidant capacity, methionine metabolism, and hepatocyte autophagy in spotted seabass (Lateolabrax maculatus). A factorial design was used with six methionine levels [0.64, 0.85, 1.11, 1.33, 1.58, and 1.76%] and two temperatures [moderate temperature (MT): 27 ℃, and high temperature (HT): 33 ℃]. The results revealed the significant effects of both dietary methionine level and water temperature on weight gain (WG) and feed efficiency (FE), and their interaction effect was found on WG (P < 0.05). In both water temperatures tested, fish WG increased with increasing methionine level up to 1.11% and decreased thereafter. The groups of fish reared at MT exhibited dramatically higher WG and FE than those kept at HT while an opposite trend was observed for feed intake. Liver antioxidant indices including reduced glutathione and malondialdehyde (MDA) concentrations, and catalase and superoxide dismutase (SOD) activities remarkably increased in the HT group compared to the MT group. Moreover, the lowest MDA concentration and the highest SOD activity were recorded at methionine levels between 1.11% and 0.85%, respectively, regardless of water temperatures. Expression of methionine metabolism-related key enzyme genes (mat2b, cbs, ms, and bhmt) in the liver was increased at moderate methionine levels, and higher expression levels were detected at MT compared to HT with the exception of ms gene relative expression. Relative expression of hepatocyte autophagy-related genes (pink1, atg5, mul1, foxo3) and hsp70 was upregulated by increasing methionine level up to a certain level and decreased thereafter and increasing water temperature led to significantly enhanced expression of hsp70. In summary, HT induced heat stress and reduced fish growth, and an appropriate dietary methionine level improved the antioxidant capacity and stress resistance of fish. A second-order polynomial regression analysis based on the WG suggested that the optimal dietary methionine level for maximum growth of spotted seabass is 1.22% of the diet at 27 ℃ and 1.26% of the diet at 33 ℃, then 1.37 g and 1.68 g dietary methionine intake is required for 100 g weight gain at 27 ℃ or 33 ℃, respectively.

Dietary supplementation with 2-hydroxy-4-methyl(thio) butanoic acid and DL-methionine improves productive performance, egg quality and redox status of commercial laying ducks

This experiment aimed to study the effects of supplemental methionine sources, 2-hydroxy-4 methyl(thio) butanoic acid (HMTBa) and DL-Methionine (DL-Met), on productive performance, egg quality, and redox status of laying ducks. A total of 792 healthy 25-wk-old Longyan laying ducks with similar body weights were randomly allotted to 11 treatment groups. Each treatment group had 6 replicates of 12 ducks. The trial lasted for 16 wk. Ducks were fed a basal deficient diet (Met: 0.24%; Met + Cys: 0.51%) or supplemented with DL-Met or HMTBa at 0.05%, 0.12%, 0.19%, 0.26%, and 0.33% of diet, respectively. Compared with the basal diet, supplementation with either DL-Met or HMTBa increased the average egg weight, egg mass, and decreased feed to egg ratio during the whole trial period (P < 0.05). Albumen weight and its ratio to total egg weight were increased, but yolk and shell ratio, albumen height, Haugh unit and shell breaking strength were decreased (P < 0.05). Dietary DL-Met or HMTBa supplementation increased taurine, methionine, leucine, tryptophan and arginine content, and decreased serine and lysine content in plasma (P < 0.05). The redox status of laying ducks was improved by enhancing the glutathione peroxidase and catalase activities, glutathione content and its ratio relative to glutathione (oxidized) content and decreasing malondialdehyde content and increasing mRNA expression of superoxide dismutase-1, glutathione peroxidase-1, hemeoxygenase-1 and nuclear factor-like 2 in liver and ileum with the supplementation of DL-Met or HMTBa (P < 0.05). Liver health status measured by average area proportion lipid droplet was improved with supplementation of DL-Met or HMTBa (P < 0.05). Villus height and villus height to crypt depth ratio in the ileum and the ileal gene expression of tight junction protein and occludin were increased with DL-Met or HMTBa supplementation (P < 0.05). Taken together, these results suggested that the efficacy of dietary supplementation of HMTBa was similar to DL-Met, and it ranged from 98% to 100% for productive performance and egg albumen ratio in laying ducks (25 to 41 wk).

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.

Isolation, culture, and identification of duck intestinal epithelial cells and oxidative stress model constructed

Intestinal epithelial cells (IECs) not only have an absorption function but also act as a physical barrier between the body and the intestinal bacterial flora. Damage to IECs leads to the breakdown of this barrier and has negative effects on animal health. Intestinal epithelial damage is frequently associated with long-term acute stress, such as increased temperature and new stress management models. The intestinal epithelial damage caused by environmental stress has been linked to oxidative stress. Until now, the effects of intestinal epithelial antioxidant activity from feed additives and treatments could be tested in ducks only in vivo because of the lack of in vitro cell culture systems. In this study, we describe our protocol for the easy isolation and culture of IECs from the small intestine of duck embryos. Immunofluorescence was used for the cytological identification of IECs. In addition, IEC marker genes (IAP and CDH1) could also be detected in cultured cells. And cell status assessments were performed, and cell proliferation viability was analyzed by CCK-8 assay. Furthermore, we constructed an oxidative stress model to be used to research the oxidative stress response mechanism, and drugs acting on the cell signal transduction pathway. In conclusion, we have developed an effective and rapid protocol for obtaining duck primary IECs and constructed an oxidative stress model. These IECs exhibit features consistent with epithelial cells and could be used to explore the physiological mechanisms of oxidative stress ex vivo.