Four experiments were performed to investigate the role of the mitogen-activated protein kinase (MAPK) signaling pathway in intestinal absorption of phosphorus (P) and calcium (Ca) in broiler chickens. Experiment 1 assessed how dietary levels of 1,25-dihydroxyvitamin D₃ (1,25(OH)₂D₃) influence the gene expression of intestinal P and Ca transporters in broilers. Experiment 2 evaluated the effects of 1,25(OH)₂D₃ administered via intraperitoneal injection on the extracellular signal-regulated kinase (ERK) and p38 mitogen-activated protein kinase (p38MAPK) signaling pathways. Experiments 3 and 4 investigated the effect of ERK and p38MAPK inhibitors on the expression of intestinal P and Ca transporters. The findings demonstrated that broilers (1-21 days old) fed a 1,25(OH)₂D₃-deficient diet (0.625 µg/kg) exhibited reduced body weight, tibia P and Ca levels, and mRNA levels of P transporters (NaPi-IIb, PiT-1, and PiT-2), Ca transporters (NCX1, PMCA1b, and CaBP-D28k), vitamin D receptors (VDR), ERK, and p38MAPK in the duodenum (Experiment 1) (P < 0.05). By comparison, the growth, bone quality, and mRNA levels of genes (except for duodenal NaPi-IIb) in broilers were similar to those in broilers fed the control diet when dietary 1,25(OH)₂D₃ was adequate (5 µg/kg) (Experiment 1) (P > 0.05). After intraperitoneal injection of 1,25(OH)₂D₃, the mRNA level of jejunal NaPi-IIb and the protein level of p-p38MAPK/t-p38MAPK in broilers (9-14 days old) decreased (P < 0.05), whereas the mRNA level of CaBP-D28k and the protein level of p-ERK/t-ERK increased (Experiment 2) (P < 0.05). The mRNA and protein expression of jejunal NaPi-IIb and the protein expression of CaBP-D28k in broilers (9-17 days old) treated with the ERK inhibitor PD98059 were greater than those in the control group (Experiment 3) (P < 0.05). Similarly, compared with control broilers, broilers (9-17 days old) treated with the p38MAPK inhibitor SB203580 showed elevated mRNA expression of jejunal NaPi-IIb and CaBP-D28k (Experiment 4) (P < 0.05). These results suggest that adequate supplementation with 1,25(OH)₂D₃ (5 µg/kg) can restore broiler growth and bone quality by upregulating the transcription of genes involved in intestinal P and Ca absorption. Additionally, the ERK and p38MAPK signaling pathways are implicated in the modulatory effect of 1,25(OH)₂D₃ on the absorption of P and Ca in broilers.

Journal of Animal Science and Technology (JAST) is a peer-reviewed, open access journal publishing original research, review articles and notes in all fields of animal science. Topics covered by the journal include: genetics and breeding, physiology, nutrition of monogastric animals, nutrition of ruminants, animal products (milk, meat, eggs and their by-products) and their processing, grasslands and roughages, livestock environment, animal biotechnology, animal behavior and welfare.

The objective of this study is investigating the effects of Lonicerae flos extract (LFE) on antioxidant status, intestinal development, and jejunum barrier function in heat-stressed broilers. Two hundred and forty male broilers (28-day-old) were assigned to normal control group (NOR, 22°C, basal diet), heat stress group (HS, 32°C, basal diet) and Lonicerae flos extract supplementation group (LFE, 32°C, basal diet with 400 mg/kg, 800 mg/kg, 1200 mg/kg LFE). Results indicated that Heat stress significantly impaired growth performance, increased serum aspartate aminotransferase (AST) and d-lactate levels, decreased jejunal mucosal total antioxidant capacity (T-AOC) and jejunal villus height (P < 0.05) throughout the entire experimental period. Although not statistically significant for growth performance, Lonicerae flos extract numerically reduced the feed-to-gain ratio by 8.5 % after 14 days. Lonicerae flos extract, particularly at 800 mg/kg, significantly mitigated the heat stress-induced elevation in serum AST and d-lactate levels and enhanced jejunal T-AOC and superoxide dismutase (SOD) activity and jejunal villus height (P < 0.05). Lonicerae flos extract activated Nrf-2 pathway, downregulated the mRNA expressions of endoplasmic reticulum stress (ERS) and apoptosis-related genes, and enhanced the mRNA expressions of tight junction proteins in jejunum mucosa of heat stressed-broilers. The 800 mg/kg dose was identified as the most effective. In conclusion, dietary LFE effectively improved intestinal integrity and antioxidant capacity in heat-stressed broiler through activating Nrf-2 pathway, alleviating ERS-dependent apoptosis and improving jejunum barrier function.

It was of great practical significance to repair the toxicity of salt stress environment to soybean seedlings and maintain the balance between agricultural production and ecological environment in the Yellow River valley of China. ‘Xudou 20’ was used as the experimental material, a large-scale planting variety in the old Yellow River basin. Endophytes 131 and 137 isolated from soybean root nodule were taken as the research objects, and the soybean plants were cultivated by pot culture in intelligent artificial incubator. Salt stress group, bacteria suspension group and control group were set up to study the effects of inoculation treatments on the activities of superoxide dismutase (SOD) and catalase (CAT) of soybean seedlings under different NaCl stress. The results showed that when inoculated with endophyte 131 bacterial suspension and cultured for 14 days, the SOD activity was the highest (14.89 U•g−1•FW) at the salt concentration 50 mmol•L-1. When inoculated with 131 bacterial suspension (2:1) and cultured for 28 days, the SOD activity reached the highest (0.94 ug-1FW) at the salt concentration of 50 mmol•L-1, and the CAT activity amounted to the highest (1910 U•g−1•min−1). The 16S rDNA sequencing and phylogenetic analysis showed that the most similar strain of strain 137 was Bacillus cereus, and the most similar strain of strain 131 was Enterobacter ludwigii. Therefore, the activities of SOD and CAT in soybean seedlings inoculated with endophytes 131 and 137 increased at different degrees under salt stress, which could effectively alleviate the damage of salt stress environment to plants, and thus improve the stress resistance of plants.