Carbon sequestration is the primary function of biochar. Hence, it is necessary to design biochar with high carbon (C) retention and low C loss. In this study, three P compounds, including KH₂PO₄, Ca(H₂PO₄)₂, and NH₄H₂PO₄, were premixed with corn stalk (1:4, w/w), aiming to produce biochars (CSB+K, CSB+Ca, and CSB+N) with high C sequestration and slow release of P at three temperatures (300, 500, and 700 °C). The addition of all P sources obviously increased C retention, with the order of NH₄H₂PO₄ (65.6–83.5%) > Ca(H₂PO₄)₂ (60.4–78.2%) > KH₂PO₄ (50.1–76.1%), compared with the pristine biochar (47.8–73.6%). The addition of Ca(H₂PO₄)₂ and KH₂PO₄ led to an increase in aromaticity and graphitization, as evidenced by H/C, FTIR, Raman and XPS analysis, whereas an opposite result occurred on CSB+N. Furthermore, all three phosphates reduced C loss of biochars with H₂O₂ oxidation, and CSB+Ca showed the best effect. Ca(H₂PO₄)₂ and KH₂PO₄ pretreated biochars had higher resistance to K₂Cr₂O₇ oxidation and thermal treatment. In contrast, the C loss of NH₄H₂PO₄-added biochar at 500 and 700 °C with K₂Cr₂O₇ oxidation was increased by 54% and 36%, respectively. During the pyrolysis process, Ca(H₂PO₄)₂ was transformed into insoluble Ca₂P₂O₇, leading to the lowest P release rate of CSB+Ca. This study indicates that co-pyrolysis of corn stalk and Ca(H₂PO₄)₂ is optimal for increasing C retention, enhancing C stability and improving slow-release performance of P regardless of pyrolysis temperature.

Effects of different feeding strategies on meat quality and intestinal development in pigeon squabs were investigated. 120 pairs of pigeons with two squabs each were assigned to five groups (four free-choice feeding systems and one complete feeding system): T1 (corn, pea, wheat, and pelleted feed), T2 (corn, wheat, and pelleted feed), T3 (corn, pea, and pelleted feed), T4 (corn and pelleted feed), and T5 (complete pelleted feed). Compared with T5, the diet in T4 made the breast meat redder and more yellow (p < 0.05). T2 and T4 resulted in an enhanced total superoxide dismutase activity of meat. Breast muscle in T1 and T2 was determined to have higher contents of nonessential amino acids, glycine, alanine, and glutamic acid (p < 0.05). The contents of the essential amino acids, lysine, threonine, valine, histidine, and arginine were also higher in T1 (p < 0.05). Villus height, surface area, and alkaline phosphatase activity of the duodenum and jejunum in T2 were the highest among the treatments (p < 0.05). In conclusion, free-choice feeding system can improve the meat quality and intestinal development of pigeon squabs, but which combination method of whole grains to use in the production depends on the feeding purpose.

The current study aimed to evaluate the changes in lipid accumulation and oxidative status in pigeon crops during different breeding stages. Forty-two pairs of adult pigeons were randomly assigned to 7 groups. Lipid droplet accumulation in pigeon crops was visualized by using oil red O staining from d 17 of incu-bation (I17) to d 7 of chick rearing (R7). Transmission electron microscopy analysis showed swollen mitochon-dria with disintegration of cristae and typical character-istics of endoplasmic reticulum stress in crop tissues at R1 compared with those at I4. During the peak of pigeon milk formation, the concentrations of reactive oxygen species, and oxidative damage markers (advanced oxida-tion protein products, 8-hydroxy-2 deoxyguanosine, and malondialdehyde) and the enzyme activities of total superoxide dismutase and glutathione peroxidase were all elevated significantly (P < 0.05). The protein concen-tration of B-cell lymphoma-2 associated X in crop tissues was significantly higher at R1, while the level of B-cell lymphoma-2 protein in males was the highest at I4 (P < 0.05). The ratio of B-cell lymphoma-2 associated X pro-tein (Bax)/B-cell lymphoma-2 (Bcl-2) in both male and female crops peaked at R1 (P < 0.05). Gene expres-sion of the key enzymes involved in mitochondrial and peroxisomal fatty acid b-oxidation was investigated in crops. In males, the gene expression of carnitine palmi-toyltransferase 1a peaked at R15, and that of carnitine palmitoyltransferase 2 increased significantly from R1 to R15 (P < 0.05). The mRNA abundance of long chain 3-hydroxyacyl-CoA dehydrogenase increased to the maxi-mum value at R1 and I17 in males and females, respec-tively. From I17 to R7, the mRNA levels of acyl-CoA oxidase 1 and acyl-CoA oxidase 2 were decreased in pigeon crops (P < 0.05). Conclusively, lipid droplet accu-mulation was found in male and female pigeon crops from the end of incubation to the early stage of chick rearing. Although antioxidant defence and mitochon-drial fatty acid b-oxidation were both mobilized, oxida-tive stress in crop tissues still occurred during the peak of milk formation.

1. The objective of this study was to examine the keratin composition of crop milk, the variation of epithelial thickness and keratin (K) gene expression in samples from young pigeon during incubation and chick rearing. 2. Crop milk was collected from 1-, 3- and 5-day-old squab crops for keratin content analysis. Results showed that K4 accounted for the highest proportion of all detected keratins. 3. In total, 42 pairs of adult pigeons were allocated to seven groups according to different stages to collected crop samples. Gene expression studies showed that the K3 gene expression was maximised at rearing Day 15 (15) and R1 in males and females, respectively. K6a gene level was the greatest at R15 in females, whereas it peaked at incubation Day 4 (I4) in males. The K12, K13, K23 and K80 gene levels were inhibited at the peak period of crop milk formation in comparison with I4. In females, K cochleal expression peaked at I10, whereas it was the greatest at R25 in males. K4 and K14 gene expression was the highest at I10 in females, while K4 and K14 were minimised at I17 and R7 in males, respectively. Gene expressions of K5, K8, K19 and K20 in males and K19 in females were maximised at R1. The K5, K20 and K75 gene levels in females peaked at R7. K75 and K8 expressions in males and females reached a maximum value at R25 and I17, respectively. 4. The epithelial thickness of male and female crops reached their greatest levels at R1 and had the highest correlation with K19. 5. These results emphasised the importance of keratinisation in crop milk formation, and different keratins probably play various roles during this period. The K19 was probably be marker for pigeon crop epithelium development. The sex of the parent pigeon affected keratin gene expression profiles.

Biochar is widely used in composting to reduce nitrogen loss; however, the application of acid-modified and alkali-modified biochar in composting remains insufficient. We hypothesize that acid-modified maize straw biochar can simultaneously reduce NH₃ and N₂O losses during the composting process. To test this, a composting experiment was conducted with four treatments: a control with pig manure and corn straw only (CK), adding 5% corn straw biochar (BC), adding 5% HNO₃-modified corn straw biochar (BCN), and adding 5% NaOH-modified corn straw biochar (BCNa). The results showed that, compared to CK, NH₃ emissions were not decreased by BC, but significantly reduced (p < 0.05) by 32.6% in BCN and 36.8% in BCNa, respectively. N₂O was significantly decreased (p < 0.05) by 27.6% in BC and 30.9% in BCNa, respectively. However, BCN significantly increased N₂O emission (p < 0.05) by 368.7%, compared to CK. Compared to CK, the global warming potential (GWP) in the BCNa treatment was significantly reduced by 35.2% (p < 0.05), while the GWP in BCN was significantly decreased by 10.3%. Overall, although BCN treatment may increase N₂O emissions, it can still reduce the GWP. In comparison, BCNa treatment achieves the most significant reduction in GWP during pig manure composting.