This study was to investigate the effect of dietary supplementation with xylanase and protease on growth performance, digesta viscosity, apparent ileal digestibility (AID) of nutrients, and gut health in nursery pigs. Forty-eight pigs (24 barrows and 24 gilts at 21 d of age with 7.2 ± 0.4 kg BW) were randomly allotted to 4 dietary treatments (2 × 2 factorial arrangement) in a randomized complete block design and fed in 2 phases (phase 1 for 10 d and phase 2 for 14 d). Factors were xylanase (0 or 45,000 XU/kg) and protease (0 or 300,000 U/kg). Feed intake and BW gain were measured on d 10 and 24. Titanium dioxide (0.25%) was added to all diets as an indigestible external marker from d 20 to 24. On d 24, all pigs were euthanized to obtain jejunal and ileal digesta to measure viscosity and apparent ileal digestibility. The jejunal mucosa was collected to measure immune and oxidative stress status. Jejunal tissues were used to measure morphology and crypt cells proliferation. In phase 2, xylanase increased (P < 0.05) the average daily gain (ADG) which was further increased (P < 0.05) when combined with protease. Overall, combinational use of xylanase and protease increased (P < 0.05) ADG compared with the use of xylanase or protease alone, whereas protease improved (P < 0.05) feed efficiency. In jejunum, xylanase reduced (P < 0.05) viscosity of digesta, mucosal malondialdehyde (MDA), crypt depth and crypt cells proliferation, and protease increased (P < 0.05) villus height, and decreased (P < 0.05) crypt depth and crypt cells proliferation. Collectively, xylanase improved growth performance, digesta viscosity, and oxidative stress, whereas protease improved feed efficiency and gut morphology. The combinational use of xylanase and protease enhanced growth performance of newly weaned pigs.

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Due to problems such as unbalanced intake of nutrients or excessive intake of energy, cultured fish accumulate fat in places such as the abdominal cavity, liver, and muscle, resulting in fatty liver, reducing the quality of fish meat, and even causing many fish deaths, resulting in losses to aquaculture production. Therefore, research on lipid metabolism in fish is important and has attracted increasing attention. The detection of fish body fat distribution and content is a key to such research. The existing methods for detecting fat distribution and content in fish have limitations, such as cumbersome procedures and damage to fish tissues, and thus, is imperative to develop a simple, fast, nondestructive fat detection technology. Taking zebrafish as the research material, this study established an imaging technology for the rapid and nondestructive detection of the fat distribution and content of fish by micro-computed tomography (micro-CT), optimized the fat CT-scanning method, determined the steps of fat quantitation in the CTAn data processing software, and constructed a three-dimensional (3D) model of zebrafish adipose tissue. This technology reveals the distribution of fish adipose tissue in an all-round way, and thus, it will play an important role in the study of lipid metabolism in fish.