饲料中蛋白水平对三疣梭子蟹雌体生长、卵巢发育和生化组成的影响

本研究配制蛋白水平分别为32.16％、36.13％、39.59％和41.24％的等脂等能配合饲料(分别记为饲料1～4),对初始体重为(10.98±0.28)g的三疣梭子蟹(Portunus trituberculatus)雌体进行池塘养殖120 d,以探究饲料蛋白水平对三疣梭子蟹雌体生长、卵巢发育和生化组成的影响.结果...     

UVA补光时间对凡纳滨对虾肌肉主要营养成分影响研究

紫外光A波段(Ultraviolet A, UVA)是自然光的重要组成部分,具有一定的生态功能。本研究选取450尾体重为(9.56±0.10) g的凡纳滨对虾(Penaeus vannamei)以光周期为12L︰12D的全光谱LED灯[光强(1.00±0.02) W/m2]作为背景光源,在不同UVA [光强(1.00±0.02) W/m2]补光时间(0 h, T0 h; 2 h, T2 h; 4 h, T4 h; 8 h, T8 h; 12 h, T12 h)下进行为期28 d的养殖实验。结果显示,在不同UVA补光时长下,对虾肌肉中水分和粗灰分含量无显著差异,T2 h和T4 h组的粗脂肪含量显著增加,T2 h组的粗蛋白显著高于T4 h组外的其他组(P<0.05),T8 h和T12 h组的粗脂肪显著低于其他各组(P<0.05),但两组间差异不显著;T2 h和T4 h组氨基酸总量、必需氨基酸含量和赖氨酸含量均显著高于其他组(P<0.05);凡纳滨对虾饱和脂肪酸(SFA)含量为27.85%~40.70%,单不饱和脂肪酸(MUFA)含量为10.63%~16.31%,多不饱和脂肪酸(PUFA)含量为38.81%~49.61%,其在T2 h和T4 h组显著高于其他各组(P<0.05),且在两组间无显著差异。综上所述,2~4 h的UVA补光时间能够改善凡纳滨对虾肌肉的营养成分。     

Physiological function and application of dietary fiber in pig nutrition:A review

Dietary fiber (DF), divided into soluble dietary fiber (SDF) and insoluble dietary fiber (IDF), has attracted increasing attention in the field of pig nutrition. Although DF reduces nutrient digestibility and inhibits energy deposition in most cases, fiber-rich feeds have been widely used in pig diets. This is not only because of lower feed costs, but also from the continuous discovery about the nutritional value of DF, mainly including the improvement of piglet intestinal health and sow reproductive performance. The addition timing has also been further considered, which potentially enables the nutritional value of DF to be accurately used in applicable pig models. Furthermore, fiber degrading enzymes have been shown to alleviate the anti-nutritional effects of DF and have ensured the improvement effect of fiber on intestinal health in young piglet models. However, the regulatory effect of fiber on pork quality is still unclear, which requires consideration of the wide range of fiber sources and the complexity of the basic diet composition, as well as the impact of pig breeds. Taken together, future research needs to gain more insight into the combined effects of SDF and IDF, processing methods, and addition timing to improve the nutritional value of DF, and further explore the physiological functions and regulatory mechanisms of DF fermentation products short-chain fatty acids in pigs.     

Effects of dietary concentrate level and chromium-methionine supplementation on ruminal fermentation,and ruminal bacterial and fatty acid composition in Tan lambs北大核心CSCD

This study evaluated the effects of dietary concentrate level and chromium methionine(Cr-Met)supplementation on ruminal fermentation and fatty acid composition, and ruminal bacteria abundance in Tan lambs. Forty male Tan lambs [(21.00±1.23) kg body weight, 5 months of age] were randomly assigned to four treatment groups with 10 lambs in each treatment. The treatments were: a low-concentrate (LC) diet (concentrate:forage, 35:65) without Cr-Met supplementation; a high-concentrate (HC) diet (concentrate:forage, 55:45) without Cr-Met supplementation; groups fed the HC diet with 0.75 or 1.50 g·d-1·lamb-1 Cr-Met (HCM and HCH, respectively). Ruminal fluid was collected on day 65 with an oral stomach tube about 3 h after the morning feed and samples used for fermentation analysis, fatty acid composition determination and bacterial DNA extraction. It was found that: 1) Ruminal pH, acetate proportion and acetate:propionate were greater (P<0.05) with the LC diet whereas microbial crude protein, propionate and valerate proportions were greater (P<0.05) with the HC diet. The acetate:propionate was greater (P<0.05) in the HCM group than in the HC group. 2) For the HC diet, the DNA abundances of Butyrivibrio fibrisolvens vaccenic acid subgroup (Butyrivibrio VA) and Ruminococcus flavefaciens were decreased (P<0.05), compared with the LC diet, whereas the DNA abundance of Anaerovibrio lipolytica was increased (P<0.05). For lambs fed the HC diet, DNA abundances of B. fibrisolvens stearic acid subgroup, Butyrivibrio VA, Butyrivibrio proteoclasticus, and A. lipolytica showed a linear decrease (P<0.05) with increasing Cr-Met supplementation level; However, the DNA abundance of R. flavefaciens showed a linear increase (P<0.05). 3) Compared with the LC group, the concentrations of t11 C18:1, trans C18:1, c9t11 CLA, t10c12 CLA, C18:2n6, and C18:3n3 were decreased by the HC diet without Cr-Met supplementation whereas the concentration of C18:0 was increased. There was a linear increase in t11 C18:1 and trans C18:1 with increasing Cr-Met supplementation level in lambs fed the HC diet. The results suggest that the HC diet inhibited the growth of ruminal bacteria involved in the ruminal biohydrogenation process, and the addition of Cr-Met had a potentially positive effect on conjugated linoleic acid (CLA) synthesis in body tissue. © 2022, Editorial Office of Acta Prataculturae Sinica. All rights reserved.     

黄土丘陵区柠条人工林土壤水分动态变化特征及降雨特征对其影响

明确黄土丘陵区降雨对土壤水分影响，对准确评估降雨格局变化对生态系统结构和功能的影响具有重要意义。以陕北黄土丘陵区退耕地栽植后自然撂荒23年的柠条人工纯林为研究对象，通过土壤湿度传感器监测不同土层土壤体积含水量，探讨不同土层土壤水分补充增量对降雨特征(降雨量、降雨历时和降雨强度)的响应。结果表明：(1)土壤水分消耗和补充主要集中于0-500 cm土层，其月变化在垂直剖面呈“双峰”(4—5月)、“单峰”(6月)和“双峰”(7—10月),随土层深度增加变化率减弱；(2)当降雨量>4 mm时表层土壤水分得到有效补充，当其超过142.8 mm时补充深度可到达200 cm土层，其中长历时强降雨较短历时强降雨对土壤水分补充增量小，但其补充深度较深，达到峰值时间长，但小降雨长历时则土壤水分补充增量较小；(3)降雨特征对土壤水分影响随土层深度增加而减弱，其中降雨量和降雨历时对土壤水分影响主要在0—50 cm土层，而降雨强度对其影响主要在0—30 cm土层。降雨量(降雨历时)和土壤水分补充增量对数拟合最优，而降雨强度与其则表现为幂函数拟合最优，其可分别解释土壤水分补充增量的39%～76%(降雨量)、...