功能性氨基酸——精氨酸和精氨酸生素在猪生产中的研究与应用进展

功能性氯基酸——精氦酸（Arg）具有重要的生理、代谢和营养作用,几乎机体中所有组织均利用Arg合成胞浆蛋白和核蛋白,精氨酸在促进肌肉蛋白质合成、增强机体的免疫力、细胞分裂、伤口复尿和激素分泌等各种生理过程中,也都有着重要的角色。Arg为条件性必需氨基酸,在应激状态下和特殊生长阶段,为必需氨基酸,仔猪体内合成的精氨酸不能满足生理代谢需要。但是精氨酸的吸收与赖氨酸等桔抗,因此,对精氨酸及其内源性合成调控研究具有极大的应用价值和实践意义。精氨酸生素（Arginineactivatoradditive,AAA）是N-乙酰谷氨酸（N-acetylglutamate,NAG）的类似物,作为一种新型的功能性氨基酸,可以有效调控内源性精氨酸合成,进而促进动物生长性能。本文就精氨酸和精氨酸生素特别是其对机体内源性精氨酸合成调控及其在仔猪和母猪中的研究进展与应用作一综述。     

中草药饲料添加剂的应用现状

中草药饲料添加剂能提高动物生产性能、繁殖机能、改善畜产品品质、抗应激,且毒副作用小,不易在肉、蛋、奶等食用畜禽产品中产生有害残留,是确保饲料和动物性食品安全及人体健康的理想添加剂。     

Crossbreeding effects for post-weaning growth traits in a project of Spanish V-line with Baladi Red Rabbits in Egypt

A four-year crossing scheme involving Spanish V line (V) and Egyptian Baladi Red (B) rabbits was carried out to produce five genetic groups: V, B, 1/2B1/2V(F₁), (1/2B1/2V)²(F₂), and ((1/2B1/2V)²)². The last genetic group was considered a new line, named APRI. Body weights (BW) and daily gains in weight (DG) from four to twelve weeks were evaluated for 13,383 rabbits produced by 330 sires and 1074 dams. An animal model was used to estimate heritabilities and common litter effects and a generalized least squares procedure was used to estimate direct additive effects, and direct and maternal heterosis.Heritabilities for growth traits were mostly moderate, ranging from 0.075 to 0.240 for BW and from 0.020 to 0.104 for DG. The V line was heavier and had better gains at each weighing than B rabbits. The F₂ and APRI were also lower in most post-weaning growth performance measures than V line rabbits. APRI rabbits were significantly lighter by 39, 26, 46, 64, and 50 g at ages of 4, 6, 8, 10, and 12 weeks, respectively, relative to the purebred V line, while APRI was significantly heavier by 36 and 127 g relative to the B line at 4 and 12 weeks. The V line, in general, had a higher DG than B line. The differences were 3.15, 7.91 and 1.95 g/d at age intervals of 8–10, 10–12 and 4–12 weeks. Differences in direct additive effects between the two lines were in favor of V line rabbits reaching 15.0% (76 g) at 4 weeks and 13.3% (195 g) at 12 weeks. Direct additive effects for DG were significant during most age intervals reaching 35.7% (7.19 g/d) in the interval of 10–12 weeks. All estimates of direct heterosis were positive and ranged from 4.9 to 16.7% for BW and 14.4 to 29.5% for DG, but the estimates for maternal heterosis were, in most cases, significantly negative and ranging from − 4.5 to − 15.2% for BW and from 20.6 to − 36.9% for DG. If the results are confirmed at commercial farms, the APRI line could be reared in heat stress conditions.     

Antimicrobial peptides as a feed additive alternative to animal production,food safety and public health implications: An overview

In the last few years, feed additives have been used in animal nutrition to improve nutrient utilization, health parameters and animal performance. However, the use of antibiotics as feed additives has allowed the occurrence of antimicrobial resistance (AMR), which can bring as a consequence, an increase in the morbidity and mortality of diseases that were previously treatable with antibiotics. In this context, antimicrobial peptides (AMP) have appeared as a promising strategy because they have multiple biological activities and represent a powerful strategy to prevent the development of resistant microorganisms. Despite the small number of studies applied in vivo, AMP appear as a potent alternative to the use of antibiotics in animal nutrition, due to an increase in feed efficiency and the prevention/treatment of some animal diseases. This review discusses the problems associated with antimicrobial resistance and the use of AMP as a strong candidate to replace conventional antibiotics, mainly in the animal industry.     

Environmental variability controls recruitment but with different drivers among spawning components in Gulf of St. Lawrence herring stocks

The factors affecting herring recruitment are still poorly understood, complicating the prediction of stock dynamics and the choice of operational management strategies. We investigated effects of intrinsic (SSB) and extrinsic factors (physical and biological environments, including competition and predation) on recruitment of the spring and fall spawning components of each of the two herring stocks occurring in the Gulf of the St. Lawrence between 1971 and 2014. Effects of potential explanatory factors on recruit (age 2) abundance were tested using Generalized Additive Models. Model fit was significantly improved by incorporating both physical and biological environmental variability, but effects of herring SSB and predation were not significant. Indices of zooplankton abundance and phenology explained more variance in recruitment than physical indices. Our results emphasize the dominance of bottom‐up processes over SSB in the regulation of herring recruitment. Environmental variability did not seem to act uniformly on the recruitment of either stock or their respective spawning components. A long‐term trend of decreasing recruitment in spring spawners was associated with a long‐term decline in abundance of cold water copepods. In fall spawners, optimal recruitment was dependent on warmer environmental conditions combined with an adequate supply (species composition and phenology) of zooplankton. These results provide the first empirical evidence that spring and fall spawning herring are adapted to contrasting environmental conditions and shed light on the potential mechanisms linking herring recruitment to key zooplankton community characteristics and phenology. Management strategies can be improved by incorporating this new knowledge on environmental drivers of herring recruitment.     

Evaluating diel, ontogenetic and environmental effects on larval fish vertical distribution using Generalized Additive Models for Location, Scale and Shape

Changes in ichthyoplankton vertical distributions can have important consequences with respect to larval transport and survivorship, yet determining the relative importance of environmental influences on vertical migrations in a statistically meaningful framework remains challenging. Here we use Generalized Additive Models for Location, Scale and Shape (GAMLSS) and Akaike Information Criteria (AIC) to model the vertical distribution of larval Urophycis regia collected over a 108-h time series on the Mid-Atlantic Bight shelf. Depth was the response variable weighted by two measures of larval abundance: concentrations (number 100 m⁻³) and proportions at depth. Mean and variance of depth were modeled as a function of time, wind stress, current velocity, water column stratification and ontogeny. Model results indicated a large effect of stage for both concentration- and proportion-based analyses. Subsequent and separate analyses on preflexion and postflexion U. regia indicated a differential response to the environmental parameters based on ontogeny. Model results suggested preflexion U. regia do not have a diel pattern in vertical distribution, but do avoid areas of high surface turbulence related to wind stress. In contrast, postflexion larvae have a significant diel pattern of vertical distribution mediated by surface turbulence (increased variance). The statistical approaches applied here offer the potential to evaluate the effect of multiple factors on vertical distribution and have provided significant insight into the factors that influence the vertical distribution of spotted hake larvae.     

“食品添加剂”课程混合式教学模式研究

混合式教学作为一种新型的教学模式,是将传统的课堂教学与线上教学相结合产物。该教学模式既能有效提高学生对“食品添加剂”课程的学习兴趣,锻炼学生自主学习的能力,也能有效提高学生对所学知识的分析和解决问题的能力。以探索“食品添加剂”课程混合式教学模式的实施为目的,分析研究了混合式教学模式的优点,从而提出混合式教学模式建立的措施和实施内容。