短链有机酸及其盐替代抗生素对猪生产性能的影响研究

本文就短链有机酸的种类、对猪的生产性能影响及可能的作用机理等作一综述,旨在为猪日粮无抗营养调控技术的研发与实践提供参考。     

ω-3多不饱和脂肪酸对公猪精液质量的影响及其机制

在规模化养猪生产中,公猪的精液品质直接影响母猪的繁殖性能,这对猪场的生产成绩非常重要.多不饱和脂肪酸(PUFA)对精子质膜的流动性和脂质过氧化反应的敏感性有重要作用,同时也影响精子的授精能力.研究表明,在公猪饲粮中添加ω-3 PUFA能提高公猪精液品质,但效果重复性还不稳定;公猪饲粮中添加ω-3 PUFA能增加猪精子中ω-3 PUFA的含量和延长精液的保存时间.本文主要综述公猪饲粮中添加ω-3 PUFA对公猪精液品质的影响及其主要的作用机制,为其在现代规模化养猪生产中有效提高精液品质、猪场生产成绩和经济效益提供参考.     

套测法和直接强饲法测定肉雏鸭饲粮中小麦氨基酸及能量营养价值的比较研究

本试验旨在评价肉雏鸭饲粮中小麦氨基酸和能量的营养价值,并比较套测法和直接强饲法测定结果的差异。选取48只15日龄樱桃谷肉鸭(SM3品系),随机分为4个处理,每个处理12个重复,每个重复1只鸭,单笼饲养。处理1为基础饲粮组,处理2为80%基础饲粮+20%小麦组(套测组),处理3为100%小麦组(直接强饲组),处理4为饥饿组,用以测定内源损失。结果表明:1)小麦干物质中的粗蛋白质和总能含量分别为16.09%和18.56 MJ/kg。2)除了谷氨酸、脯氨酸、胱氨酸外,套测法测定的其余氨基酸的表观(真)氨基酸代谢率均高于直接强饲法测得到的结果(P<0.01);套测法和直接强饲法测得的总氨基酸的表观代谢率分别为86.59%和82.42%,真代谢率分别为92.36%和90.80%。3)2种方法测定的能量代谢率和代谢能差异不显著(P>0.05)。套测法测得小麦能量表观代谢率和真代谢率分别为77.51%和86.23%,表观代谢能和真代谢能分别为14.38和16.00 M J/kg;直接强饲法测得小麦能量表观代谢率和真代谢率分别为75.95%和84.81%,表观代谢能和真代谢能分别为14.09和15.74 M J/kg。由此得出,套测法和直接强饲法皆可用于评定小麦代谢能;而使用套算法测定小麦氨基酸代谢率时,合适的替代比例还有待进一步研究。     

Effects of sodium butyrate stimulation on immune‐related mRNA‐miRNA network in intestine of grass carp

Sodium butyrate is one of the most popular feed additives in animal husbandry. In recent years, sodium butyrate has been increasingly used as supplement in aquaculture. The present study is to investigate the intestinal mRNA and microRNA response to diet with sodium butyrate in grass carp (Ctenopharyngodon idella), an important aquaculture species in China. mRNA and microRNA profiles of intestine of grass carp fed with diet contained 0, 1.0, 2.5, 5.0, 7.5 and 10.0 g/kg sodium butyrate were obtained by RNA‐seq using Illumina Hiseq 2,500 platform. The feeding trial was performed using 18 individuals of 1‐year‐old grass carp (n = 3 for each group) and lasted for 40 days in tanks in laboratory. A total of 349,860,852 sequence reads were generated from six intestinal libraries. Functional analysis of differentially expressed genes showed that genes participated in immune pathways tend to be activated by sodium butyrate supplementation. A total of 700 microRNAs were obtained, including 275 conserved microRNAs and 425 novel microRNAs which are potentially involved in regulating 14,300 genes. Spearman's correlation analysis identified 18 pairs of microRNA‐mRNA associated with immune pathways (p < .01 and R<?0.5). The potential genes targeted by microRNAs include CXCL12, AKT1S1, Cab39 and MHCII which are important genes associated with intestinal immune pathways. To our knowledge, this is the first integrated profiling of both mRNA and microRNA in intestine with supplementation of sodium butyrate in grass carp. The present results suggest that sodium butyrate affects intestinal immune system by regulating microRNA‐mRNA interaction in fish.     

Time‐related changes in nutrient digestibility and faecal bile acid loss of rainbow trout (Oncorhynchus mykiss) as affected by dietary fat level and non‐starch polysaccharide level

Time‐related changes in apparent digestibility coefficients (ADC) and faecal bile acid loss as affected by dietary fat level and non‐starch polysaccharide (NSP) level were studied in rainbow trout (Oncorhynchus mykiss). Low‐Fat versus High‐Fat and Low‐NSP versus High‐NSP diets were formulated. Fish were fed for 6 weeks to apparent satiation and faeces were sampled in week 2, 4 and 6. Most nutrient ADC increased with time and increases were consistently larger for the High‐Fat and High‐NSP diets. Nevertheless, time of adaptation was equal between diets/nutrients and steady‐state digestion was reached at week 3. Although faecal bile acid loss was affected by diet, the observed time‐related decrease in faecal bile acid loss was mainly driven by a decrease in feed intake and faeces production. Fat ADC improved over time regardless of NSP level, which does not support the hypothesis that enhanced faecal bile acid loss (related to satiation feeding of high‐NSP diets) causes a depletion of the total body bile acid pool size that is critical for proper fat digestion. The high‐fat diets consistently resulted in the lowest Fat ADC, which might have been related to a lower availability of bile acids relative to the level of dietary fat.     

Effects of feed particle size at dietary presence of added organic acids on caecal parameters and the prevalence of Salmonella in fattening pigs on farm and at slaughter

In a field study with fattening pigs, effects of feed particle size at the dietary presence of organic acids on Salmonella prevalence were measured. On two farms (f1/f2), each holding ～800 pigs, diets based on finely ground (control) or coarsely ground ingredients (experiment) were fed as crumbs. On f1 both control and experimental grower and finisher diets contained identical concentrations of formic and propionic acid (0.4% and 0.2% respectively). On f2 only finisher diet of the experimental group contained 1.2% potassium diformate. At the start of the fattening period no statistical differences were measured between Salmonella prevalence in animals fed control and experimental diets on both farms. At slaughter Salmonella prevalence in caecal contents was lower (p < 0.05) on f1 in animals fed the experimental diet. Furthermore, the number of seronegative meat juice samples taken from these animals [optical density (OD) <10] was higher (p < 0.001); seropositive as well as distinct seropositive samples (OD ≥20 and ≥40 respectively) were less frequent (p < 0.01) compared to samples from animals fed the control diet. Feeding the experimental diet on f2 resulted in a lower Salmonella detection rate in faeces before slaughter (p < 0.01). Salmonella prevalence was lower in caecal content at slaughter for pigs fed the experimental diet compared to those fed control diet (p < 0.0001). The number of distinct seropositive meat juice samples (OD ≥40) was lower (p < 0.01) for pigs fed the experimental than for those fed the control diet. In comparison to pigs in the control group, starch concentrations in the caecal content from pigs in the experimental groups on both farms were higher (p < 0.05) and the pH values lower (p < 0.05). Propionate (p < 0.0001) and butyrate (p < 0.01) concentrations were higher in the caecal content taken from pigs in the experimental group on f2.     

The effects of short intensive exercise on plasma free amino acids in standardbred trotters

The aim of this study was to investigate the effect of short intense exercise on plasma amino acid concentrations in trotters and to test the repeatability of plasma amino acids concentration in samples obtained on two independent days under field conditions. Plasma amino acid concentrations were analysed in blood samples of 36 standardbred trotters before and after intense exercise over a distance of 2000 m. Sampling was repeated in 20 horses after 35 days. Exercise intensity was estimated from post‐exercise lactate levels. Horses were divided in two groups according to a cut‐off lactate concentration at 15 mmol/l. The plasma concentrations of alanine, aspartate, glutamate, isoleucine, leucine, lysine and taurine increased and arginine, asparagine, citrulline, glutamine, glycine, histidine, methionine, serine, tryptophan and 3‐methylhistidine decreased after exercise. Ornithine, threonine, tyrosine, phenylalanine and valine concentrations remained constant. Higher intensity of exercise significantly decreased tryptophan and increased taurine concentrations. Sampling day had a significant effect on the absolute pre‐ and post‐exercise amino acid concentrations. Exercise had a significant influence on the concentrations of most plasma amino acids in trotters. These changes could reflect shifts between the free amino acid compartments, but there were also some indications for muscle catabolism. The amino acid supply of sporting horses could be of specific significance for maintaining muscle integrity and for the improvement of post‐exercise recovery of competition horses.     

2007~2008年国际反刍动物营养研究进展 Ⅳ.蛋白质与氨基酸营养

蛋白质是生命活动的最基本物质。随着反刍动物蛋白质营养研究的深入,如何最大化提高瘤胃微生物蛋白量,增加瘤胃后非降解蛋白（rumen undegraded protein, RUP）的消化率,合理搭配日粮,减少氮的排放量,通过日粮途径改善乳蛋白含量和产量,提高氮的利用率已成为当今研究的热点。同时,蛋白质、氨基酸和肽营养在瘤胃、小肠、大肠和乳腺中的代谢机理、影响其利用的因素还不是很清楚,但随着分子生物学技术、血插管技术和动静脉差异技术在蛋白质、氨基酸和肽的转运、吸收及乳蛋白合成机理上的应用,为深入研究其转运、利用机制提供了可能。牛奶中的活性功能成分近年来随着消费需求也日益成为研究的热点。作者主要从蛋白质如何在瘤胃内代谢及影响因素、小肠内代谢及影响因素、大肠内代谢及影响因素、乳腺内代谢和乳蛋白合成、乳中的免疫活性蛋白等方面对蛋白质营养研究作一综述。     

Acanthopanax senticosus extract as a dietary additive enhances the apparent ileal digestibility of amino acids in weaned piglets

The present study was conducted to determine the effects of Acanthopanax senticosus (AS) extract as a dietary additive on serum contents and apparent ileal digestibility (AID) of amino acids (AA) in weaned piglets. In Exp. 1, 60 piglets with an average body weight (BW) of 5.64 kg were randomly assigned into 3 treatment groups who received maize-soybean-based diets supplemented with 0 or 1 g/kg of AS extract or 0.2 g/kg of colistin (n = 20 in each group). Blood samples were randomly collected from 5 piglets per group on days 7, 14 and 28 after the initiation of supplementation to determine the serum contents of free AA. In Exp. 2, 12 barrows with an average initial BW of 7.64 kg were also randomly assigned into 3 dietary treatment groups after being surgically fitted with a simple T-cannula at the terminal ileum. Samples of terminal ileal digesta were collected on day 7 for analysis of the AID of AA. The data showed that the serum contents and AID of most AA in the AS extract-supplemented group gradually increased by 15.3–80.8% and 4.1–30.8%, respectively, as the experiment proceeded in comparison with the colistin-supplemented group and/or control group. In conclusion, these findings indicated that AS extract could enhance the digestion and absorption of AA, which may be a potential mechanism of growth promotion.