中链脂肪酸调控猪禽生理代谢和健康的研究进展

中链脂肪酸(MCFA)是一类由6～12个碳原子构成的饱和脂肪酸,主要包括已酸、辛酸、癸酸和月桂酸.MCFA及其衍生物是良好的抑菌剂、防腐剂和饲料添加剂,在化工、化妆品、医药、畜牧等行业广泛应用.文章综述了MCFA的理化性质、消化代谢特征以及脂质代谢调节、杀菌、抗炎等生物学功能,为MCFA在猪、禽养殖中的应用提供参考.     

中链脂肪酸在仔猪生产中的研究与应用

中链脂肪酸是一类含有6~12个碳原子的饱和脂肪酸,广泛存在于天然食物中,其对机体具有广泛的有益作用。本文就中链脂肪酸的消化吸收代谢特性、抗菌特性、抗炎抗氧化作用以及在仔猪生产中的应用进行综述,旨在为新型饲料添加剂的开发与利用提供应用和理论依据。     

Utilization of medium-chain triglycerides by neonatal piglets: I. Effects on milk consumption and body fuel utilization

Two experiments were conducted utilizing neonatal piglets. In the first experiment, 18 piglets were used to determine the effect of an oral supplement of 0, 12 or 24 ml of a medium-chain triglyceride (MCT) product on subsequent milk consumption. Results from the weight-suckle-weight experiment showed that force-feeding 24 ml of the MCT decreased (P less than .05) milk intake but 12 ml did not. In the second experiment, two trials (each with 24 piglets) were used to investigate the effect of 12 ml of MCT or 12 ml of MCT plus .6 mmol of L-carnitine on the concentration of blood glucose, ammonium N and urea N at 0, 12 or 24 h and liver and biceps femoris glycogen at 24 h post-treatment. Blood urea N decreased (P less than .05) in piglets receiving the MCT. Blood ammonium N and glucose concentrations were not different (P greater than .10) among treatments. In Trial 1, the predicted loss of liver glycogen was less (P less than .05) in pigs given the MCT treatment, but this response was not repeated in the second trial. In general, supplemental carnitine provided no added benefit over the MCT treatment alone. The results from this study indicate that MCT is utilized as a fuel by the newborn piglet and that its use may spare critical fuels, glycogen and protein, that were stored in the piglet prior to birth.     

Effects of medium chain triglycerides on hepatic fatty acid oxidation in clofibrate-fed newborn piglets

To investigate whether increasing tricarboxylic acid (TCA) cycle activity and ketogenic capacity would augment fatty acid (FA) oxidation induced by the peroxisome proliferator-activated receptor-alpha(PPARa) agonist clofibrate,suckling newborn piglets (n=54) were assigned to 8 groups following a 2(±clofibrate)×4 (glycerol succinate[SUC],triglycerides of 2-methylpentanoic acid[T2M],valeric acid[TC5]and hexanoic acid[TC6]) factorial design.Each group was fed an isocaloric milk formula containing e...     

Anticoccidial efficacy of medium-chain triglycerides (MCT) in calves

Anticoccidial efficacy of dietary fat was evaluated in calves with coccidial infection (Eimeria spp., including E. bovis and E. zuernii). Medium-chain triglycerides (MCT)--natural edible fats composed of caprylic (C8), capric (C10), and lauric (C12) acids -- were given orally with milk to 5 calves and with 10% glucose solution to 3 older, weaned calves by using the reticular groove reflex. After 3 to 11 days of MCT feeding, all Eimeria spp. oocysts had disappeared from the feces of all calves. MCT had no adverse effects on appetite or on fecal pH, ammonia, lactic acid, or volatile fatty acid levels. MCT feeding for coccidial control in calves has minimal side-effects and has benefits in terms of residue-free food production.     

Efficacy of medium-chain fatty acid salts distilled from coconut oil against two enteric pathogen challenges in weanling piglets

Background: The search for alternatives to antibiotics in pig production has increased the interest in natural resources with antimicrobial properties, such as medium-chain fatty acids(MCFA) as in-feed additives. This study evaluated the potential of a novel blend of MCFA salts(DIC) from distilled coconut oil with a lauric acid content to reduce enteropathogens and control intestinal diseases around weaning. Two experimental disease models were implemented in early-weaned piglets, consisting of two oral challenges: Salmonella Typhimurium(1.2 × 10~8 CFU)or enterotoxigenic Escherichia coli(ETEC) F4(1.5 × 10~9 CFU). The parameters assessed were: animal performance,clinical signs, pathogen excretion, intestinal fermentation, immune-inflammatory response, and intestinal morphology.Results: The Salmonella challenge promoted an acute course of diarrhea, with most of the parameters responding to the challenge, whereas the ETEC F4 challenge promoted a mild clinical course. A consistent antipathogenic effect of DIC was observed in both trials in the hindgut, with reductions in Salmonella spp. plate counts in the cecum(P = 0.03) on d 8 post-inoculation(PI)(Salmonella trial), and of enterobacteria and total coliform counts in the ileum and colon(P 0.10) on d 8 PI(ETEC F4 trial). When analyzing the entire colonic microbiota(16 S rRNA gene sequencing), this additive tended(P = 0.13) to reduce the Firmicutes/Bacteroidetes ratio and enriched Fibrobacteres after the Salmonella challenge. In the ETEC F4 challenge, DIC prompted structural changes in the ecosystem with increases in Dialister, and a trend(P = 0.14) to increase the Veillonellaceae family. Other parameters such as the intestinal fermentation products or serum pro-inflammatory mediators were not modified by DIC supplementation, nor were the histological parameters. Only the intraepithelial lymphocyte(IEL) counts were lowered by DIC in animals challenged with Salmonella(P = 0.07). With ETEC F4, the IEL counts were higher with DIC on d 8 PI(P = 0.08).Conclusions: This study confirms the potential activity of this MCFA salts mixture to reduce intestinal colonization by opportunistic pathogens such as Salmonella or E. coli and its ability to modulate colonic microbiota. These changes could explain to some extent the local immune cell response at the ileal level.     

The development of microflora and production of short-chain fatty acids in the digestive tract of suckled piglets and replacer-fed piglets

The objective of this study was to obtain knowledge about the postnatal development of microflora and the production of short-chain fatty acids in 24 piglets suckled by sows and 26 piglets fed on milk replacement. On day 14 piglets which had received no colostrum had higher counts of Enterobacteriaceae (p < 0.001) and coliform bacteria (p <0.001) in the jejunum contents than piglets suckled by their mother sow. Depending on age, concentrations of both lactic and acetic acid were higher in the contents of the small intestine of piglets suckled by sows compared to milk replacer-fed piglets. Replacement of maternal milk by artificial feeding adversely affected the postnatal development of the piglets. This resulted in higher morbidity and mortality in those piglets.     

Inhibition of African swine fever virus in liquid and feed by medium-chain fatty acids and glycerol monolaurate

Background: The ongoing African swine fever virus(ASFv) epidemic has had a major impact on pig production globally and biosecurity efforts to curb ASFv infectivity and transmission are a high priority. It has been recently identified that feed and feed ingredients, along with drinking water, can serve as transmission vehicles and might facilitate transboundary spread of ASFv. Thus, it is important to test the antiviral activity of regulatory compatible,antiviral feed additives that might inhibit ASFv infectivity in feed. One promising group of feed additive candidates includes medium-chain fatty acids(MCFA) and monoglyceride derivatives, which are known to disrupt the lipid membrane surrounding certain enveloped viruses and bacteria.Results: The antiviral activities of selected MCFA, namely caprylic, capric, and lauric acids, and a related monoglyceride, glycerol monolaurate(GML), to inhibit ASFv in liquid and feed conditions were investigated and suitable compounds and inclusion rates were identified that might be useful for mitigating ASFv in feed environments. Antiviral assays showed that all tested MCFA and GML inhibit ASFv. GML was more potent than MCFA because it worked at a lower concentration and inhibited ASFv due to direct virucidal activity along with one or more other antiviral mechanisms. Dose-dependent feed experiments further showed that sufficiently high GML doses can significantly reduce ASFv infectivity in feed in a linear manner in periods as short as 30 min, as determined by infectious viral titer measurements. Enzyme-linked immunosorbent assay(ELISA) experiments revealed that GML treatment also hinders antibody recognition of the membrane-associated ASFv p72 structural protein, which likely relates to protein conformational changes arising from viral membrane disruption.Conclusion: Together, the findings in this study indicate that MCFA and GML inhibit ASFv in liquid conditions and that GML is also able to reduce ASFv infectivity in feed, which may help to curb disease transmission.     

仔猪脂肪利用的营养因素

本文针对影响仔猪脂肪利用的因素,包括肉碱、胆碱、甜菜碱、卵磷脂及高剂量铜、锌等进行综述。     

Response of plasma glucose, free fatty acids and triglycerides to starving and re-feeding in cockerels and geese

The effect of starving cockerels and geese for 8 d followed by re‐feeding on plasma glucose, FFA and triglycerides has been studied. In both species plasma glucose concentration fell while FFA concentration rose during starvation. The fall in plasma glucose was followed by a secondary gradual increase. Re‐feeding caused a rebound in plasma glucose, and restored the FFA to its initial concentration. Plasma triglycerides were not affected by starvation in either species. Re‐feeding was followed by a rise in plasma triglycerides in geese only.     

The effects of dietary medium-chain fatty acids on ruminal methanogenesis and fermentation in vitro and in vivo: A meta-analysis

The efficacy of methane (CH₄) suppression using medium-chain fatty acids (MCFA) remains inconclusive, despite a number of studies on this topic are available. We thus carried out a meta-analysis to integrate the published data on different concentrations and types of MCFA such as lauric acid and myristic acid, which investigated ruminal methanogenesis and fermentation in in vitro and in vivo experiments. In vitro MCFA sources were classified either as pure MCFA (lauric acid, myristic acid and their combinations) or as natural MCFA-rich oils (canola oil enriched with lauric acids, coconut oil, krabok oil and palm kernel oil). The MCFA sources used in the in vivo studies were coconut oil, lauric acid, myristic acid and the combination of lauric and myristic acids. A total of 41 studies (20 in vitro and 21 in vivo studies) were compiled in our database, which included the data on CH₄ emission, digestibility, ruminal fermentation products and microbial populations. The results showed that the amount of CH₄ production per unit of digested organic matter decreased linearly under in vitro conditions (p < .01) and tended to decrease quadratically under in vivo conditions (p < .07) with increasing doses of MCFA. Populations of protozoa (p < .01) in both in vitro and in vivo responded negatively in a linear manner, whereas Archaea population diminished quadratically (p = .04) only in the in vitro conditions with increasing doses of MCFA. Increasing dietary MCFA concentrations also reduced the fibre digestibility linearly (p < .05) in both in vitro and in vivo conditions. CH₄ production for different sources of MCFA decreased in following order: coconut oil > lauric acid > myristic acid > mixed lauric and myristic acids > palm kernel oil > canola oil enriched with lauric acids > krabok oil. It can be concluded that the effect of MCFA on ruminal methanogenesis depends on the amount and type of MCFA.     

Effects of medium-chain fatty acids on performance,carcass characteristics,blood biochemical parameters and immune response in Japanese quail

1. This study had the aim of evaluating the effects of medium-chain fatty acids (MCFA) on performance, carcass characteristics, some blood parameters and antibody titre against sheep red blood cells (SRBC) in quail.

2. A total of 240 quail chicks were allotted to 4 treatments consisting of respectively 0, 1, 2 and 4 g/kg dietary MCFA.

3. There were no significant differences in body weight, feed intake and feed conversion ratio among treatments at different stages of the experiment.

4. MCFAs had no significant effect on breast, thigh, liver, spleen and bursa of Fabricius weight ratios. However, the relative weight of abdominal fat significantly decreased in quail receiving 0.2 and 0.4 MCFA as compared to other treatments.

5. Concentrations of low-density lipoprotein-cholesterol (LDL), triglycerides and total cholesterol were decreased and high-density lipoprotein (HDL)-cholesterol was increased in quail chicks receiving MCFA compared with control quail chicks. The concentrations of SRBC antibody were not statistically different among treatments.

6. It is concluded that MCFA significantly decreased LDL, triglycerides, cholesterol and abdominal fat and increased HDL in quail chicks.

     

Clinical evaluation of a new formulation of propofol in a medium-chain and long-chain triglycerides emulsion in dogs

Propofol formulated in a mixed medium-chain and long-chain triglycerides emulsion has been recently introduced for clinical use as an alternative to the conventional long-chain triglycerides formulation. This prospective multicentric study evaluated the clinical effectiveness and the complications associated with the use of this new formulation of propofol in dogs. Forty-six Spanish veterinary clinics participated in this study. A total of 541 anaesthesias (118 ASA I, 290 ASA II, 101 ASA III and 32 ASA IV) performed for various diagnostic and therapeutic purposes were evaluated. The anaesthetic protocol was not controlled, with the exception that propofol had to be used at least for induction of anaesthesia. The induction dose of propofol and the incidence of anaesthetic complications throughout the procedure were recorded. A chi-square test compared the incidence of complications according to the maintenance agent used (propofol vs. inhalatory anaesthesia), anaesthetic risk (ASA classification) and the reason for the anaesthesia. The patients premedicated with alpha2 agonists needed lower doses (mean +/- SD, 2.9 +/- 1.3 mg/kg i.v.) than the animals premedicated with phenothiazines (3.9 +/- 1.4 mg/kg i.v.) or benzodiazepines (4.0 +/- 1.4 mg/kg i.v.). The most frequent complications were difficult endotracheal intubation (1.3%), postinduction apnoea (11.3%), cyanosis (0.6%), bradypnoea (2.6%), tachypnoea (2.8%), bradycardia (2%), tachycardia (2.6%), hypotension (0.2%), shock (0.2%), vomiting (4.6%), epileptiform seizures (2.8%), premature awakening (7.4%) and delayed recovery (0.9%). There were no cases of pain on injection or aspiration pneumonia. Three dogs died (0.55%), one during induction and two during recovery from anaesthesia. This study demonstrates that the new formulation of propofol is an useful and effective drug to induce general anaesthesia in dogs.     

中链脂肪酸在畜牧业上应用的研究进展

中链脂肪酸(MCFA)是指含有6~12个碳原子组成碳链的脂肪酸,在动物体内,它们的消化、吸收、转运、氧化等都具特点。表现出特殊的生理活性功能,能迅速有效地为幼小动物提供能量的需要,对病原菌具有独特的抑菌以及调整动物肠道结构等的作用,具有显著的抗菌、促生长和提高饲料转化率等功效。文章综述了MCFA的代谢特点与作用机制以及在现代畜牧业中的运用研究进展。     

发酵料的营养特性及在仔猪生产中的应用

发酵料适口性好,有酸香风味,内含丰富益生菌,营养价值高,易消化,具有抗生素替代潜力。因此,近年来发酵料在仔猪生产上的应用备受关注,且收到较好的效果。文章旨在对发酵料的营养特性、加工方式及在仔猪生产上的应用进行综述。     

Effects of dietary medium-chain fatty acids on performance,carcass characteristics,and some serum parameters of broiler chickens

1. This study aimed to evaluate the effects of dietary medium-chain fatty acids (MCFAs) on the performance, carcass characteristics, and some serum parameters of broiler chickens.

2. A total of 176 one-day-old male broiler chicks (Ross 308) were assigned to four treatments including control treatment (basal diet), 0.1% MCFA, 0.2% MCFA, and 0.3% MCFA treatments according to a completely randomised design. Each treatment consisted of 4 replicates with 11 chicks for each replicate. In MCFA treatments, the amounts of MCFAs were added to basal diet as a substitution of soybean oil.

3. There were not any significant differences in body weight, feed intake, and feed conversion ratio among the treatments in different stages of the experiment. However, MCFA treatments had a lower abdominal fat and a higher breast yield compared to control treatment.

4. Blood glucose, cholesterol, and low-density lipoprotein (LDL)-cholesterol concentrations were significantly decreased, but blood high-density lipoprotein (HDL)-cholesterol concentration was significantly increased in the MCFA treatments compared to the control treatment.

5. These results indicate that dietary MCFA has a positive effect on the health and productivity of broiler chickens.     

Effect on the immune system of germ-free piglets of probiotics potentiated with polyunsaturated fatty acids

The present study investigated the influence of polyunsaturated fatty acids (PUFA) on the immune system of germ-free piglets. Oil with increased content of omega-3 PUFA was administered to piglets from the experimental group (EG) for four weeks. Piglets from the control group (CG) received identical volumes of saline solution. At the age of 21 days both groups of germ-free piglets were inoculated perorally with Lactobacillus casei subsp. casei at a dose of 2 ml (1x10(8) mli). At the age of 28 days, i.e. after one-week colonisation of germ-free piglets with Lactobacillus casei subsp. casei, significant differences were recorded in phagocytic activity of neutrophils (PANe) and phagocytic activity of potentially phagocytizing cells (PA) (P < 0.05). Between EG and CG there have been observed no significant differences in absolute numbers of CD4+ and CD8+ T lymphocytes and numbers of IgM cells and in additional investigated parameters - number of CD2+ T lymphocytes, index of phagocytic activity of neutrophils (IPANe) and index of phagocytic activity (IPA).The total number of leukocytes (Le) in EG was also higher. Of the parameters determined in blood serum we observed a significant increase in concentration of alpha linolenic, eicosapentaenoic and docosahexaenoic acids and a parallel decrease in the level of arachidonic acid.     

Body composition and muscle glycogen contents of piglets of sows fed diets differing in fatty acids profile and contents

To study the influence of sow dietary fat on piglet body characteristics, multiparous sows were allocated to one of four different dietary treatments: a conventional low fat (3%) diet (LF) and three high fat (6%) diets; high fat saturated (HFS), high fat oats (HFO), and high fat linseed (HFL). All sows were fed the allocated diet from weaning of the preceding litter until the day after farrowing. At farrowing, one liveborn piglet per litter (NB), was sacrificed and dissected immediately after birth. The heaviest (H) and the lightest (L) piglets in the litter were killed and dissected in the same manner at one day of age. Measurement of body length and circumference, organ weight, body chemical composition and muscle glycogen content were determined. Body measurements were adjusted to the mean body weight (1.67 kg). Dietary treatment did not have any significant influence on body components or carcass traits except for lung weight, being lower in HFO and HFL than in LF piglets. Piglet category affected almost all parameters considered, showing the lowest values for NB piglets, except for lung and circumference that were higher in NB than in L and H piglets; and length which was lower in NB than in L piglets. NB piglets had the highest amount of muscle glycogen content, no difference was found between H and L piglets. Dietary treatments influenced piglet chemical composition, showing the highest overall values of dry matter (DM), protein, and fat for the HFL piglets' carcasses. The present data provide additional information on the depletion of energy reserves; it would appear that sow dietary fat has relatively little effect on progeny since only body chemical composition was significantly influenced by HFL diet.