Effect of dietarymedium-chain fatty acids on nursery pig growth performance, fecalmicrobial composition, and mitigation properties against porcine epidemic diarrheavirus following storage

Jordan TGebhardt, Katelyn AThomson, Jason CWoodworth, Steve S Dritz, Michael D Tokach ...

Journal of Animal Science, Volume 98,Issue 1, January 2020, skz358, 

https://doi.org/10.1093/jas/skz358

Published: 23 November2019

本试验使用了360头20日龄的断奶仔猪，测试中链脂肪酸对断奶仔猪生长性能的效果、对粪便微生物菌群的影响、以及在经过储存的饲料中对传染性胃肠炎病毒的减轻作用。

试验结果显示，随着中链脂肪酸用量的提高（0%、0.25%、0.5%、1.0%、1.5%），猪的生长速度和采食量提高（P<0.01）, 料肉比改善（P<0.004）。

在本试验中，断奶乳猪料添加1.5%中链脂肪酸对粪便微生物菌群没有影响。

原文摘要

An experiment was conducted to evaluate the effect of dietarymedium-chain fatty acid (MCFA) addition on nursery pig growthperformance, fecal microbial composition, and mitigation of porcine epidemicdiarrhea virus (PEDV) following storage. A total of 360 pigs (DNA 400 ×200, Columbus, NE; initially 6.7 ± 0.07 kg) were randomized to pens (5 pigs perpen) on the day of weaning (approximately 20 d of age), allowed a 6-dacclimation, blocked by BW, and randomized to dietary treatment (9 pens per treatment).All MCFA (Sigma–Aldrich, St. Louis, MO) were guaranteed ≥98% purity, includinghexanoic (C6:0), octanoic (C8:0), and decanoic (C10:0) acids. Treatment dietswere formulated in 2 phases (7 to 11 and 11 to 23 kg BW) and formulated to meetor exceed NRC requirement estimates. Treatments (n = 8) were a dose response including 0%, 0.25%, 0.5%,1.0%, and 1.5% added MCFA blend (1:1:1 ratio C6:0, C8:0, and C10:0), as well astreatments with individual additions of 0.5% C6:0, C8:0, or C10:0. Fecalsamples were collected from pigs fed control and 1.5% MCFA blend diets on days0 and 14 and analyzed using 16s rDNA sequencing. Following feed manufacture,feed was stored in bags at barn temperature and humidity for 40 d beforelaboratory inoculation with PEDV. Subsamples of retained feed were inoculatedwith PEDV to achieve a titer of 104 TCID50/g andseparate sample bottles were analyzed on 0 and 3 d post-inoculation (dpi).Overall, ADG and ADFI wereincreased (linear, P ≤ 0.010) and feed efficiency (G:F) improved(linear, P = 0.004) with increasing MCFA blend. Pigs fed 0.5% C8:0 had greater (P= 0.038) ADG compared with pigs fed the control diet, and G:F was improved (P ≤0.024) when pigs were fed 0.5% C6:0, 0.5% C8:0, or 0.5% C10:0 compared with control.An inclusion level × day interaction was observed (quadratic, P =0.023), where PEDV Ct values increased (quadratic, P = 0.001) on 0 dpiwith increasing levels of MCFA blend inclusion and also increased on 3 dpi(linear, P < 0.001). Fecal microbial diversity and composition weresimilar between control and 1.5% MCFA blend. In summary, the use of MCFA innursery pig diets improves growth performance, provides residual mitigationactivity against PEDV, and does not significantly alter fecal microbialcomposition.

试验结果分析：中链脂肪酸作为优秀的能量来源，可以改善乳猪的生产性能，但需要添加量比较大（中链脂肪酸作为能量物质，添加量小看不到明显效果）。

中链脂肪酸在体外抑菌试验中，对有害菌有明显的抑制效果。但在本次体内试验中，添加量高达1.5%仍然不能改变粪便微生物菌群，是因为中链脂肪酸在小肠前端很容易就被消化吸收了，到了小肠后端已经所剩无几，对小肠后端和大肠中的微生物菌群已经没有效果，也就不会影响到粪便的微生物菌群。

为了发挥脂肪酸在动物肠道内的杀菌效果，需要把脂肪酸做成肠溶制剂，在消化道前端不被消化吸收，到小肠后端和大肠发挥杀菌效果。

肉豆蔻是一种中药，治疗肠炎、腹泻。赛金素是用肉豆蔻酸做成的肠溶制剂，在消化道前端不被消化吸收，所以，只要少量添加，就可以发挥杀菌效果。

另外，从体外的抑菌效果来看，肉豆蔻酸（C14）比月桂酸（C12）、癸酸（C10）有更强的抑菌效果。以下是这三种脂肪酸对有害菌的最小抑菌浓度MIC90（ppm）。数值越低代表抑菌效果越好。

优秀的教槽料、保育料要有很好的抗拉稀效果。赛金素在教槽料中的推荐用量是1.5公斤/吨，在保育料中使用1-1.2公斤/吨，配合使用氧化锌+单宝、杀菌型酸化剂可肥酸50，可以达到理想的抗拉稀效果。在中大猪料上使用200-300克/吨赛金素，对回肠炎、猪密螺旋体造成的血便有很好的防治效果。

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