最新英文期刊

PAPERMonobutyrine: a novel feedadditive in the diet of broilerchickensMauro Antongiovanni,

Arianna Buccioni, Sara Minieri,Ilaria Galigani, Stefano RapacciniDipartimento di Biotecnologie Agrarie,Università di Firenze, Italy

Abstract

Purpose of the present work was to validatethe monoglyceride of butyric acid (MB) as analternative to antibiotics as growth promotersin the diet of broiler chickens. The approach isa kind of prolongation of previous works, inwhich a blend of mono-, di- and tri-glycerides ofbutyric acid have been previously tested.

The results indicated that MB was very effi-cient in limiting the mortality of birds chal-lenged with Eimeria spp., but did not apprecia-bly impair the performance of unchallengedbirds. In conclusion, the metabolisable energycontent of MB appeared comparable with thatof soybean oil and MB a reliable coccidiostat.

An adequately developed and healthy gastro-intestinal tract (GIT) is the necessary conditionto the best animal performance. In addition tothe functions of proper feed digestion and nutri-ent absorption, the GIT performs the basic taskof protection against microbial and viral infec-tions which may attack the animal via its intes-tine. In chickens, also sub-clinical factors maynegatively affect feed efficiency and growth rate,so representing an important cost to poultryindustry. Since the GIT welfare depends greatlydepends on a healthy symbiotic micro-popula-tion, the management of intestinal microbes isthe key to success in poultry production.

The use of antibiotics in feeds, as growthpromoters to prevent intestinal pathologies hasproven inefficient over the years because of thewell-known problem of acquired resistance ofpathogenic microbes to specific antibiotics,leading to their banning in 2006 in the EU.Butyric acid, a saturated fatty acid with fourcarbon atoms, is a natural product of fermenta-tion of dietary fibre produced by the symbioticcellulolytic microbes of the digestive tract of allsuperior animals.

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omIntroduction

Butyric acid has been acknowledged to be animportant beneficial factor since it acts as: i)promoter of cell proliferation of colon epithelialcells (Sakata, 1987; Sharma et al., 1995); ii)stimulator of the gut immune system(Friedman and Bar-Shira, 2005); iii) modulatorof the composition of intestinal micro-popula-tion against harmful microbes (Van Der Wielenet al., 2000; Isolauri et al., 2004; Jósefiac et al.,2004); iv) prevention factor against colon can-cer (Hassig et al., 1997). As a consequence ofthe banning of antibiotics in the EU, valid alter-native solutions to counteract the gut pathogen-ic microbes and the consequent enteric diseasehave been looked for. Butyric acid in the feedappears to be the key to solve the problem.However, it is not actually possible to introduceit as such into the diet, due to its unpleasantodour which limits, when doesn’t completelywaste, the palatability of feeds. Butyric deriva-tives of some kind of protection must thereforebe used, like sodium butyrate or the expensivecoating protection. Butyric glycerides may be aneven better solution to the problem. The mono-,di- and tri-glycerides of butyric acid are to bepreferred because easily absorbable and practi-cally odourless. A blend of butyric glycerides pro-duced very good results in previous trials withbroilers (Leeson et al., 2005; Antongiovanni etal., 2007). The subject of the present study isthe effect on the performance of broiler chick-ens of the monoglyceride of butyric acid (MB),as the unique butyric glyceride supplementedinto the diet of broilers, possibly more efficientthan the previously tested blend, because moreeasily absorbable.

Corresponding author: Prof. Mauro Antongiovanni,Dipartimento di Biotecnologie Agrarie,Università di Firenze, via delle Cascine 5, 50144 Firenze, Italy.

Tel. +39.055.3288332 - Fax: +39.055.321216.E-mail: mauro.antongiovanni@unifi.it

Key words: Butyric acid, Monobutyrine, Broilers,Coccidiostat.

Acknowledgements: the authors would like tothank the company SILO S.r.l., Firenze (Italy),both for the financial support and for providingthe butyric glycerides.

The contribution of Mr. Silvano Lancini, animaltechnician of the Department, was essential tothe accomplishment of the whole work.Received for publication: 23 February 2010.Accepted for publication: 17 July 2010.

This work is licensed under a Creative CommonsAttribution 3.0 License (by-nc 3.0).©Copyright M. Antongiovanni et al., 2010Licensee PAGEPress, Italy

Italian Journal of Animal Science 2010; 9:e69doi:10.4081/ijas.2010.e69

ercial useMaterials and methods

The experimental design consisted of twogrowth trials: experiment one with Eimeria spp.challenged birds and experiment two withunchallenged birds. Both experiments lasted 6weeks. At the 21stday of experiment one, all thebirds were orally challenged with Eimeriaacervulina, Eimeria maximaand Eimeria tenel-la(5¥104; 8¥103and 1¥103).

The additive containing prevalently MB wastested at two concentrations of butyric acid:20% of the additive (MB 20) and 30% of theadditive (MB 30), as illustrated in Table 1, andat different times of the experiments (seeTable 2). The blend of glycerides, tested in thecited previous experiments and characterisedby 60% butyric acid, was tested again in exper-iment one as a kind of blank test. One-day oldmale chicks Ross 708, vaccinated at the hatch-ery against coccidiosis (Paracox 5), were pur-

m onlchased from a commercial hatchery. One hun-dred and fifty birds were randomly allotted to 30pens (5 birds per pen, 10 pens per treatment)in experiment one and another 150 birds wererandomly allotted to 15 pens (10 birds per pen,5 pens per treatment) in experiment two. Thebirds were fed usual maize-soybean non-med-icated mixed feeds in both experiments. Thecomposition and calculated nutritional charac-teristics of the diets are illustrated in Table 3.The starter diet was administered for the firsttwo weeks, and then the animals were fed thegrower-finisher one. As indicated in Table 2,soybean oil was partially replaced by the differ-ent glycerides, according to the rationale of theexperiments.

In experiment #1 (Table 2), the birds weresubmitted to 3 treatments: C (control), with noglyceride added other than 5% soybean oil; T1,with MB 30 at the 1% level in the feed, replac-ing the same amount of soybean oil; and T2with BG at the 0.2% level, in substitution for thesame amount of oil.

In experiment #2 (Table 2) the birdsreceived again 3 treatments: C (control), with5% soybean oil and no other glyceride added;T1, with MB 20 replacing 1% oil all the time; T2with MB 30 for the first week only, then withMB 20 for another two weeks and soybean onlyfor the final three weeks. Live body weights andfeed intakes were recorded weekly per single

y Antongiovanni et al.°Glycerides of butyric acid as the only fatty acid, diluted in glycerol; #blend of glycerides with butyric acid in the 1 or 3 position (30%),in both 1 and 3 positions (50%) and in all the three positions (20%).

Live body weights at the end of the secondweek resulted statistically comparable, between470 and 488 g. Feed/gain ratios were not toobad for challenged birds, around 1.8, again sta-tistically not different from one another. On thecontrary, at the end of the trial, the MB treatedanimals (T1) were lighter, even though not sig-nificantly. The T1 birds resulted with the worstfeed/gain ratio but, again, statistically not dif-ferent from that of the other experimentalgroups. The BG chickens (T2) exhibited practi-cally the same performance as the control ones.Also the weights of the carcasses and the breastmeat yields resulted statistically comparable inany case. Amid all these meaningless results,an important significant piece of informationcomes from the mortality rates: the incidenceof mortality was quite heavy in the untreatedbirds, in comparison with the MB ones, 14% vs.2% (P<0.05). The autopsy examination of thedead animals revealed the incidence of heavycoccidial infections.

Non-comExperiment #1

Table 3. Diet composition.

Diets

Starter, 0-14 days

51.9038.005.002.500.800.500.300.300.300.200.2022.012.231.060.510.1814.29.9

Grower-finisher, 15-42 days 55.35 35.50 5.00 2.00 0.80 0.50 0.30 0.10 0.25 - 0.20 20.5 12.44 0.93 0.42 0.18 12.0 9.2

Experiment #2

When the environment was strictly controlledin order to avoid contaminations from outside,

IngredientsMaize, %

Soybean meal 48, %Soybean oil°, %

Dicalcium phosphate, %Limestone , %Premix#, %Salt, %

Lysine HCl, %DL Methionine, %Choline Cl, %

Sodium bicarbonate, %Calculated analysisCrude protein, %

Metabolizable energy, MJ/kgCalcium, %

Available phosphorus, %Sodium, %Lysine, g/kg

Methionine + cystine, g/kg

°Partially replaced by glycerides, as indicated in Table 2. #Supplied per kg diet: Vitamin A, 3000 U; cholecalciferol, 1600 U; a-tocopherolacetate, 15 mg; riboflavin, 7 mg; panthotenic acid, 7 mg; cobalamin, 8 󰀀g; niacin, 20 mg; menadione, 1.5 mg; biotin, 0.25 mg; Mn, 50 mg;Zn, 50 mg; Cu, 5 mg; Fe, 30 mg; Se, 0.3 mg.

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mPerformance results are detailed in Table 4.Previous experiments of ours (Leeson et al.,2005; Antongiovanni et al., 2007) indicated thatthe effect of butyrate on the birds’ gut is at themaximum level within the first two weeks. Thisis the reason why the results relative to 14 daysare reported in Table 4 as the performance ofthe starter period.

Experiment #1 Soybean oil, % MB20, % MB30, % BG, % Weeks Experiment #2 Soybean oil, % MB20, % MB30, % Weeks

Control5.0---0-6

erciControl5.0--0-6

al useResults

Table 2. Rationale of treatments (% of mixed feed).

T1 T2 4.0 4.8 - - 1.0 - - 0.2 0-6 0-6 T1 T2 T2 T2 4.0 4.0 4.0 5.01.0 - 1.0 -- 1.0 - -0-6 0-1 2-3 4-6

onlpen, as the statistical unit. At the end of the sixweeks of the experiments, the birds wereslaughtered by an authorized slaughter house,according to the Italian animal welfare stan-dards. The chilled carcasses were then meas-ured for carcass weights, i.e. the weight of thesingle bird after removal of feathers andabdominal viscera, except kidneys and forbreast yields. All the birds dead during theexperiment were submitted to autopsy in orderto ascertain the cause of the death.

Statistical analysis: the design of the experi-ments was a completely randomized one withthe pen as the experimental unit. The perform-ance results were analysed by a one-wayANOVA using the procedure of SAS (1999),keeping the factor “diet” as the fixed one. Themortality figures were analysed by the c2test.

the mortality of untreated unchallenged birdsresulted very low and not significantly differentfrom the mortality of the treated groups. Thesame situation was reported by Leeson et al.(2005) with 0.1% butyric acid in the diet. Theautopsy examinations revealed no coccidial infec-tion as the cause of death, but excessive intakesof feed in the crop (too palatable?). However, the

c2test did not attribute statistical significance tothe differences.

In this second experiment, all the differencesresulted devoid of statistical significance. Thetrend was that the growth rates of the T2 treatedbirds appeared poorer than those exhibited byboth the control and the T1 treated chickens,together with the feed/gain ratios, decidedly good.

Table 1. Characterisation of butyric glycerides tested as feed additives.

MB 20° MB 30° BG#

CompositionMono-butyrineDi-butyrine Tri-butyrineGlycerol

Butyric acid in the mixture

34.0 51.0 305.6 8.4 500.4 0.6 2060.0 40.0 -20 30 60

y Monobutyrine in broilers’ diet

Discussion

Short chain fatty acids acetic, propionic andbutyric, have been used as water sanitizers inthe poultry industry. Unlike acetic and propi-onic, free butyric acid is quickly absorbed in theupper small intestine (Bolton and Dewar,1965). As a consequence, it may be of little useto the gut environment if not stabilized in someway. If administered as butyric glyceride, itsabsorption rate is reduced and it is allowed toproceed further down the digestive tract andexert it antimicrobial action where required.Moreover, while free butyric acid is character-ized by a strong unpleasant odour, which possi-bly makes the feed in which it is incorporatedpoorly palatable, supplemented butyric glyc-erides do not depress feed intake, so confirm-ing the results of the cited previous works ofours (Leeson et al., 2005; Antongiovanni et al.,2007). Aim of the present work was a furtherstep forward with reference to previous experi-ments by studying the effect on the chickens’performance of a nove form of butyric glyceride:the monoglyceride diluted in glycerol. The newform was expected to be more easily, even nottoo rapidly, absorbed and to enter quickly intothe pathogenic microbial cell, due to itshydrophilic behaviour. Finally, to be even morepalatable, due to the sweet taste of glycerol.The results confirmed no negative effects offeeding butyric acid even throughout the whole6 weeks growth period and at much higherdosages than in our previous experiments: inexperiment one 1% MB 30 is equivalent to 0.3%butyric acid and in experiment two 1% MB 20 isequivalent to 0.2% butyric acid, as compared to0.12% only in the case of the BG blend. Theantimicrobial effect upon the pathogenicmicrobes was confirmed by the mortality rate,significantly reduced in experiment one in chal-lenged birds. It doesn’t seem necessary to pro-vide monobutyrine throughout the whole growthperiod. In fact, in experiment 2 MB 30 wasrestricted to the first week only and MB 20 to thefollowing two weeks, with no statistically appre-ciable differences in the chickens’ performance.

Table 4. Performance traits of broiler chickens.

Control T1 T2Experiment #1 Live body weight, 14 d, g 470 475 488Feed/gain, 0-14 d 1.78 1.84 1.81Live body weight, 42 d, g 2,777 2,691 2,782Feed/gain, 0-42 d 1.93 2.04 1.96Carcass weight°, g 2,385 2,419 2,499Breast meat, g 512 563 579Breast meat, % carcass 20.6 21.3 22.1Mortality, % 14a 2b 4bExperiment #2

Live body weight, 14 d, g 472 476 457Feed/gain, 0-14 d 1.34 1.35 1.39Live body weight, 42 d, g 2,751 2,799 2,711Feed/gain, 0-42 d 1.74 1.73 1.75Carcass weight°, g 2,319 2,326 2,231Breast meat, g 566 517 512Breast meat, % carcass 24.5 22.2 23.0Mortality, % 2 6 2

SEM100.060.061.1-70.03480.0291492.9-

°Weight of the sacrificed bird after removal of feathers and abdominal viscera except kidneys; a,bdifferent superscripts show sig-nificant differences (P<0.05).

and MB 30 partially replaced soybean oil in thediet, the final body weights resulted statisticallynot different, with comparable feed/gain ratios,with respect to those of the control group. Thefollowing speculation may then be proposed:since the MB supplements tested in the twoexperiments of the present work are character-ized by a heat of combustion which is abouthalf the heat of combustion of soybean oil (19-20 vs. 39 MJ/kg), but there was no depressionin the birds’ performance, we can assume thatMB 20 and MB 30 must have the same apparentmetabolizable energy content of soybean oil(associative effect?) if, when replacing thesame amount of oil, no statistically differentperformance traits were observed. The specula-tion could be expressed in these terms: if thetabulated metabolizable energy content of soy-bean oil is 38 MJ/kg (Sauvant et al., 2002), thatis 97% of its heat of combustion, MB 20 and MB30 appear to have paradoxically the samemetabolizable energy content (38 MJ/kg), thatis about 210% their heat of combustion!

Conclusions

The protective effect of monobutyrine on thegut environment has been confirmed with theexperiment with Eimeria challenged birds. Infact, the mortality recorded in the group ofbirds treated with 1% MB 30 resulted signifi-cantly much lower than in the group of untreat-ed chickens. In both experiments, when MB 20

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