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KMID : 1025520090510060503
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Journal of Animal Science and Technology
2009 Volume.51 No. 6 p.503 ~ p.510
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Effects of Tannic Acid Added to Diets Containing Low Level of Iron on Performance, Blood Hematology, Iron Status and Fecal Microflora in Weanling Pigs.
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Lee Seung-Hyung
Prashant Shinde
Choi Jae-Yong
Kwon Ill-Kyong
Lee Jeong-Koo
Park Son-Il
Cho Won-Tak
Chae B. J.
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Abstract
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This study investigated the effects of tannic acid(TA) in the diets for weanling pigs prepared with/without supplemental Fe on performance, hematology, fecal microflora and diarrhea incidence. Limestone and calcium phosphate used in Experiment 1 and 2 were of semi-synthetic and feed-grade quality, respectively; while the trace-mineral premix used in both the experiments was prepared without any added Fe source. In Experiment 1, 108 weaned pigs(Landrace×Yorkshire×Duroc, initially 6.46±1.04kg BW) were allotted to 3 treatments including control(diet added with FeSO4 and antibiotic), T1(diet devoid of FeSO4 and antibiotic) and T2(T1 diet added with 125mg/kg TA). Each treatment had 4 replicates with 9 pigs in each pen. Feeding of T1 diet had a negative effect on the performance and plasma Fe status of pigs, while addition of TA to T1 diet resulted in performance of pigs comparable to pigs fed the control diet, reduced diarrhea incidence but had a negative influence on the hematological and plasma Fe indices. Additionally, pigs fed T2 diet had fewer(p<0.05) total anaerobic bacteria, Clostridium spp. and coliforms than pigs fed T1 diet, and greater number of Bifidobacterium spp. and Lactobacillus spp. in feces when compared with pigs fed control and T1 diets. In Experiment 2, 144 weaned pigs(Landrace×Yorkshire×Duroc, initially 6.00±1.07kg BW) were allotted to 4 dietary treatments including control(diet added with FeSO4 and antibiotic) and diets devoid of supplemental Fe added with antibiotic(An), TA and both(AnTA). Each treatment had 4 replicates with 9 pigs in each pen. Addition of An, TA or both to diets devoid of supplemental Fe did not have any effect on performance, blood hematology and plasma Fe but resulted in reduced(p<0.05) diarrhea incidence and lower(p<0.05) fecal coliform population than pigs fed the control diet. These results suggest that TA has a negative influence on blood hematology and plasma Fe status when diets are inadequate in Fe; however, TA reduced diarrhea incidence and might have antimicrobial activity.
Tannic acid (TA) is an important gallotannin belonging to the hydrolysable class, which is made up of phenolic acid esters and a polyol, usually glucose(Khanbabaee and van Ree, 2001). A number of antinutritional effects have been attributed to tannins. Previous studies demonstrating the effects of tannins in feedstuffs on animal performance have been carried out by using tannins isolated from feedstuffs or with commercial tannins(Wareham et al., 1993; Marzo et al., 2002). The antinutritional effects of tannins in terms of poor palatability, feed efficiency, growth rate, nutrient digestibility, and increased endogenous losses of minerals and amino acids in simple stomach animals have been extensively reviewed by Jansman (1993).
Tannins have been reported to have bacteriostatic and bacteriocidal properties against wide range of pathogenic bacteria (Chung et al., 1998), including Escherichia coli, Salmonella, Proteus spp., and obligate anaerobes such as Clostridium spp. (Sotohy et al., 1995). However, there have been very few attempts demonstrating the in vivo reduction of bacteria by tannins.
Diarrhea represents 11% of all postweaning piglet mortality (Alexander, 1994), and enterotoxigenic Escherichia coli diarrhea is the most common enteric disease in piglets, accounting for 5% of the 10 million piglets that die annually worldwide(Gyles, 1994). The Fe concentration of most nursery diets is in excess of the NRC (1998) postweaning dietary Fe requirement of 80 mg/kg. This occurs because many feed ingredients have a high Fe concentration, including monocalcium phosphate and limestone (Rincker et al., 2005). In our previous study we had noticed supplemental Fe(50 to 250 mg/kg) can linearly increase diarrhea incidence and fecal coliform count in weaned pigs(Lee et al., 2008). All micro-organisms require iron to facilitate basic cellular processes such as respiration and DNA biosynthesis(Rouault, 2004). Tannins are known to have an affinity for binding with Fe and this might reduce Fe absorption and also prevent Fe from being obtained by intestinal microbes thus limiting their growth in intestine and might act as an antidiarrheal agent(Ericsson, 2005).
Thus this study was conducted to evaluate the effect of TA in the diet for weaned pigs which had low Fe(Experiment 1) and sufficient Fe(Experiment 2) contents.
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KEYWORD
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Fecal microflora, Hematological status, Iron, Tannic acid, Weanling pigs
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