Effect of in feed talc supplementation on broiler performance
Effect of in feed talc supplementation on broiler performance
Serge MALLET 2
Patrick DELORD 0
Hervé JUIN 1
Michel LESSIRE 2
0 Luzenac Europe , 31036 Toulouse , France
1 INRA, Station Expérimentale du Magneraud , 17700 Surgeres , France
2 INRA, Station de Recherches Avicoles , 37380 Nouzilly , France
- Four experiments were performed to study the effects of the addition of 1 or 2% of talc to the diets of broiler chickens compared to an unsupplemented diet and a control diet containing 5 ppm of avilamycin. Both additives improved bird performance, weight gain (W.G.) and feed conversion ratio (F.C.R.) especially when poor performances were observed for the unsupplemented control group. Overall, when all the experiments were computed together, avilamycin significantly improved bird performance (W.G. and F.C.R.) compared to the unsupplemented diet. The effect of talc was positive but lower than avilamycin. No dose effect was observed with talc. Intestinal microflora, tested in the excreta, was decreased by avilamycin but no effect was observed with talc.
The progressive suppression in poultry
diets of growth factors such as antibiotics,
suspected to induce some resistance in
human bacterial strains [
], has motivated
the research of new alternatives but also an
emerging interest for substances already
known but not yet extensively used as feed
additives for poultry, especially for their
Talc, a hydrated magnesium silicate, is
a mineral belonging to the class of
Phyllosilicates such as bentonite, kaolinite or
sepiolite. These substances are mainly used in
the feed industry for their technological
properties that are different from one type
to another according to their composition
]. Talc has been approved as a
technological additive in the animal feed
industry under the European code E560. Its
composition is thus defined as a natural
mixture of steatite and chlorite with a minimum
purity of 85% and free of asbestos .
The advantages of Phyllosilicates as
zootechnical additives in animal feed are
well documented and improvements of
weight gain or of feed consumption ratio
have been observed for broilers in some
4, 11, 19
]. Nevertheless, these
effects are highly variable according to the
type of product or experimental conditions.
Concerning the use of talc, some
experiments were performed but relatively few
studies have been published. Talc is named
Stealim® in referenced studies. In 1973 and
1976, Ferrando [
] noted that, on the
contrary to what occurred with some other
Phyllosilicates, adding 3 to 6% of talc to the
diet of rats, previously deprived of vitamin A,
did not affect its absorption but improved
its hepatic storage. In 1974, Bourdillon 
observed that adding 3% of talc to the diet
did not affect the performance of pigs and
that, as previously observed by Ferrando
with rats, vitamin A absorption was
maintained and its hepatic storage improved. In
1975, Tournut et al. [
] observed a
significant decrease of ulceration by adding talc
to the diet of pigs with gastro-oesophageal
ulcers experimentally induced by
overcrowding and finely milled feed. In 1977, Ladrat
] observed that the iron atoms present in
talc were not used by calves (unchanged
hematocrit level) and that, when diluted up
to 1.18% in the diet, talc addition did not
affect the feed conversion ratio. In 1978,
] reported a positive effect of
talc on the intestinal flora of rabbits
experimentally exposed to mucoid enteritis with,
as a consequence, a significantly increased
weight gain. In 1994, Lebas et al. [
observed that adding 2% of talc in the diet
of rabbits did not affect their performance,
even if the energy value of the feed was
reduced by 2%.
As only few data were published on the
effect of talc on poultry performance, we
studied the effects of this mineral in four
experiments involving broilers fed diets
containing two additional levels of Luzenac
talc or a growth promoter.
2. MATERIALS AND METHODS
2.1. Animals and experimental design
Four experiments were performed over
a 3-year period in two experimental
facilities in France according to similar
experimental protocols (Tab. I). One-day-old male
broiler chickens (Ross PM3) were weighed
the day of arrival (D0) and randomly
allocated to floor pens (3 m2) littered with wood
shavings (one pen for each treatment group).
The birds were reared together during the
starter period in order to allow a better and
more homogenous bacterial contamination
of their digestive tract. At the end of the
starter period, the birds were weighed and
allocated to individual cages for the
growing period. Birds with extreme weights
(lowest and highest) were discarded in order to
maintain, during the growing period in each
treatment group, the same mean weight
value as the one measured at the end of the
1 Std. = standard diet, L.C. = low calorie diet.
2 Number of birds per experimental group; Avila.: Avilamycin.
3 1 pen per treatment.
4 36 or 48 cages per treatment.
2.2. Experimental diets
The birds were fed either standard diets
(Std.) (Exps. 1–4) or low calorie diets (L.C.)
in which nutrient contents were reduced by
approximately 5% (Exps. 3, 4). Moreover,
in these latter diets, high levels of water
soluble non-starch polysaccharides were
introduced by viscous wheat (Rialto
variety). Palm oil of poor digestibility [
also added instead of rapeseed oil. The
composition of the diets is presented in
In experiments 1 and 2, the birds were
fed the standard diet and two diets
containing respectively 1% and 2% of Luzenac talc
(Stealim®). These three diets were
compared to a diet containing 5 ppm of
avilamycin (Maxus G200). In experiments 3 and 4,
only the dose of 1% of talc was used. Talc
was substituted by the same amount of
cellulose (not assimilated by the birds) in order
to maintain the same characteristics
without any dilution due to talc addition for all
the treatment groups. All the diets were
pelleted (∅ 2.5 mm).
The chickens were weighed individually
at D0, at the end of the starter period and at
the end of the experiment. The weight gains
(W.G.) were calculated for each animal and
each experimental period. The feed was
weighed at D0 and at the end of each
experimental period. The Feed Conversion Ratio
(F.C.R.) was calculated for each animal
during the growing period (Feed
Bacteriological studies were performed
in experiments 1, 2 and 3. For each
treatment group, excreta were collected and
analysed individually for 20 animals (Exps. 1,
2) or for 4 pools of 10 animals (Exp. 3). They
were stored at –80 °C pending bacterial
numerations. Viable bacteria were counted
] after successive 1/10 dilution in 0.5%
NaCl. Lactobacilli, coliform and total
aerobic bacteria were counted using MRS
agar, Drigalski agar and BHI agar growth
culture media respectively. The media were
incubated aerobically at 37 °C for 24 h
(Drigalski agar) or 48 h (MRS and BHI agar).
The results are expressed as the Log of
Colony Forming Units (CFU) per g of faeces.
Data were computed using Statview 5
software. Significant differences between
treatment group means were determined by
analysis of variance and the means were
separated using the Fisher test (P ≤ 0.05).
When the experiments were tested together,
1 Premix composition Vitamins (for 100 g of diet): A (retinyl acetate) 1000 IU, D3 (cholecalciferol)
200 IU, E (DL-α-tocopherol acetate) 3 mg, B1 (thiamine mononitrate) 0.15 mg, K3 (M.N.B. or M.P.B.
form) 0.2 mg, B2 (riboflavin) 0.4 mg, B6 (pyridoxine chlorhydrate) 0.25 mg, B12 (cyanocobalamine)
0.0015 mg, calcium Pantothenate 1 mg, Folic acid 0.04 mg, Biotin 0.02 mg, Choline 50 mg, PP (nicotinic
acid or amide, niacin) 3 mg. Minerals (mg for 100 g of diet): Co (Carbonate) 0.06, Cu (Sulphate) 2.5, Fe
(Sulphate) 5, I (calcium Iodate) 0.1, Mn (Oxide) 8.5, Se (sodium selenite) 0.025, Zn (Sulphate) 6. Others:
B.H.T 12.5 mg for 100 g of diet.
1 P value: *, P < 0.05; **, P < 0.01; ***, P < 0.001; NS, Not significant.
a, b, c Means in the same line with no common subscripts differ significantly (P < 0.05).
the experiment number was used as a
second independent variable in order to take
into account all the differences between
experiments (location, diet, duration of
rearing periods). When comparing
experiments 3 and 4, the effect of diet (Standard
or low calorie) was also tested to compare
the potential interaction between the diet
and additive effect.
3.1. Effect of avilamycin
In birds fed the standard diet, W.G. or
F.C.R. was significantly improved by the
antibiotic (Tab. III). The overall mean
response of chickens was +3.8% for W.G. and
–1.9% for F.C.R. The responses varied among
the four experiments from –0.7 (Exp. 4) to
+12.3% (Exp. 1) for W.G. and from –0.9
(Exp. 4) to –7.5% (Exp. 1) for F.C.R.
3.2. Effect of talc
3.2.1. Dose effect
The incorporation of 1 or 2% of talc was
compared in experiments 1 and 2. No
difference was observed between the two
doses for the mean W.G. (talc 1%, 829 ±
24 g; talc 2%, 827 ± 22 g) or F.C.R. (talc
1%, 1.64 ± 0.02; talc 2%, 1.65 ± 0.02).
3.2.2. Effect of 1% talc
When the results of birds fed standard
diets were pooled (Tab. III), the effect of
1% talc appeared intermediate between the
control and avilamycin treatment. For
W.G., the effect was low (+0.6%) and not
significantly different from the
unsupplemented control group but, for F.C.R., it was
significantly different (–1.3%) and similar
to avilamycin. When comparing the effect
in the different experiments, the range was,
for W.G., –0.6 to +7.8% in experiments 3
and 1 respectively and, for F.C.R., +0.3 to
–3.5% in experiments 4 and 1 respectively.
The highest improvements were observed
in experiments 1 and 2.
3.3. Effect of low calorie diet
By comparison with the standard diet,
the low calorie diet in experiments 3 and 4
(Tab. IV) significantly reduced bird
performance (by 3% for W.G. and 13% for
Control (no additive)
Avilamycin 5 ppm.
Interaction diet × additive
Interaction exp.× additive
Control (no additive)
Avilamycin 5 ppm
1232 ± 23b
1257 ± 20a
1222 ± 24b
1188 ± 19b
1216 ± 20a
1193 ± 19b
1.63 ± 0.02b
1.58 ± 0.02a
1.62 ± 0.02b
NS (P = 0.052)
Std. = standard diet, L.C. = low calorie diet.
1 P value : *, P < 0.05; **, P < 0.01; ***, P < 0.001; NS, Not significant.
a, b, c Means in the same column with no common subscripts differ significantly (P < 0.05).
1 P value: *, P < 0.05; **, P < 0.01; ***, P < 0.001; NS, Not significant.
a, b Means in the same column with no common subscripts differ significantly (P < 0.05).
F.C.R.). No significant interaction was
observed between diet and additive effect,
nevertheless, the interaction was close to
the significance level (P = 0.052) for F.C.R.
Even if it was not significant, the mean
effects of talc were higher in the low calorie
(+0.4% for W.G. and –1% for F.C.R.)
compared to the standard diet (–0.1% for W.G.
and no effect for F.C.R.). The effect of the
low calorie diet was also similar with
avilamycin for F.C.R. (–3% with low calorie
compared to –1% with the standard diet) but
not for W.G. (+2% with both low calorie
and standard diets).
3.4. Bacterial counts
Bacterial counts (Tab. V) were
significantly different between the experiments. A
decrease of all the bacterial populations
tested was observed with avilamycin but it
was significant only for lactobacilli. No
difference was observed with talc
supplemented feed compared to the control group.
Differences were clearly observed between
the experiments regarding the effect of talc
and avilamycin on bird performance. In
their review, Thomke and Elwiger [
noted an overall response of broiler
chickens to different antibiotic growth promoters
in comparison with the unsupplemented
control diet that may be calculated to be, on
average, +3.9 for W.G and –2.9% for
F.C.R. with values ranging respectively
from –0.8 to +10.2% and from –0.9 to –
5.5%. The effects observed in the present
experiments for avilamycin were in the
same range, thus confirming that they were
representative of what might be observed in
field conditions. It was also noted [
the promoters, especially antibiotics, were
more effective when used in diseased rather
than in healthy birds and that the expected
response level for performance should be
lower for animals in production systems
with high standards of hygiene. In the
present experiments, the interaction between
experiment and additives was almost
significant (P = 0.058) and a clear tendency
was observed for a higher effect of the
additives in birds with low performance. Thus,
the higher improvement was observed with
avilamycin and talc supplemented diets in
experiments 1 and 2 presenting the lower
performances while, on the contrary, the
lower effect was observed in experiment
4 presenting the higher performances of
the unsupplemented control group. This
was confirmed by the higher improvement
observed with both additives in the low
calorie diet compared to the standard diet, also
with a clear tendency for F.C.R (interaction
diet-additive, P = 0.052).
Even though the efficacy and mode of
action of antibiotic growth promoters is
now well documented [
], the effect of
the different additives recently developed
as alternatives is a more controversial
subject. The improvement of performance, when
observed, is generally lower than with
antibiotics, inconstant and rarely significant,
even with well known and widely used
additives such as probiotics [
]. In the
present experiments, except for experiment
4 in which performances were high and
with no effect of avilamycin, a beneficial
effect of talc was observed on W.G. and
F.C.R. Even if this effect was only
statistically significant in two of the four
experiments, when standard diets of all the
experiments were computed together, the
beneficial effect was significant on F.C.R.
compared to the negative control group and
similar to avilamycin. This was in
accordance with the beneficial effects observed
with clay minerals, sometimes up to 5% on
W.G. and F.C.R [
4, 11, 19
] or with talc that
showed beneficial effects on health [
or no detrimental effects on performance [
5, 6, 8, 9
As reported in the literature [
avilamycin, known to be active on
gram-positive bacteria, decreased bacterial populations.
No effect on microflora was observed with
talc and the improvement of performances
could not be explained by a modification of
the level of the bacterial populations tested.
As for the other phyllosilicates used in the
feed industry, more work will be necessary
to explain how talc improves feed
efficiency. With clay minerals, it has been
suggested that adsorbent aptitudes increase
nutriment absorption by lowering the time
of feed intestinal transit; also, a protective
effect on intestinal mucosa may act on the
improvement of feed efficiency but these
potentialities depend on the type and
physical properties of the additive and have rarely
completely explained the effects observed
4, 11, 19
In conclusion, positive effects were
observed with the incorporation of 1% of
talc in the diet, especially on F.C.R. As for
avilamycin, the improvements of broiler
performance were variable from one
experiment to another. Even when the positive
effects of avilamycin were low, talc never
significantly reduced bird performance.
When an improvement was observed with
talc, it was lower than that observed with
avilamycin. In two of the four experiments,
when the effects of avilamycin were high,
talc significantly improved W.G. or F.C.R.
Thanks are due to the staff of the INRA
experimental stations of Nouzilly and Le
Magneraud for performing these experiments
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