Active plant extracts show promise
Plant extracts have a wide
range of activities, including:
• inhibitory actions on pathogens
Table 4 Performance of broilers fed a blend of essential oils compared to a
negative control and an antimicrobial growth promoter (avilamycin at 10ppm)
(bacteria, fungi, parasites and
some fungi
• effects on physio-pathologies,
e.g. anti-inflammatory, anti-diarrhoea properties
• activity in different body
systems, e.g. endocrine,
immune system
Scientists working in this
field generally focus on the
management of the different gut
microflora, as well as general gut
health and function.
Plant products can comprise
the whole plant or various
fractions in the form of
powders, extracts or essential
oils. Essential oils include
molecules that are volatile and
usually obtained by extraction.
Although the gut flora may be
affected by all types of extracts,
it is the essential oils that are of
most interest because of their
composition and concentration
of active molecules.
Control Avilamycin Essential oils
P
Initial weight (g)
40 40 40
Starter period (day 0-21)
Bodyweight of males, day 21 848 NS
Bodyweight of females, day 21 784 NS
Feed conversion (day 1-21) 1.307 NS
Grower period (day 21-35)
860 869
793 798
1.284 1.278
Bodyweight gain males (g)
1246 1235
Bodyweight gain, females (g)
1005 1037
Feed conversion (day 21-35)
1.680 1.661
1232 NS
1029 P=0.08
1.681 NS
Overall (day 1-35)
Feed conversion 1.532 a 1.505 b 1.514 ab P<0.05
Source: Juin & Reco/////quillay, 2003
Table 5 Results of a field trial with broilers receiving the same diet, with or
without a blend of essential oils (days 1-42)
Control
Initial number of birds 21,800
Final number of birds 21,063
Mortality (%) 3. 38
Average final weight (kg) 2.08
Feed consumed (t) 86.6
Overall feed conversion 1.93
Source: Feix, Phytosynthese, Czech Republic
Control + essential oils
21,800
21,087
3. 27
2. 22
89.7
1.86
Many authors have
investigated the efficacy of
essential oils against bacteria
in the broiler. One set of results
is shown in Table 2, showing
that many molecules affect the food poisoning in humans. In The first trial was conducted
growth of individual bacterial vitro work in our laboratory by H. Juin at the INRA institute
pathogens. Single molecules (shown in Table 3) shows that a at Le Magneraud, comparing the
were used in this work, but our concentration of 0.025% of the performance of broilers using
research indicates that mixtures essential oil brought the number a diet containing essential oils
of different molecules may of campylobacter down to below with those fed an antimicrobial
have a synergistic effect. the detection limit. growth promoter (avilamycin)
Plant extracts benefit Plant extracts have activities and a negative control group.
digestive health beyond the purely antimicrobial. Overall, the performance of the Curcuma, for example, has been group of birds fed the essential
Our first focus was on Cl. shown in vitro to increase the oils matched that for those
perfringens, the pathogen activity of the digestive enzymes receiving avilamycin.
associated with necrotic enteritis. lipase, alkaline phosphatase, acid A second efficacy trial was
The Minimum Inhibitory phosphatase, sucrase, lactase and carried out at ENCAP in Spain,
Concentration of cassia oil maltase. with 500 broilers in two groups:
was found to be 250ppm for one was fed a diet containing
Cl. perfringens, and more than Essential oils improve a blend of essential oils and
500ppm for bifidobacteria, performance the other group received the
indicating that this substance same diet without any additive
can control the pathogen without In co-operation with other (control). Mortality rates were
disturbing other beneficial research centres, we have 3. 2 and 6.0%, respectively. The
bacteria in the gut. conducted a series of trials that final weight and overall feed
Campylobacter is another demonstrate improvements in conversion were 1630g and
pathogenic bacterium, carried by broiler performance by including a 2. 19 for the controls, compared
broilers or turkeys, which causes blend of essential oils in the feed. to 1801g and 1.85 for the birds
