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Vitamin requirements: is there basis for re-evaluating dietary
specifications?
From Vitamin requirements: is there basis for re-evaluating dietary specifications? S. LEESON1, adapted and
modified by M. Di Benedetto2
1
Department of Animal & Poultry Science, University of Guelph, Guelph, Ontario, Canada N1G 2W1 E-mail:
[email protected]
2
DVM, Consulenze Aziendali Zootecniche studio associato e-mail: [email protected]
During the last 40 years there have been few studies aimed to estimate the
vitamin requirements in poultry, so that consequently the NRC values (1994)
still are the standard reference.
table 1: Vitamin requirements NRC (1994) compared to commercial and field
recommendations (Leeson, 2007)
Layers
(ingestion
100gr/head/die)
Vitamin
NRC
A (UI)
D3 (UI)
3.000
300
E (mg)
K (mg)
B12 (µg)
Biotin (µg)
Choline (mg)
Folic acid (mg)
PP (mg)
Pantot. Ac.(mg)
B6 (mg)
B2 (mg)
B1 (mg)
5
0,5
4
100
1.050
0,25
10
2
2,5
2,5
0,7
1
Leeson
and
Summers1
8.000
3.500
Leeson and Summers (2005)
DSM (2006)
Biotin for Maize-based diets
2
50
3
10
100
400
1
40
10
3
5
2
DSM2
8-12.000
2.5003.500
15-30
2-3
15-25
100-150
300-500
0,5-1
20-50
8-10
3-5
4-7
1,5-3
Broilers starter
NRC
Leeson and DSM2
Summers1
1.500
200
8.000
3.500
8-12.500
3-5.000
10
0,5
10
150
1.300
0,55
35
10
3,5
3,6
1,8
50
3
12
100
400
1
40
14
4
5
4
150-240
2-4
15-40
150-300
300-600
1-2
50-80
10-18
3-6
7-9
2-3
VITAMIN REQUIREMENTS NRC 1994
These requirements are quite far from the present ones commercially used,
since:
•
Their elaboration is long time dated, as it goes back to the period
between 1990 and 1994.
•
They are based on studies appeared on sector books and magazines
issued during the last 40 years, without taking into considerations the
enormous progress attained by genetics, nutrition, and breeding
techniques in recent years.
•
Several trials, among those ones considered, have been carried out by
using purified or semi-purified diets, characterised by digestibility
definitively higher than in the commercial diets. (i.e. soy isolated protein
or casein as protein and amino acid source; and dextrose, starch, and
saccarose as energy source).
•
Considered the difficulty that such diets present for pelletisation, the
physical form of feed utilised in these trials basically was as meal, with
no homogeneous characteristics, as for particle size, colour and
consistency. Moreover it has to be considered that most feed for poultry
is nowadays manufactured in pellets or crumbles, necessary to reach
the performances foreseen by the genetics producers.
•
Most of the studies taken into consideration by NRC (1994) about
vitamin requirements are based on the observation of presence/absence
of deficiency status and/or basis yielding parameters such as eggs
weight, growth and conversion rate, without considering health data,
slaughtering data, final product organoleptic characteristics.
A revision of such information indicates that several figures come from
estimation, or are taken from similar species, or as in broiler breeders simply
not available.
CHANGES IN THE GENETIC POTENTIAL
The present interest in the vitamin level formulation in diets for poultry is due
to the observation that improvements in the genetic potential of layers and
broilers impose a re-evaluation of the requirements since the conversion rate
improvements (decrease of the feed intake per product unit) has implied a
continuous decline of vitamins ingestion related to eggs weight or produced
meat. Such decrease is estimable around 1% in layers, and around 0.6 – 0.8%
in broilers.
The following table (n. 2) shows this phenomenon throughout the last 20 years
in layers (white), broilers, turkeys, taking as an example vitamin E:
table 2: Ingestion of vit. E per production unit, diets containing 20 UI vit. E/Kg
(Leeson, 2007)
Layers
(1Kg)
Broilers
(2Kg)
Turkeys
(14Kg)
1985
2005
∆/year
2,7 UI/egg
2,1 UI/egg
-1,1%
40 UI/Kg
growth
55 UI/Kg
growth
34 UI/Kg
growth
48 UI/Kg
growth
-0,8%
-0,6%
This lower ingestion of vitamins represents the basis of performance
improvements when feed containing vitamin levels higher than normal are
administered. For several vitamins what was described in 1993 as “high level”
of supplementation nowadays is described in a better proper way as “modest”
or “low level”.
In layers early maturity reached at a lower body weight imposes a further
variable on the vitamin diet specifications. Most feeds for layers nowadays are
formulated on the basis of the daily ingestion. Considering the expectation of
lower ingestions, the level of nutrients in the diet, such as amino acids and
calcium have been invariably increased. However the adjustment of the
vitamin levels on ingestion basis remains unusual. At every production stage,
the ingestion of Vitamin D3 represents a critical factor for the achievement of
both egg shell and skeleton integrity quality.
Table 3 shows how the ingestion of vitamin D3 is affected by the ingestion of
feed at the beginning of the yielding phase:
table 3: Feed specification for Ca, dig. P and vitamin D3 necessary to keep daily
ingestions of: Ca 4g, P dig. 0,4g, vit. D3 330 IU in white layers at the beginning of
yielding (Leeson, 2007)
Age
Yielding (%) Ingestion
(g/gg)
Ca (%)
dig. P (%)
vit.D3
(IU/Kg feed)
18
19
20
22
24
1
20
50
90
95
5,30
5,00
4,70
4,40
4,20
0,53
0,50
0,47
0,44
0,42
4.400
4.125
3.880
3.660
3.470
75
80
85
90
95
VARIATION OF THE IMPORTANCE OF THE PARAMETERS USED TO
EVALUATE VITAMIN REQUIREMENTS
Our expectations on the role of various nutrients have changed through time.
As previously mentioned most vitamin requirements expressed by NRC (1994)
have been evaluated through criteria bond to yielding parameters that
nowadays honestly appear to be simplistic. At present these evaluation criteria
have been extended and the nutritionist role is to evaluate the requirements to
reach such targets in the most profitable way in terms of cost/benefit. Table 4
underlines the evaluation criteria that are now often applied to requirements of
vitamins and other nutrients.
table. 4: Evaluation criteria for vitamins (Leeson, 2007)
NRC (1994)
Present additional criteria
Layers
n° of eggs
eggs weight
egg shell quality
egg composition
solid part
immunity effect
wellness
Broilers
weight
convertion rate
mortality
carcass characteristics
breast yield
microbiologic quality
Immunity effect
At present the potential on nutrients such as vitamins to act as substances
“nutriceutical” is very important, both in terms of wellness and health in
poultry, and in particular of capacity of immune response.
In particular there is the suspect that virtually all data used to determine the
vitamin requirements NRC (1994) come from studies in which animals were in
optimal health status, not under immunity stress. In fact in most of these
studies there has been no need to effect any vaccination on animals under
testing.
REQUIREMENTS TO SUPPORT GENERAL HEALTH OF ANIMALS
The effect of vitamins of health and in particular on the immune response in
animals is one of the elements of most impact on the re-evaluation of the
vitamin addition in diets.
•
Sell et al. (1997) assert that the levels of vitamin E from NRC (1994) are
probably sufficient in growing turkeys with no pathologies, but previous
studies (Soto-Salanova e Sell, 1996) demonstrate that deposits of atocopherols in poults are low and decline rapidly during the first 14 days
of life. The administration of vit. E per parenteral route or added to feed
(150mg/kg), although it did not eliminate the phenomenon, it weakened
it in a significant way. The decrease of vit. E in liver of stressed poults
did not determine effects on their health, but after administration of vit.
E less sensitiveness to haemolysis of red cells was highlighted.
•
High levels of vitamin E in feed can support the egg production in layers
under heat stress. Through heat stress induced at 32°C Bollengier-Lee et
al. (1998) demonstrated a higher egg production in layers fed with 500
vs. 10 mg vitamin E/kg. In other trials the effect, although less evident,
was always confirmed as increase of calcium, vitellogenine, and VLDL in
the blood of tested animals. Moreover these animals have always
recovered more rapidly from short-term heat stress. These authors
concluded that the extra vitamin E helped these stressed animals
through the improvement of the hepatocytes membrane integrity, and/or
through Estradiol activity modulation or concentration. Similar results
were obtained by Whitehead et al. (1998) by using the same levels of
vitamin E (500 mg/kg feed); the level of vitamin E in plasma was linearly
related to the one in the diet, and it returned to basic levels four weeks
after having removed the extra vitamin E from the diet.
These authors suggest that the antioxidant function that vitamin E in
general exerts has an effect on the vitellogenine level (that represents
yolk most important precursor) in blood. The control of the vitellogenine
level in plasma and in liver suggests that heat stress does not
compromise the actual vitellogenine production, but it compromises its
release in the general circulation.
•
In recent time several studies have been carried out also on vitamin D3:
A study carried out by Atencio et al. on broilers fed with feed containing
3200 IU vitamin D3 highlighted higher weights when born from breeders
that received at least 4000 IU vitamin D3/kg feed.
Whitehead et al. (2004) suggests that requirements for modern broilers
is remarkably higher than that suggested by NRC (1994) and even
higher than the legal limits fixed by the E.U.. In two trials better growth
have been obtained by feeding the animals with feed containing 10,000
IU vitamin D3 compared to others fed with diets containing also a high
level of 6000 IU vit. D3. Tibia strength resulted to be proportional to the
feed level of vitamin D3, whereas tibia dyschondroplasia incidence was
lower with 6,000 IU, and at zero with 10,000 IU.
REQUIREMENTS TO FAVOUR THE IMMUNE RESPONSE
Several studies have been carried out on the effect of a vitaminic
supplementation (especially of vitamin A, D3, E, and C) on the immune
response in broilers, layers, breeder. In general any response to vitamin
administration is registered at 10 times the level suggested by NRC (1994) and
often equal to 2-3 times the one commercially used.
•
Vitamin E and its dosage concerned most of recent studies.
Sijben et al. (2002), starting from the observation of the
polyunsaturated fat acids (PUFA) effect on the immune response they
have investigated the possible synergism between PUFA and vitamin E
on the immune response. By using a feed containing 80 mg/kg vitamin
E and 10% PUFA no apparent interaction has been observed or any
beneficial effect on PUFA accumulation in tissues or on their activity (in
this regard it is opportune to remark how synergism between vitamin E
and PUFA, documented in several studies, is probably due to the vitamin
proper antioxidant effect and that therefore it occurs only in case of the
fatty acids oxidation (MDB).
Puthpongsiriporn et al. (2001) studied the effect of vitamin E on
lymphocytes proliferation and on the oxidative status in layers under
heat stress and fed with feed containing levels of vitamin E up to 65
mg/kg. Heat stress was simulated through daily fluctuations of
temperature 21 to 35°C, or through constant temperature of 35°C. The
65mg level increased the mass of produced eggs in animals under heat
stress, but not on control. An increase of lymphocytes proliferation was
also found after administration of S. typhimurium in groups fed with 45
and 65 mg compared to that with 25 mg.
Table 5: effect of various levels of vitamin E on the mass of eggs produced by
layers under heat stress (Puthpongsiriporn et al., 2001).
Moreover an effect on some qualitative characteristics of eggs was also
observed:
Table 6: effect of various levels of vitamin E on the quality of eggs produced
by layers under heat stress (Puthpongsiriporn et al., 2001).
The figures shown in previous table confirm the hypothesis that in
condition of heat stress levels slightly higher than the commercial ones
increase the yolk weight through an increase of the circulating
vitellogenine.
In a further study, besides confirming previous data, the same authors
also found a synergetic (or additional) effect between vitamin E and
vitamin C both on the number and on the mass of produced eggs.
Table 7: effect of various levels of vitamin E in combination or not with
vitamin C on productive parameters in layers under heat stress
(Puthpongsiriporn et al., 2001).
From the point of view of the antibody production Leshchinsky (2001) at
the end of numerous studies highlighted that the most effective level of
vitamin E was 50 mg/kg feed, level beyond which the immune response
is no longer linear.
A cause of variability in the immune system response at various dosages
of vitamin E (and probably of other vitamins) is to be found in the
different response by the various genetic kinds. Boa-Amponsen et al.
(2000) used three different pure broiler lines to study the response to
two diets characterised by a different content of vitamin E (10 vs. 300
IU/kg). Two out three lines the higher level of vitamin E helped to keep
a higher response of primary and secondary antibodies after injection of
heterologous red cells, whereas in the third genetic line the response
was even negative. Even the effect of IgF and IgM showed the same
line-depending performance. The authors concluded that vitamin E
improves the immune system phagocytal capacity despite it has a
limited effect on the mediated-cell immunity. However all effects seem
to have an element bond to genetics, and this can explain the variability
in the immune responses to vitamin E.
•
Vitamin D3 activity is well known on ossification processes, but it was
also studied for its implications on the immune system. Aslam et al.
(1998) proved that inadequate levels of this vitamin in the diet
compromise the immune response. In fact the response to an
inadequate diet was a reduced activity of basophiles as response to the
cutaneous hemagglutinin. Also the thymus weight per body weight unit,
and the macrophages activity resulted to be depressed. The authors
conclude that the deficiency of vitamin D3 interferes negatively on the
immune response of mediate-cell type.
Another series of studies have been carried out on the immune response
compared to vitamin 25-OH D3. Such studies did not highlighted any
effect bond to the source of vitamin D, but have clarified that levels of
2000 (layers) and of 4000 (broilers and turkeys) IU/kg feed are
necessary for a normal immune system functioning.
NEOFARMA SUGGESTION TO OPTIMISE THE VITAMIN
SUPPLEMENTATION
( Select "NEWS" )