Bioavailability of two sources of zinc in weanling pigs
Anim. Res.
Bioavailability of two sources of zinc in weanling pigs
Pierre-Stéphane REVY 0 2
Catherine JONDREVILLE 2
Jean-Yves DOURMAD 2
François GUINOTTE 0
Yves NYS 1
0 Calcialiment, ZI de la gare , 22690 Pleudihen , France
1 Institut National de la Recherche Agronomique, Station de Recherches Avicoles , 37380 Nouzilly , France
2 Institut National de la Recherche Agronomique, Unité Mixte de Recherches sur le Veau et le Porc , 35590 Saint-Gilles , France
- Thirty-two pigs, weaned at 28 days of age with an average body weight of 9 kg, were used in an experiment devoted to the assessment of the bioavailability of an organic Zn source (ZnOrg) compared to Zn sulfate. Pigs were fed a basal diet containing 28 mg·kg-1 of Zn supplemented with ZnSO4 or ZnOrg to provide 0, 10, 20 and 30 mg·kg-1 of supplemental Zn. In order to reduce the amount and the variability of their Zn stores, pigs were fed the basal diet for a 7-day adjustment period preceding a 19-day experimental period. Growth performance and bone bending moment were not affected by the level nor the source of zinc. On the contrary, plasma zinc concentration and alkaline phosphatase activity (P < 0.001), bone zinc concentration (P < 0.001), liver and empty body zinc concentrations (P < 0.01) as well as the amount of Zn retained estimated both by the balance technique (BT) (P < 0.001) and by the comparative slaughter technique (CST) (P < 0.01) increased linearly in response to supplemental Zn. However, the two Zn sources exhibited a similar bioavailability. Twenty-seven percent of Zn intake was retained when measured by means of the balance technique, regardless of the dietary level or zinc source. Zn retention was 54% lower when measured by means of the CST as compared to the BT.
-
de croissance et le moment de flexion de l’os n’ont été affectés ni par le niveau ni par la source de zinc
supplémentaire. Au contraire, la teneur en zinc et l’activité de la phosphatase alcaline du plasma
(P < 0,001), les teneurs en zinc osseuse (P < 0,001), hépatique et corporelle (P < 0,01) ainsi que la
quantité de zinc retenu estimée par la technique du bilan (P < 0,001) et celle des abattages comparés
(P < 0,01) augmentaient linéairement avec l’addition du zinc. Cependant, aucune différence entre les
sources n’a été détectée. Le coefficient de rétention de zinc, estimé par la technique du bilan, était de
27 % en moyenne, indépendamment du niveau ou de la source de zinc supplémentaire. Estimée par la
technique des abattages comparés, la rétention de Zn était de 54 % inférieure à la valeur obtenue selon
la technique du bilan.
porc / zinc / biodisponibilité / source / indicateur
1. INTRODUCTION
Zinc is an essential trace element which
is involved in many metabolic functions. Zinc
is a cofactor of more than 300 metalloenzymes
and is required for at least one enzyme in all
six enzyme classes [
6
]. Zinc deficiency in
pigs is associated with parakeratosis,
degraded growth performance (decreased
food intake and weight gain) and diarrhea,
particularly in young animals. Zinc
requirements decrease from 100 to 50 mg·kg–1 diet
when pig body weight increases from 5 to
50 kg and remain steady thereafter [
19
].
Such a dietary supply allows an optimal
growth but also the maximization of zinc
concentration in some tissues [
36
].
However, zinc contained in most plant feedstuffs
is poorly available to chicks [
20
] and pigs
[
21
], because it forms insoluble complexes
with some organic ligands, mainly phytates.
Therefore, the diets must be supplemented
with zinc. In practice, because large safety
margins are applied or because of their
growth factor effect, zinc and other trace
elements like copper are often oversupplied
in pig diets and are highly concentrated in
pig manure. Consequently, excessive zinc
and copper accumulation in soils occurs in
areas of intensive animal production, which
may cause phytotoxicity of cultivated
plants [
8, 15, 27
]. Because of this risk of
environmental pollution, European
regulation should move to a drastic reduction of
maximal trace element concentrations
authorized in pig diets. Zinc supplementation
of pig diets can be achieved by means of
different sources. Zinc sulfate (ZnSO4) and
zinc oxide (ZnO) are commonly used in pig
feeding. Organic (complexes or chelates)
zinc sources have been suggested to
exhibit a higher bioavailability in broilers
than inorganic sources [
33
]. An enhanced
bioavailability of organic Zn could allow
the reduction of zinc supply in pig diets and,
in turn, would contribute to environmental
protection. A zinc-methionine complex
exhibited a higher bioavailability (206%) than
ZnSO4 in chicks fed corn-soybean meal
diets [
35
]. In contrast, studies with pigs have
failed to demonstrate differences in zinc
bioavailability between organic and
inorganic sources [
7, 10, 34, 36
].
This study was conducted to compare
the bioavailability of zinc from an organic
Zn source with that of ZnSO4, on the basis
of a wide ra (...truncated)