The immune system had been over-activated in weaning piglets and it caused the decrease of animals performance. (Qian et al., 2006) Cytokines are small peptide molecules that are important mediators in the regulation of the inflammatory responses. Interleukins were produced by T lymphocytes, can play an role in the cellular immunity. Diet modulated immune functions in multiple ways and kept healthy. We had previously showed that plasma protein supplementation prevented the activation of lymphocyte populations of Payers patches and mesenteric lymph nodes. Supplementing standard ration with animal plasma protein improved animal growth and performance in farm animals challenged with pathogenic Escherchia coli (Van Dijk and Enthoven, 2002) and animals in unsanitary environments (Zhao and Harper, 2007).
Therefore, the aims of this study were to evaluate the effects of diets supplemented with spray-dried chicken plasma protein on performance and the level of interleukins in serum in piglets, which fed in normal status, so as to afford a theoretical reference for applicating of chicken plasma protein powder in piglets.
MATERIALS AND METHODS
Experimental animals and diets: All animals were cared for according
to the guidelines set by the Animal Protection Committee of the Ministry for
Agriculture and Nature Protection, Schwerin, Germany. The animal feeding trial
was performed using weaning pigs (DLY type) with an initial body weight of 8.78
DLY pigs were assigned randomly to 1 of the 2 dietary groups, with 4 pens/group (4 pigs/pen). Each pen was equipped with a feeder and a nipple water to allow the pigs free access feed and drinking water. Temperature (25-27oC) and a cycle of 16 h light: 8 h dark were maintained in the mechanically ventilated room. One group was fed the basal diet (control), the other group was fed chicken plasma protein diet. The basal diet met or exceeded the National Research Council (NRC) nutrient requirements for piglet, all diets are free from antibiotics (Table 1).
Performance, blood sampling: Piglets in each pen were weighed as a group on d 0 (weaning), 7, 14 and 28. Feed intake was determined weekly. Average Daily Gain (ADG), Average Daily Feed Intake (ADFI) and Gain: Feed ratio (G: F) were calculated per pen.
Eight hours after the last feeding, blood samples were collected through the anterior vena cave puncture into 10-mL heparin-free Vacutainer tubes. Blood samples were centrifugated at 3500 x g for 15 min to obtain sera, which were stored at -20oC for determination of IL-1, IL-4, IL -1 receptor antagonist (IL-1ra) and IgG, IgA, IgM. IL-4, IL-1, IL-1ra are determinated by radioimmunoassay kit determination and IgG, IgA, IgM are determinated by Immunoturbidimetry determination.
Statistical analysis: Weight gain, feed intake, feed efficiency, serum
IL-4, IL-1, IL-1ra and IgG, IgA, IgM levels were subjected to analysis of variance
using the general linear model procedure of SAS10 according to a completely
randomized one-factorial design.
||Composition and nutrient levels of basal diets
|Notes: 1, each containing kg premix: Vitamin A 2200 IU; Vitamin
D3 1500 IU; Vitamin K3 0.5 mg; Vitamin B1 0.5 mg; vitamin B2 20 mg; vitamin
B6 2 mg; vitamin B1217.5 mg; niacin 30 mg; Calcium Pantothenate 10 mg; folic
acid 1 mg 2, premix per kg can be expected to provide full price: Cu-6mg,
Fe-100mg, Mn-4mg, Se-0.3 mg, I-0.3 mg
||Effect of chicken plasma protein on growth performance of
|1Each mean represents 4 pens with 16 pigs per treatment.
A,BWithin a row, mean with different superscripts differ (P<0.01).
Statistical differences between groups were denoted by different letter superscripts.
Individual piglet was used as the experimental unit for all data except that
pen used as the unit for weight gain, feed intake, feed efficiency. Each experiment
was repeated at least three times and data represent the mean ± SEM of
Chicken plasma protein on performance of piglets: The ADG, ADFI in the
chicken plasma protein improved and F/G decreased significantly in the whole
time (p<0.01). In 0-14d, ADG, ADFI in chicken plasma protein powder group
significantly raised by 65.50%, 37.11%, respectively (p<0.01), F/G declined
by 16.41% (p<0.01). During 14-28 d, ADG, ADFI in chicken plasma protein powder
group significantly raised by 27.27%, 17.04%, respectively (p<0.01), F/G
declined by 7.88% (p<0.01) (Table 2).
Chicken plasma protein in 0-14,14-28 d after weaning of piglets serum cytokine content: Compared with control group, in 0-14 d, chicken plasma protein lowered serum IL-1 8.6% and IL-4, IL-1ra have a higher trend by 21.61%, 23.73%, respectively; 14-28 d serum IL-1 decreased by 10.92% and IL-4, IL-1ra increased by 16.96%, 6.78%, respectively in chicken plasma protein powder group.
chicken plasma protein in 0-14,14-28 d after weaning of piglets immunoglobulin content: Compared with control group, In 14-28 d, the content of IgG in chicken plasma protein powder group raised by 20.44% and the content of IgG, IgM is lower than the control group.
In the study, In day 0-28, supplementing chicken plasma protein powder could
improve performance, expressing as average daily gain, the average intake was
significantly improved (p<0.01), feed/gain declined evidently (p<0.01);
Many studies report the changes in the expression of inflammatory cytokines
in serum of humans and animal during weaning. (Oswald and Dozois, 2001).
||Effects of chicken plasma protein on IL-1 and IL-4 of weanling
Local expression of IL-1, IL-6 and TNF-alpha mRNA has been largely documented
after bacterial or viral infection in pigs. (Fossum, 1998) To our knowledge,
there are no other reports on the cytokine expression we observed in the serum
when supplementing with chicken plasma protein powder. Post-weaning piglets
had undergone many stresses, for instance, feed sources, environment, psychological
stress and so on, which formed an over-activated situation in vivo, inflammatory
factory (such as: IL-1ß) raised rapidly. (Gu, 2003). The increasing of
IL-1ß in post-weaning pigs is according to others. (Chen and Peng, 2001)
Compared with the control group, chicken plasma protein decreases the serum
IL-1ß by 8.60% in day 0-14; IL-1ra is a protein that is antagonist for
IL-1, founding in animal, the activity of IL-1 can be closed through combination
of IL-1 (IL-1) receptors. (Arend et al., 1998) The results suggest that
chicken plasma protein powder can reduce the levels of IL-1ß and increase
IL-1ra production. That is according to previous studies on intravenous immunoglobulin.
(Sharief and Ingram, 1999) The possible reasons are that chicken plasma protein
contains 15% immunoglobulin, which can exert its effect in vivo. (Pierce,
2005). T cells, a major producer of cytokines, can be separated into two distinct
subsets, Th1 and Th2 cells, on the basis of the pattern of cytokines secreted.
(Mosmann and Coffman, 1989) IL-1ß is a typical cytokines of Th1, It can
lead to disequilibrium when is over-produced in the body and IL-4 is a typical
Th2 cytokine with anti-inflammatory. In day 0-14, IL-4 in the chicken plasma
protein group was raised by 21.7% compared to the Control.
The effect of humoral immunity are performed by B cells (plasma cells), which
is secreting antibodies and antigens for removing the antigen-specific binding;
The effect of cellular immunity is performed through T cells (anti-T cells),
which is secreting perforin for making target cells apoptosis. They can keep
body healthy either or both. (Lebman and Coffman, 1994) The type and quantity
of immunoglobulin in vivo reflect animal's ability to resist diseases.
IgG is the mainly immunoglobulin antibodies in the serum, approximately 85%
of serum immunoglobulin is used for anti-infective immunity.
||Effects of chicken plasma protein (SDCP)onplasma immunoglobulin
concentration of weanling pigs
The level of IgG in body is not only high, but lasted for a long time and
it could play an antibacterial, antiviral, anti-toxins roles in vivo.
In this study, in day 0-14, compared with the control group, chicken plasma
protein powder deceased the serum IgA, IgM. The results are inconsistent with
others (Gao et al., 2004).
It can be suggested that the chicken plasma protein can reduce the over-activation of the immune status by controlling the cellular immunity, so as to promote performance of pigs. In 0-14 d, supplementing chicken plasma protein powder could improve performance, expressing as average daily gain, the average intake was significantly improved (p<0.01), feed/gain declined evidently (p<0.01); It could be caused by decreasing of over-activated of immune responses and improving of cellular immunity. During 14-28 d, the chicken plasma protein was still to improving ADG, ADFI, which was according to the previous results on the broilers. (Li et al., 2002). The results suggested that supplementary of chicken plasma protein powder could shift nutrients that maintaining immunological activity to growth in our study. It maybe also the reason for reducing the secretion of antibody in plasma. But the evidence of it needs to be verified by exploring the regulatory mechanism of metabolism of nutrients in vivo.
This work was supported by Program for Changjiang Scholars and Innovative Research Team in University (Project No. IRT0555).