Experimental design, piglet selection and sampling
During the formation of the experimental
groups, piglets were selected randomly, but taking into
account piglet weight, so that each group contained
piglets of similar weight. All sows in the study were
from the second to the fifth farrowing parity. At 3 days
old, male piglets were surgically castrated. On farm I,
1200 piglets from 110 litters were included in the study,
and on farm II 420 piglets or 40 litters. The piglets were divided into 4 groups: in the first, the piglets received
200 mg of an iron dextran complex intramuscularly
(IM) on the third day of life; in the second group, the
piglets received 200 mg of iron per os (feed using the
doser) in the form of a micro-emulsion on the third day
of life (PO); the third group of piglets were given 200
mg of an iron dextran complex subcutaneously (SC);
while the fourth group of piglets did not receive iron,
so acted as the control group (C). Subsequently, piglets
were labeled with tattoo numbers and ear color tags (4
colors), to enable easier tracking.
Prior to the application of iron in each litter,
four piglets were randomly selected from each group
(IM, PO, SC and C) and blood samples were taken from
them by puncture of brachiocephalic plexus. These pig-
lets were additionally marked with a stamp on the other
ear, and at weaning on 28th day of life, blood samples
were again taken from them. Approximately 2 mL of
blood was collected into tubes containing heparin (the
anticoagulant for determination of iron concentration
in blood plasma) or ethylenediaminetetraacetic acid
(the anticoagulant for determination of Hb and Hct).
Blood samples were sent to the laboratory for analysis
within 30 min of collection. On farm I, blood samples
were taken from 440 piglets (110 from each group),
and on farm II from 160 piglets (40 from each group).
Blood analyses and production performance monitoring
Blood was sampled and after 4 h centrifuged
for 10 min at speed of 6000 revolutions per min. The
iron analysis was done using the Ferrozine method.
The readout was performed on an automated analyzer
Biosystems Model A15, at the wavelength of 560 nm.
The control sera produced by Biosystems were used
in two levels (normal and pathogen) and in duplicates.
Hb concentration and Hct values in donor blood were
analyzed using a Siemens ADVIA 120 analyzer. The
controls were performed at three levels with the con-
trol blood.
The following indicators of production per-
formance were monitored in all piglets in the study:
weight of piglets, average daily gain (ADG) and
mortality of piglets. Piglet weight and ADG were
measured for each litter separately and in total for
each experimental group. All piglets were measured
on the third day of life, at weaning (28th day of life)
and at the end of the nurturing stage (70th day of life).
The mortality rate of piglets was calculated for each
experimental group. Statistical analysis of productivity performance
Data were entered into an Excel spreadsheet
(Microsoft Excel 2010) and imported into Stata (Stata
8 Intercooled for Windows 9x) in which data were
analyzed. Descriptive analysis was completed using
Minitab version 14 (MiniTabR14b) and Excel (Mi-
crosoft Excel 2010). For ADG, the differences among
the methods of iron administration were statistically
analyzed with a one-way ANOVA test in a completely
randomized design using Statistical Packages for the
Social Sciences [15]. The significant differences among
means were compared using Post Hoc Test. Mortality
rates were analyzed in a logistic regression using the
procedure GENMOD in SAS (chisquared (χ2
) values
were generated as the test statistic) and the results are
expressed in percentages.