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African Journal of Pig Farming ISSN 2375-0731 Vol. 8 (1), pp. 001-006, January, 2020. Available online at 
www.internationalscholarsjournals.org © International Scholars Journals 

 

Author(s) retain the copyright of this article. 

 

 

Full Length Research Paper 

 

The influence of the different content of 
protein fractions in sows’ milk in piglet rearing 

 
Ewa Skrzypczak1*, Karolina Szulc1, Monika Demkowicz2, Damian Knecht3, Anna Jankowska-

Mąkosa3 , Janusz T. Buczyński1 and Marek Babicz4
 

 
1
Department of Pig Breeding and Production, Poznań University of Life Sciences, ul. Wołyńska 33, 60-637 Poznań, 

Poland. 
2
Department of Cattle Breeding and Milk Production, The Institute of Animal Breeding, Wrocław University of 

Environmental and Life Sciences, ul. J. Chełmońskiego 38C, 51-630 Wrocław, Poland. 
3
Department of Pig Breeding, The Institute of Animal Breeding, Wrocław University of Environmental and Life Sciences, 

ul. J. Chełmońskiego 38C, 51-630 Wrocław, Poland. 
4
Department of Breeding and Technology of Pig Production, University of Life Sciences in Lublin, ul. Akademicka 13, 20- 

950 Lublin, Poland. 
 

Accepted 15 June, 2019 
 
The aim of this study was to investigate the influence of the percentage content of protein fractions in total 
protein of sow`s colostrums and milk and their influence on the traits related with piglet rearing. The animal 
specimens were 20 sows of the native Złotnicka White breed. Złotnicka pigs were subjected to the National 
Genetic Resources Conservation Programme. Colostrum and milk were collected between the 20th and 24th h 
after parturition and on the 2nd, 3rd, 7th, 14th and 21st day of lactation. A total of 120 samples (60 colostrum 
samples and 60 milk samples) were collected from all active mammary glands. Individual fractions of total 
protein were separated by means of electrophoresis on polyacrylamide gel in the presence of sodium dodecyl 
sulphate (SDS). The piglets’ body weights average daily gains and mortality were checked consecutively after 

24 hours after parturition and on the day 7
th

, 14
th

, and 21
st

 of lactation. 207 piglets were examined. A highly 
significant correlation between the number of piglets, daily growths and protein fractions was observed. The 
most favourable rearing results were obtained at the highest level (III) of individual fractions. The study also 
proved most of the piglets are lost from the litters when the level of fractions is the lowest (I). 

 
Key words: Sows, milk, protein fractions, Złotnicka White, piglet rearing. 

 
INTRODUCTION 

 
Sows’ colostrum and milk are the main sources of 
necessary nutrients during the first days of piglets’ lives 
(Devillers et al., 2004; Skrzypczak et al., 2012a). Milk 
proteins are particularly significant due to the fact that 
they participate in all life processes (Wheeler et al., 2007; 
Stelwagen et al., 2009), they are  
 
 

 
*Corresponding author. E-mail: ewa.skrzypczak@op.pl. 

 
Abbreviations: SDS, Sodium dodecyl sulphate; LSM, least 
square means; SE, standard errors. 

 
 
 

 
an important building block and play an enormous role in 
the development of the immune system (Bernatowicz and 
Reklewska, 2003; Sangild, 2003; Lipiński, 2007; Płusa, 
2009). The proteins whose role has only partly been 
recognised deserve attention. Lactoferrin and β-
lactoglobulin exhibit the antineoplastic effect (McIntosch 
et al., 1998; Szulc, 2010), β-lactoglobulin and immuno-
globulins G also exhibit the supportive effect in viral and 
bacterial infections (Pan et al., 2006, 2007; Płusa, 2009), 

α-lactalbumin is a Ca
2+

 carrier and it is an anti-

carcinogenic, antibacterial, immunological and supportive 
factor. In stressful situations, it may lower the blood 
pressure (Meisel, 1997; Zimecki and Arytm, 2005). 



  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

 
Figure 1. Polyacrylamide gel with milk protein fractions. 

 

 

Casein has above all anticoagulant properties and it 
inhibits thrombocyte aggregation and serotonin liberation 
(Kuczyńska, 2008; Płusa, 2009). Therefore, investigation 
of the correlation between sows’ milk protein fractions 
and results of piglet rearing is justified. 
 

 
MATERIALS AND METHODS 
 
Animals 
 
The animal materials were 20 sows of the native Złotnicka White 
breed, which were subject to the National Genetic Resources 
Conservation Programme ( Szulc et. al., 2012).  

The research was carried out from October, 2009 to September, 
2010. All experimental sows were housed in identical conditions 
meeting all welfare requirements. The sows were housed in single 

farrowing crates from about the 10
th

 day before parturition to the 4
th

 
week of lactation. They were fed individually with standard total 
mixed rations according to polish Nutrient Requirements for Pigs 
(1993). Feed in the amount of 2 kg in one dose was supplied twice 
a day with ad libitum access to water.  

The sows in the experiment were naturally mated according to 
the mating plan approved on the farm and the offspring came from 
one boar. Each farrowing it was supervised by personnel. The 
piglets’ body weight was checked consecutively after 24 h, on the 
7th, 14th, and 21st day of lactation. Altogether 207 piglets from 20 
sows were examined. 
 

 
Collection of materials for analysis and analytical methods 

 
Colostrum and milk were collected after earlier intramuscular 
injection of 2 to 4 ml of oxytocin. The amount of oxytocin 
administered depended on the day of lactation. Colostrum and milk 
were manually collected from all active mammary glands to test 
tubes with a preservative (MILKOSTAT). The samples were 

 
 
 
 
 
 
 
 

 

Serum albumin 
 
 

 

α-casein 
 

β-casein 
 
 
 

 
κ-casein 

 
α-lactalbumin 

 
 
 
 
 
 

 
collected between the 20th and 24th h after parturition and on the 
2nd, 3rd, 7th, 14th and 21st day of lactation. Then the samples 
were cooled down to the temperature of -20°C. Altogether 120 
samples were collected (60 colostrum samples and 60 milk 
samples).  

The electrophoretic separation of individual fractions of total 
protein, that is, serum albumin, α- casein, β- casein, κ- casein, 
immunoglobulins G and α- lactalbumin and other protein structures 
were carried out according to Laemmli’s method (1970) on 
polyacrylamide gel in the presence of sodium dodecyl sulphate 
(SDS). The qualitative and quantitative analysis was carried out 
according to the electrophoretic separations developed by Kim and 
Jimenez-Flores (1994). The percentage share of individual fractions 
of total protein was calculated by defining their sum as 100%. The 
electrophoretic separations were compared by means of a protein 
marker. The separations were archived by means of an optical 
scanner. Bio Rad 6 program was used for qualitative and 
quantitative analysis. Figure 1 shows the vertical electrophoresis of 
colostrum and milk proteins on polyacrylamide gel. 
 

 
Statistical analysis 
 
The obtained data was statistically processed with SAS (2007) ver.  
8.11. Package with the use of the following methods: 
 
1. Normality test (UNIVARIATE).  
2. Multivariate analysis of variance with PROC GLM LSM.  
3. The results were presented as least square means (LSM) and 
standard errors (SE).  
4. For discrete random variables (the number of piglets aged 24 h, 
7, 14 and 21 days) probit transformation described by Żuk (1989) 
and Lynch and Welsh, (1998) was applied, which enables 
transformation from discrete random variables to continuous 
random variables.  
5. The protein fractions were divided according to their levels in 
total protein (Table 1). 

In the statistical models applied for  the  analysis  apart  from  the 



  
 
 

 
Table 1. Protein fractions and their various medium levels.  

 
 

Protein fraction 
 Protein Levels (%)  

 

 

I (low) N = 40 II (medium) N = 40 III (high) N = 40 
 

  
 

 Serum albumin ≤ 0.645 0.646 - 0.963 ≥0.964 
 

 α- casein ≤ 0.673 0.674 - 0.858 ≥0.859 
 

 β- casein ≤ 0.665 0.666 - 0.884 ≥0.885 
 

 κ- casein ≤ 0.722 0.723 - 0.989 ≥ 0.990 
 

 α- lactalbumin ≤ 0.651 0.652 - 0.881 ≥0.882 
 

 Immunoglobulins G ≤ 0.879 0.880 - 1.212 ≥1.213 
 

 Other fractions ≤ 0.860 0.861 - 1.407 ≥1.408 
 

 

 
Table 2. The influence of protein fractions on the average number of piglets  

 

Protein fraction 
 Number of piglets (head) 

 

 

I II III 
 

  
 

Serum albumin LSM 10.31 9.00
a
 10.54

b
 

 

SE 0.68 0.48 0.42 
 

 
 

α – casein LSM 10.21 9.00
a
 10.64

b
 

 

SE 0.66 0.47 0.43  

 
 

β – casein 
LSM 9.53 9.36 10.66 

 

SE 0.60 0.50 0.44  

 
 

κ – casein LSM 10.25 9.06
a
 10.56

b
 

 

SE 0.71 0.48 0.42 
 

 
 

α - lactalbumin LSM 10.36 9.07
a
 10.54

b
 

 

SE 0.74 0.47 0.42 
 

 
 

Immunoglobulins G 
LSM 9.48 9.68 10.57 

 

SE 0.55 0.50 0.48  

 
 

Other protein structures 
LSM 9.92 10.59 10.47 

 

SE 0.59 0.52 0.49 
 

 
 

 
Means designated with small letters (a, b) statistically differ significantly at P ≤ 0.05. 

 

 
main effects under investigation, other effects were also taken into 
consideration: 
 
(i) Season of sample collection (autumn, winter, spring, summer). 
(ii) Sows’ lactation (according to the sow parity number)  
(iii) Colostrum and milk collection (time specified). 
(iv) Piglet’s sex (male, female). 
 

 

RESULTS 

 

Tables 2 and 3 show characteristics of the level-
dependent influence of individual protein fractions on the 
number and growth of piglets in the litter. The average 

 
 

 

number of piglets and their growth rate was proved to be 
the most favourable when the level of fractions in total 
protein was the highest. Those differences were con-
firmed at the level P ≤ 0.01 and P ≤ 0.05.  

The lowest level of protein fractions (I) was also found 
to be decisive for the highest piglet mortality (Table 4) 
and it was proved to affect the piglet’s mean body weight 
(Table 5). The trait was proved to have statistically 
significant differences. 

 

DISCUSSION 
 
In  contrast  to many other species of animals and 



 
 
 

 
Table 3. The influence of protein fractions on the growth of piglets  

 

Protein fraction 
 Week's growth of piglets (kg) 

 

 

I II III 
 

  
 

Serum albumin LSM 0.36
a
 0.52

a
 0.81

b
 

 

SE 0.14 0.10 0.09 
 

 
 

α – casein LSM 0.44
a
 0.51

a
 0.80

b
 

 

SE 0.14 0.10 0.09  

 
 

β – casein LSM 0.43
a
 0.53

a
 0.81

b
 

 

SE 0.13 0.10 0.09  

 
 

κ – casein LSM 0.37
a
 0.51

a
 0.80

b
 

 

SE 0.15 0.09 0.08 
 

 
 

α - lactalbumin LSM 0.38
a
 0.50

a
 0.82

b
 

 

SE 0.16 0.10 0.09 
 

 
 

Immunoglobulins G LSM 0.47
a
 0.52

a
 0.84

b
 

 

SE 0.11 0.10 0.10  

 
 

Other protein structures LSM 0.51
A

 0.53
A

 1.03
B
 

 

SE 0.15 0.13 0.12  

 
 

 
Means designated with capital letters (A, B) differ statistically significantly at P ≤ 0.01. 
Means designated with small letters (a, b) statistically differ significantly at P ≤ 0.05. 

 

 

Table 4. The influence of protein fractions on the piglets mortality.  
 

Protein fraction 
 Mortality of piglets (%)  

 

 

I II III 
 

  
 

Serum albumin LSM 21.00
a
 9.00

b
 11.75 

 

SE 3.69 2.61 1.85  

 
 

α – casein LSM 21.00
a
 9.00

b
 11.75 

 

SE 3.69 2.61 1.85 
 

 
 

β – casein LSM 21.00
a
 9.00

b
 11.75 

 

SE 3.69 2.61 1.85 
 

 
 

κ – casein LSM 21.00
a
 9.00

b
 11.75 

 

SE 3.69 2.61 1.85  

 
 

α - lactalbumin LSM 21.00
a
 9.00

b
 11.75 

 

SE 3.69 2.61 1.85  

 
 

Immunoglobulins G LSM 21.00
a
 9.00

b
 11.75 

 

SE 3.69 2.61 1.85 
 

 
 

Other protein structures 
LSM 9.0 10.0 12.33 

 

SE 2.90 4.11 2.37 
 

 
 

 
Means designated with small letters (a, b) statistically differ significantly at P ≤ 0.05. 



  
 
 

 
Table 5. The influence of protein fractions on the piglet`s body weight  

 

Protein fraction 
  Average body weight of piglet (kg) 

 

  

I II III 
 

   
 

Serum albumin 
 LSM 5.13

Aa
 3.81

b
 2.83

Ba
 

 

 

SE 0.45 0.32 0.27 
 

  
 

α – casein 
 LSM 4.86

Aa
 3.83

a
 2.83

Bb
 

 

 

SE 0.44 0.32 0.29  

  
 

β – casein 
 LSM 4.86

Aa
 3.65

b
 2.84

Bb
 

 

 

SE 0.40 0.33 0.29  

  
 

κ – casein 
 LSM 5.19

Aa
 3.84

ab
 2.83

Bb
 

 

 

SE 0.47 0.31 0.26  

  
 

α - lactalbumin 
 LSM 5.26

Aa
 3.85

ab
 2.80

Bb
 

 

 

SE 0.49 0.31 0.27 
 

  
 

Immunoglobulins G 
 LSM 4.62

Aa
 3.62

b
 2.76

Bb
 

 

 

SE 0.36 0.33 0.32  

  
 

Other protein structures 
 LSM 3.44

a
 3.82

Aa
 2.17

Bb
 

 

 

SE 0.41 0.36 0.34 
 

  
   

Means designated with capital letters (A, B) differ statistically significantly at P ≤ 0.01.  
Means designated with small letters (a, b) statistically differ significantly at P ≤ 0.05. 

 

 

humans, pigs are in practice born without any immu-
nological preparation for life in outer environment due to 
their placenta, which is impermeable to immune bodies. 
Therefore, colostrum is the only possibility to obtain 
immunoglobulins from the mother (Butler and Kehrli, 
2005; Hurle and Theil, 2011). Later, when the level of 
immunoglobulins decreases and they can no longer be 
passively absorbed, the essential role of milk proteins is 
to provide the necessary amino acids for the needs of 
existence, growth and development of newly born 
animals (Patureau-Mirandi et al., 1990; Xu, 1996; Blӓttler 
et al., 2001; Sauter et al., 2004; Senda et al., 2011). 
Therefore, obtaining appropriate growths has a 
considerable influence on piglets’ balanced weight when 
weaned and thus produces the best results of pig 
fattening.  

The authors’ own research proved a statistically signifi-
cant correlation between individual protein fractions of 
colostrum and milk, and the number of piglets and their 
daily gains. The results are also confirmed by experi-
ments on other species of animals. Wroński and 
Sosnowska (2008) proved that bulls fed with colostrum 
with higher specific weight and higher content of whey 
proteins and immunoglobulins gained higher body 
dimensions than those fed with colostrum with a lower 
content of those proteins. 

 
 

 

The experiment on deer calves made by Landete-
Castillejos et al. (2001) confirms the fact that the body 
weight is strongly correlated with the content of protein in 
the milk (P ≤ 0.05). The authors also noted a high 
correlation between the protein and fat ratio and calf 
growth.  

Buczyński et al. (2008) proved that the mean weight of 
the piglet (2.82 kg) and growths were higher in the group 
of sows whose milk had the highest content of protein. 
Boruta et al. (2009) also arrived at similar conclusions in 
their studies on Polish Large White and Polish Landrace 
breeds and their crossbreeds. The authors proved that 
the piglets from the sows with the highest share of protein 
in their milk achieved better rearing results. They also 
noticed a correlation between piglet mortality and the 
share of whey proteins. A higher content of whey proteins 
increased piglets’ survival rate.  

The authors’ own studies confirm the fact that the 
highest mortality of piglets (up to 21%) was according to 
the lowest content of all protein fractions in their mothers 
milk (level I). The results were statistically confirmed.  

Those results were not confirmed in an analogical 
experiment made by Walkiewicz et al. (2004). They noted 
that crossbreeds piglets (Puławska x Duroc) from the 
sows with a higher level of protein grew worse than the 
piglets from the sows with a lower content of total protein. 



 
 
 

 

To sum up the importance of milk proteins in the 
processes of growth and development, it is necessary to 
add that they are not only decisive in piglets’ acquisition 
of immunity but they are also significant in piglet rearing. 
In view of those facts, it is particularly important to ensure 
the piglet’s access to its mother and feeding on colostrum 
as soon as possible after birth. This will guarantee 
minimisation of losses and achievement of high growths 
of piglets. 
 

 
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