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African Journal of Pig Farming ISSN: 2375-0731 Vol. 12 (2), pp. 001-008, February, 2024. Available online at 
www.internationalscholarsjournals.org © International Scholars Journals 

 

Author(s) retain the copyright of this article. 
 

 
 
Full Length Research Paper 

 

Optimizing pig artificial insemination with imported 
fresh semen: Key success factors 

 
Vincent Niyiragira1, Kugonza Donald Rugira1,2* and Hirwa Claire D’Andre1

 
 

1
Rwanda Agriculture Board (RAB), P. O. Box 5016, Kigali, Rwanda. 

2
Department of Agricultural Production (DAP), 

School of Agricultural Sciences (SAS), College of Agricultural and Environmental Sciences (CAES), Makerere 
University, P. O. Box 7062, Kampala, Uganda. *Corresponding author. E-mail: aridian181@gmail.com. 

 
Received 6 July, 2023; Accepted 17 November, 2023  

 
This study was conducted to assess the factors that affect pig litter size, proportion of live pigs at birth, 
number of inseminations per conception, and efficiency of artificial insemination. The main factors 
assessed were sow breed (n = 2), sire breed (n = 3), sow parity (n = 7) and insemination method (n = 2). 
The sow breeds used were Landrace, LL (n = 27) and Landrace × Pietran crossbreds, LP (n = 37); boar 
breeds used were Landrace (LL), Pietran (PP) and Landrace × Pietran crossbreds (LP). Sows were 
randomly inseminated either by boar or artificially, with semen freshly imported from Belgium to 
Rwanda. Landrace (LL) sows had significantly smaller (P<0.05) litter sizes at birth (9.04±0.72) compared 
to LP sows (11.49±0.45). On the other hand, the litter size for LL (9.04±0.58) and LP (11.49±0.67) sires did 
not differ, while PP sires had the highest (P<0.05) litter size (13.37±1.43). Interestingly, the method of 
insemination, whether use of a boar or artificially did not (P>0.05) affect the number of inseminations 
per conception, litter size, and proportion of piglets born live. Sow parity was found to have a linear 
relationship with a mean litter size at birth of 6.9±0.43 piglets for primiparous sows and 15.2±1.12 
piglets for a sow of parity 7. However, the number of piglets born dead increased with parity, peaking at 
3.0±0.66 (parity 7), while it was only 0.2±0.2 for parity 1. Therefore, the LP crossbred sows and Pietran 
sires are recommended. Artificial insemination should be promoted since it performed as well as 
natural insemination but provides other advantages such as African swine fever and inbreeding 
prevention, and avoids boar management costs. 

 
Key words: Breeding, genetic merit, performance, Pietran, pigs.  

 
 
INTRODUCTION 

 
The global pig population in 2017 was estimated at 
784.83 million head (National Hog Farmer, 2017), with 
China leading in pig population at 435.04 million head, 
the top pork-producing country at 51.85 million tons 
(47.9% of world total), top pork-importers (40% of world 

 

 
 
 
 

 
total), and also the leading per capita pork consumer at 
40.9 kg (National Hog Farmer, 2017; Statista, 2018). In 
Africa Uganda leads the per capita pork consumption at a 
meagre 3.5 kg (Birungi et al., 2015; Kugonza et al., 
2015), and hence a lot still has to be done on the 

 
 



2 

 

 
 
 

 

continent. Pig production has been growing on the 
African continent, and particularly in Rwanda; the growth 
has been consistent especially during the post-conflict 
years. The most recent census put the national pig herd 
at 706,000 animals (NISR, 2011), having risen by 35.4% 
during the period 2005 to 2010. The massive shifts are 
being driven by increased demand for pork and pork 
products such as sausages, bacon and special cuts. 
Along with other livestock species, notably cattle, goats 
and sheep; pigs contribute 12% of the Rwandan GDP, 
and a significant 32% to the agricultural GDP (NISR, 
2017). Pig farming in peri-urban areas is highly 
competitive when compared to goat and cattle farming 
(Nabikyu and Kugonza, 2016). This is attributed to pigs 
requiring less land per livestock unit for acceptable levels 
of production. Farmers in peri-urban areas in much of 
East Africa also have access to agro-industrial by-
products such as wheat pollards, brewers waste, 
molasses, and brans of maize, rice and wheat 
(Mwesigwa et al., 2013; Kugonza et al., 2015). These 
feedstuffs form the basal diet of pigs under commercial 
production. A major drawback to improving productivity is 
the breeding management, especially regarding 
unavailability and limitations in propagation of superior 
pig genetic material.  

The use of artificial insemination (AI) technique for pigs 
and non-bovine livestock is very limited in Rwanda. The 
major driver of AI use is the need to disseminate superior 
genes within a given population at a reasonable cost. The 
greatest advantage of promoting AI use is that it will 
make possible, the widespread use of outstanding 
breeding sires and dissemination of valuable genetics to 
both big and small farms. This will lead to faster genetic 
improvement of the national pig herd. Pig AI technology 
has been in use in Northern Rwanda at a private farm but 
is yet to be tried out at community level, where breeding 
boars are still communally used through natural service. 
Small/medium scale farmers who do not own boars on 
their farms rely on a neighbour’s boar to breed their sows. 
This has also been reported in neighbouring Uganda 
where over 52% of smallholder pig farmers do not own a 
breeding boar (Bamundaga et al., 2018). However, this 
practice of communal boars promotes the spread of 
diseases especially African swine fever and various 
reproductive diseases because of the movement and 
contact between animals. Also, the sharing of the boar by 
many farmers leads to its overuse which might explain 
the occurrence of small litter sizes at subsequent births. 
This ultimately leads to a low number of pigs per sow per 
year and economic loss.  

AI of the pig involves collection of semen from a boar 
and then introducing it into a sow or gilt later on by means 
of a catheter (Ikani and Dafwang, 1999; Bamundaga et 
al., 2018). It differs from natural service which involves a 
boar mounting the sow and introducing his semen by 
copulation. Sperm, the main ingredient in semen was first 
seen by Leeuwenhoek and Hamm in 

  
  

 
 

 

1678 (Foote, 2002). Then, the first successful 
insemination was performed in dog by Spallanzani in 
1784 and over a century later, in 1897, AI in livestock 
specifically rabbits and horses was then reported (Foote, 
2002). Pig AI was first performed by Ivanoff in Russia 
almost a century ago (Ombelet and Van Robays, 2015) 
however, its wide commercial application in pig 
production is more recent. It is just over two decades ago 
when insemination protocols for pig AI were standardized 
(Gadea, 2003), and related work continues. A 
contemporary study (Bamundaga et al., 2018) has 
recently established that single and double AI protocols 
lead to non-varying conception rates (94.4 versus 
89.6%), and litter sizes (8.16±0.34 versus 9.00±0.39 
piglets).  

Recent estimates put pig AI at nineteen million 
inseminations worldwide per year and of these, almost all 
(99%) are done using boar semen preserved at 
temperatures of 15 to 20°C (Johnson et al., 2000). AI in 
pigs: (i) Allows for the wider use and distribution of boars 
of high genetic merit; (ii) Allows up to 25 sows to be 
served with semen from one boar ejaculate, each dose 
given to a sow containing 2 to 3 billion spermatozoa in 80 
to 100 ml (Maes et al., 2010); (iii) Prevents the 
transmission of diseases from farm to farm by the 
movement of sows to and from the boar as well as the 
sale of diseased boars; (iv) Helps to overcome the 
challenge of differences in size of males and females, 
especially the limited use of heavy boars which may be of 
high genetic caliber; (v) Eliminates the need to purchase, 
house and feed boars especially on small scale 
agriculture; (vi) Reduces the farmers risk of handling 
boars for use in natural service (Ikani and Dafwang, 
1999).  

Currently, the pig breeds reared in Rwanda include 
Large White (on 22.9% of pig farms), Landrace (37.7%), 
Pietrain (7.3%), Duroc (1.6%), Local (2.3%) and non-
descript crossbred (28.1%) pigs (Mbuza et al., 2016). The 
local pigs are black in colour or black in mixture with 
white. The productivity of the local pigs is still very low, 
characterised by low birth weight and slow growth rate. 
The average age at first farrowing of sows is between 18 
and 24 months, while the number of piglets born from the 
black pigs range from 8 to 10 piglets, and a mature 
weight of 120 kg is attained in pigs aged 18 months 
(RARDA, 2010). For the Large White breed, the average 
weight of 70 kg is attained at 5 months, while first 
farrowing occurs at 12 months, with a litter size of 10 to 
12 piglets. Growth performance of the Landrace breed is 
generally better than the Large White although 
performance data is not readily available (RARDA, 2010). 
Pietrain pigs on the other hand generally have lower 
growth rates but produce predominantly lean carcasses 
when the effect of feed is accounted for. This study was 
therefore conceived to study the major factors that 
influence the success of an artificial insemination 
programme that uses imported fresh boar semen. 



3 

 

 
 
 

 
MATERIALS AND METHODS 
 
Ethical approval 
 
This research followed ethical standards and complied with 
regulations of the Rwanda National Council for Science and 
Technology. 

 

Study location 
 
The study was conducted at Centre de Perfectionnement agricole 

et elevage de Kisaro (1
o
37'41.99''S; 30

o
01'39.11''E), a private farm 

located at Kisaro sector, Rulindo district in the Northern province of 
Rwanda. The site is at around one and half hours’ drive from Kigali 
City. 

 

Experimental animals 
 
Sixty-four sows of Landrace breed (n = 27) and Landrace × Pietrain 
crossbreed (n = 37) were used in this study. The sows were of 
parities ranging from one to seven. Semen or boars used were of 
Landrace breed (n = 28), Pietrain breed (n = 15) and Landrace × 
Pietrain crossbreeds (n = 21). Forty of the total experimental sows 
were bred using artificial insemination, while twenty four were bred 
using natural mating with the boar. The experiment was conducted 
over eight month duration. 
 

 
Source of semen for artificial insemination 
 
Fresh semen was imported from Hypor (a Hendrix genetic 
company), a breeding company based in Belgium (HYPor Belgium 
V, Leie Rechteroever19870, Olsene Belgique, T 014 63 53 47, 
F014 63 54 79, (www.hyvarselect.be). Semen collection was 
performed the day prior to shipment to Rwanda. Semen was 
collected from several boars, pooled and then extended using 
standard protocols before being shipped. 
 

 
Housing 
 
All pigs at the farm were kept indoors, adults in individual pens, 
while weaners and growers were reared in groups of up to ten. 
Individual pens were made of a concrete floor, with walls of brick 
measuring up to 1.5 m in height. The average floor space area per 
adult pig was up to six square metres. Farrowing pens measured 
2.5 m by 2.5 m, boar pens measured 2.5 m by 1.25 m while grower 
pigs were kept in pens measuring 2.5 m by 1.25 m. Pig house roofs 
were made of corrugated iron sheets. 
 

 
Feeding 
 
The main diet of the pigs was a composite ration made of maize 
bran, wheat bran, bone meal, soybean meal, fish meal, vitamin 
mineral premix and salt. The wheat and maize used in feed 
formulation was largely produced on the farm. The pigs were fed 
twice a day, at 09:00 to 10:00 h, and at 15:00 to 16:00 h. On 
average, each mature pig was given 2.5 kg of the composite ration 
per day, with bigger sows getting proportionately higher amounts. 
Water was provided ad libitum. 

Piglets were farrowed in specialized farrowing pens (2.5 m x 2.5  
m) and received an injection of iron on the 3

rd
 day of their lives. 

Piglets stayed with their mother from birth until weaning at two 
months, though they had access to creep feed placed in a 

 
 
 
 

 
specialized creep area, accessible only to piglets. Castration of 
male piglets was done within one to two and a half months of age. 
At weaning sows were removed from the pens and the weaned 
piglets were allowed to stay in the pens for extra one week. 
Afterwards, the weaners were segregated by sex and relocated to 
grower pens (2.5 m x 1.25 m) in groups of up to ten. 

 

Breeding and health management 
 
Sows naturally came on heat 3 to 7 days after weaning their litters, 
and had never been induced using hormonal treatment, but were 
regular breeders. Gilts were bred on their second heat, at the age of 
seven months. The sows were allocated individual pens next to 
adult boars to enable estrus detection. In addition, the back 
pressure test for standing heat reflex was performed and those that 
responded were considered to be in estrus. The sows were either 
taken to the boar for supervised service or were inseminated with 
imported extended fresh semen. Twenty four sows were served by 
boars twice using the AM-PM rule, so as to maximize on the 
conception rate. Each boar was allowed to serve a maximum of four 
sows a week to avoid them being overworked. Sows and gilts were 
served by boars in rotation to mimic AI where semen from several 
boars was pooled, in consideration of the desired breed. On the 
other hand, 40 sows were artificially inseminated twice, about 24 h 
between the inseminations using the AM-PM rule. Each dose 
inseminated by AI contained 2.5 billion spermatozoa in 80 ml. The 
intra-cervical method was used in all inseminations (Darwin, 2007), 
with extra care taken to minimize backflow. Conception was 
indicated by a non-return to heat after 18 to 22 days, the few gilts 
that did not conceive on first insemination were served again on the 
subsequent natural heat.  

The pigs were washed every week using water and soap. There 
was no practice of spraying against ecto-parasites, instead, double-

acting dewormer Ivermectin
®

 was used for this purpose. The pigs 
were dewormed once every three months. Disease outbreaks were 
described by the farm management as being very rare on the farm. 

 

Record keeping 
 
Records on each piglet farrowed were kept on the farm. Records 
that were taken included farrowing date, sow breed, boar breed, 
parity of sow, litter size (number born alive and stillborn), method of 
insemination used, and live body weight (taken monthly). Dates of 
treatment in cases of disease, inseminations and routine animal 
management practices were recorded as well. The farrowing rate 
recorded was 86% and above. 

 

Study design, data collection and data analysis 
 
The study used a completely randomized design with sows that 
were recruited into the study randomly selected from the herd. Also, 
sows that were subjected to artificial insemination were randomly 
selected from the experimental group so as to avoid bias. Data 
were collected over an eight months period following 
specified/standard procedure, taking care to avoid stressing the 
animals, in consonance with the national provisions on animal 
welfare and ethics in handling experimental animals.  

Data was checked for validity and was then entered into MS 
Excel spreadsheets. It was then subjected to analysis of variance 
using the generalized linear model procedure of Statistical Analysis 
Systems, version 9.2 (SAS, 2004). The fixed effects were sow 
breed, boar breed, sow parity, and insemination method. The model 
used for data analysis was: 
 

Yijklm = Si + Bj + Pk + Il + SBij + SPik + BPjk + PIkl + eijklm N (0, σ
2

e) (i) 



4 

 

  
 
 

 
Table 1. Least square mean litter size, piglets born alive, stillborn piglets, inseminators per conception.  

 
 

Factor Level Litter size 
Piglets born Stillborn Inseminations 

 

 
alive piglets per conception  

    
 

 
Sow breed 

Landrace × Pietrain (n = 37) 11.49
a
 10.81

a
 0.67 1.02 

 

 

Landrace (n = 27) 9.04
b
 7.79

b
 1.25 1.11 

 

  
 

  Landrace × Pietrain (n = 21) 7.99
a
 7.51

a
 0.47 1.09 

 

 Boar breed Landrace (n = 28) 9.43
a
 8.29

a
 1.14 1.10 

 

  Pietrain (n = 15) 13.37
b
 12.09

b
 1.27 1.01 

 

  1
st

 (n = 21) 6.91
a
 6.76

a
 0.15

a
 1.06 

 

  2
nd

 (n = 15) 8.27
ab

 7.77
a
 0.50

a
 1.12 

 

  3
rd

 (n = 9) 9.96
ab

 8.75
ab

 1.21
ab

 0.98 
 

 Parity 4
th

 (n = 6) 9.28
ab

 8.28
a
 1.00

ab
 1.24 

 

  5
th

 (n = 5) 9.84
ab

 8.66
ab

 1.17
ab

 1.01 
 

  6
th

 (n = 4) 12.29
ab

 12.44
c
 -0.14

a
 1.02 

 

  7
th

 (n = 4) 15.29
c
 12.44

c
 2.85

b
 1.02 

 

 
Insemination method 

AI
§
 (n = 40) 8.06 7.45 0.61 1.17 

 

 

NS
∫
 (n = 24) 12.47 11.15 1.31 0.97 

 

  
 

 SEM  0.429 0.404 0.164 0.025 
 

 LSD  1.48 1.32 0.60 0.10 
  

§
AI = artificial insemination; 

∫
NS = Natural service. 

abc
 = means with similar superscripts within column and factor are not different (P<0.05) 

 
 

 
Where, Yijklm = observation of the variable for the a sow breed i, 
mated to boar breed j, for sow parity k and for insemination method  
l; µ = overall mean; Si = effect of sow breed (i = 1,2); Bj = effect of 
boar breed (j = 1,2,3); Pk = effect of sow parity (k = 1,2,3,4,5,6,7); Il  
= effect of sow insemination method (l = 1,2); SBij = effect of the 
interaction between sow and boar breed; SPik = effect of the 
interaction between sow breed and parity; BPjk = effect of the 
interaction between boar breed and sow parity; PIkl, = effect of the 
interaction between sow parity and insemination method; eijklm is the 
random effect on the trait, independently and identically distributed 

with mean = 0 and variance = e
2
.  

Model (i) above was used in the preliminary analysis. Due to the 
finding that the sow and boar breed interaction effect SBij, the sow 
breed and parity interaction effect SPik, the boar breeds and sows 
parity interaction affect BPjk, and the sow parity and insemination 
method interaction effect PIkl did not significantly affect the 
variables, they were eliminated from the model, subsequently, the 
model finally used is shown as follow: 
 

Yijklm = Si + Bj + Pk + Il + eijklm N (0, σ
2

e) (ii) 
 
Duncan’s multiple range test was used to separate means. 
 

 

RESULTS 

 

The mean number of piglets born alive was 39% higher 
for crossbred sows compared to pure landrace sows 
(Table 1). However, the differences in number of piglets 
born live between boars of the two breed types were not 
significant; instead, it is the value for Pietrain boars that 
stood out; 53% piglets more than the other categories. 
Parity of the sow did not influence the number of piglets 

 
 
 

 

born alive, but it did significantly influence the total litter 
size. Litter size clearly increased with parity, rising 
consistently from 6.91 piglets for sows of first parity to 
15.29 piglets for sows of parity 7, a 121% increment. The 
litter size as well as the number of piglets born alive did 
not differ between sows bred using artificial insemination 
and those that were bred using natural service.  

The number of stillborn piglets was not affected by sow 
breed, boar breed, and insemination method; but was 
influenced significantly (P<0.05) by parity of the sow. In 
general, the number of stillborn piglets increased with 
parity (Figure 1), rising from 0.15 for primiparous (first 

parity) sows to 2.85 for 7
th

 parity sows.  
Considering the number of inseminations per 

conception, all the factors namely sow breed, boar breed, 
sow parity, and insemination method did not show 
significant differences (P>0.05). 
 

 

DISCUSSION 
 
This study focused on establishing the determinants of 
success in a pig artificial insemination programme using 
semen freshly imported from Europe to Central Africa. 
Sows inseminated artificially had a litter size of 8.06±0.42 
piglets quite comparable to 9.06±0.4 piglets reported by 
Bamundaga et al. (2018) and 10.8±2.2 (Chanapiwat et 
al., 2014), and despite being in varying locations, the 
studies used landrace breed and its combinations with 
other breeds. Improvements in the management of 



5 

 

  
 
 

 

 18       
 

 16       
 

 14    y = 1.1807x + 5.54   

      
 

o
f 

p
ig

le
ts

 12    y = 0.9389x + 5.5443  
 

10       
 

8       
 

N
u

m
b

e
r       

 

6       
 

4       
 

       
 

 2    y = 0.2421x - 0.0057   

      
 

 0       
 

 1 2 3 4 5 6 7 
 

 -2   
Parity 

  
 

      
  

 
Figure 1. Effect of parity on litter size, piglets born alive and those born dead. 

 
 
 
 

 

 Litter size 

 
 

 Piglets born live  

 

 Stillborn piglets 
 

 

 Inseminations 
per conception 

 

Linear (Litter size)  
 
 

Linear (Piglets born 
live) 

  

Linear (Stillborn  

piglets) 

 

 

 

artificial insemination imply that the technology can 
continue to impact the pig industry. Despite Chanapiwat 
et al. (2014) reporting that the main limitation of the 
extended fresh semen is the short timing of semen 
storage, and the likelihood that semen cannot be 
transported for a long distance, results of this study that 
used semen transported from Northern Europe shows 
that this is not an issue. Instead, the chance of 
distributing a good genetic resource across countries and 
particularly, enabling locally raised sows to be bred with 
semen having the best estimated breeding values 
available in Europe is very real. Use of AI for breeding 
pigs has become instrumental for facilitating global 
improvements in fertility, genetics, labour, and herd 
health (Bortolozzo et al., 2015; Knox, 2016).  

The differences in number of piglets born live between 
boars of the two breed types in this study were not 
significant (Table 1), instead, it is the value for Pietrain 
boars that stood out over the other categories. The 
establishment of AI centers for management of boars and 
production of semen has allowed for selection of boars 
for fertility and sperm production using in vitro and in vivo 
measures (Ringwelski et al., 2013; Knox, 2016).  

Parity of the sow did not influence the number of piglets 
born alive (Table 1), but it did significantly influence the 
total litter size. Second parity sows have been reported to 
produce an average litter size of 8.36±0.28 when 
artificially inseminated, and 10.6±0.64 when naturally 
served by the boar (Ronald et al., 2013). While that study 

 
 

 

found the differences between the two methods were 
significant, this study found contrary results. Though the 
superiority of natural mating in both studies is vivid and 
indeed, this study found a higher litter size (12.47) than 
that of the Indian study, which was also done at a private 
farm. Low parity females especially pregnant gilts and 
primiparous sows have also been reported elsewhere to 
have lower reproductive performance than sows in 
parities between second and fifth parity (Koketsu et al., 
2017). Sow fertility is also closely associated with varying 
doses of semen volume and spermatozoa count for AI 
(Apic et al., 2015).  

While stillbirths were found in both artificially and 
naturally inseminated sows, other studies (Ronald et al., 
2013) reported still births only in naturally inseminated 
sows. The variance between the two studies could be 
attributed to the parity factor, since the study had mixed 
parities, with older sows having high stillbirths and the 
values must have been responsible for swaying the 
overall mean.  

Other contemporary studies also strongly support the 
position that number of piglets born and the number of 
live born piglets are highest in 2 to 3 parity sows and drop 
significantly in sows of more than five parities (Wegner et 
al., 2014). While the number of still born piglets was 
lowest in second parity sows (0.5), Wegner et al. (2014) 
found the lowest (0.8) in first parity sows, and the highest 
(1.44) in sows of more than five parities, slightly higher 
than 1.17 that was found in the current study. 



6 

 

 
 
 

 

Conception failures in pigs have been known to result 
from effects of the season, mode of insemination, age of 
the sow, and the number of times the female is 
inseminated, and the females’ birth litter sex ratio 
(Drickamer et al., 1997; Wegner et al., 2014), this study 
differs having found that the mode of insemination and 
number of times the female is inseminated did not have 
significant effects. 
 

 

Conclusion 

 

Litter size of weaned sows bred by natural service or AI 
was the same. In addition AI has the significant 
advantage of enabling locally raised sows in Rwanda to 
be bred with semen having the best estimated breeding 
values available in Europe, from Belgium. AI relying on 
imported semen should be promoted especially for 
introduction of superior genetics for which grade boars 
may not be manageable in tropical Africa. 
 

 

ACKNOWLEDGEMENTS 

 

The comments of the reviewers are strongly appreciated 
as they have contributed to improvements to the 
manuscript. 
 

 

CONFLICT OF INTERESTS 

 

The authors declare that there is no conflict of interests. 
 

 
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