AABArchives Animal BreedingAABArch. Anim. Breed.2363-9822Copernicus GmbHGöttingen, Germany10.5194/aab-58-49-2015The impact of season, parity and breed on selected reproductive
performance parameters of sowsKnechtD.ŚrodońS.sebastian.srodon@up.wroc.plDuzińskiK.Institute of Animal Breeding, Wroclaw University of Environmental and Life
Sciences, Chelmonskiego 38C, 51-630 Wroclaw, PolandS. Środoń (sebastian.srodon@up.wroc.pl)4March2015581495611February201413November2014This work is licensed under a Creative Commons Attribution 3.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by/3.0/This article is available from https://aab.copernicus.org/articles/58/49/2015/aab-58-49-2015.htmlThe full text article is available as a PDF file from https://aab.copernicus.org/articles/58/49/2015/aab-58-49-2015.pdf
The aim of the study was to identify the detailed impact of the season,
parity and breed on reproductive performance of sows. The experimental
material consisted of 2100 sows, in 3 breed variants: 700 PL, 700 PLW, 700
crossbreeds PL × PLW. Sows were observed until parity 5. In the
context of the breed, depending on the order of parity groups of 140 sows
were isolated. Then, sows were divided in terms of farrowing season into
subgroups numbering 35 sows. At the age of 8 months gilts were allocated for
reproduction performance. The highest seasonal impact was noted for piglet
birth weight (P≤0.01). Parity had less effect only on the number of
piglets weaned (P≤0.05). Breed influenced to a lesser extent the number
of piglets born live and weaned (P≤0.05), while birth and weaning
weight had greater importance for piglets (P≤0.01). The interaction
between the studied factors was also observed. The impact of season, parity
and breed interdependence on the number of piglets born live were confirmed
statistically (P≤0.05). The analysis of piglet birth weight allowed the
stronger interaction effect of parity × breed on this parameter to
be noted (P≤0.01). The analysis of variance for piglet weaning weight
confirmed strong relations between all tested factors (P≤0.01). Our
study has shown that reproductive parameters can be strongly affected by
season and parity. In addition, it must be emphasized that the impact of
these factors was different for the studied breeds of sows.
Introduction
Improving the efficiency of piglet production is only possible through
detailed analysis of all factors. It is estimated that over the course of
their whole lives sows rear an average of only 30–40 piglets (Patterson et al., 2010),
thus the validity of a careful evaluation of the reproductive
performance of sow determinants.
Among the most frequently mentioned factors affecting the reproductive
performance of sows should be highlighted: season, parity, breed, lactation
length and nutrition (Bloemhof et al., 2008). The last two factors can be easily
eliminated or at least standardized using identical/similar levels of
nutrition and lactation length. The season, parity and also breed directly
affect the volume of production, therefore it is important to perform a
detailed analysis of the impact of these factors.
Season is an issue which is one of the most important environmental factors
directly affecting the reproductive performance of pigs (Love et al., 1993). It
has been proved that season has a direct impact on litter size and piglet
survival after birth (Tummaruk et al., 2010). Additionally, it may affect results
in the rearing of piglets, for example due to heat stress and feed intake
during lactation. Within the season, temperature variation and photoperiodic
reaction are considered the main causes influencing fertility (Knecht et al., 2013), although the resistance of individuals is dependent on the breed
(Wysokońska and Kondracki, 2013).
Parity order is associated with physiology, primarily with growth of the
organism, and in particular with the development of the reproductive system.
Lengthening the production life of sows should be an important foundation of
production because from the 3rd parity sows generate financial profitability
in terms of their exploitation (Engblom et al., 2007). It should be noted that the
results of research into parity are not clear. Takai and Koketsu (2008)
observed that thanks to repeated insemination of sows higher numbers of
piglets were born only in the 1st and 2nd parity, but not in subsequent
ones. Hoving et al. (2011) found that sows attain the best reproductive
parameters between parity 3 and 5.
Breed is very important factor affecting the reproductive performance of
sows. Producers striving to increase productivity use not only pure breed
but also crossbreed sows (Vanderhaeghe et al., 2010). The genetic potential of
pigs has drastically changed over the last 50 years, affecting the
improvement of production parameters (Brown-Brandt et al., 2004). The most severe
pig selections have been made in nucleus herds from temperate climates in
combination with improved environmental conditions (Knap, 2005). High
performance is also achieved through the application of appropriate crossing
programs on the maternal side (Bösch et al., 2000). The result is the effect
of heterosis which effects an improvement of reproductive traits burdened
with low heritability.
The aim of this study was to determine not only the simple effect of the
season, the parity and breed on the selected reproductive performance
parameters of sows, but primarily to investigate the interaction between the
factors studied and an indication of the periods in which producers can
expect decrease and increase in the number of live born and weaned piglets
and also the periods in which piglets have lower and higher birth and weaned
weight to ensure the uninterrupted stability and continuity of production.
Material and methodsExperimental location and design
The research was carried out on an industrial pig farm located in Opole
province, Poland. The farm is located in a temperate climate zone, which is
distinguished by the four seasons – climatic periods. On this basis, the
sows were divided into the four experimental groups on the basis of
farrowing time: Winter (January–March), Spring (April–June), Summer
(July–September) and Autumn (October–December).
The impact of the season, parity, breed and interaction of these factors on
selected reproductive performance parameters of sows.
FactorParameter The total number The total number Average pigletAverage pigletof live born pigletsof weaned pigletsbirth weightweaned weightSeason – a*****Parity – b*******Breed – c******Season × Parity – (ab)*ns***Season × Breed – (ac)nsns***Parity × Breed – (bc)*ns****Season × Parity × Breed – (abc)nsns***
ns: not significant, * statistically significant differences, with
0.01<P≤0.05, ** statistically highly significant differences,
with P≤0.01.
Experimental animals, housing and feeding
The experimental material consisted of 2100 sows, in 3 breed variants: 700 PL, 700 PLW, 700 crossbreeds PL × PLW. Sows were observed until
parity 5. In the context of the breed, depending on the order of parity
groups of 140 sows were isolated. Then, sows were divided in terms of
farrowing season into subgroups numbering 35 sows. At the age of 8 months
gilts were allocated for reproduction performance.
After insemination, sows were housed for a period of one month in separate
pens. Then, sows were kept in group pens (10 sows), with access to range.
Sows were moved to the farrowing pens a week before the end of pregnancy.
During the first period of pregnancy, sows were fed 2.80 kg day-1, which
consisted of 11.22 MJ metabolic energy, 139.40 g crude protein, 6.30 g
lysine, 5.25 g methionine + cystine, 8.85 g Ca, 6.35 g P and 2.75 g Na.
After day 85 of pregnancy daily feed was increased to 3.25 kg day-1, which
consisted of 12.64 MJ metabolic energy, 170.23 g crude protein, 10.23 g
lysine, 6.75 g methionine + cystine, 8.87 g Ca, 7.24 g P and 2.90 g Na.
During lactation, sows were fed ad libitum.
Insemination
Signs of heat were detected in the presence of a boar twice a day. Heat was
diagnosed observing the occurrence of standing reflex tolerance when
pressure was applied on the spine. Sows were inseminated with Duroc
× Pietrain [D × P] boar's semen. Spermatozoa
concentration in seminal doses was 3.5 × 109 in 100 mL.
Dilution of semen was made with a BTS boar semen extender (Version
13525/0100 Antibiotic free, Minitube International, Verona, USA). Sows were
inseminated with fresh semen or semen stored at a temperature of 15 ∘C, but for no longer than 48 h. Before insemination,
insemination doses were heated to a temperature of 35 ∘C.
Insemination was repeated after 24 h. Pregnancy diagnosis was performed
twice between 28 to 35 days after insemination using USG DRAMINSKI® SonoFarm profi (DRAMINSKI S.A, Olsztyn, Poland).
Reproductive performance analysis
The assessment of reproductive performance was carried out for each sow
participating in the experiment. Four selected reproductive parameters were
analysed: the number of live born piglets (head), the number of piglets
weaned (head), average piglet birth weight (kg) and average piglet weaned
weight (kg). The evaluation was performed on litters immediately after the
completion of delivery and during the end of the lactation period. To assess
the weight of the piglets electronic scales were used. Piglets were weaned
from sows after 28 days. The age structure of the sows involved in the
experiment was similar.
Statistical analysis
The numerical material was analysed using the STATISTICA PL program
(StatSoft, Inc. Tulsa, OK, USA). The values in the tables are arithmetic
means (x¯), standard deviations (SD). The collected data were checked
for normality with the Kolmogorov-Smirnov (K-S) test with Lilliefors
correction. In addition, the Brown-Forsythe test (B-F) determined whether
the distributions of the variables have the same variance. To determine the
effect of season, parity and breed on selected reproductive performance
parameters, the three-way analysis of variance (ANOVA) was used. An advanced
mixed model using the GLM procedure was used and this performed an analysis
of variance for factorial designs. The significance of differences was
calculated on the basis of Tukey's test. The levels of significance of
differences were given conventionally: significant 0.01<P≤0.05
and highly significant P≤0.01. The statistical model was as follows:
Y=μ+a+b+c+(ab)+(ac)+(bc)+(abc)
where Y is the value of the dependent variable, μ is the general average, a is
the main effect of the season [Winter, Spring, Summer, Autumn], b is the main
effect of the parity [1 parity, 2 parity, 3 parity, 4 parity, 5 parity], c is
the main effect of the breed [PL, PLW, PL × PLW], (ab) is the
interaction effect of season and parity, (ac) is the interaction effect of
season and breed, (bc) is the interaction effect of parity and breed, (abc) is the
interaction effect of season, parity and breed.
The impact of season, parity and breed on the total number of live born
piglets.
a,b In the same row signifies statistically significant differences
between breeds, with P<0.05, c,d in the same column signifies
statistically significant differences between seasons for the specific breed
within the same parity, with P<0.05, e,f in the same column
signifies statistically significant differences between parities for the
specific breed within the same seasons, with P<0.05.
The impact of season, parity and breed on the total number of weaned piglets.
a,b In the same row signifies statistically significant differences
between breeds, with P<0.05, c,d in the same column signifies
statistically significant differences between seasons for the specific breed
within the same parity, with P<0.05, e,f in the same column
signifies statistically significant differences between parities for the
specific breed within the same seasons, with P<0.05.
The impact of season, parity and breed on average piglet birth weight.
a,b In the same row signifies statistically significant differences
between breeds, with P<0.05, c,d in the same column signifies
statistically significant differences between seasons for the specific breed
within the same parity, with P<0.05, e,f in the same column
signifies statistically significant differences between parities for the
specific breed within the same seasons, with P<0.05.
The impact of season, parity and breed on average piglet weaned weight.
a,b In the same row signifies statistically significant differences
between breeds, with P<0.05, c,d in the same column signifies
statistically significant differences between seasons for the specific breed
within the same parity, with P<0.05, e,f in the same column
signifies statistically significant differences between parities for the
specific breed within the same seasons, with P<0.05.
Results
The statistical analysis confirmed the significant impact of three studied
factors for all the evaluated parameters of sow reproductive performance
(Table 1). The highest seasonal impact was noted for piglet birth weight
(P≤0.01). Parity had less effect only on the number of piglets weaned
(P≤0.05). Breed influenced to a lesser extent the number of piglets
born live and weaned (P≤0.05), while birth and weaning weight had
greater importance for piglets (P≤0.01).
The interaction between the studied factors was also observed. The impact of
season, parity and breed interdependence on the number of piglets born live
were confirmed statistically (P≤0.05). Additionally, the existence was
observed of four interactions on piglet birth and weaning weight. The
analysis of piglet birth weight allowed the stronger interaction effect of
parity × breed on this parameter to be noted (P≤0.01). The
analysis of variance for piglet weaning weight confirmed strong relations
between all tested factors (P≤0.01).
Detailed results of the effects of factors on the number of live born
piglets are shown in Table 2. A significant decrease in the number of
piglets for PL breed, in comparison with PLW breed and PL × PLW was
recorded in parity 3 during Summer, and the fourth parity also during Summer
(P≤0.05). The largest differences between seasons for PL sows was noted
in parities 3, 4, and 5 (P≤0.05). The greatest number of live born
piglets for PL sows was observed in parity 5 during Winter (P≤0.05).
PLW sows bore the lowest number of piglets in parity 1 (P≤0.05). A very
low value of this parameter was also observed in parity 2 during Winter
(P≤0.05). A large variation in the number of live born piglets was
listed for PLW sows between seasons in parities 2, 3, and 5 (P≤0.05).
The highest number of live born piglets was reported in parity 3 during
Winter (P≤0.05).
Similar to PLW sows, PL × PLW crossbreed sows bore the smallest
number of piglets in parity 1 (P≤0.05). Crossbreeds achieve the highest
number of live born piglets in parity 4 during Summer (P≤0.05). In
terms of the parity data there were no differences between seasons for
crossbreed sows.
The results of the analysis of the effect of season, parity and breed on the
number of piglets weaned are shown in Table 3. A considerable reduction in
the number of piglets weaned for PL breed compared to other breeds was
observed in parity 3 during Winter and Summer, and parity 4 during Summer
(P≤0.05), which has a direct relationship with the number of live born
piglets during these periods. Significant differences between seasons for PL
sows were noted in parities 1 and 5 (P≤0.05). The highest number of
piglets weaned from the sow was recorded in parity 5 during Autumn (P≤0.05).
In the case of PLW sows the smallest number of piglets weaned were shown
during parity 1 (P≤0.05), which resulted from the very small number of
live born piglets per litter in this parity. It should be noted that the
lowest value of this parameter was also recorded in parity 2 during Winter
(P≤0.05). Significant differences in the number of piglets weaned were
observed for these sows between seasons in parities 2, 3, and 4 (P≤0.05). The highest number of piglets was weaned from PLW sows in parities 3
and 4 during the Summer (P≤0.05).
Crossbreed PL × PLW sows weaned the lowest number of piglets in
parity 1, especially during Winter (P≤0.05). The highest number of
piglets weaned was achieved in parity 4 during Summer (P≤0.05).
Differences in the number of piglets weaned were noted between seasons in
parities 1 and 4 for PL × PLW sows (P≤0.05).
Table 4 shows the influence of the examined factors on the birth weight of
piglets. It can be noted that piglets born by PL and PLW were characterized
by a lower birth weight compared to piglets born by PL × PLW
crossbreeds (P≤0.05). Lower birth weights of piglets born in parity 1
were observed for all the studied breeds (P≤0.05). Large differences
between seasons were noted for PL breed in parities 3, 4 and 5 (P≤0.05). However, for PLW sows differences between seasons were recorded in
parities 2, 3 and 5 (P≤0.05). Significant fluctuations in birth weights
of piglets were confirmed statistically between seasons only in parity 5 for
PL × PLW crossbreed sows (P≤0.05).
Sows of PL breed bore the highest number of piglets in parities 3 and 4
during Summer (P≤0.05). The highest birth weight for PLW sows were
observed in parity 3 during Autumn (P≤0.05), while for crossbreeds PL × PLW in parity 4 during Summer and Autumn (P≤0.05).
Table 5 presents the effect of the analysed factors on weaning weights of
piglets. It should be noted that piglets weaned from purebred sows PL, PLW
were lighter than piglets weaned from crossbreed sows PL × PLW
(P≤0.05). The lowest weaned weights were observed in parity 1 (P≤0.05). Significant fluctuations between seasons were observed for PL sows
in all parities (P≤0.05). Changes in the weaning weight of piglets
between seasons for PLW sows were observed in parities 1, 3 and 4 (P≤0.05). Only in parity 1 were differences in the weaning weight of piglets
for PL × PLW sows within seasons were not confirmed statistically.
The highest numbers of piglets for PL sows were weaned in parity 3 during
Summer (P≤0.05). The highest weaning weights for PLW breed were
achieved in parity 3 during Autumn (P≤0.05), while for crossbreed sows
PL × PLW also in parity 3 during Autumn (P≤0.05).
Discussion
The results of our study indicate differing (equivocal) impacts of the
studied factors on the reproductive performance of sows. Its effect on the
reproductive parameters occurs regardless of the reproductive management
level in a herd (Auvigne et al., 2010) and a far greater impact is created by
genetic potential, environmental factors and climate (Hoving et al., 2011). In our
study the lowest number of litters were born during Autumn; however, this
effected the highest birth weight and associated with it weaning weight. The
observed results might be explained by increased space in the female genital
tract during foetal development, the relevant conditions during lactation
and positive relationships between litter size and birth weight (Lund et al., 2002). Litter size and birth weight are conditioned by ovulation rate,
embryonic survival and uterine capacity (Tummaruk et al., 2001). The reduction of
piglets during rearing is mainly affected by factors dependent on sows, such
as litter size and parity number (Weber et al., 2009). Therefore it is also
confirmed by the none interaction effect of all analysed factors. Pére
and Etienne (2000) demonstrated that uterine blood flow is increased to a
lesser extent than the number of foetuses and a lower flow may result in
less nutrition for foetuses. Additionally, Bérard et al. (2008) confirmed
that weaning weight is directly proportional to birth weight. A significant
effect of piglets birth weight on the growth rates showed in their studies
Škorjanc et al. (2007). In contrast to the study conducted by Quesnel et
al. (2008) there was no observed higher birth weight for piglets born in Spring.
Maximum weight is in fact limited by the morphology and physiology of the
sow.
Lower weaned weights in Summer were probably a result of microclimate
conditions affecting lactation. Pigs are sensitive to high temperatures,
mainly because of the reduced ability for perspiration (Nardone et al., 2010). It
is very important to observe a body condition of sows during late pregnancy
because of the later litter performance (Beyga and Rekiel, 2010).
Physiological changes during farrowing and lactation are compounded by a
change in diet, postnatal stress and microclimatic factors (Quesnel et al., 2009).
Therefore, additional heat stress during Summer may have contributed to
changes in the composition of milk, less milk secretion or decreased food
consumption by piglets. On the other hand, heat stress may also impair the
development of embryos and shape the reproductive performance of sows
(Nardone et al., 2010), although our results recorded in Summer do not confirm
such relationships.
Changes in reproductive parameters are also observed in the case of boars
(Kawęcka et al., 2008). The effects of photoperiod on semen volume and total
number of motile spermatozoa have been reported (Knecht et al., 2013). Our earlier
studies presented changes in the total number of piglets born and birth
weight of piglets according to boar birth season (Knecht et al., 2014). It should
be noted, however, that these studies concerned collected ejaculate. In our
present experiment, all sows were inseminated with sperm doses containing an
identical spermatozoa concentration, which eliminated the effect on the
measured parameters of seasonal changes in boar semen.
One of the factors was also the parity. The observations already made by
Scholman and Dijkhuizen (1989) had shown that it was economically viable to
keep sows at least until parity 5. Therefore, in our methodology we adopted
just such a scope of parities. In the early 1990s it had been proved that a
low degree of culling and basing production on sows with a large number of
litters is the most profitable, because young gilts/sows are most vulnerable
to various types of dysfunctions (Faust et al., 1993).
The farrowing results of the first parity may decide on parameters of
further condition (Hoving et al., 2011). Engblom et al. (2007) even show that with the
increase of parity, there is an increase in the number of live born and
weaned piglets, because the correlation between these parameters is high.
Such observations confirmed Čechová and Tvrdoň (2006) and it is
strictly correlated with backfat thickness. Our results confirm the
influence of parity on the number of live born piglets. Quesnel et al. (2008)
found that, sows in the 1st and 2nd parities showed the most homogeneous
litters. This may be due to the lower number of piglets born and therefore
the increased space for foetal development in the uterus. We obtained the
best results in parity 3 where a production peak was observed, then
parameters began to fall slowly at paritiy 4 and drastically at 5. However,
in parity 5 all analysed parameters declined, and these were much better
than the results of only parity 1. This should be translate by the increased
exploitation of the body and reproductive disorders.
There are differences between the breeds and their reactions to the examined
factors. The improvements implemented in the direction of increased
ovulation rates and greater embryonic survivals were made without a
concomitant improvement of the uterine capacity (Foxcroft, 2007). Crossbreed
sows covered by the study showed a number of born and weaned piglets
compared to purebred which was similar for PL and lower for PLW. This is in
contrast to the observations of Quesnel et al. (2008), who compared LW breed and
LW × L crossbreed always achieve higher number of live born piglets
for crossbreeds. The birth and weaning weight of piglets from crossbreed
sows was higher. However in our opinion, higher weaning weight was due to
higher birth weight (Quesnel et al., 2008). In our results, no positive effect of
crossbreeding on the number of piglets born live and weaned was noted.
Improving reproductive performance is one of the reasons for the use of
crossbreed sows (Vanderhaeghe et al., 2010). A higher number of live born piglets
may reflect individual potential in the reproductive physiology of the
breeds and crossbreeds in terms of not only high uterus capacity but also
more resistance to environmental conditions such as climatic conditions,
nutrition, etc. (Hoving et al., 2011). Bloemhof et al. (2008) reported that different
lines respond differently to environmental factors and it is a possible
genetic selection to heat stress tolerance. Selection in the direction of
the number of piglets born also translated into the number of stillborn
piglets, resulting in a small improvement in parameters of rearing (Rosendo
et al., 2007). This follows from a positive correlation between litter size and
the number of live born piglets (Quesnel et al., 2008).
In conclusion, the results have a very important practical character,
because they show dynamic changes of reproductive performance parameters on
an industrial piggery farm. The strength of the impact of season, parity and
breed was very diverse. Season had the strongest effect on the weaning
weight of piglets. Parity had less effect only on the number of piglets
weaned. Breed most influenced piglet birth and weaned weight, especially for
crossbreed sows [PL × PLW]. The study has shown the existence of
interactions between the analysed factors for the number of piglets born
live, birth and weaning weight. Research has shown that the worst
reproductive parameters were noted in first parity. Gilts regardless of
season and breed born the least alive piglets with the lowest birth weight,
as well as weaned the smallest number of piglets with the very low weight.
To ensure the uninterrupted stability and continuity of production, it is
recommended to increase the number of PL, PLW and [PL × PLW] gilts
in structure of technology groups. The best results in terms of the studied
parameters were noted in sows with 3 and 4 parity. We observed that sows
during this period born the largest number of alive piglets with a high
weight and furthermore weaned greatest amount of piglets with higher
weights. Increase in the average age of the sows in the herd improves the
reproduction performance which results in higher piglets production.
Acknowledgements
The authors wish to thank K. Bernhardt for revising the English version of
the manuscript.
Edited by: K. Wimmers
Reviewed by: two anonymous referees
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