ABSTRACT
This study was conducted to
investigate the effect of dietary selenium (se) supplementation on the
reproductive performance of sows, preweaning growth performance of their
piglets, haematological and antioxidant status of pigs. Twelve (12) crossbred
sows (Landrace × Large White) aged 1-2 years with an average body weight (BW)
of 56.1 ± 5kg were randomly allotted to four treatment groups of three sows per
treatment in a completely randomised design (CRD). The treatment groups
comprised T0 (no Se supplementation), and T1,
T2, T3 administered with 0.30 mg/Kg selenium‐methionine during second
trimester of gestation, third trimester of gestation and lactation
respectively. Selenium supplementation significantly (P<0.05) improved
reproductive efficiency as measured by larger litter size (T0; 5.67 ± 0.33, T1;
6.00 ± 92.47, T2; 7.66 ± 1.20, T3; 8.33 ±
8.33) reduced mortality,( T0; 2.33 ± 0.33%, T1; 1.00 ±
0.49%, T2; 0.66 ± 0.33%, T3; 0.47 ± 3.05%), and increased
litter weight at weaning (T0; 5.07 ± 5.92 kg, T1; 5.79 ± 0.02kg, T2;
5.76 ± 2.64kg, T3; 5.93 ± 1.85kg), in the Selenium treated groups
when compared to the control group. Haematological parameters were not
significant (P>0.05) among treatments during the second trimester of
gestation. However, Se supplementation significantly (P<0.05) increased Pack
Cell Volume (PCV) (T0; 32.50 ± 0.25%, T1; 38.50 ± 0.08%,
T2; 37.00 ± 1.00%, T3; 34.50 ± 0.50%) and Red Blood Cell
(RBC) (T0; 131.50 ± 28.5, T1; 185.0 ± 35.0, T2; 177.5 ±
32.5, T3; 210.0 ± 20.0) during the third trimester and Red Blood
Cell (RBC) (T0; 108.0 ± 2.00, T1; 165.0± 15.0, T2; 175.0
± 5.00, T3; 165.0± 5.00) and White Blood Cell (WBC) (T0;
22.07±0.44, T1; 11.20±0.80, T2; 9.00± 1.00, T3;
10.00±3.60) during lactation. All Se supplemented groups showed significantly
increased plasma Selenium concentration in all stages compared with the
control. Dietary selenium supplementation significantly increased plasma
Glutathione –S- Reductase, Glutathione peroxidase (GSH-Px) activity during
lactation (T3) and significantly (P<0.05) decreased plasma
Malondialdehyde (MDA) (T0; 3.76 ± 1.74, T1; 0.12 ± 0.03,
T2; 0.11±0.35, T3; 4.36 ± 0.62), ( T0; 7.26 ±
0.08, T1; 3.60 ± 0.22, T2; 3.70 ± 0.27, T3;
2.27 ± 0.11), content in the third tremester of gestation and Lactation
respectively. Superoxide Dismutase (SOD) and catalase activity in all treatment
groups was significantly (P<0.05) different compared to the control.
From these results, it was concluded that dietary selenium supplementation
increased reproductive efficiency and enhanced haematological and serum
anti-oxidant enzyme activities of pigs especially during gestation and lactation.
CHAPTER ONE
1.0 INTRODUCTION
Food security refers to the availability of food and one’s access to it
and it exists when all people, at all times, have physical, social and economic
access to sufficient, safe and nutritious food to meet their dietary needs and
food preferences for an active and healthy life (WHO, 1996). As human
population continues to grow, with the greatest growth expected in countries
that are already suffering from chronic hunger and malnutrition, there will be
need to ensure food safety for all and especially the more susceptible sector
of human population (Adeola and Olukori, 2009). It is a well known fact that
the growth rate of human population far exceeds that of animal protein supply
and this great disparity creates a problem for food security. Consequently, the
demand for animal protein exceeds the supply (Ikani and Dewfang, 2004).
The present average daily protein intake among Nigerians is 45.5g per
head per day as against the FAO’s recommended minimum intake of 62g per head
per day (FAO, 1996). Similarly, the International Conference on Nutrition (ICN)
reported that low income rural and semi urban adult dweller in Nigeria consumed
less than 60% of their caloric need (which is 2400Kcal/head/day) and less than
40% of their protein needs (ICN, 1992). It seems apparent that animal protein
intake of average Nigerian has not yet improved over the years irrespective of
government policies towards achieving food security in Nigeria. This therefore
suggests more radical approach to the problem.
Pig production which is recently on the increase is part of the efforts
and one of the fastest means of bridging the prevailing animal protein
deficiency gap which has developed over the years due to increasing population
(Serres, 1992). Eusebio, (1980) described the pig as one of the most prolific
and fast growing livestock that can convert food waste to valuable product.
Their annual growth rate (3.8%) is higher than that of the human population
(2.3-
Trace minerals/ micronutrients like Zinc, Selenium, Vitamin A, Vitamin E,
Copper and Molybdenum have been known to reduce or ameliorate these
reproductive challenges in animals. For instance, Vitamin E functions as an
intra-cellular antioxidant scavenging for free reactive oxygen and lipid
hydroperoxides, and converting them to non-reactive forms, thus maintaining the
integrity of membrane phospholipids against oxidative damage and peroxidation
(Surai, 1999). Vitamin A is known to reduce delayed puberty, low conception
rate, high embryonic mortality and improve libido (Allan et at., 1999,
Smith and Somade, 1994). Zinc on the other hand reduces impaired
spermatogenesis and aid development of secondary sex organs in males, improves
fertility and litter size in multiparous species (Underwood and Suttle 2003).
Copper is involved in steriodogenesis and prostaglandins secretion which in
turn improves fertility, prevents delayed/depressed oestrus, and
abortion/foetal resorption (Smith and Akinbamijo 2000).
Selenium (Se) is an essential element playing an important role in animal
reproduction (Surai, 2002). It can be found in the body parts as a part of at
least 25 selenoproteins. These selenoproteins are considered to be involved in
the regulation of various physiological functions including anti-oxidant
protection, regulation of gene expression, thyroid metabolism, immune response,
reduction of inflammation and maintenance of sperm structure integrity (Surai,
2002, Arthur and Geoffrey 2003 and Schomburg et al., 2004). There are
two main sources of selenium in the diet: organic selenium (mainly
selenomethionine) and inorganic selenium (selenite and selenate). Surai (2002)
indicated that the organic form of selenium provides more selenium reserves in
the body and a more efficient transfer to the egg in poultry and milk in
lactating animals.
Feeding selenium to male farm animals have shown that selenium seems to
be essential for normal spermatozoa development but little attention has been
devoted to female reproductive performance.
1.1 Objectives of the study
The broad objective of this study was to evaluate
the effect of dietary selenium supplementation on the reproductive performance
of sows.
1.1.2 Specific Objectives
1. To determine the effect of dietary selenium
supplementation on the reproductive performance of sows.
2. To determine the effect of selenium supplementation
on pre-weaning growth performance of piglets.
3. To evaluate the effect of dietary selenium
supplementation on the haematological and oxidative enzyme status of sows.
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