*Corresponding author: Musa, Suleman Ibrahim, Department of Animal Science, Nasarawa State University, Keffi, Shabu- Lafia Campus, Nigeria
How to cite this article: Musa Suleman Ibrahim, Briskila Oliver Ombugadu and Yusuf Ibrahim Hussaini. Effect of Pregnancy on Oxidative Status of Sheep. Dairy and Vet Sci J. 2023; 15(3): 555914.DOI: 10.19080/JDVS.2023.15.555914
The objective of the study was to determine the effects of pregnancy on oxidative status of sheep Specific goal of the study was to determine the impact of pregnancy on serum concentration of antioxidant enzymes and the level of lipid peroxidation. Two groups of sheep (10) consisting of pregnant and non-pregnant ewes were used for the study. The pregnant ewes were at third trimester of pregnancy which was confirmed by abdominal palpation and serum progesterone level above 2.2ng/ml. Serum levels of catalase, superoxide dismutase, glutathione peroxidase enzymes and malondialdehyde were determined. The results indicated similar [p>0.05] mean values of serum concentration of catalase, superoxide dismutase and glutathione peroxidase. The serum level of malondialdehyde was significantly higher in pregnant ewes compared to non-pregnant animals. It can be concluded that the third trimester of pregnancy is associated with higher serum levels of malondialdehyde.
Reactive oxygen species play a critical role in many physiological processes but are detrimental to body cells at high concentration Hohn . Pregnancy is associated with proinflammatory state due to increased activity of monocytes and macrophages resulting in high concentration of oxidative stress biomarkers Ness . Adverse effects of oxidative stress on reproductive performance of sows have been documented, decrease litter size and birth weight were associated with oxidative stress Zhao . Oxidation of proteins can modify their structure thereby causing adverse effects on functions of the protein. Oxidized proteins can also generate antigens that stimulate immune response Halliwell & Whiteman . Increase oxidative stress has been associated with prolonged concentrate feeding in dairy cows, this is attributed to increase rumen endotoxins associated with high concentrate and low neutral detergent fiber content which may stimulate Para inflammatory reactions and reactive oxygen species Golder . Lipid mobilization associated with low energy balance has also been associated with the increase of reactive oxygen species Pedemera .
Reactive oxygen species play a critical role in reproductive processes such as ovulation, fertilization, and early embryo development. However, oxidative stress is associated with embryo losses, and it is involved in the pathogenesis of follicular cyst and repeat breeder syndrome in dairy cows Talkdor . Insufficient antioxidant activity can lead to poor pregnancy outcome including fetal growth restrictions. The metabolic changes associated with pregnancy may result in impaired oxidative status leading to
adverse effects on pregnancy establishment and maintenance.
The objective of this study, therefore, was to determine the effects of pregnancy on serum concentration of superoxide dismutase, catalase, and glutathione peroxidase enzymes. The impact of pregnancy on lipid peroxidation was also evaluated as indicated by serum level of malondealdehyde.
The objective of the study was to determine the effect of pregnancy on oxidative status of sheep. Two groups of sheep [n=10] consisting of pregnant and non-pregnant ewes were used for the study. The pregnant ewes were at the third trimester of pregnancy which was confirmed by abdominal palpation and serum progesterone level above 1.2 ng/ml. Blood samples were collected through the jugular vein for determination antioxidant enzymes concentration.
Determination of Serum Antioxidant Enzymes
Serum level of superoxide dismutase was determined by calorimetric method based on the ability of the enzyme to inhibit phenazine methosulphate mediated reduction of nitro blue as described by Weydert . Catalase activity was measured using a combination of optimized enzymatic conditions and spectrophotometric assay of hydrogen peroxide as described by Laszo . Glutathione peroxidase activity was measured using hydrogen peroxide as a substrate as described by Liu . Serum malondialdehyde was determined in terms of thiobarbituric acid reactive substances using spectrophotometer as reported by Surapon .
Data obtained was subjected to student t test using statistical
tool for agricultural research [STAR]. Means separation was done
using least significant difference where significant differences
The effects of pregnancy on oxidative status of sheep are
shown on Table 1.
Means within same row bearing different superscript are significantly
different (P<0.05), Ns = Not significant, * = Significant (P<0.05), Los =
Level of Significance
The results indicated similar mean values of catalase,
superoxide dismutase and glutathione peroxidase enzymes in both
groups. The serum level of malondialdehyde is however, higher
[p>0.05] in pregnant ewes compared to non-pregnant ewes. The
concentration of malondialdehyde is an established indicator of
cellular injury as well as a biomarker of oxidative stress in cells
and tissues Simek . Pregnancy is associated with the increase
of generation of reactive oxygen species which is linked to oocyte
maturation, luteolysis and embryo implantation. Oxidative
stress adversely affects placental functions which may lead to
poor pregnancy outcome Hussain . This may be attributed
to changing metabolic demands associated with pregnancy.
Oxidative stress results from disruption of balance between
antioxidant system and reactive oxygen species. Decrease plasma
antioxidant have been observed in early phase of pregnancy, while
total antioxidant capacity improves in the second and third stage
of pregnancy Toescu . The findings of this study showed that
pregnancy is associated with potential impairment of oxidative
status. Increased serum malondialdehyde indicating higher level
of lipid peroxidation was recorded in this study. Supplementation
with antioxidants is recommended in pregnant ewes.
It can be concluded that serum levels of catalase, superoxide
dismutase and glutathione peroxidase enzymes were not
influence by pregnancy at third trimester, whereas the serum
level of malondialdehyde was elevated indicating higher lipid
peroxidation at third trimester of pregnancy in ewes.