Research Article

Litter Size and Its Relationship to Leptin and Visfatin Hormones in Hamdani Sheep

Tamadhur H. Hussein, Layth H. Merzah, Tahreer M. Al-Thuwaini*

Department of Animal Production, College of Agriculture, Al-Qasim Green University, Al-Qasim, Babil, Iraq.

Received | April 02, 2024; Accepted | June 30, 2024; Published | September 25, 2024

*Correspondence | Tahreer M. Al-Thuwaini, Department of Animal Production, College of Agriculture, Al-Qasim Green University, Al-Qasim, Babil, Iraq; Email: tahrearmohammed@agre.uoqasim.edu.iq, tahreermohammed@ymail.com

Citation | Hussein TH, Merzah LH, Al-Thuwaini TM (2024). Litter size and its relationship to leptin and visfatin hormones in Hamdani sheep. J. Anim. Health Prod. 12(4): 517-521.

DOI | http://dx.doi.org/10.17582/journal.jahp/2024/12.4.517.521

ISSN (Online) | 2308-2801

 

 

Copyright: 2024 by the authors. Licensee ResearchersLinks Ltd, England, UK.

This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).

INTRODUCTION

Enhancing ewe productivity and reproduction is beneficial to sheep producers on both an economic and biological level (Habtegiorgis et al., 2022). Many factors affect sheep reproduction, such as litter size, season, photoperiod, and genetics (Ajafar et al., 2022; Al-Thuwaini and Kareem, 2022). Litter size is influenced by several factors, including ewe’s body fat, ovulation rate, and uterine capacity (Sarvinda et al., 2022; Al-Khammas and Al-Thuwaini, 2023). In ewes, body fat reserves and live weight at mating influence reproductive and productive behavior (Ptacek et al., 2014; McNamara and Huber, 2018). Numerous studies have examined the effects of fat on fat-tailed sheep’s reproductive traits, productivity, and physiological functions. These studies focus on adipokines produced by adipose tissue that are associated with productive traits (Xu et al., 2015; Yue et al., 2016; Ibrahim, 2021). The adipokines produced by adipose tissue, such as leptin, visfatin, adiponectin, and chemerin, are among the most abundant (Häussler et al., 2022; Al-Jumaili et al., 2023). The functions of these adipokines include energy metabolism, glucose homeostasis, angiogenesis, and reproduction (Louveau et al., 2016; Pereira et al., 2020). The hormone leptin serves as a crucial signal connecting body fat and reproduction, influencing the metabolism of the reproductive system (Kuźnicka et al., 2020). Moreover, leptin plays a crucial role in stimulating gonadotropin-releasing hormone (GnRH), follicle-stimulating hormone (FSH), and luteinizing hormone (LH) production in ruminants (Agarwal et al., 2009; Ghoneimy et al., 2020). Leptin modulates reproduction directly and through receptors and neurotransmitters at gonadal sites (Williams et al., 2002). Additionally, leptin could activate both guanylate cyclase and cyclooxygenase 1 in GnRH neurons, subsequently triggering the release of GnRH (Agarwal et al., 2009). Through direct activation of nitric oxide synthase, leptin could stimulate the pituitary release of LH and FSH (Moschos et al., 2002). Additionally, leptin has also been implicated in reproductive functions, such as the growth and development of ovaries, maturation of oocytes, embryo development, implantation, and placental development (Pérez-Pérez et al., 2015).

The second adipokine, Visfatin, is also known as nicotinamide phosphoribosyl transferase (NAMPT) and is abundantly secreted by adipose tissue (Mlyczyńska et al., 2023). The function of Visfatin is to regulate the hypothalamic structures releasing GnRH, the key hormone controlling the pituitary and ovaries, thereby increasing the secretion of steroid hormones by the granulosa cells (Juengel et al., 2021; Kaminski et al., 2021). The expression of visfatin in gonads and its role in regulating ovarian steroidogenesis in hens and buffaloes’ granulosa cells is now clear (Diot et al., 2015; Thakre et al., 2021). Furthermore, a study conducted by Kaminski et al. (2021) revealed that porcine visfatin is expressed in the hypothalamus. Estrous cycle hormones and early pregnancy hormonal environments are intricately linked to this expression. In light of this data, adipokines may provide valuable information regarding potential associations between reproductive traits and sheep breeds. Awassi (Naimi), Karadi (Hamdani), and Arabi sheep are three breeds of Iraqi sheep that differ from each other in terms of phenotypic and productive traits (Oramari et al., 2014). The Hamadani sheep are considered one of the most important and desirable indigenous breeds of Karadi sheep due to their twinning ability, large frame, heavy fleece weight, and fat tails. They are mainly used for carpet wool production, as well as for meat and milk production (Bingöl and Bingöl, 2016; Al-Barzinji, 2022). Despite this, no publications have associated litter size in Hamadani ewes with adipokines from adipose tissue. Therefore, study objectives included examining the relationship between leptin and visfatin hormones and birth type, highlighting the significance of the Hamadani breed as a sheep breed.

Materials and Methods

Sheep population and phenotypic measurements

This study was conducted at Al-Qasim Green University between July 2022 and September 2023 with approval from the ethics committee (Agri, No. 01, 7, 22). A total of 100 Hamadani ewes, aged 3 to 4 years, were included in the study. These ewes were sexually mature, not pregnant or lactating, and in good health. The number of ewes after parturition was determined by random selection at Karbala station, resulting in 57 ewes with singletons and 43 ewes with twins. The animals were fed 59% barley, 40% bran, 1% salt, 3 kilograms of alfalfa, and 1 kilogram of straw, amounting to 2.5% of their body weight. Fresh water was available to all animals throughout the day. Blood (5 ml) was collected from the sheep’s external jugular vein using an 18-gauge disposable needle. Blood was centrifuged for 15 minutes at 2,000 xg and the serum was stored at -20°C for hormone analysis. To measure the hormones in adipose tissue, SunLong Biotech Co., Ltd. (Hangzhou, China) provided an ELISA kit. Leptin (SL00009Sp) and visfatin (SL00147Sp) levels were determined using ELISA kits. Body measurements and weights of Hamadani ewes (kg) were taken using a suspended spring balance in the morning (Kadhem and Al-Thuwaini, 2022).

Statistical analysis

Various animal traits were investigated with birth type. A general linear model was used in this study, and SPSS version 23.0 was utilized for analysis:

Yijk= μ + Bi + Pj + eijk

Where Yijk = characteristics phenotypically, μ = overall mean, Bi = fixed effect of ith birth type (i = single, twin), Pj = fixed effect of jth parity (j = 1, 2, 3), and eijk = random error associated with Yijk observation and assumed to be NID (0, σ2e). A comparison of means was conducted using the Bonferroni test with a significance level of 0.05. No significant differences were found between phenotypic traits related to season and factor interactions. Therefore, these variables were excluded from the general linear model.

RESULTS AND DISCUSSION

This study examined the association between Hamadani ewe progeny type and animal traits. The least-square means of animal traits affected by progeny type are shown in Table 1. Ewes with twin births had higher live body weight, chest girth, tail length, tail width, leptin, and visfatin hormones (65.35 ± 0.65 kg), (102.12 ± 0.38 cm), (35.15 ± 0.10 cm), (31.72 ± 0.22 cm), (268.51 ± 7.12 pg/mL), and (5.88 ± 0.19 ng/mL), respectively, compared to ewes with single births. However, the age, body length, and abdomen girth of Hamadani ewes did not show a significant difference (P ≥ 0.05). Univariate regression analyses further explored the association of the progeny type with animal traits (Table 2). It was noted that progeny type showed a significantly higher association with the live body weight (P = 0.04, OR (95% CI) = 1.50 (1.08-3.24)), tail length (P = 0.03, OR (95% CI) = 1.69 (0.96-3.86)), and hormones leptin (P = 0.02, OR (95% CI) = 2.31 (1.51-5.18)) and visfatin (P = 0.01, OR (95% CI) = 2.03 (1.34-5.21)).

 

Table 1: The effect of progeny type on animal traits in Hamadani ewes.

Indices	Progeny type (LSM ± SE)		P value
	Single	Twin
Age (year)	3.58 ± 0.14	3.50 ± 0.13	0.46
Live body weight (Kg)	58.33 b±1.49	65.35a ± 0.65	0.01
Body length (cm)	75.19 ±0.22	75.56 ±0.15	0.68
Chest girth (cm)	101.01 b ±0.12	0.38±02.12a	0.01
Abdomen girth (cm)	104.11 ±1.32	103.55 ±0.15	0.53
Tail length (cm)	34.65 b ±0.13	35.15 a ±0.10	0.04
Tail width (cm)	30.34 b ±0.25	31.72 a ±0.22	0.03
Leptin (pg/ml)	183.70b±8.75	268.51a±7.12	0.02
Visfatin (ng/ml)	3.21 b ± 0.35	5.88 a ± 0.19	0.03

LSM ± SE, Least square means ± Standard error. A,b Significant differences in means represent differences in the same row within each classification.

 

Table 2: Logistic regression analysis of progeny type with phenotypic parameters in Hamadani ewes.

Characteristic	Univariate logistic regression
	Estimate	Odds ratio (95% Cl)	P value
Age (year)	0.09	1.09 (0.84-2.58)	0.43
Live body weight (Kg)	0.41	1.50 (1.08-3.24)	0.04
Body length (cm)	0.30	1.34 (1.11-4.53)	0.36
Chest girth (cm)	0.14	1.15 (0.91-4.17)	0.11
Abdomen girth (cm)	0.06	1.06 (0.95-3.74)	0.26
Tail length (cm)	0.53	1.69 (0.96-3.86)	0.03
Tail width (cm)	0.21	1.23 (1.01-3.91)	0.48
Leptin (pg/ml)	0.84	2.31 (1.51-5.18)	0.02
Visfatin (ng/ml)	0.71	2.03 (1.34-5.21)	0.01

The P-value with statistical significance is indicated in bold numbers; CI: confidence interval.

Reproduction efficiency is crucial for the economic viability of livestock production. Thus, improved livestock reproductive traits require an understanding of the factors that influence these traits (Ajafar et al., 2022; Al-Jaryan et al., 2023). Live body weight and body measurements could serve as functional indicators of reproductive and productive traits in ewes (Al-Thuwaini et al., 2020). Live body weight is a good indicator of ewes’ litter size, with heavier ewes bearing more lambs than ewes bearing a single lamb. Ewes with a heavier live body weight have a higher twinning rate (Al-Thuwain and Al-Hadi, 2022). Additionally, ewes body dimensions provide insights into their reproductive capabilities. According to Corner-Thomas et al. (2015), sheep’s reproductive performance is affected by body measurements. Kenyon et al. (2012) also revealed that ewes with larger body measurements are more likely to efficiently manage multiple births compared to ewes with smaller body sizes.

Moreover, sheep’s reproductive traits are influenced by the complex interaction between the pituitary gland, the ovary, and the adipose tissue. The adipokines secreted by the adipose tissue play a crucial role in reproduction (Al-Thuwaini, 2022; Al-Thuwaini et al., 2024). One of the adipokines, leptin, acts centrally in the hypothalamus by stimulating the release of gonadotropins, which are crucial for the initiation and maintenance of reproduction, by increasing neuronal activity and releasing gonadotropin-releasing hormone (GnRH) (Hausman et al., 2012; Kuźnicka et al., 2020). Leptin could enhance GnRH production, specifically follicle-stimulating hormone (FSH) and luteinizing hormone (LH), and restore fertility in animals (Priyadarshini et al., 2015). Leptin also modifies the sensitivity of GnRH in the pituitary gland, influencing ovarian follicular and luteal steroidogenesis (Hausman et al., 2012). Leptin and leptin receptor proteins regulate ovarian follicle development and oocyte maturation in sheep. Sheep with high leptin levels also develop their antrum faster, produce more oocytes, and mature their oocytes faster (Ma et al., 2022). Furthermore, leptin has been shown to have a significant impact on reproductive function, particularly in the regulation of ovarian function, the maturation of oocytes, the development of embryos, and the successful implantation of embryos (Pérez-Pérez et al., 2015). There is a positive relationship between leptin levels and litter size has been found by Kuźnicka et al. (2020). According to the findings of this study, the lowest levels of leptin were found in ewes with single births, while the highest levels were found in ewes with twin births. Possibly, this is explained by the inverse relationship between leptin and estradiol levels. Suppression of estradiol synthesis by leptin in sheep could lead to the development of additional vesicles (Bobowiec et al., 2001). Another important adipokine, visfatin is found in ovarian follicles, cumulus cells, and oocytes of bovines, leading to increased levels of progesterone and estradiol (Reverchon et al., 2016). Additionally, vifatin stimulates progesterone production in the corpus luteum of water buffaloes (Thakre et al., 2021). Visfatin could affect not only the reproductive system directly but also the hypothalamic-pituitary-gonadal axis (HPG), which includes the pituitary. All the structures of the HPG axis express visfatin (Szymanska et al., 2023a). As well, visfatin could regulate LH and FSH secretion by stimulating the signaling pathways INSR, AKT/PI3K, MAPK/ERK1/2, and AMPK in porcine anterior pituitary cells to allow reproduction and energy balance to be physiologically integrated (Szymanska et al., 2023b). However, studies on leptin and visfatin in Hamadani ewes have not been published yet.

CONCLUSIONs and Recommendations

Animal traits were associated with the litter size of Hamadani ewes. Ewes with twin births had higher live body weights, body measurements, leptin, and visfatin hormone levels than ewes with single births. An understanding of the relationship between litter size and adipokines may lead to improvements in animal production and provide further evidence that adipokines are critical for reproduction.

Acknowledgement

The authors gratefully acknowledge the staff of the sheep station in Karbala for their facilities that supported the Hamadani ewe population.

NOVELTY STATEMENT

This research examined the relationship between lamb birth rates and adipose tissue biomarkers for the first time. Hamadani ewes with twin births showed higher levels of leptin and visfatin, indicating a potential correlation between adipose tissue hormones and litter size.

AUTHOR’S CONTRIBUTION

All authors contributed equally. All authors checked and approved the final version of the manuscript for publishing in the Journal of Animal and Health Production.

Conflict of interest

The authors have declared no conflict of interest.

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