Association Between Thyroid Metabolic Hormones and Awassi Sheep Reproductive Performance
Association Between Thyroid Metabolic Hormones and Awassi Sheep Reproductive Performance
Tamadhur H. Hussein1, Zainab M.A. Alrubayei2, Tahreer M. Al-Thuwaini1*
ABSTRACT
The thyroid gland in sheep plays a vital role in reproduction by regulating the secretion of reproductive hormones in the hypothalamus, which influences gonadotropin neurons. This study aimed to determine whether thyroid hormones are associated with litter size. A total of 100 healthy, sexually mature ewes, aged 3 to 4 years, participated in the research. The ewes were divided into three groups: non-pregnant ewes (28), pregnant ewes with singletons (42), and pregnant ewes with twins (30). Blood samples were collected from the sheep and analyzed for hormone levels after collection. The findings revealed that lamb weight and hormone levels varied significantly (P ≤ 0.05) with litter size among both non-pregnant and pregnant ewes. Awassi ewes with twin births exhibited significantly higher (P ≤ 0.05) follicle-stimulating hormone levels (1.13 ± 0.11 ng/ml) compared to those with single births. Conversely, lamb weights at birth (4.08 ± 0.27 kg) and weaning (22.25 ± 1.41 kg), as well as triiodothyronine (T3) hormone levels (369.40 ± 18.80 pg/ml), were significantly higher (P ≤ 0.05) in Awassi ewes with single births. Univariate regression analyses confirmed the association between litter size and phenotypic traits in Awassi ewes. In conclusion, Awassi ewes with twin births had lower thyroid hormone levels. These results provide valuable insights into the relationship between litter size, thyroid hormone, and lamb growth. In this context, further investigation into thyroid hormones may enhance understanding of sheep breeding and reproduction.
Keywords | Birth type, Lamb weight, Pregnancy, Reproduction, Sheep, Thyroid hormones
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