Premium
Reproductive and Endocrine Characteristics of Delayed Pubertal Ewe‐Lambs after Melatonin and l ‐Tyrosine Administration
Author(s) -
ElBattawy KA
Publication year - 2006
Publication title -
reproduction in domestic animals
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.546
H-Index - 66
eISSN - 1439-0531
pISSN - 0936-6768
DOI - 10.1111/j.1439-0531.2006.00600.x
Subject(s) - melatonin , endocrinology , medicine , estrous cycle , reproduction , endocrine system , tyrosine , biology , hormone , zoology , ecology , biochemistry
Contents The investigation was carried out to study the impact of melatonin and l ‐tyrosine administration on the onset of cyclicity in delayed pubertal ewe‐lambs. Fifteen delayed pubertal ewe‐lambs (age >16 months) were used in this study after being assigned randomly into three groups. In the first group (melatonin treated group, n = 5), each lamb was administered 3 mg melatonin orally at 16:00 hours from 1 July to 15 September while in the second group ( l ‐tyrosine treated group, n = 5), each lamb was administered l ‐tyrosine at the level of 100 mg/kg b.w. as a single oral dose. The third group (n = 4) served as control. Lambs were exposed to mature, fertile rams daily and blood samples were collected twice weekly. The progesterone concentrations (P 4 evaluations) were significantly higher (p < 0.05) in treated groups than the control group. Ovarian activity, assessed by P 4 evaluations, showed that all animals in the first group came in oestrus and from them four got pregnant (80%) while in the second group, only three lambs came in heat and from them two became pregnant (40%). On the contrary, none of the control lambs showed oestrus. In conclusion, this study confirmed that the oral administration of melatonin and l ‐tyrosine played an essentially physiological roles to induce cyclicity in delayed pubertal ewe‐lambs and improved their reproduction.