Neuropeptide Y (NPY) plays a major role in the regulation of food intake, regulation of homeostasis and neuroendocrine function. We have previously shown that third ventricular infusion of this peptide delays the estradiol benzoate (EB)-induced surge in luteinising hormone (LH) secretion in ovariectomised (OVX) ewes. To determine the receptor subtype that transmits this effect, we have now used the same model to infuse a Y1 receptor agonist [NPY Leu³¹ Pro³⁴], a Y2 receptor agonist (PYY_3-36), and a Y4 receptor agonist (Pancreatic Polypeptide; PP). We monitored the surges in animals given these agonists or artificial cerebrospinal fluid by measuring plasma LH levels and we also measured daily voluntary food intake (VFI). A low (7 µg/h) dose of Y2 agonist delayed the surge but did not affect VFI, whereas a higher dose (14 µg/h) also stimulated VFI. A dose of 18 µg/h of the Y1 agonist did not affect surge generation, but stimulated VFI. A dose of 24 µg/h of Y4 agonist affected neither surge generation nor VFI. These specificities are different to those reported for the rat and the human (in which a Y2 agonist causes reduction in VFI). We conclude that, in sheep, the negative regulation of the reproductive axis by NPY and Y-receptor agonists is effected via the Y2 receptors whereas the orexigenic effects are most likely effected via the Y1 receptors.