ACHIEVING PUBERTY IN A TIMELY FASHION IS IMPORTANT FOR MAXIMIZING PROFITABILITY FOR THE LIVESTOCK PRODUCER AND NUTRITION HAS A MAJOR IMPACT ON THAT TIMING WITH INADEQUATE NUTRITION SIGNIFICANTLY DELAYING ITS START. PUBERTY ONSET DEPENDS ON PROPER BRAIN FUNCTION AND THE BRAIN MECHANISMS RESPONSIBLE FOR PUBERTY ONSET, INCLUDING HOW INADEQUATE NUTRITION AFFECTS THOSE MECHANISMS, ARE UNKNOWN. THE OVERALL PURPOSE OF THIS GRANT IS TO BEGIN TO UNRAVEL THE PATHWAYS THROUGH WHICH THE BRAIN CONTROLS PUBERTY AND HOW POOR NUTRITION AFFECTS THEM. THE SPECIFIC AIMS OF THE GRANT ARE FOCUSED ON THE HYPOTHESIS THAT TWO BRAIN CHEMICALS IN SPECIFIC, NEUROKININ B AND ALPHA-MELANOCYTE STIMULATING HORMONE, ARE IMPORTANT FOR BOTH NORMAL PUBERTY ONSET AND THE DELAY IN PUBERTY ONSET WHICH OCCUR IN RESPONSE TO INADEQUATE NUTRITION. THIS GRANT WILL LOOK AT THEIR ROLES IN BOTH SITUATIONS AND HOW THEY INTERACT WITH EACH OTHER. WE EXPECT TO FIND THAT NEUROKININ B IS IMPORTANT FOR NORMAL PUBERTY ONSET AND THAT ALPHA-MELANOCYTE STIMULATING HORMONE IS IMPORTANT FOR MEDIATING THE EFFECTS OF INADEQUATE NUTRITION ON PUBERTY ONSET. FURTHER, THE INTERACTION BETWEEN THESE CHEMICALS WILL BE IMPORTANT IN DETERMINING HOW POOR NUTRITION DELAYS PUBERTY ONSET. UNDERSTANDING HOW THE BRAIN CONTROLS PUBERTY ONSET WILL ALLOW THE PRODUCER TO BETTER UNDERSTAND THE IMPACT OF POOR NUTRITION ON PUBERTY AND BETTER CONTROL ITS ONSET TO INSURE TIMELY PUBERTY ONSET OR TARGET ONSET TO SPECIFIC TIMES OF THE YEAR, ALL OF WHICH WILL SIGNIFICANTLY AID IN MAXIMIZING HIS PROFITABILITY.