Relationship Between the Appearance of First estrue (Puberty) with Leptin and Body Condition Score Levels in Bali Cattle

The appearance of puberty needs the GnRH secretion, due to the high amplitude and frequency of the GnRH pulsatile and the estradiol feedback system of the ovary with the hypothalamus. However, there are things to note, which is the complex system of neural pathways, neurohormones, and peptides that modulate the secretion of GnRH itself and mediate the effect of estradiol on GnRH. In line with the increasing age and growth of heifers, some factors induce and interact with various metabolic signals, one of which is leptin, where its receptors know leptin in the central nervous system. Leptin concentration increases during puberty development. However, leptin concentration must reach a certain threshold to activate the axis of the ovarian pituitary hypothalamus. This study aims to determine leptin levels, and body conditions score (BCS) when the first estrus emergence (puberty) and find out the first estrus quality (puberty) in bali cattle. This study is an analytic observational study with cross-sectional Study design. The sample used is cattle at puberty. The research sample had a health status that showed no signs of illness. The collection of blood samples from Balinese cattle was carried out in several simantri in Mengwi District, Badung Regency. Pa- rameters measured were leptin levels and physical signs of estrus, namely the presence of transparent coloured springs. Techniques for measuring hormone levels with the Direct Elisa method, Double Antibody Sandwich. The result showed that the level of leptin when the appearance of the first estrus (puberty) in Bali cattle is an average of 5.62 ng/ ml, the average of body condition score (3.06), and puberty age (21.44 months). Correlation test showed a correlation between body condition score and the appearance of the first estrus with regression correlation value (r) 0.852. Cor- relation test showed a correlation between the levels of leptin hormone and the appearance of the first estrus with the regression correlation value (r) 0.805. If r approaches 1 or -1, the relationship between the two variables is strong, and there is a high correlation. Keywords | Puberty, Leptin, Bali cattle, GnRH, Body conditions score