Abstract: The objective of this study was to investigate the change regularity of production performance, milk composition, blood physiological and biochemical indexes and nutrient intake and relationship among them in Xinong Saanen dairy goat during lactation period. Fifteen healthy Xinong Saanen dairy goats with similar body weight, parity, milk yield and delivery date were selected. After 54 weeks of single fold feeding, the production performance, milk composition, blood physiological and biochemical indexes, nutrient intake for each individual were accurately measured during the experiment period, and the change regularity model of each index along with lactation period and the correlation model between indexes during lactation period were established. The results showed that:1) The production performance (DMI, milk yield, feed to milk ratio), milk composition (milk protein percentage, milk fat percentage, TS) and nutrient intake (EE, CP, OM, ADF, NDF) were significantly affected by stage of lactation (P<0.05). 2) The change regularity of milk yield, milk fat percentage and milk protein percentage along with lactation period were successfully fitted through Wood model; CP was fitted by the quadratic curve; The DMI, feed to milk ratio, SNF, TS and NDF were fitted by the cubic curves. The best fitting results were obtained for milk yield, milk fat percentage and feed to milk ratio, their degree of fitting was above 0.94. 3) For production performance, DMI, milk yield and feed to milk ratio were extremely significantly correlated (P<0.01); For milk composition, milk protein percentage, milk fat percentage, SNF and TS were extremely significantly correlated (P<0.01); For nutrient intake, DMI, OM, CP, NDF and ADF were extremely significantly correlated (P<0.01). Significant correlation indexes could be fitted by quadratic curve, cubic curve, linear model, exponential model and S curve. The average annual milk yield of Xinong Saanen dairy goat was 504.91 kg. The production performance, milk composition, blood physiological and biochemical indexes and nutrient intake of dairy goats were significantly correlated, and were also significantly affected by lactation period. The lactation curve fitted by Wood model was Y=1.233t^0.414×e^-0.041t. Feed to milk ratio could be predicted by milk yield according to the fitting curve, and milk fat percentage, milk protein percentage and TS content could be predicted by each other. Our findings are of great significance to understand the basic physiological status and production rules of dairy goats, and provide an important guidance for the rational production, accurate feeding and efficiency improvement of dairy goats at different lactation stages.

Key words: Xinong Saanen dairy goat, lactation curve, lactation period, change regularity