Effect Of Lactation Law Of Xinong Saanen Dairy Goat And The Data Collection Method On Lactation Curve Fitting Equation Accuracy

Xinong Saanen dairy goat was took as study object. Using the Wood model to fit the data and get the curve equation, the regularity of ewe lactation within 240 days of its postpartum was researched and characteristic parameters of lactation curve equation has been applied in the flock breeding program. Based on this, we studied the effect of data collection methods of lactation quantity on the fitting accuracy of lactation curve equation and put forward a simplified basic data acquisition method which the fitting lactation curve equation with higher accuracy required. The accuracy of the method was verified with relevant data, which provides a methodological basis for the application of lactation curve equation. Experiment 1: Study on Lactation Law of Xinong Saanen Dairy GoatA total of 50 Xinong Saanen dairy goat lambed at the same period with a full 240 days lactation record were chosen as study object. Plotting the lactation curve, and fitting the lactation data with the wood model, researching the regularity of ewe lactation and putting the characteristic parameters of lactation curve equation into effect in the flock breeding program. The results show that:1. The average milk yield during 240 days is 544.39±111.56 kg; the peak value of lactation appeared in 39 th day and the peak milk yield is 2.76 kg/d.2. Wood model for the lactation curve of Xinong Saanen dairy goat showed a reasonable fit to the milk production data, and the lactation curve can be described by the equation: Y=1.6997t0.1885e-0.0048t(R2=0.9297)3. The parity has a significant effect on the parameter c, peak production, durability and total milk yield(P<0.05).4. In conditions of mechanical milking, the amount of lambing has no significant effect on the lactation curve equation(P>0.05).5. Based on the characteristic parameters of lactation curve, b is the first limiting parameter.6. In the flock breeding program, taking the parameters B as the reference, eliminating the flock with the parameter b below the average of 10% and 20%, milk production increased by 3.71% and 6.96% respectively in the abstract. Experiment 2: The Effect of Data Collection Methods on the Fitting Accuracy of Lactation Curve EquationWe studied the effect of data collection methods of lactation quantity on the fitting accuracy of lactation curve equation and put forward a simplified basic data acquisition method which the fitting lactation curve equation with higher accuracy required. The results show that:1. The amount of measured months of lactation data collection was an influence on the accuracy of lactation curve equation(P<0.05). However, it will not make any difference to the accuracy of estimating the milk production with lactation curve equation as well as the basic rules of lactation curve when the measured months are more than 60% of the total lactation(P>0.05).2. The measured days of lactation each month was an influence on the accuracy of lactation curve equation(P<0.05). Data collected from the mid-month are much better than those from the beginning and the end of a month in fitting the lactation curve equation. Using 3 days data from the mid-month to fit the lactation curve equations does not significantly influence the predicted accuracy of milk production(P>0.05), as well as the lactation curve(P>0.05).Experiment3: Application of the Simplified Data Acquisition Method of Lactation to Predict Milk Production of Shanbei White Cashmere GoatA total of 24 Shanbei White Cashmere goat ewes lambed at the same period with a full lactation record of 75 days were chosen as the study objects. The simplified basic data acquisition method of fitting the lactation curve equation that recommended in the experiment two was verified with relevant data. The results show that:1. On the basis of the measured months of lactation reached 60% of the total lactation, we adopted the “mid month” data acquisition method to collect 3 days of lactation data from mid-month to fit the lactation curve equations, there is no significant difference between the predicted value and the real value of lactation parameters with an accuracy above 95%.(P>0.05).2. The simplified basic data acquisition method which the fitting lactation curve equation of Xinong Saanen dairy goat requires is also suitable for Shanbei White Cashmere goat.