| (Objective) In ruminants, quantitative data can be obtained regarding milk synthesis by simultaneously measuring mammary absorption of milk precursors and their appearance in milk components. In these types of experiments, measurement of the mammary blood flow is required. The mammary nutrition research in lactating ruminants, especially in dairy cows, has become a hot spot of animal nutrition research at present, and mammary blood flow is one of the key factors that affect the absorption, uptake and utilization of mammary nutrients, therefore, the accurate measurement of mammary blood flow has the theoretical and practical significance. Increasing interest in the physiology and biochemistry of milk synthesis and removal has reemphasized the need for an accurate and reliable method for measuring mammary blood flow in conscious animals. According to the principle of measurement, the present flow measurement methods are divided into two types of volumetric method and speed method. The Transit-time ultrasonic blood flow measurement used in this article is the capacity flow. There are many methods for measuring blood flow, including continuous thermodilution, antipyrine absorption method, electromagnetic induction method, Doppler ultrasound method, Transit-time ultrasonic blood flow meter method etcetera. Using Transit-time ultrasonic blood flow meter is an effective method for accurate and reliable. (Method) This article took the mammary gland of dairy goats as the object and the Transit-time ultrasonic blood flow meter was used to assess the measurement of mammary blood flow and the accuracy under different conditions. (Result) The results showed that external pudendal vein ligation could effectively prevent external pudendal vein blood refluxed into the mammary vein and did not affect the mammary blood flow (P>0.05); The effect of nutrition on mammary blood flow was slow but significant (P<0.01); Milking had little effect on mammary blood flow (P>0.05), but lying could increase mammary blood flow significantly (P<0.01); Increasing the feeding times could reduce mammary blood flow fluctuations and enhance the rate of accuracy of measuring mammary blood flow, the mammary blood flow was decreased gradually from 01:00 to 12:00 o'clock and then increased, at the same time the milk yield was in a positive correlation with the average of the blood flow; Blood flow during the day generally lower than during the night. (Conclusion) In conclusion, the external pudendal vein ligation can effectively prevent the blood flow measurement from inaccuracy; Nutrition has a great effect on the mammary blood flow, when the nutrient supply was decreased, mammary blood flow may be decreased significantly in one day because of the nutrition supplied to body's maintenance energy firstly; Milking can cause fluctuations in mammary blood flow of the dairy goats, but not significantly; Lying can increase blood flow significantly, in order to obtain the accurate mammary gland blood the goats should have to be measured in the standing postures; When the feeding times increased to 12 times in one day, the mammary blood flow reduced gradually from 01:00 to 12:00 and then increased gradually, the fluctuation is also small, the milk production and the mean value of mammary blood flow tends is being related, the result is more accurate; When the feeding times reduced to 3 times in one day, after feeding 2 to 3 hours at 6:00 and 18:00 the mammary blood flow arrives at the peak value, and the peak value is not significant after which at 12:00, there is no variation in the blood flow change, in this case it is not easy to measure mammary blood flow accurately; The measurement of mammary blood flow will be more accurate under the conditions of increasing the feeding times, reduce the feeding interval time can help to reduce the absorption nutrient effect on mammary blood flow; The results of this study can provides the reference for the standards of the measurement of the mammary blood flow on the lactating ruminant animals.
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