This study established a fluorescence-based quantitative real-time polymerase chain reaction method for the detection of caprine-derived ingredients in milk powder. The specificity, sensitivity, and stability of the caprine-specific primers were evaluated. By linear fitting of the difference in cycle threshold (ΔCt) as a function of the mixing proportion between goat and horse milk powder, a calibration curve for the relative quantitation of caprine-derived ingredients in milk powder was established as follows: y = 0.720 9x + 5.651 9 (R2 = 0.987 5), and the minimum detection limit of this method was 0.000 1 ng/μL. The recoveries of the proposed method were 96.22%-112.00%, and the inter- and intra-group coefficient of variation was ≤ 0.79% and ≤ 1.77%, respectively.

The purpose of this study was to explore the differences in nutritional components and whey protein components between sheep milk and milk from humans and other animal species used for dairy production. The whey protein components of milk from Hu sheep, East Friensian Milk sheep and their F1 hybrid at different stages of lactation were analyzed and compared with those of goat, cow and human milk. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Native-PAGE were used to identify landmark proteins that differed between milk samples. The contents of milk macronutrients like protein, fat and lactose significantly varied between sheep breeds, between lactation stages, and between sheep and other animal species (P < 0.05) and they showed a certain trend. SDS-PAGE showed that β-lactoglobulin and lactoferrin differed between sheep and human milk, α-lactalbumin differed between sheep and goat milk, and immunoglobulin G (IgG) heavy chain differed between sheep and cow milk. Native-PAGE indicated that there was one protein band that differed between sheep and goat whey as well as three ones that differed between sheep milk and human and cow whey.