Exploring Interrelationships between Colour, Composition, and Coagulation Traits of Milk from Cows, Goats, and Sheep

Abstract

This study explores the interrelationships between the composition, coagulation, and colour of sheep, goat, and cow milk to identify their similarities and differences and to assess whether the relationships between the variables are common to all species or whether they emerge from species-specific relationships. For this purpose, 2400 individual milk samples were analysed. The differences and similarities between the species were determined using discriminant analysis and cluster analysis. The results show a clear differentiation between species. Sheep milk stands out for its cheesemaking capacity and shows similarities with goat milk in composition and coagulation. Nonetheless, colorimetry highlights a greater similarity between sheep and cow milk. Composition and colorimetry were more discriminating than coagulation, and the variables that differed the most were fat, protein, curd yield, lightness, and red–green balance. Using canonical correlation, the interrelationships between the different sets of variables were explored, revealing patterns of common variation and species-specific relationships. Colorimetric variables were closely related to milk solids in all species, while in sheep milk, an inverse relationship with lactose was also identified. Furthermore, a strong relationship was revealed for all species between colour and curd yield. This could be modelled and applied to estimate the technological value of milk, proving colorimetry as a useful tool for the dairy industry.

Exploring Breed-Specific Milk Coagulation in Spanish Dairy Sheep: A Canonical Correlation Approach

“…In recent years, canonical correlation analysis has been used in some studies involving dairy ruminants for the analysis of aspects such as milk immunoglobulin profiles, genomic characterisation, or the impact of housing on animal health [ 59 , 60 , 61 , 62 ]. Moreover, a recent study from our research group has used CCA to explore species-specific differences in milk processing [ 43 ]. However, to our knowledge, there are no available studies that use this approach to analyse differences and similarities in the technological performance of milk from different breeds.…”

“…Hence, the emergence of third-country breeds in the early 80s, as is the case of Assaf, introduced into dairy flocks (whether in purity or by crossbreeding) to enhance milk yields, led to more intensified production systems [ 18 , 35 ]. Differences in composition and coagulation can also be attributed to a wide variety of factors, including genetic and physiological characteristics of each breed, as well as their environment and management [ 43 ]. Each breed can have different genetic profiles, that may include variations in genes responsible for protein and fat synthesis in milk, as well as others related to enzymatic activity and casein structure, which strongly affect the milk coagulation capacity [ 64 , 65 ].…”

“…Subsequently, a canonical correlation analysis (CCA) was used to examine the interrelations between milk composition and coagulation properties, and to explore whether these relationships are consistent across the four breeds or if there are breed-specific interrelations. This methodological approach has recently been employed to analyze similar interrelations in cow, sheep, and goat milk [ 43 ]. The technique was developed by Hotelling [ 44 ] and deals with the degree of linear association between two sets of variables, X and Y.…”