Chemometric Approaches to Analyse the Composition of a Ewe's Colostrum

Colostrum is a major source of immunity in lambs and, in general, in all newborn ruminants. It allows the transfer of antibodies from the ewe to the lamb, and it becomes the exclusive source of nutrients for a newborn. Among the most significant Pearson correlations, the positive correlation between the Brix refractive index (Brix) and protein (0.90) should be noted. Both parameters (protein percentage and Brix) were then positively correlated with the percentage of fat (0.38 and 0.41), urea (0.81 and 0.67), calcium (0.39 and 0.29), and magnesium (0.58 and 0.59), as well as the yellowness (0.78 and 0.75). Somatic cell count (SCC) and pH, parameters which are indicators of subclinical mastitis, were positively correlated (0.49), and SCC was positively correlated with sodium (0.37) and negatively correlated with potassium (-0.28). Among the macroelements in colostrum-calcium, potassium, magnesium, and sodium-the correlations were largely positive. With respect to the colour parameters, yellowness was negatively correlated with lightness (-0.41) and redness (-0.45). The factor analysis split the total of variance into three latent factors. The first factor was named "Colostrum quality of grazing sheep" because it was positively correlated primarily with SCC, pH, Poly Unsatured Fatty Acids (PUFA), and the sum of the omega-3 Fatty Acids (FAs). The second factor, named "Good quality colostrum", was positively correlated primarily with the refractive index, protein and fat percentages, urea content, phosphorus, Mono Unsatured Fatty Acids (MUFA), and yellowness. The third factor was positively correlated primarily with calcium, potassium, magnesium, and sodium, and it was therefore termed "Mineral component of colostrum". Stepwise discriminant analysis showed that the protein percentage, calcium, and magnesium were able to explain more than 85% of the Brix refractive index, which remains a good parameter for simply evaluating the nutritional quality of sheep colostrum at the level of a farm.