Lactoferrin concentrations in goat milk throughout lactation

Lactoferrin is an iron-binding glycoprotein and is considered a major part of the non-specific disease resistance complex in the mammary gland. For cows, the influence of physiological factors on the lactoferrin concentration in milk has been reported. In addition, lactoferrin concentrations have been demonstrated to be proportional to somatic cell counts (SCC) in cows milk. In this study, we aimed to analyse the effects of lactational stage, lactation number and SCC in 19 goats throughout an entire lactational period. Lactoferrin concentrations in weekly composite milk samples were analysed with a competitive ELISA developed for caprine lactoferrin. Maximal lactoferrin concentrations were observed in the colostral samples (387 ± 69 μg/ml). In the following week, less than 20% of these concentrations were observed (62 ± 25 μg/ml) and thereafter until week 32 p.p., the weekly mean concentrations ranged between 10 and 28 μg/ml. Toward the end of lactation, approximately during the 33rd week, the concentrations began to increase and were reaching about 3.2-fold higher values in week 44 (107 ± 19 μg/ml). SCC were only available in monthly intervals and could thus not be directly related to the weekly lactoferrin recordings. When classifying the individual goats according to the median of their SCC values obtained during midlactation, the goats with SCC medians >430,000 had higher lactoferrin milk concentrations during this time than the ones with SCC below this threshold (P < 0.05). In addition, sampling week and parity significantly affected the lactoferrin concentration (P < 0.05 and P < 0.01, respectively). Comparing SCC and lactoferrin, both parameters are significantly affected by various physiological factors. Further studies are needed to clarify if the relationship between Lf and bacterial counts is closer compared to the relationship between SCC and bacterial counts.