Prediction of milk coagulation properties by Fourier Transform Mid- Infrared Spectroscopy (FTMIR) for genetic purposes, herd management and dairy profitability

Milk coagulation properties (MCP) are fundamental in cheese production, particularly in countries where a large amount of milk is destined to cheese industry. Several studies have demonstrated the role of MCP on cheese yield and quality. Lasting years, a general worsening of MCP at the herd and animal level has been detected. The coagulation of milk is influenced by several factors such as type and quantity of clotting enzyme, acidity and calcium content of milk, and protein content and composition. Milk coagulation properties are currently determined using several instruments, the most common being Reomether, Coagulometer, Formagraph, and Optigraph, which measure rennet coagulation time (RCT, min) and curd firmness after rennet addition (a30, mm). Nevertheless these instruments have strong limitations for the use at population level, mainly because they are time-consuming, expensive and require skilled personnel. The Fourier Transform MidInfrared Spectroscopy (FTMIR) allows for a reduction of costs needed for the analysis, high throughput, and possibility of large-scale application, i.e., the implementation in milk recording programs. In 2008 the feasibility to predict MCP using FTMIR was investigated in dairy herds located in north-east Italy and the results were encouraging; correlation coefficients for the prediction models of technological properties were comparable to those used for other novel traits (e.g., protein fractions and fatty acids). The northeast of Italy is characterized by a strong synergy among the dairy chain stakeholders (farms, dairy cooperatives, milk quality labs, animal breeding companies and research institutions). Since 2009 several regional projects have been financed and coordinated by the University of Padova (Italy) with many stakeholders of the Veneto region dairy chain, achieving a consistent improvement in efficiency of the dairy sector. The projects aimed at studying the technological characteristics of milk through an innovative approach (from cow’s milk to cheese), and it was developed through the implementation of MCP calibration models to a MilkoScan which routinely analysed individual and bulk milk samples from all the associated farms and dairies of the region. Data of individual milk samples (about 200,000 records), mainly from Holstein-Friesian cows, and herd bulk milk samples (about 15,000 records) from the 3 major dairy cooperatives, were recorded. Genetic analysis was carried out on MCP and estimated breeding values were obtained. Bulk milk samples were used [1] to study the sources of variation of MCP at herd level focusing more on management and feeding characteristics, [2] to optimize the cheese production at dairy level according to technological aptitude of milk to be converted into cheese, and [3] to define new quality payment systems that take into account the MCP. Currently, the projects are undergoing and the opportunity to extend the regional prototype at national level and at different dairy species is under evaluation.