Cheesemaking and sustainability index – Parmigiano Reggiano: a new breeding index for the Italian Holstein

The Italian dairy industry is specialised in the manufacturing of high quality, long ripened cheese. The objective of the present study was to develop a new breeding index (ICS-PR) for Holstein cattle producing milk for long ripened cheeses such as Parmigiano Reggiano PDO; the final breeding goal is to maximise net profit per day of life. Net profit for commercially available AI bulls was calculated as the difference between total estimable revenue and the total estimable costs using EBV released with the official genetic evaluations. Costs included heifer rearing, cow feeding for maintenance and production, fertility, udder health, calving difficulty and milk delivery whereby revenue considered cream, cheese and whey production, as well as, culled cow value. Dry matter intake and cheese yield were estimated using available prediction formulae; economic values for both costs and revenue were retrieved from the literature. Stepwise multiple linear regression was employed to develop a prediction equation for net profit from official AI bulls EBV having rank >59 and reliability >50. The 10-year genetic gain achievable for official EBV with selection for ICS-PR was calculated from P and G matrixes constructed using (co)variances routinely used for BLUP genetic evaluation and it was compared to the 10-year genetic gain achievable with selection for PFT index. EBVs retained (relative emphasis) from the multiple linear regression were: kg of protein (30%) and fat (5%), stature (−2%), locomotion (3%), udder depth (2%), somatic cell score (14%), calving ease (9%), longevity (10%), mastitis resistance (5%), and fertility (20%). Moreover, results demonstrated that, although the gain in production traits with ICS-PR was 85–96% the potential gain achievable with PFT, the selection for ICS-PR would result in a much faster genetic gain for welfare characteristics, such as calving ease (22%), longevity (22%), udder health (18%), while the gain for fertility was three times larger. In 10 years’ time, bovine production and productive life genetically will increase at a different rate depending on breeding decisions. However, in a scenario of selection for ICS-PR, cow lifetime production of Parmigiano Reggiano, calculated applying cheese yield prediction formulae used in the present study, is expected to be almost 100 kg higher compared to that achievable with selection for PFT.