Effect of 3-Nitrooxypropanol on milk composition and cheese-making properties in milk from Danish Red cows

The objective of the present study was to determine the effects of supplementing 3-nitrooxypropanol (3-NOP) to the diet of lactating Danish Red cows on compositional traits and cheese-making properties of milk. A total of 320 cows from a commercial farm were used in a cross-over design study with 2 periods and assigned to 1 of 2 treatment groups in each period: (1) control diets, (2) control diets supplemented with 3-NOP at 58 mg/kg feed dry matter. A subset of milk samples was collected from individual cows from each treatment group and analysed for gross composition, fatty acid (FA) composition, protein composition, casein micelle size, and coagulation properties. In addition, enteric gas emissions were measured in a subset of animals using GreenFeed units. The supplementation of 3-NOP was associated with a decrease in concentration of β-hydroxybutyrate (BHB) in milk, while no significant changes were observed in milk fat, protein contents, and FA composition. Regarding protein composition, the relative proportion of α s1 -CN was increased, whereas no changes in other major proteins or their proteoforms were observed upon supplementation of 3-NOP. Furthermore, rennet-induced coagulation abilities of milk were not affected by supplementing 3-NOP. Gas emission measurements documented methane reducing effects of 3-NOP. Overall, feeding 3-NOP to lactating Danish Red cows at 58 mg/kg feed dry matter decreased methane emission with no adverse effect on the composition and coagulation ability of milk for cheese production.