The study was conducted from August 7th to October 7th, 2007 on a 10,000 lactating cow commercial dairy near Stanfield
(AZ, USA). The University of Arizona’s Institute of Animal Care and Use Committee approved all protocols and use of cows.
Four hundred and twenty seven lactating primiparous and multiparous Holstein cows were balanced for days in milk (DIM;
166
±
11.0), milk yield (38.2
±
0.21 kg/d) and parity (1.73
±
0.20) prior to the start of the study and assigned to either a
control (n = 213) with 0 g encapsulated niacin product/d, or with 12 g of an encapsulated niacin (NIA; n = 214) product/d
(NIASHURETM®; Balchem Corp.; New Hampton, NY, USA) in a crossover design. The dose selected for this study (12 g/d) was
chosen as the lowest dose of Di Constanzo et al. (1997)