This study was conducted at a dairy farm located near Ithaca, New York. Cows
were enrolled from 24 August until 29 September 2011; the follow-up period continued
until 4 July 2012. The farm milked 3300 Holstein cows three times daily in a
double 52-stall parallel milking parlor. The cows were housed in freestall barns,
with concrete stalls covered with mattresses and bedded with manure solids. All
cows were offered a total mixed ration (TMR) consisting of approximately 55%
forage (corn silage, haylage and wheat straw) and 45% concentrate (corn meal,
soybean meal, canola, cottonseed and citrus pulp) on a dry matter basis. The diet
was formulated to meet or exceed the NRC (2001) nutrient requirements for lactating
Holstein cows weighing 650 kg and producing 45 kg of 3.5% fat corrected
milk. Nutrient contents of the diets are described in Table 1.
Samples of TMR from pre-fresh and lactation diets were obtained on two different
days of a given week during the study period. The samples were combined
into 2-day composite samples and submitted (for both pre-fresh and lactation
diets) to a commercial laboratory (Dairy One Cooperative) for wet chemistry analysis.
Samples were analyzed for dry matter, crude protein, acid detergent fiber,
neutral detergent fiber, and macro and micro minerals.