A TMR composed of 65% (on DM basis) early 1st cut grass silage and 35% commercial concentrate feed was prepared at least 3 times per week. The TMR was mixed using a Siloking Duo 1814 (Kverneland, Bryne, Norway) mixing machine with about 20 min of chopping the grass silage followed by 10 min of mixing the chopped silage and concentrate feed. The grass silage was prepared from timothy (Phleum pratense) based stand of a 3rd year ley seeded as SPIRE Surfôr/Beite Pluss 10 (Felleskjøpet Rogaland Agder, Stavanger, Norway) containing 42% timothy, 23% meadow fescue, 15% blue grass, 10% white clover and 10% perennial ryegrass. The commercial concentrate feed (i.e., Drøv Energirik Høg) was manufactured by Norgesfôr (Norgesfôr AS, Oslo, Norway) suited for high yielding NRF dairy cows (i.e., 7000–10,000 kg energy corrected milk per lactation; https://www.norgesfor.no/strand-unikorn/produkt/drov-energirik/ ; accessed on 15 November 2022).
During the feeding period, the cows were given ad libitum access to a TMR delivered in three split portions, i.e., 40%, 30% and 30% of their daily allowance at 07.15, 14.15 and 19.15 h local time, in respective order. The TMR was offered in individual feed troughs with collection of daily orts just before the 07.15-h feeding.
Freeze-dried and crushed AT was blended with 400 mL of a sugar beet molasses and water mixture (50:50 w/w). For the 0.125% AT and 0.25% AT cows, the AT–water–molasses mixture was hand mixed with the TMR in individual feed troughs with amounts proportional to their DM offer. The control group was given the same amount of molasses–water mixture to avoid any distortion in chemical composition of the feed offered.
The cows had free access to their feed except for a brief moment when feed refuse was collected and when the AT and water–molasse mixture was hand mixed at the three feed delivery times. Areas around the feed troughs were maintained clean and feed tossed from the troughs, whenever this happened, was put back during any given time of the day.
During the feeding period, the cows were given ad libitum access to a TMR delivered in three split portions, i.e., 40%, 30% and 30% of their daily allowance at 07.15, 14.15 and 19.15 h local time, in respective order. The TMR was offered in individual feed troughs with collection of daily orts just before the 07.15-h feeding.
Freeze-dried and crushed AT was blended with 400 mL of a sugar beet molasses and water mixture (50:50 w/w). For the 0.125% AT and 0.25% AT cows, the AT–water–molasses mixture was hand mixed with the TMR in individual feed troughs with amounts proportional to their DM offer. The control group was given the same amount of molasses–water mixture to avoid any distortion in chemical composition of the feed offered.
The cows had free access to their feed except for a brief moment when feed refuse was collected and when the AT and water–molasse mixture was hand mixed at the three feed delivery times. Areas around the feed troughs were maintained clean and feed tossed from the troughs, whenever this happened, was put back during any given time of the day.
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