Preference for and acceptability of a fat-microencapsulated anionic salt by dry dairy cows

The objectives of this study were to determine (1) the preference for, and acceptability of, a novel, fat-microencapsulated anionic salt by nonlactating dairy cows and (2) whether these responses were influenced by cow personality. Twenty-four pregnant Holstein dairy cows (parity at dry-off: median = 2; range = 1- 5) were enrolled at dry-off (56 d to calving), in cohorts of 6, and housed in a tiestall facility. After adapting to a base dry cow diet for 14 d, cows were exposed to each of 2 treatment diets in a crossover design (with 7-d periods): (1) base dry cow diet with added fat-microencapsulated anionic salt (ANIC) at 0.30 kg/cow/d DM (providing -2,544 mEq/d at that dosage; formulated DCAD = -101.5 mEq/kg of expected DMI), or (2) base dry cow diet with fat placebo (PLCB) at 0.15 kg/cow per day DM (formulated DCAD = +64 mEq/kg of expected DMI). Following the crossover design, cows were offered both diets simultaneously in a 3-d preference test; feed was offered in a split bunk, in large enough quantities to ensure ad libitum daily access to both diets. Following the preference test cows were assessed for personality traits using a combined arena test comprised 3 parts: a novel arena test, a novel object test, and a novel human test. Dry matter intake was calculated for each day, and urine pH was measured 2×/wk for every cow throughout the study. When cows consumed the ANIC diet, they had lower urine pH values than when on the PLCB diet (7.6 vs. 8.2). No difference in DMI was detected between the ANIC and PLCB diets (19.3 vs. 19.5 kg/d DM). During the preference phase, cows chose to eat a similar proportion of their total daily DMI for the ANIC and PLCB diets (48.6% vs. 51.4% of total DMI). Cows sorted against long particles of the PLCB diet and against fine particles of both diets during the acceptability phase. During the preference test, cows sorted against the longest ration particles of the PLCB diet. Principal component analysis of the behaviors recorded during the personality assessment revealed 2 factors interpreted as personality traits, "active" and "bold." Less bold cows consumed a higher portion of the ANIC diet during the preference test. Less active cows sorted more for the medium particles of both diets, whereas more active cows sorted more for the short particles of both diets during the preference test. Overall, the results demonstrate that dry cows showed no preference between a TMR containing a fat-microencapsulated anionic salt or a fat placebo, and demonstrated similar acceptability of both diets. Further, feed sorting and diet preference were influenced by cow personality.