As the dairy industry strives for efficiency, the cell metabolic rate increases, and the neutrophil function decreases. In the last 15 years, there has been a 28% increase in milk production (33.9 to 39.5 kg/cow/d), a 12% decline in total-tract feed passage rate (9.72 to 8.52 h), and a 1% decline in DM digestibility (66.02 to 65.12). A study was conducted to determine the response of dairy cows to different levels of vitamin supplementation based on the 2018 BASF Industry vitamin supplementation survey (Coelho, 2018). A total of 835 Holstein cows were used in a randomized complete block design with cow as the experimental unit, treatment as the fixed effect, and block as the random effect (167 cows × 5 treatments). Cows were blocked by age, reproductive and productive performance, and were fed corn/corn silage diets formulated to meet or exceed 2001 NRC recommendations. Treatments were T1 = 2001 NRC, T2 = low 25%, T3 = AVG, T4 = high 25% and T5 = high 5% vitamin supplementation (Table 1). Vitamin supplementation significantly increased several productive and reproductive parameters. Bulk tank somatic cell count (T1 = 356, T2 = 194, T3 = 172, T4 = 161 and T5 = 146 cells/mL, P = 0.03, respectively; days dry (68, 60, 58, 56 and 56 d, P = 0.04, respectively); incidence of clinical mastitis (35.2, 19.7, 17.6, 12.0 and 11.7%, P = 0.03, respectively); conception rate of 1st service (32.1, 49.3, 52.7, 58.4 and 58.9%, P = 0.03, respectively); conception rate, all services (31.2, 45.7, 48.2, 53.1 and 53.1%, P = 0.02, respectively); heat detection rate (45.2, 63.5, 67.8, 72.1 and 73.0%, P = 0.03, respectively); calving interval (14.5, 13.6, 13.4, 13.1 and 13.0 mo, P = 0.04, respectively; peak milk, first lactation (37.2, 41.3, 42.0, 43.1 and 43.6 kg, P = 0.02, respectively) and peak milk, third lactation (50.8, 56.1, 59.1, 59.9 and 60.7 kg, P = 0.02, respectively). In conclusion, vitamin supplementation in low 25%, AVG, high 25% and high 5% vitamin supplementation significantly (P < 0.05) increased productive and reproductive dairy cow parameters versus the 2001 NRC, AVG versus low 25%, high 25% versus AVG and high 5% versus high 25% supplementation. Table 1 (Abstr. 334). Lactation for 658-kg cow BW

Vitamin1	Unit/hd/d	NRC	Low 25%	AVG	High 25%	High 10%	High 5%
A	IU	72,531	90,000	174,375	258,750	297,563	327,319
D3	IU	0	30,000	38,779	45,000	51,750	56,925
E	IU	435	1,000	1,750	2,012	2,561	3,157
Riboflavin	mg	0	0	500	1,000	1,150	1,265
Niacin	mg	0	0	3,000	6,000	6,900	7,590
Choline	mg	0	0	10,000	15,000	17,250	18,975
Thiamine	mg	0	0	0	120	138	152
Pyridoxine	mg	0	0	0	66	76	83
Biotin	mg	0	0	0	180	207	228
B12	mg	0	0	0	135	155	171
Pantothenic acid	mg	0	0	0	240	276	304
Folic	mg	0	0	0	201	231	254

¹B vitamins were coated.