Cows gave more milk after pregancy if given Calcidiol (semi-activated Vitamin D) – RCT March 2021

Effect of 25-hydroxyvitamin D3 during prepartum transition and lactation on production, reproduction, and health of lactating dairy cows

Journal of Dairy Science. online 2 March 2021, https://doi.org/10.3168/jds.2020-18901
H.M.Golder1J.McGrath2I.J.Lean1

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Highest milk yield for CON-TRT in all 4 daries (samples)

Mistakes were made at some daries - failed to give the vitamin D

We hypothesized that feeding 25-hydroxyvitamin D3 [25-(OH)D3] during lactation and prepartum in conjunction with negative dietary cation-anion difference diets would improve milk production, increase the probability of pregnancy, and reduce the incidence of postcalving diseases. Cows from 4 dairies with prepartum transition diets negative in dietary cation-anion difference were used in 2 randomized cohort experiments.

In Experiment 1 (Exp. 1), cows were assigned to control [CON; n = 645; no 25-(OH)D3] or treatment [RT; n = 537; 2 mg/d of 25-(OH)D3 from ∼21 d prepartum to parturition and 1 mg/d in lactation] groups at ∼21 d prepartum. Cows were monitored for weekly milk yield, milk composition every 60 d, and health and reproductive measures.

In Experiment 2 (Exp. 2), cows (n = 2,064; median 147 d in milk) were assigned to 4 groups and monitored for the same measures as in Exp. 1 to the end of that lactation (L1), the subsequent transition (∼21 d prepartum to parturition), and the next lactation (L2). Groups were as follows, with the amount of 25-(OH)D3 fed (mg/d) indicated in parentheses for L1, transition, and L2, respectively:

• (A) control-control (CON-CON; 0–0–0),
• (B) treatment-treatment (TRT-TRT; 1–2–1),
• (C) control-treatment (CON-TRT; 0–2–1), and
• (D) treatment-control (TRT-CON; 1–0–0).

For L1, a total of 1,032 cows entered the control groups A or C and a total of 1,032 cows in groups B or D. The number of cows in groups A to D that entered L2 was 521, 523, 273, and 248, respectively. Blood calcium, phosphorus, and 25-(OH)D3 concentrations were measured from 17 cows/group at 5 times.

In Exp. 1, TRT cows had 0.2 lower log somatic cell count than (LnScc) CON cows (4.21 ± 0.045 vs. 4.01 ± 0.050, respectively) and multiparous TRT cows had 41 ± 23% higher probability of pregnancy/day than multiparous CON cows, resulting in a 22-d median decrease in time to pregnancy.
Primiparous TRT cows had 1.67 ± 0.40 times greater odds of mastitis/day than primiparous CON cows.

In Exp. 2 TRT-TRT cows had between 16 and 29% lower probability to be bred/day than other groups. Multiparous CON-CON and TRT-CON cows had 20 ± 8% and 30 ± 17% greater probability of pregnancy, respectively, than multiparous TRT-TRT cows. Serum calcium concentrations were not affected by group, but phosphorus and 25-(OH)D3 concentrations were highest in the TRT-TRT cows. The study provides further insights into the use of 25(OH)D3 in transition and lactation.

Treatment plan (I could not figure it out)