Effects of postpartum oral calcium supplementation on milk yield, milk composition, and reproduction in multiparous Jersey and Jersey × Holstein crossbreed cows

The objective of the present study was to evaluate effects postpartum oral calcium supplementation on milk yield, energy-corrected fat concentration, protein and somatic cell count linear score across first 3 monthly tests postpartum, peak risk pregnancy at service, hazard by 150 d in 1,129 multiparous Jersey × Holstein crossbreed cows from 2 commercial dairies. After calving, were systematically assigned control (no supplementation; n = 567) or 0 1 (oral Ca; 50 60 g as boluses; 562). Monthly test composition, information obtained Dairy Herd Improvement Association. records used for reproductive data. Statistical analysis conducted using generalized multiple linear, Poisson, Cox's regressions. Treatment evaluated considering cow-level available parturition (parity, breed, previous lactation length, dry period gestation body condition, locomotion calving ease, calf sex). In addition, a subset serum concentration before treatment administration (n 756). Overall, did not affect productive variables. However, conditional length observed. Milk yield 1.8 kg/d higher supplemented with within fourth quartile, compared same quartile. Energy-corrected tended be 1.1 lower counterparts. Peak 1.6 kg ≥2, score. administration. Our results suggest that are factors such cows.