Effects of calving interval of dairy cows on development, metabolism, and milk performance of their offspring.

Extending the voluntary waiting period (VWP) for insemination in dairy cows is of interest as a strategy to reduce the frequency of calving events and inseminate at a moment with fewer fertility problems. Little is known about the calves born from dams with a different VWP followed by a different calving interval (CInt). The objective of the current study was to identify the effect of dam's CInt on body condition, metabolic status, and milk production of their offspring from birth until 100 DIM of the offspring's first lactation. Holstein-Friesian dairy cows (n = 154, 41 primiparous, 113 multiparous) were blocked according to parity, milk yield, and SCC and randomly assigned to a VWP of 50, 125, or 200 d. Female calves (n = 62) from cows with different CInt were monitored from birth until their first calving event as heifer. Certain dams were not successfully inseminated soon after the planned VWP, resulting in differences between the intended VWP and the actual CInt. Calves were regrouped according to their dam's actual CInt (CInt_1: 324-408 d; CInt_2: 409-468 d; CInt_3: 469-586 d). The dam's CInt did not affect calf birth weight. From birth to weaning, the calves born to dams in CInt_1 had a higher plasma nonesterified fatty acids (NEFA) concentration (0.34 mmol/L; CI: 0.30, 0.37) than CInt_2 (0.28 mmol/L; CI: 0.26, 0.31) and CInt_3 (0.26 mmol/L; CI: 0.24, 0.29) calves. Calves born to dams with a shorter CInt (CInt_1) had greater IgG and IgM against keyhole limpet hemocyanin (KLH) than CInt_3 (IgG: 6.05 ± 0.30 vs. 4.64 ± 0.30; IgM: 6.45 ± 0.17 vs. 5.89 ± 0.16, respectively; mean ± SE) before weaning. After weaning till calving, CInt_1 calves tended to have greater plasma NEFA concentration than CInt_3-calves. During the first 100 DIM, a longer CInt of the dams resulted in lower plasma IGF_1 (CInt_2), lower milk lactose (CInt_3), and lower fat- and protein-corrected milk (FPCM; CInt_2) in offspring, compared with shorter CInt of the dams (CInt_1). Collectively, a longer CInt in dams did not affect birth weight of their calves or BW during the weaning or rearing phase. From birth till weaning, a longer CInt in dams resulted in less anti-KLH IgG and lower plasma NEFA concentration in plasma of the calves. During the first lactation of their offspring, a longer CInt in dams can result in a lower plasma IGF_1 and FPCM during the first 100 DIM, although effects were not present in all CInt categories.