Precalving Effects on Metabolic Responses and Postpartum Anestrus in Grazing Primiparous Dairy Cows

Mean (± SEM) for BW (a) and BCS (b) from 10 wk before until 10 wk after calving in heifers with low BCS 6 wk before calving and restricted access to pasture for the final 6 wk prepartum (BC4+RES, △; n=15), low BCS 6 wk before calving and unrestricted access to pasture for the final 6 wk prepartum (BC4+FF, ○; n=12), and moderate BCS 6 wk before calving with unrestricted access to pasture for the final 6 wk prepartum (BC5+FF, ■; n=13).

Percentage of cows cycling during the first 12 wk postpartum in heifers with low BCS 6 wk before calving and restricted access to pasture for the final 6 wk prepartum (BC4+RES, △; n=15), low BCS 6 wk before calving and unrestricted access to pasture for the final 6 wk prepartum (BC4+FF, ○; n=12), and moderate BCS 6 wk before calving with unrestricted access to pasture for the final 6 wk prepartum (BC5+FF, ■; n=13).

Total milk, fat, protein, and lactose yields (kg) during 24 wk of lactation for heifers with low BCS 6 wk before calving and restricted access to pasture for the final 6 wk prepartum (BC4+RES, △; n=15), low BCS 6 wk before calving and access to pasture for the final 6 wk prepartum (BC4+FF, ○; n=12), and moderate BCS 6 wk before calving with unrestricted access to pasture for the final 6 wk prepartum (BC5+FF, ■; n=13).

Mean plasma concentrations of a) insulin, b) IGF-I, c) leptin, d) growth hormone (GH), e) glucose, and f) NEFA from 6 wk before until 10 wk after calving, in heifers with low BCS 6 wk before calving and restricted access to pasture for the final 6 wk prepartum (BC4+RES, △; n=15), low BCS 6 wk before calving and unrestricted access to pasture for the final 6 wk prepartum (BC4+FF, ○; n=12), and moderate BCS 6 wk before calving with unrestricted access to pasture for the final 6 wk prepartum (BC5+FF, ■; n=13).

Mean (± SEM) for a) LH pulse frequency, b) LH pulse amplitude, and c) mean plasma LH concentrations measured over 16h at 2 and 5 wk after calving in heifers with low BCS 6 wk before calving and restricted access to pasture for the final 6 wk prepartum (BC4+RES, white bar; n=15), low BCS 6 wk before calving and unrestricted access to pasture for the final 6 wk prepartum (BC4+FF, gray bar; n=12), and moderate BCS 6 wk before calving with unrestricted access to pasture for the final 6 wk prepartum (BC5+FF, black bar; n=13). Superscripts represent differences between treatments (P<0.05).

Mean plasma concentrations of a) glucose, b) insulin, c) IGF-I, and d) leptin following infusion of glucose at 0min in heifers with low BCS 6 wk before calving and restricted access to pasture for the final 6 wk prepartum (BC4+RES, △; n=15), low BCS 6 wk before calving and unrestricted access to pasture for the final 6 wk prepartum (BC4+FF, ○; n=12), and moderate BCS 6 wk before calving with unrestricted access to pasture for the final 6 wk prepartum (BC5+FF, ■; n=13).