title: Effects of twice-daily nursing on milk ejection and milk yield during nursing and milking in dairy cows.
abstract: Milk production and hormonal responses to milking in Holstein cows that were milked twice daily, and that either also nursed calves twice daily 2 h after milking for 9 wk after calving (n = 10) or that served as nonnursing controls (n = 8) were examined to assess how nursing affected responses to machine milking. Milk yield at milking during the 9 wk of nursing was lower in nursing cows compared with control cows (26.1 +/- 1.0 vs. 35.5 +/- 1.1 kg) that were only machine milked. During nursing, the amount drunk by calves increased from 6.5 +/- 0.7 kg/d on wk 1 to 12.5 +/- 1.4 kg/d on wk 9. When this was added to the amount of milk obtained at milking, nursing cows did not differ from control cows in total milk produced (35.5 +/- 1.0 vs. 35.5 +/- 1.0 kg). Residual milk yield, after i.v. injection of oxytocin after milking, was higher in nursing cows than in control cows (8.7 +/- 0.8 vs. 3.2 +/- 0.8 kg). During the 6 wk after weaning, milk production was the same for the nursing and control cows (34.0 +/- 1.35 vs. 34.7 +/- 1.42 kg). Plasma oxytocin levels during milking were greater for control cows than for nursing cows (31.7 +/- 5.4 vs. 18.0 +/- 2.8 pg/mL), but were equivalent to concentrations in nursing cows during nursing (35.5 +/- 7.5 pg/mL). Plasma concentrations of prolactin and cortisol increased after both milking (control vs. nursing: prolactin: 40.2 +/- 6.8 vs. 32.9 +/- 6.1 ng/mL; cortisol: 6.4 +/- 1.23 vs. 7.4 +/- 1.10 ng/mL) and nursing (control vs. nursing: prolactin: 18.6 +/- 7.3 vs. 38.9 +/- 6.6 ng/mL; cortisol: 2.34 +/- 1.15 vs. 7.37 +/- 1.04 ng/mL). In contrast to previous studies, there was no obvious advantage for milk production by keeping a calf with the cow. This appears to result from the reduced oxytocin secretion during milking for the nursing cows.
authors: Pacific Agri-Food Research Centre, Agriculture and Agri-Food Canada, Agassiz, British Columbia, Canada V0M 1A0. depassilleam@agr.gc.ca
authors: A M
authors: AM
authors: de Passillé
authors: P-G
authors: PG
authors: Marnet
authors: H
authors: H
authors: Lapierre
authors: J
authors: J
authors: Rushen
mesh_terms: D000818:Animals; D000833:Animals, Suckling; D002417:Cattle / Q000502:physiology*; D003612:Dairying / Q000379:methods*; D005260:Female; D006728:Hormones / Q000097:blood; D007774:Lactation / Q000187:drug effects / Q000502:physiology*; D008892:Milk / Q000378:metabolism* / Q000502:physiology; D008893:Milk Ejection / Q000187:drug effects / Q000502:physiology; D010120:Oxytocics / Q000008:administration & dosage / Q000494:pharmacology; D010121:Oxytocin / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology; D013997:Time Factors; D015430:Weight Gain / Q000502:physiology
chemical_list: D006728:Hormones; D010120:Oxytocics; D010121:Oxytocin