Emma CL Bleach and Carrie Gauld
Harper Adams University, Edgmond, Newport, Shropshire

Introduction: Transition milk is the milk produced by the cow 2 to 3 day after calving (e.g. Godden 2008); it is the transition between colostrum and saleable whole milk. This product has a higher fat and protein content than whole milk and also contains non-nutritive bioactive molecules that are present in colostrum, albeit at lower concentrations (Blum and Hammon 2000). The beneficial effects of feeding transition milk are implied by studies such as that of Pyo et al. (2020). However, it is of variable composition and should be pasteurised before feeding. An alternative is to feed a transition milk replacer. The following study investigates the long-term effects of feeding a transition milk replacer to Holstein Friesian heifer calves during the first 10 days of life.

Materials and methods: Holstein Friesian heifer calves (n=36) born on the Harper Adams University Dairy Unit, Newport Shropshire were recruited to the study in two blocks during Spring (n=13) and Autumn (n=23) 2020. At birth (day 0) all calves received four litres of pasteurised colostrum (BRIX reading >22%), fed via a teated bottle. They were allocated to Transition or Control group taking account of birth weight and dam parity. Control calves were fed 5.2 litres of milk replacer (CMR; Shine, Bonanza Calf Nutrition, Ireland; 20% protein and 17% fat; 150g/l) from day 1 to day 10. From day 11 until day 42, 7.6 litres/day of CMR were fed. This was reduced to 5.2 litres/day of CMR from day 42 until 49 days. From 49 days CMR was reduced further, to 2.6 litres once a day until weaning on day 56. Following colostrum feeds, Transition calves were fed 5.2 litres / day of a transition milk replacer (Transformula, Bonanza Calf Nutrition, Ireland; 23% crude protein and 22% crude fat; 150 g/l) from day 1 to day 10, then from day 11 the calves were fed CMR as described for the Control calves. All calves were also offered ad libitum calf starter pellet with chopped straw and water from birth.

At weaning calves were moved into group hutches of 4-6 calves and fed the same calf starter pellet with chopped straw. From approx. 4 months of age until first calving heifers were managed in groups of approx. 20 with other dairy herd replacements of similar age. They were all fed the same total mixed ration (TMR; ME – 12.0 MJ/kg DM, CP – 167 g/kg DM, NDF- 318 g/kg DM) ad libitum when housed during winter and during the service period. They were turned out to grass during summer months. Heifers were artificially inseminated from 13 months of age. Following first calving, heifers joined commercial dairy herd. They were housed in cubicle shed through first lactation, milked twice daily and fed the same lactating cow TMR (ME – 12.0 MJ/kg DM, CP – 170 g/kg DM, NDF – 330 g/kg DM). Milk yields were recorded at each milking and milk fat and protein composition was assessed monthly. Effects of treatment (Transition vs Control) on birth weight weaning weight, growth rate birth to weaning and age at first calving (AFC) were assessed taking account of treatment and batch. The effects of treatment on first lactation yield milk yield and yield of fat & protein were assessed taking account to treatment and batch and AFC.

Results: There were no significant effects of treatment on calf liveweight at weaning (75.1±0.96 vs. 74.2±1.45 kg; Transition vs. Control p=0.595) or calf growth rate from birth to weaning (0.63±0.02 vs. 0.61±0.02 kg/d; p=0.141). There was no significant effect of treatment on age at first calving (797±12.7 vs. 782±12.0 days; p=0.377). Transition heifers produced more milk (8625±294.5 vs. 7678±300.8 kg; p=0.002) and a greater weight of fat and protein (617±21.7 vs. 532±22.2 kg; p=0.006) in their first lactation.

Conclusions: Feeding transition milk for the first 10 days of life is associated with higher milk yield in first lactation of Holstein Friesian heifers.

Acknowledgements: The authors are grateful to the Harper Adams University Dairy team for care of animals and to Bonanza Calf Nutrition for provision of the milk replacers.

References: Godden, 2008. Veterinary Clinics of North America: Food Animal Practice, 24(1), pp.19-39; Blum and Hammon, 2000. Livestock Production Science, 66(2), pp.151-159; Pyo et al., 2020. Journal of dairy science, 103(5), pp.4236-4251.