Randomized prospective study exploring health and growth outcomes for 5 days of extended transition milk feeding in pre-weaned Scottish replacement dairy heifers

Typically, calves are fed a single feed of first milking colostrum followed by milk replacer, but there is an increasing body of evidence to suggest that feeding transition milk or 'extended colostrum feeding' may have health, growth and production benefits in dairy calves. Transition milk (milkings 2-6) may be preserved for extended feeding with potassium sorbate to prevent bacterial proliferation (even at ambient temperatures). The objective of this study was to observe the effects of feeding potassium sorbate preserved transition milk on calf health and growth outcomes on two commercial Scottish dairy farms. Calves were fed one feed of 4-5 L of first milking colostrum followed by either milk replacer (FC group) or 5 days (10 feeds) or preserved second and third milking transition milk (PTM group). Calves were blood sampled within the first week of life, health scored every second day and weighed at birth and weaning. First milking colostrum and transition milk samples were tested for Brix (%) and bacterial contamination. Small differences in health outcomes and average daily gains were observed, but first milking colostrum was highly contaminated (median total bacteria count = 107,250 colony forming units per ml (CFU/ml), range = 0- 3,120,000 CFU/ml), which may have interfered with the results. Several risk factors including age and season were significantly associated with health outcomes. Transition milk feeding could be a viable alternative for neonatal calves where first milking colostrum for feeding in an extended fashion is in short supply, but special attention must be given to scrupulous hygiene practices on farm.