Effects of short and no dry period on milk yield and behaviour of dairy cows

A non-lactating period or ‘dry period’ (DP) of 6-8 weeks before calving is common practice. It is often seen as a rest period for the cow, and it maximises milk yield in the next lactation. A higher milk yield, however, can result in a more severe negative energy balance (NEB) in early lactation, associated with impaired health and fertility. A short or no DP reduces milk yield and the NEB after calving, at the expense of the ‘rest period’ before calving. We studied effects of a short (30 days) and no DP on walking, lying, and feeding behaviour of dairy cows 4 weeks before and 4 weeks after calving. Moreover, relations between milk yield, NEB, and behaviour were analysed. 86 Holstein-Friesian cows were given a short (n=29) or no (n=57) DP. All cows were housed in a free stall system with cubicles. Lactating cows were milked twice daily and received a lactating cow diet; dry cows received a dry cow diet. Diets were provided in feeding boxes that recorded visits, time spent feeding, and feed intake. Walking and lying behaviour were measured with accelerometers. DP categories were compared with unpaired t-tests; periods before and after calving were compared with paired t-tests. Before calving, cows with no DP tended to spend less time lying than cows with a short DP (12.7 vs 13.5 h/d; P: 0.05), whereas they walked more (1,134 vs 661 steps/d; P<0.01). Also, cows with no DP spent 0.9 h/d less on feeding than cows with a short DP (P<0.01). After calving, cows had shorter lying times than before calving (P<0.01). Cows with no DP spent 1.0 h/d more time lying and had 4.1 kg/d higher feed intake than cows with a short DP. The number of steps and feeding duration did not differ between the DP categories. Cows with no DP had a 3.5 kg/d lower milk yield (P: 0.01) and less severe NEB (-26 vs -197 kJ kg-0.75/d; P<0.01) 4 weeks after calving than cows with a short DP. There was no correlation between daily lying and feeding time, or between daily lying time and milk yield. In conclusion, cows with no DP spent less time lying and feeding and walked more during their extended lactation than cows with a short DP, which is in line with not having a ‘rest period’. Although both groups spent similar times on feeding after calving, cows with no DP spent more time lying than cows with a short DP. Moreover, lying and feeding behaviour were more constant between 4 weeks before and 4 weeks after calving for cows with no DP than for cows with a short DP. A DP may not be a necessity for rest, and no DP increased daily lying time and feed intake in early lactation.