Although short dry periods seem to be a promising strategy, most research indicates that short dry periods might reduce milk production in the new lactation, particularly in primiparous cows (Annen et al., 2004). Another research group (Gillund et al., 2001), using data from several dairy herds, studied the association of different body condition scores (BCS) near calving, the proportion of cows presenting ketosis, and some fertility parameters. These authors found that cows with BCS > 3.5 were nearly three times more likely to present postpartum ketosis than cows with lower BCS.
As evidenced in other studies, Gillund et al., 2001 also supported the concept that this is probably the result of lower dry matter intake (DMI) in animals with higher BCS near calving. In agreement with that, previous studies found that cows with greater BCS near calving have lower DMI and lost more body weight after calving than thinner cows (Garnsworthy and Topps, 1982).
Gillund et al. also found that cows presenting ketosis lost more weight after calving and ultimately had lower conception at first breeding and longer calving to conception intervals. Therefore, it is always recommendable to follow BCS throughout lactation. In fact, monitoring BCS throughout lactation is a very effective tool to measure body condition loss after calving, as shown in the Figure 3, below.
WHAT IS THE IDEAL ‘DAYS DRY’ FOR CONFINED DAIRY HERDS?
Several research groups have studied this topic in the last decade. In general, they found that shorter dry periods tend to reduce problems related with negative energy balance (NEB), but lower milk production might be a concern when using short days dry (30 to 35 days) in primiparous cows.
Pezeshki et al., 2007 evaluated the effects of different days dry on milk production, milk composition, and energy balance of dairy cows. They used three dry period lengths 56 days, 42 days, and 35 days. Their data confirmed previous reports describing that cows in the short dry period had less problems with NEB. However, primiparous cows receiving the shorter dry period of 35 days produced less milk in the new lactation, in agreement with previous research (Annen et al., 2004).
Pezeshki’s et al. data also argue that multiparous cows and cows with higher body condition scores (BCS) might benefit from shorter dry periods. Therefore, most of the research articles seem to recommend a 40 to 45 days dry for multiparous cows and 60 days for primiparous cows.