Under ideal conditions, dairy cows produce milk during 305 days of the year and are dry the remaining 60. In reality, feeding for high production should begin during the dry period or towards the end of the previous lactation. With dry periods shorter than 40 days, there’s not enough time to regenerate the mammary tissue; this may result in production losses of 20-40 percent during the next lactation.
Dry periods longer than 70 days do not promote an increase in production and may result in calving difficulties that are costly to the producer. Recent research has demonstrated that the minimum days dry to maximize production depends on parity (Kuhn et al., 2006).
Cows of first and second lactation had little production losses with shorter periods of 40 to 45 days. For mature cows, dry periods of 50 to 65 days were needed, probably because they are less persistent.
How long must be the dry period in dairy cows?
The authors concluded dry periods shorter than 30 days and longer than 70 days reduced lifetime productivity, with the impact of dry periods in excess of 80 days even worse than those shorter than 30 days. One advantage of 40-day dry periods is that cows can be maintained in a higher energy plane of nutrition, which reduces the negative energy balance after calving and, therefore, fat mobilization.
Up to 2007, only 14% of the dairy herds in the U.S. had dry periods between 40 and 49 days, with the majority (51.8 percent) between 60 and 69.
Continue reading this article published in Progressive Dairyman.
