1. Shortened dry cow periods Gabriella Varga Pennsylvania State University

2. Why a dry period?  Recommended as a “rest” period  Based on observations that milk production decreased when no dry period was allowed  To allow adequate mammary tissue regrowth before the next lactation

3. The majority of the studies used historical data

4. Optimizing dry period length  Although no income is collected directly during the dry period, managing the length of the dry period may play a crucial role in maximizing profits for both current and upcoming lactations.

5. Why 60 days dry?  Regeneration of the mammary gland Two to three weeks are needed for secretory cell growth in the late dry period This is essential for maximum colostrum production and milk secretion in the next lactation  Observations that this resulted in maximum milk production

6. Mammary gland development

7. Regression and repair of the digestive tract  Ruminal papillae may partially regress as a result of feeding lower energy diets during the early dry period  Allows for repair of ruminal ulcers that may have developed in the previous lactation

8. Dry period length 56 d28 d Dry matter intake, kg/d1416.8 Milk yield, kg/d42.3 91 Fat,% 3.86 4.08 Protein, % 2.83 2.97 No effect on calf weight or colostral quality Rastini and Grummer, 20030-70 DIM

9. planned dry period 30 day 60 day Schairer et al, 200111,63510, 222 Bachman, 2002 9,799 9,978 Gulay et al, 2003 9,580 9,836 Recent studies conducted with planned dry periods: Milk production annually, kg No significant differences within experiments

10. dry period (d) 60 30 0 Number of cows30 30 30 Milk, average for 120 d, lb/d Primiparous95 88 71 Multiparous 104 100 92 Recent studies conducted with planned dry periods Annen at al, 2003

11. Gulay, 2003 Average for 305 d ME was 71 lb/d for all groups Period of negative energy balance 25% less for 30-day vs 60 d dry periods

12. Square= no dry Triangle=28 d dry Circle=56 d dry Annen et al, 2004

13. Square= no dry Triangle=28 d dry Circle=56 d dry

14. Shorter dry period: Mammary tissue studies Little evidence for the loss of epithelial cells No net loss of mammary cells Tissue area occupied by epithelium did not decline Alveolar structures remained intact The dry period is important for replacement of aging alveolar cells before the next lactation (Capuco and Akers, 1999) = 3 weeks adequate

15. Cow health and reproduction  Potentially less metabolic problems with shorter days dry  Return to estrus sooner (ovulated 22 vs 29 d)  No difference in udder health  All limited data, more research necessary !!!!!!!

16. Other benefits  Dry cow facilities may become less crowded or more crowded  Less movement of cows  Cows easier to dry off due to the fact they are producing less milk?  Simplify management as all cows are on one ration

17. Shorter dry period?  Most high producing, mature cows qualify  Choose cows with second lactation of higher  Don’t enroll cows that have a history of short calving intervals  Avoid cows with a high twinning rate  Heat stressed cows: heat stress has been shown to reduce gestation length  Exclude cows if you do not know their calving date

18. Antibiotic residues a problem?  Dry treating is necessary  Dump milk from fresh cows for at least 6 milkings and run a milk antibiotic test after the 6 th milking  Keep testing until milk free of antibiotics don’t assume 6 milkings is for all cows  One reason a 40 day dry period may be appropriate

19. How to feed cows during a short dry period  Anionic salts?  1.58 Mcal of energy /kg of DM  13-14% CP, adequate metabolizable protein  Adequate rumen filling capacity, adequate chewing  Need to have minimal change in transition to lactation diets and contain ingredients from lactating cow diets

20. Other questions and/or concerns?  Will lactating cow facilities handle 5% more cows?  Will the parlor handle 5% more cows?  Will you still need two groups of dry cows in order to manage cows dried off early?  Can you manage first calf heifers separately from mature dry cows?  Will there be other drug residue problems?  REMEMBER average daily milk yield per cow will decline, and average DIM will increase BUT total milk shipped will increase

21. Economics  If milk price is $0.12 per lb (US)  Total variable expenses while milking is $3.00 per day  Total expenses while dry are $1.25 per day  ($3.00 - $1.25)= $1.75 per day  $1.75/ $0.12 per lb = 14.6 lb milk per day  THERFORE as long as milk income is worth more than $1.75/d you are better off milking her and they need to milk at least 14.6 lb/d to justify continued milking

22. Potential benefits to a 40 day dry period  By not feeding a far-off ration, the rumen is less at risk of acidosis from drastic changes in carbohydrate levels  Less group changes may mean less social changes and higher DMI during this critical period  A shorter dry period may mean less total dry cows to house  Less risk of subclinical mastitis, especially due to environmental streptococci

23. Management strategies  Need to have excellent information about calving dates Inaccurate records may lead to early calvings and reduced yield Late calvings may suffer from gain of additional condition  Enough housing to prevent overcrowding Dirty housing Increased mastitis Decreased DMI  Very good management necessary

24. CONCLUDING REMARKS  May not be for all producers  Still lots more work to be done  Research not really conclusive with regards to benefits to cows and/or producer  Length of the dry period should be continuously evaluated as changes in milk price, replacement availability, cash flow, and plans for the future change  May try 42-45 days initially