Soakers to cool cows: Can we reduce water use?

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1 Soakers to cool cows: Can we reduce water use? January 29, 2015 Jennifer M. Chen PhD Candidate Department of Animal Science Using water efficiently for cooling Help cows cope with heat Potable water use 1

2 Trying to maintain body temperature Gain heat Release body heat Trying to maintain body temperature death Normal = to Milk production drops Fertility impaired 2

3 Avoid gaining heat by using shade death Milk production drops Fertility impaired Body temp normal Seek shade Release excess body heat through sweating death Milk production drops Fertility impaired Body temp normal Sweat 3

4 Release excess body heat by breathing faster death Milk production drops Fertility impaired Body temp normal Normal 40 breaths/min Elevated = 80+ breaths/min Breathe faster Release excess body heat by panting death Milk production drops Fertility impaired Body temp normal Pant 100+ breaths/min Breathe faster 4

5 How to identify panting Typically starts at 100+ breaths/min Mouth open Tongue may be out May be drooling (Need to replenish water lost through evaporation) death Milk production goes down Fertility goes down Pant Breathe faster Sweat Drink water 5

6 Avoid gaining heat by eating less death Milk production goes down Fertility goes down Eat less Early sign: breathing rate goes up before problems start death Milk production goes down Fertility goes down Panting Breathing faster 6

7 How do we measure breathing rate? Count flank movements 1 full breath = in + out Calculate breaths/min Normal: < 40 breaths/min Elevated: > 80 breaths/min Free tool: Thermal Aid Free smartphone app Built-in stopwatch will give breaths/min thermalnet.missouri.edu/thermalaid 7

8 Measure respiration rate Normal (~ 40 breaths/min) Elevated (~ 90 breaths/min) 8

9 At 70 F, there is some variation in breathing rates As it gets warmer, there is more variation some are elevated 9

10 As it gets warmer, more are elevated Eventually, all are elevated 10

11 Early intervention Soakers help cows release body heat 11

12 Water is expensive Tulare County Farm Bureau: 2013 = $140 / acre-foot 2014 = $1,200 to $1,800 / acre-foot Potable water use varies 12

13 Weighing the costs and benefits: Is water being used efficiently? 1. When do cows benefit from spray? When a pen is out for milking, cows aren t using soakers Timers eliminate water use when cows don t benefit 13

14 What temperature threshold? Cows may benefit from a lower temperature threshold Increases the costs but also the benefits With only shade, body temp went up (air temp = avg high of 97 F) Body temperature ( F) Shade only Normal ( ) 14

15 Cows started using soakers at 73 F Body temperature ( F) Shade only Normal ( ) Body temperature stayed normal Body temperature ( F) Shade only Normal ( ) Shade and soakers 15

16 Weighing the costs and benefits: Is water being used efficiently? 1. When do cows benefit from spray? 2. What is the right amount of water for cooling? Common rule of thumb 16

17 What is the right amount of water for cooling? Common recommendations vary (0.20 to 2.00 gpm) We compared soaker nozzles Control (0 gpm) 0.10 gpm 0.35 gpm 1.20 gpm 3 min on + 12 min off x 4 (1 hour total) 17

18 Breathing rate started high Baseline 88 breaths/min Avg air temp = 90 F 0.35 gpm lowered breathing rate below baseline Baseline 88 breaths/min Avg air temp = 90 F 18

19 0.35 gpm more efficient than 1.20 gpm Used ~ 10 extra gal to decrease by 4 breaths/min Each extra gal lowered by < ½ breath/min Baseline 88 breaths/min Avg air temp = 90 F Body temperature started normal Normal ( ) Baseline

20 Breathing rate goes up before body temperature does death Milk production goes down Fertility goes down Panting Breathing faster 0.35 gpm maintained normal body temperature during the hour Normal ( ) Baseline

21 Cooling continued after the 1-hour soaking session (that body temperature stayed below baseline) 0.35 gpm more efficient than 1.20 gpm Used ~ 10 extra gal to keep cool for 15 more min Each extra gal added only 1.5 min 21

22 We also tested how well different soakers cooled loose-housed cows We compared the 2 most effective nozzles from before Control (0 gpm) 0.35 gpm 1.30 gpm 3 min on + 9 min off (24 h/d) 22

23 With only shade, body temp went up (air temp = avg high of 91 F) Body temperature ( F) Normal ( ) shade only Body temperature stays lower when cows have soakers Body temperature ( F) Normal ( ) shade only + soakers (0.35 gpm) + soakers (1.30 gpm) 23

24 Milk yield was higher with soakers lbs/day 0.35 gpm shade only 1.30 gpm Conclusion: lower flow rate cooled cows more efficiently 0.35 gpm 1.30 gpm They both cooled effectively Cows used them equally But one used about ¼ of the water 24

25 How do lower flow rates perform on a commercial scale? Dry matter was the same for both of our flow rates No difference in drift but we had partitions that reduced wind 25

26 What are other ways to improve water use efficiency? How do lower flow rates perform on a commercial scale? Can we adjust spray intervals / timing? Can we develop technology to detect cows? your ideas? jmchen@ucdavis.edu thermalnet.missouri.edu/thermalaid 26