Slide 1: Benefits of Mitigating Heat Stress in Dairy Cows
5/11/20 Benefits of Mitigating Heat Stress in Dairy Cows Lance Baumgard PhD Jacobson Professor Iowa State University Baumgard@iastate.edu Department of Animal Science 1 2 1
Slide 2: Reminder: Intestinal Functions
5/11/20 Reminder: Intestinal Functions ¨ GIT is a tube running from the mouth to the anus ¤ Everything inside of the tube is technically “outside” of the body ¨ Digest and absorb nutrients ¤ GIT lumen is a inhospitable environment ¨ Prevent parasites, pathogens, antigens, enzymes, acids, toxins etc.
Slide 3: Human GIT Surface Area
5/11/20 Human GIT Surface Area: Skin 2 ~2 m That’s an enormous amount of area to “defend”! Lungs No wonder 70% of the ~50X immune system resides in GIT GIT ~150 X 5 Baumgard Research Group Priorities: Ruminants and Pigs Feed Restriction Transition Period Heat Stress Hind Gut Acidosis Mycotoxins Leak
Slide 4: "Normal" Metabolism Review
5/11/20 “Normal” Metabolism Review ¨ Ad Libitum Intake ¨ Suboptimal Intake ¤ ↑ Insulin ¤ ↓ Insulin ¤ ↓ NEFA ¤ ↑ NEFA ¤ ↓ catabolic hormones ¤ ↑ catabolic hormones Cortisol Glucagon Epinephrine Insulin Growth Hormone (depending upon energetic state) Responsive to feed intake 7 Friendly Reminder of Gl
Slide 5: Heat Stress: Economics and Food Security
5/11/20 Heat Stress: Economics and Food Security ¨ Cost: (lost productivity, mortality, product quality, health care etc.) ¤ American Agriculture: > $4 billion/year n $1.7 billion in dairy industry ¤ Global Agriculture: > $350 billion/year ¨ It will get worse in the future if: ¤ Climate change conti
Slide 6: Effects of HS on Milk Yield
5/11/20 Effects of HS on Milk Yield 50 Heat-stressed Pair-fed 45 40 Milk Yield (kg) 35 30 Heat stress ¯ yield ~45% Pair-feeding ¯ yield by ~19% 25 Thus, ¯ feed intake only accounts for ~50% of the reduction in milk yield 20 0 1 2 3 4 5 6 7 8 9 Day Rhoads et al., 2009 11 Heat Stress Increases Cortiso
Slide 7: Heat Stress Reduces Basal and Stimulated Adipocyte Lipolysis
5/11/20 Body Weight Loss During 9 days 0 -10 -20 UF Pair-fed -30 kg Heat Stress HS -40 -50 -60 Rhoads et al., 2009 13 Heat Stress Reduces Basal and Stimulated Adipocyte Lipolysis 600 500 400 NEFA (uEq/l) Heat-stressed 300 Pair-fed 200 100 0 1 2 3 4 5 6 7 8 9 Day Rhoads et al., 2009 Wheelock et al.,
Slide 8: Lipid Metabolism
5/11/20 Lipid Metabolism ¨ Basal and stimulated (epinephrine) lipolysis is blunted during heat stress in multiple species ¤ Ruminants ¤ Pigs ¤ Chickens ¤ Rodents ¨ What is preventing lipid mobilization? ¨ What’s the purpose of preventing lipid metabolism during a hyper-catabolic state? 15 Circulatin
Slide 9: HS and Hyperinsulinemia
5/11/20 HS and Hyperinsulinemia ¨ Basal and stimulated (GTT) increases conserved across species ¨ Especially when compared to pair-fed thermal neutral controls ¤ Dairy ¤ Beef ¤ Pigs ¤ Rodents ¤ Rabbits ¤ Snakes ¤ Human 17 Milk Sugar Output 0 -50 -100 Heat Stress Cows -150 Secrete -200 ~400 g less la
Slide 10: Whole Body Glucose Production
5/11/20 Whole Body Glucose Production 800 PF 700 HS Extra mammary tissues utilize ~ 400 g more glucose/day 600 during heat stress. mmmol/h 500 Indicates 400 glucose is preferentially being utilized for processes 300 milk synthesis (maybe the immune system?) other than 200 during heat stress. 100 Per
Slide 11: Heat Stress and Gut Health
5/11/20 Heat Stress and Gut Health ¨ Diversion of blood flow to skin and extremities ¤ Attempting to maximize radiant heat dissipation ¨ Coordinated vasoconstriction in intestinal tissues ¤ Reduced nutrient and oxygen delivery to enterocytes ¤ Hypoxia increases reactive oxygen species (ROS) ¨ Reduce
Slide 12: Heat Stress and Gut Health
5/11/20 Heat Stress and Gut Health ¨ Lipopolysaccharide (LPS) stimulates the immune system ¨ LPS promotes inflammation production….catabolic condition ¤ TNFa, IL-1 etc.. n Reduced appetite n Stimulates fever n Causes muscle breakdown n Induces lethargy n ....reduces productivity 23 Lumen Hypoxia Act
Slide 13: The Effects of Heat Stress are Rapid
5/11/20 The Effects of Heat Stress are Rapid! 7 6 5 z Jugular Vein LPS, AU 4 3 2 y xy xy 1 x 0 0 2 4 6 12 Time of heat stress (h) Pearce et al., 2015 25 Acute Phase Proteins Increase During Heat Stress LBP SAA 7 ↑ 2-fold 400 6 Day: P < 0.01 5 300 Day: P < 0.01 µg/mL µg/mL 4 200 3 2 100 ↑ 4-fold 1 0
Slide 14: Heat Stress Summary
5/11/20 Heat Stress Summary ¨ Direct and indirect effects ¤ ↓DMI only accounts for 50% of reduced milk yield ¨ Hyperinsulinemia ¤ Blunted adipose mobilization ¤ Explains why heat-stressed pigs & chickens prioritize adipose tissue ¨ Liver remains sensitive to catabolic signals ¨ Leaky gut ¤ Inflammat
Slide 15: Insulin?? Mammary LPS Infusion Increased Circulating Insulin
5/11/20 Insulin?? ¨ Increased during heat stress ¨ Increased or not changed in ketotic cows ¤ Metabolically, a ketotic cow should be hypoinsulinemic ¨ What’s insulin’s role during immuneactivation and inflammation? 29 Mammary LPS Infusion Increased Circulating Insulin Waldron et al., 2006 30 15
Slide 16: Professor Otto Warburg
5/11/20 Friendly Reminder of Glucose’s Importance Glucose is primarily made from propionate Lactose is made from glucose 72 g of glucose/ 1 kg of milk (Kronfield, 1982) Milk yield is primarily determined by the amount of synthesized lactose Liver Glucose ATP Feed Propionic Lactose Bacteria Milk Yiel
Slide 17: How much glucose is the entire body using??
5/11/20 Warburg Effect Resting Immune Cell Activated Immune Cell GLU GLU GLU GLU GLU G-6-P G-6-P Insulin ATP Pyr Pyr Pyr Pyr Acetate Lac Amino Acids TCA TCA NEFA ETC A TP ATP ETC TL R4 LPS Shouse and Baumgard, 2017 33 How much glucose is the entire body using?? 80 years later and we still not know h
Slide 18: LPS Challenge & Blood Glucose
5/11/20 LPS Challenge & Blood Glucose Hepatic Glucose output & > immune system utilization Peripheral Insulin Resistance Glucose Immune system glucose utilization > Hepatic Glucose output & Peripheral Insulin Resistance Time LPS Bolus 35 LPS Challenge & Blood Glucose Glucose Can we quantify this amo
Slide 19: Total Glucose Deficit
5/11/20 Kvidera et al., 2015 37 P=0.06 1800 Trt: P<0.01 1600 1400 Total Glucose Deficit (g) 1200 1000 1553800g – 483 g = 1070 g glucose/12 h 600 400 200 483 1259 1553 0 Control LPS LPS-Eu Kvidera et al., 2015 38 19
Slide 20: Conserved Response
5/11/20 8.4 Mcal of energy! 39 Conserved Response Species: Immune glucose utilization ¨ Steers: 1.0 g/kg BW0.75/h (Kvidera et al., 2016) ¨ Pigs: 1.1 g/kg BW0.75/h (Kvidera et al., 2015) ¨ Cows: 0.7 g/kg BW0.75/h (Kvidera et al., 2017) ¨ Cows: 1.0 g/kg BW0.75/h (Horst et al, unpublished) 40 20
Slide 21: Billion Dollar Question
5/11/20 Remember: We couldn’t account for almost 1 pound of glucose during heat stress 0 -50 -100 Heat Stress Cows -150 Secrete -200 ~400 g less lactose/day g/d -250 -300 than Pair-Fed Thermal -350 Neutral Controls Is the liver producing ~ 400 g less glucose/day?? -400 or is-450 extra-mammary tissue
Slide 22: Heat Abatement
5/11/20 Heat Abatement ¨ By FAR the biggest impact a dairy producer can do to alleviate the negative consequences of heat stress is physically modifying the environment ¤ Shade, Fans, Soakers, Misters etc… 43 Why Invest in Cooling Cows?? ¨ Improve production efficiency and profitability ¨ Improve su
Slide 23: Effects of Shade on Surface Temperatures
5/11/20 Heat Stress Abatement Priorities 1) reduce solar radiation 2) increase evaporative heat loss in conjunction with fans 45 Effects of Shade on Surface Temperatures Bare ground surface temperature before and after shading at various times during the daya Shaded time Temperature of Ground Surfac
Slide 24: Physics Review: Energy and Phase Changes, Evaporation
5/11/20 Physics Review Energy and Phase Changes 47 Evaporation ¨ Evaporation is a cooling process! ¨ The Heat of Vaporization is 540 calories per gram of condensed water at 100 degrees. ¨ Why do you feel chilly when getting out of a swimming pool or out of the shower? ¤ The energy (heat) required to
Slide 25: Three Ways to Utilize Evaporative Cooling
5/11/20 Three Ways to Utilize Evaporative Cooling ¨ Cool the Cow ¤ Evaporate water off the skin ¤ Does not change air temperature ¨ Cool the Air ¤ Change air temperature through evaporation ¨ Combination ¤ Cool the air and the cow 49 Priorities to Reduce Heat Stress (Lactating & Dry Cows) ¨ 1. Water
Slide 26: Where to cool cows?
5/11/20 Where to cool cows? ¨ Tie-stalls, Free stalls or dry lot pens ¨ Holding pen ¨ Maternity pen ¨ Parlor exit lane ¨ Feed lines/feed alleys ¨ Feed bunks ¨ Pre-fresh barn ¨ ………………………………..EVERYWHERE 51 Summary of Heat Abatement Cool cows by providing good shade and a combination of evaporative coo
Slide 27: Pre-partum Cooling: Saudi Arabia
5/11/20 Pre-partum Cooling: Saudi Arabia Reproductive Effects Services per Pregnant after 1st or Cows Culled for Conception 2nd Service Reproductive Failure Cooled Control Cooled Control Cooled Control Dairy Al Kharj 2.30 2.60 63% 55% 2% 16% Durma 3.34 4.46 30% 27% 16% 27% Al Zaid 3.63 3.98 40% 34%
Slide 28: Dietary and Management Strategies
5/11/20 Dietary and Management Strategies to Reduce the Negative Effects of Heat Stress ¨ Reduce walking distance ¨ Reduce time in holding pen ¤ Ventilate and cool ¨ Exit lane cooling ¨ Don’t “lock up” during the mid day ¨ Consider “short-feeding” the day before a heat wave ¨ Feed early in the morni
Slide 29: Encapsulated niacin studies
;, J Dairy Sci. 93:2387-2304 doi:10.3168/jds.2009-2557 © American Dairy Science Association®, 2010. Effects of encapsulated niacin on evaporative heat loss and body temperature in moderately heat-stressed lactating Holstein cows R. B. Zimbelman, L. H. Baumgard, and R. J. Collier’ Department of Anima
Slide 30: Can leaky gut explain suboptimal production?
5/11/20 59 Can “leaky gut” explain suboptimal production frequently observed in animal agriculture? ¨ Heat Stress ¨ Inadequate feed intake ¤ “off-feed event” n The negative effects on growth and milk yield are bioenergetically unexplainable by reduced feed intake ¤ Transition period n Cause of ketos
Slide 31: Seminar Summary
5/11/20 Stress Umbrella Mycotoxins Shipping Hind Gut Acidosis Ketosis Tissue Trauma Over-crowding Psychological Stress Heat Stress Leaky Gut ↑ LPS ↑Insulin ↓Feed Intake Immuno-activation ↓Performance Immune System Nutrient Utilization 61 Seminar Summary ¨ Heat Stress decreases almost every metric of
Slide 32: Acknowledgments
5/11/20 Acknowledgments Funding Support • USDA NRI/AFRI/NIFA • # 2005-35203-16041 • # 2008-35206-18817 • # 2010-65206-20644 • # 2011-67003-30007 • # 2014-67015-21627 • # 2015-10843 • # 2017- 05931 • # 2017 -10843 • # 2019 -07859 • Alltech • Zinpro Inc. • FormAFeed • TechMix • Elanco Animal Health •