Global warming and climate change, causing a constant increase in the earth temperature, negatively affects the production and health of dairy animals by causing heat stress. Animal's inability to dissipate sufficient heat to maintain homeothermy results in heat stress. Both environmental temperature and humidity impact the severity of stress faced by the animals and is manifested as reduced feed intake, decreased production and reproductive performance with comprised immune functions of livestock. This paper will focus on the micronutrients which help to alleviate the negative impact of heat stress on dairy animals.Micronutrients are essential elements needed by life in small quantities. It includes major minerals, micro/trace minerals and vitamins. Micronutrients help to maintain the production of the animals, improve the nutrient usage, effectively neutralize the oxidant stress and strengthen the compromised immune system.Minerals play an important role in maintaining normal physiological functions in animals. However, heat stress responses are thought to increase mineral loss by excretion in animals. Hence, mineral supplement (DCAD, Zinc, Chromium, Selenium etc) to the diet might alleviate the adverse effects of thermal stress.Vitamins function as enzyme cofactors, participate in a variety of metabolic pathways as catalysts and are essential for the normal growth and development of animals. The addition of vitamins supplements (Vitamin E, Niacin etc) to the diet of dairy animals might also contribute to the relief of the negative effects of heat stress.

1. ROLE OF MICRONUTRIENTS IN
ALLEVIATING HEAT STRESS IN DAIRY
ANIMALS
Presented by:
Dr. PRASANTH M.NAIR
MVSc STUDENT
Animal Nutrition Division
ICAR-NDRI

2. PRESENTATION OUTLINE
INTRODUCTION
STRATEGIES FOR ALLEVIATION OF HEAT STRESS
ROLE OF MACROMINERALS
ROLE OF MICRO MINERALS
ROLE OF VITAMINS
CONCLUSION
2

3. •Heat stress occurs when an animal's heat load is greater than
its capacity to lose heat
•Cattle feel hot sooner than we do
•High air temperature, humidity,
solar radiation and low air movement
contribute to increased risk
INTRODUCTION
3

4. (Whitter et al, 1994)
(Hughes et al, 2019)
TEMPERATURE HUMIDITY INDEX
GRAPHICAL REPRESENTATION OF
LCT – TNZ - HCT
4

5. • Easy way to measure and evaluate heat stress
• Based only on ambient temperature and humidity
• 72 traditionally thought to be when cattle become susceptible
• Modern high producing cattle begin to experience heat stress at a THI of 65-68
• The levels of stress were separated into:
TEMPERATURE HUMIDITY INDEX
(NRC,1971)
5

6. SIGNS OF
HEAT
STRESS
(Bin-Jumah et al, 2019) 6

7. STRATEGIES FOR THE ALLEVIATION OF HEAT STRESS
1. Physical modification of the environment.
2. Genetic development of less sensitive breeds.
3. Improved nutritional management schemes.
(Conte et al, 2018)
7

8. • Micronutrients are essential elements needed by life in small quantities
• Helps to sustain the production of the animals
• Improve nutrient utilization
• Effectively neutralize the oxidant stress
• Enhance the compromised immune system
ROLE OF MICRONUTRIENTS DURING HEAT STRESS
(Hassan et al, 2018) 8
MACROMINERALS
MICROMINERALS
VITAMINS

9. MACROMINERALS
MICRO/TRACEMINERALS
VITAMINS
MICRONUTRIENTS
• Zinc
• Chromium
• Selenium
• Vitamin A
• Vitamin E
• Niacin
• Calcium
• Sodium
• Potassium
• Chlorine
MICRONUTRIENTS HELPS IN STRESS HEAT ALLEVIATION…
9

10. Need for extra micronutrients during heat stress:
• Reduced feed intake and heat stress increases mineral excretion ,whereas it
decreases serum and liver concentrations of vitamins and minerals
• Mild to severe heat stress in dairy cattle has been estimated to cause an increase
in maintenance requirements by 7 to 25%
• Moreover, mobilization of minerals and vitamins from tissues and their excretion
are increased under stress conditions, and consequently, stress may exacerbate a
marginal vitamin and mineral deficiency or lead to increased mineral and
vitamin requirements
(Sahin et al. 2005)
(NRC, 2001)
(Siegel et al, 1995)
10

11. • HEAT STRESS-INDUCED DISTURBANCES OF ACID-BASE STATUS
WITH RELATED SIGNIFICANCE TO MACROMINERAL ELEMENTS
An important thermal regulatory reaction to heat stress is increased respiration
rate, which aids in heat dissipation via evaporation from respiratory passages
RESIPIRATORY
ALKALOSIS
COMPENSATED
METABOLIC
ACIDOSIS
MACROMINERALS
11

12. (Coffeen et al, 2016)
12

13. Involvement in Renal Compensation
• During heat stress and the associated perturbations of acid-base physiology,
the demand for cations by the kidney is increased and, the excretion of HCO3
must be accompanied by the excretion of a cation. Sodium or Potassium is a
possibility; however, Na is more likely
(West et al, 1991)
FUNCTIONS OF SODIUM AND POTTASSIUM
• Increase in dry matter intake
• Increase in milk yield
• Increase in milk fat percentage
• Dietary Na and K are very important in the
maintenance of water balance and acid-base
physiology of heat-stressed dairy animals (Sanchez et al, 1994)
13

14. 1. Basal diet for cattle: TMR (33% corn silage, 7% cottonseed hull & 60% concentrate)
2. Basal diet for cattle: 38% corn silage,62% concentrate &0.18% Na in dry basis
NaHCO3 (1.7%) NaCl (0.23%) CaCl2 (2.28%)
FEED INTAKE HIGHEST HIGHER LOWEST
WATER INTAKE HIGHEST HIGHER LOWEST
MILK YEILD HIGHEST HIGHER LOWEST
MILK FAT HIGHEST HIGHER LOWEST
EFFECT OF DIETARY MINERAL BUFFERS
NaHCO3 (1%) NaCl (0.73%)
FEED INTAKE 5.6% 5.6%
MILK YEILD 6.3% INCREASED REMAINED SAME AS BASAL
4% FCM 9.4% INCREASED 6.4% INCREASED
(Escobosa et al, 1984)
(Schneider et al, 1986)
• 24 Cattle in 3
groups
• 3 month expt.
period
• 24 cattle, 2 group
• 35 days
• Split plot method ( In
shade and no shade)
14

15. ____ WINTER
……… SUMMER
3. Basal diet : TMR (40% forage blend, 60% concentrate)
K2CO3 (1.2%) KHCO3 (1.8%) NaHCO3 (1.5%)
FEED INTAKE HIGHEST HIGHER HIGHER
MILK YEILD HIGHEST HIGHER COMPA. LOWER
MILK FAT HIGHEST HIGHER COMPA. LOWER
MILK PROTEIN SLIGHT DECREASE REMAINED AS SAME REMAINED AS SAME
(WEST et al, 1986)
• 24 HF Cattle
• 4 groups
• Invivo and in
vitro trials
• 155 days in hot
climate
(SANCHEZ et al. 1994)
REGRESSION CURVES
FOR DMI
15

16. Chlorine
• Increased dietary Cl was much more detrimental to DMI during summer
1. Basal diet : 14% CP, fortified corn soya bean meal
• Study concluded that ingestion of CaCl2 increases plasma Cl concentration,
which exceeds the bicarbonate buffering power capacity and produces a
metabolic acidosis, thereby appearing to suppress appetite in pigs.
CB Barrows
3 groups with
7 animlas in each
EP : 42 days
4% CaCl2 2.22% NaHCO3
WEIGHT GAIN DECREASED INCREASED
FEED INTAKE DECREASED REMAINED SAME
FEED EFFIEIENCY DECREASED REMAINED SAME
(Yen et al, 1981)16

17. When animals, particularly cattle, are given calcium chloride or diets with
negative cation to anion balance (i.e. more anions than cations), causes an
acidifying effect.
REGRESSION CURVES
FOR DMI
____ WINTER
……… SUMMER
(SANCHEZ et al. 1994)
• Hyperchloremic metabolic acidosis
17

18. Role of DCAD diets during heat stress
• Dietary cation-anion difference has been defined as milliequivalents of (Na + K) - (Cl + S) per
kilogram of DM and has a direct impact on blood acid-base metabolism
• To calculate the DCAD from the percent element in the diet dry matter: mEq/100 g
DM = [(%Na ÷ 0.023) + (%K ÷ 0.039)] − [(%Cl ÷ 0.0355) + (%S ÷ 0.016)]
1. Basal diet with TMR (60% conc. & 40% corn silage)
16 ANIMLALS ( 4 IN 4
GROUP)
LACTATING DAIRY
CATTLE
55 DAYS TRIAL
THI A B C D
Max 86.6 83.9 86.1 80.3
Min 72.6 73.8 74.0 69.3
DCAD (Na+ K –
Cl) mEq/kgDM
-111.6 191.4 180.0 312.4
A B C D
MY 16.4 19.7 19.2 19.7
4% FCM 14.8 19.7 18.2 19.3
DMI (kg/day) 10.7 16.4 15.8 15.9
RESULTS
(West et al, 1991)
18

19. 2. Relation between DCAD & Amino acid concentration
• Serum total amino acid and essential amino acid concentrations and ratio of
essential amino acid: total amino acid were greater for high DCAD
• These results suggest that increasing DCAD improves AA availability for protein
synthesis, that would otherwise be used for maintenance of acid-base balance
• It appears that keeping the DCAD at a healthy lactating level (20 to 30 mEq /100 g
DM) remains a good strategy during the warm summer months
32 LACTATING HF CATTLE
(2 × 16)
6 WEEK TRIAL
July 8 to Aug 27 (Hot season)
• NaHCO3 & K2CO3 were used to
alter the DCAD
25 mEq/100g DM 50 mEq/100g DM
DMI Remained same Remained same
MY Remained same Slight decrease
MF Less More
Amino acid Less More
(Wildman et al. 2007)
19

20. Interaction by Calcium
•A study found that serum Ca was lowered in heat-stressed lactating
dairy animals
Respiratory alkalosis
• pH increased
• More HCO3
- ions
Blood proteins
• Released H+ ions
• Formation of CO2 & H20
Calcium bound proteins
• Reduction in free ionized calcium
(Ca+) in blood. (Odom et al, 1989)
20

21. MICRO/TRACE MINERALS
Supplementation in Heat-Stressed Dairy Animals helps in:
• Performance and Productivity
• Maintenance of proper immunity, udder health and reproduction
• Boosting up the immunity
• Reducing oxidative damage
21

22. • Zn is a very important micronutrient, involved in wide range of metabolic activities
and productive performance like growth, reproduction and immune system
(Abdel et al., 2011: Patel et al., 2017)
• Zn plays a critical role in anti-oxidant defense as an integral part of the essential
enzymes superoxide dismutase (SOD). Zn deficiency has been reported to impair
antioxidant functions and an increase in oxidative DNA damage
(Underwood, 1999 : Jing et al., 2007)
• The major sources of Zn in the mineral supplements formulated for animal feeding
are inorganic salts like Zinc sulphate (ZnSO4), Zn oxide (ZnO), Zn chloride (ZnCl2)
(Batal et al, 2001)
ZINC
22

23. 1. Inorganic zinc supplementation modulates heat shock and immune
response
• 12 Pregnant cattle (6 HF & 6 Karanfries)
• 42 days trial, TMR ration
• Zinc (0.01 mM), was used in its salt form, Zinc sulphate
• The in vitro study was conducted after isolating peripheral
blood mononuclear cells (PBMC)
• Heat shock proteins (HSP) are a family of
proteins that are produced by cells in response to
exposure to stressful conditions
• Interleukin 6 is an immune mediator which, along
with other cytokines, activates the acute-phase
inflammatory response
(Ahmad et al, 2017)
23

24. (Jumah et al, 2019)
24

25. • Milk yield and composition
Cr at 0.05 mg/kg A significant rise in milk protein, fat and lactose levels
by 1.043,1.066,1.02 %, respectively is recorded when heat
stressed dairy cattle are supplied with Cr.
(Nikkhah, 2012)
10 mg/day Cr
from 21 days pre-partum
to 35 postpartum
An increase in milk production which was associated with
decrease lipolysis and increase glucose uptake that will result in DMI
rise
(McNamara et al, 2005)
• Thermoregulatory Responses
Cr-methionine (0.05 mg
/kg)
Significantly reduced the Respiration rate (Mousavi et al., 2019)
• Growth performance
Cr–methi at 0.05 mg /kg Increases feed efficiency and dry matter intake. (Arthington et al.,1997)
Cr yeast Increased feed intake in heat stressed lactating dairy cattle
compared with control group(21.24 and 19.56 kg/day, respectively)
(Alsaiady et al, 2004)
Cr @ 10.37 ppm for buffalo Positive effect on its balance and plasma concentration. (Kumar et al, 2013)
25

26. • Effect of zinc, chromium, niacin, protected fat and yeast,
supplementation
DIET TMR
(60% Maize fodder, 40% conc. Mix)
TDN 71%
CP 20%
INGREDIENT INCLUSION LEVEL
ZINC 40 mg/kg DM
CHROMIUM 1.5 mg/kg DM
NIACIN 6g/animal/day
PROTECTED FAT 2.5% of daily DMI
YEAST 10g /animal/day
ANIMAL Cattle (Karanfries CB) (18)
Age group Heifer
Period of expt. 120 days
Season July to october
(Purwar et al, 2017)
26

27. SELENIUM
• Selenium is an essential trace mineral that is an indispensable component of the
antioxidant system
• Selenium reduces the adverse impact of heat stress on redox balance and
metabolism, resulting in improved immune function, milk quality, and dairy
animal health (Sejian et al. 2012)
• Studies found that in heat stressed dairy animals, there is significant decreases in
plasma selenoprotein, diet supplementation with Se can significantly raise plasma
selenoprotein and Se concentrations, which might be a potential mechanism to
protect dairy animals against heat stress
(Hill et al. 2012)
(Oltramari et al, 2014)
27

28. •Effect of organic and inorganic selenium sources in heat stress cattle
24 dairy cattle (HF & BS)
In 2 groups
Mean temperature : 26oC
Relavive humidity : 75%
All the animals received the
same diet: a total mixed feed
with 0.278 mg/kg DM of
selenium
Group 1 Group 2
SOURCE Organic selenium
(Selenium yeast ,
278 mg/kg DM)
Inorganic selenium
(Sodium selenite ,
0.617 mg/kg DM)
Milk yeild Same Same
Milk fat (%) 4.15 3.96
Somatic cell count Lower Higher
Respiratory rate Higher Lower
Although the supplement of organic Se in the diet did not increase milk production,
it had a positive effect on the percentage of milk fat. It also reduced SCC and
improved mammary gland health.
(Oltramari et al, 2014)
28

29. VITAMINS
• Vitamins function as enzyme cofactors (coenzymes), participate in a variety
of metabolic pathways as catalysts, and are essential for the normal growth
and development of animals
• It is possible that the addition of vitamin supplements to the diet of dairy
animals might also contribute to the relief of the negative effects of heat
stress
(LiMin et al, 2019)
29

30. • It is an antioxidant that plays important role in the maintenance of cellular
membranes, immunity and reproduction
1. Yeast Culture and Vitamin E Supplementation Alleviates Heat Stress in
Dairy Animals
VITAMIN E
Saanen dairy goats (3×3)
Mean temp: 35oC
Relative humidity : 55%
Control GP : Basal diet
GP 2 : BD + Vit E (100 IU)
GP 3 : BD + Yeast culture (30g)
14 days trial
30

31. • The supplementation of Vit E and Yeast Culture
effectively strengthens the antioxidant capacity of dairy
goats, and hence alleviates HS. Compared to YC, VE is
much more powerful in promoting antioxidant capacity
TAP : Total Antioxidant Potential
(Wang et al, 2016)
31

32. • Niacin (vitamin B3) supplementation increases resistance to heat stress by inducing greater
cutaneous vasodilatation and blood flow (Di et al. 1997)
• The greater cutaneous vasodilatation after niacin supplementation is caused by prostaglandin D
produced by epidermal Langerhans cells, which acted on vascular endothelial prostaglandin D2
receptors (Maciejewski et al. 2006)
• The increase in blood flow after niacin supplementation is associated with an increase in the
sweating rate and evaporative heat loss from the skin surface (Di et al. 1997)
• When rumen-protected niacin was fed to Holstein cattle (12 g/day), there was a small but
detectable reduction in the rectal and vaginal temperature during heat stress compared with the
control animals (Zimbelman et al. 2010)
• 800 ppm niacin supplementation to CB cows showed better stress alleviation
(Khan et al, 2013)
NIACIN
32

33. VITAMIN A
• VA supplementation in the peripartum period could improve the reproductive
performance and reduce SCC of heat stressed dairy animals
1. Effect of Vitamin A along with other vitamins and trace minerals.
Holstein dairy cattles (50)
21 days
THI : 77.7
Control group : Only basal diet
(TMR)
Treatment group : Bolus supplement
Bolus ingredient Quantity
Vitamin A 545.6 × 103 IU of
Vitamin E 1092 IU
Vitamin D3 109.1 × 106 IU
Zinc 13.32 g
Selenium 0.251 g
Copper 16.2 g
Cobalt 0.236 g
Iodine 0.491 g
Manganese 8.28 g
33

34. (Khorsandi et al, 2016)
OTHER MICRONUTRIENTS
There are several other micronutrients (eg. Sulphur, Magnesium, Iodine, Copper, Vitamin C,
B complex vitamins etc) which have also effects in heat stess alleviation.
34

35. • The most adverse effect in heat-stressed dairy animals is pronounced reduction
in feed intake and milk production. Concerning these issues, a number of
nutritional strategies using micronutrients are summarized in this presentation
are capable of significantly increasing feed intake and milk production in heat-
stressed dairy animals
• Supplementation with micronutrients may play an auxiliary function in heat
stressed dairy animals, such as the amelioration of defects in immune function,
reproductive performance, heat dissipation, water intake, energy balance and
mammary health
• Micronutrients improves growth, productivity and overall well being of the
animal during heat stress
CONCLUSION
35

36. THANK YOU…..
36