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Effect of Environment – Maintenance

Effect of Environment – Maintenance. Acute or chronic Physiological responses Metabolic responses Behavioral responses. Effect of Environment – Maintenance. Example: Sudden cold spell Eat more to increase metabolic heat production Changes in posture to reduce heat loss.

george-erickson
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Effect of Environment – Maintenance

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  1. Effect of Environment – Maintenance • Acute or chronic • Physiological responses • Metabolic responses • Behavioral responses

  2. Effect of Environment – Maintenance • Example: • Sudden cold spell • Eat more to increase metabolic heat production • Changes in posture to reduce heat loss

  3. Effect of Environment – Maintenance • Example: • Chronic cold temperatures • Longer feeding periods • Increased hair coat • Decreased rectal temperature • Decreased respiratory rate

  4. Effect of Environment – Maintenance

  5. NRC, 2007 Upper & Lower Critical Temperatures

  6. Effect of Environment • Young horses are cold stressed at higher temperatures than adults • Less than 4 wks old – remained healthy, gained normally if shelter, bedding, feed plentiful (Cymbaluk et al., 1993)

  7. Effect of Environment • Full acclimation to either hot or cold temperatures – 21 days • Therefore, LCT & UCT are not constant • Also consider rain, wind, shelter, age, body condition

  8. Effect of Environment • Shelter = 9% reduction in heat loss • Blankets = 18% reduction in heat loss • Shelter + blanket = 26% reduction in heat loss (MacCormack & Bruce, 1991)

  9. Cold Environment – Recommendations • Nutrient affected = ENERGY • Hay provided free-choice allows horses to eat to their energy reqmts • Higher digestibility hay = higher total energy intake • Growing, thin, worked, aged – may need concentrate added

  10. Cold Environment – Recommendations • Adult horses need 2.5% increase in DE for maintenance for each degree Celsius below LCT.

  11. Cold Environment – Recommendations • LCT = 5°F = -15°C • 0°F = -18°C • So 3 Celsius degrees below LCT • 3 x 2.5% = 7.5% increase in DEm

  12. Cold Environment – Recommendations • Mature QH performance gelding, 10 years old, 1,250 lb, during the off-season • DEm = 33.3 kcal/kg BW x (567.5 kg) = 18,898 kcal/1,000 kcal/Mcal = 18.9 Mcal

  13. Cold Environment – Recommendations • DEm= 18.9 Mcal • 7.5% increase in DEm • 18.9 Mcal x 0.075 = 1.4 Mcal • Adjusted DEmfor 0°F • 18.9 Mcal + 1.4 Mcal = 20.3 Mcal

  14. Cold Environment – Recommendations • Additional minerals/vitamins not necessary • Water free-choice • Water intake maximized if heated to 68°F (Kristula & McDonnell, 1994) • Minimize energy loss with bedding, shelter from wind

  15. Hot Environment – Recommendations • Water intake greatly increased = water free-choice • Electrolytes (Na, Cl) lost in sweat = salt free-choice • No preference for cooled water • Fat replacing some fiber?? • Shade

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