The Economics of Heat Stress- Albert DeVries

Supported by AFRI Competitive Grant no. 2010-85122-20623 from USDA-NIFA Economics of Heat Stress: Implications for Management Albert De Vries Department of Animal Sciences University of Florida Gainesville, Florida, USA devries@ufl.edu DAIReXNET Webinar, April 9, 2012

Topics• Cost of heat stress, value of cooling• Improved fertility in summer• Sexed semen mix

Dairy heat stress losses in USA St-Pierre et al. (2003)• Feed intake • Milk production • Reproduction • Repro culling • Death  Average losses due to heat stress • Without any heat abatement: $167 per cow per year • With optimal heat abatement system: $100 per cow per year

Annual production and economic losses in 6 states (minimum heat abatement) Annual Dry matter Repro Milk  Days Deaths hours of LossState intake  culling  (lbs/cow/yr) open   (%) heat stress ($/cow/yr) (lbs/cow/yr) (%) (%)WI 201 403 9 0.6 0.1 9 72CA 320 646 12 0.9 0.2 12 110NM 370 745 23 2.2 0.5 20 168AZ 798 1609 26 2.5 0.5 22 256FL 1971 3975 59 8.0 1.7 49 676TX 2196 4425 54 7.4 1.6 36 698 After St-Pierre et al. (2003)

Florida seasonal pregnancy rates 1976-2002 winter summer De Vries and Risco, 2005

Florida Observation• Many seasonal breeding herds – Calve in fall, breed in winter, dry in summer• Preferably no calving in late spring/summer – Heat stress during calving – Death risk  (cows, calves) – Milk production , fertility • Getting cows pregnant in summer:  late spring / summer calving• How important is it to get cows pregnant in summer?

Can we improve profitability by improved fertility andbetter insemination decisions? A story of calving patterns

Systems approach• Large spreadsheet(+) with heifers and cows, lactation curves, fertility, feed intakes, labor, prices, etc.• Decisions: replacement, insemination, calf raising• Closed herd: sell surplus heifer calves + all bull calves• Optimize profit per (milking) slot per year• Heat stress effects on milk production, fertility, death risk• This is difficult 

Relative humidity, temperature and temperature humidity index for Orlando, Florida max H max F THI min H min F

Seasonal herdconstraint: 1300 total cows cows calved heifer calves born heifer calves kept heifers calved

Seasonal herd constraint: 1300 total cows Cows present Milk Cows milkingOpen cows

• Increase probability of conception by 10%• For example: 40% + 0.1 * 40% = 44%

+10% Probability of conception constraint: 1300 total cows Normal +10% Prob. conceptionProfit/slot/year $728 $767 +$39/slot/year heifers cows

Inseminations+10% probability of conception constraint: 1300 total cows cows heifers

Delayed inseminations +10% probability of conception constraint: 1300 total cows heifers cows

Calvings+10% probability of conception constraint: 1300 total cows cows heifers

1000 milking cows constraint

Seasonal herd constraint: 1000 milking cows Cows present Milk Cows milkingOpen cows

Inseminations +10% probability of conception constraint: 1000 milking cows Normal +10% Prob. conceptionProfit/milking slot/year $587 $647 +$60/slot/year cows heifers

Present and milking+10% probability of conceptionconstraint: 1000 milking cows present milking

Delayed inseminations +10% probability of conception constraint: 1000 milking cows heiferscows cows

Calvings+10% probability of conceptionconstraint: 1000 milking cows cows heifers

Sexed, fresh IVF embryo transfer insummer increases conception rates• Summer transfer of sexed in-vitro fertilized embryos• 200% of conventional AI summer conception rate• 88% heifer calves Stewart et al. (2011)• Economics?• $90 per IVF-ET transfer• $250 sold heifer calf, $50 sold bull calf• Change in calving pattern

IVF-ET in summer: scenario Aconception rates and #inseminations, IVF-ET All summer “breedings” with IVF-ET No delayed inseminations All calves sold, heifers purchased 1300 total cows constraint conception rate inseminations/ET

IVF-ET in summer: scenario A Cows calved and milking All summer “breedings” with IVF-ET No delayed inseminations All calves sold, heifers purchased 1300 total cows constraint Value of IVF-ET: -$4 /milking slot/year milking Normal: $779, IVF-ET: $775 calved

IVF-ET in summer: scenario Bconception rates and #inseminations, #IVF-ET Optimal summer “breedings” Allow delayed inseminations 1000 milking cows constraint conception rate inseminations/ET

IVF-ET in summer: scenario B Cows calved and milking Optimal summer “breedings” Allow delayed inseminations 1000 milking cows constraint Value of IVF-ET: $88 /milking slot/yearmilking Normal: $569, IVF-ET: $657 calved

Conventional, sexed semen, and summer heat stress• $20 conventional dairy semen – Normal fertility – 48% heifer calves – Extra heifers calves sold for $250, bull calves $50• $35 female sexed semen – 80% of normal fertility – 88% heifer calves – Extra heifer calves sold for $250, bull calves $50• What is the optimal mix?

Conventional and sexed semen mix constraint: 1000 milking cows conv. cows sexed heifersProfit conventional only: $587 / milking slot / yearProfit sexed + conventional: $624 / milking slot / year (+$37)

Summary• Cooling dairy cows pays in hot climates• Value of improving fertility in summer depends on seasonality of cow performance (milk, fertility) and herd constraints (parlor capacity, cash flow)• Seasonality has major implications for optimal insemination mix Thank you devries@ufl.edu

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