Choosing a Calving Season In Oklahoma

1. Choosing a CalvingSeason In Oklahoma

2. Seasons • People determine breeding season • Breeding season determines calving season • People determine weaning time • People and markets determine selling time

3. Traditions • Summer breeding May -July or Aug • Spring calving Feb - Apr. • Fall weaning -- Oct. 15 - Nov. 1 • Sell calves -- At weaning • Winter cows on hay and supplement

4. Breakeven Price $0.93/pound Oklahoma, Texas, New Mexico SPA data for 397 producers

5. Choosing a Calving Season Length: Year long 120 day 90 day 75 day 60 day 45 day Season: Feb-Mar Mar-Apr May-June Sept-Oct Nov-Dec

6. Choosing a Calving Season One Season per year All spring All fall Two Seasons per year Both fall and spring

7. One Calving Season Advantages • Concentrate calving time labor • Can put together package of calves • Simplify and optimize pasture management, feeding, and health

8. Two Calving Seasons Advantages • Double use of bull power • Calve heifers at 2 1/2 yrs • Give young cows 2nd chance • Spread out marketing

9. Calving Season Length

10. Reasons for Controlled Calving Season • More efficient supplementation • More effective and less expensive herd health program • More options for retained ownership • Larger lot sizes at weaning

11. Effect of Lot Size on Sale Price ($/cwt) of Eastern Oklahoma Feeder Calves Steers Steers Heifers Heifers Lot Size Price Difference Price Difference 1 $72.39 Base 64.11 Base 2-5 76.40 4.01 67.28 3.17 6-10 78.08 5.69 68.42 4.31 >10 79.53 7.14 68.81 4.70

12. Influence of Breeding Season Length on Cost of Production SPA data from 397 herds (Texas, Oklahoma, New Mexico) For 1 each day increase in breeding season ----cost of each cwt of calf weaned increased by $0.047 Reducing breeding season from year round to 75 days is associated with $13.63/cwt less cost

13. Starting a Controlled Calving Season 1. Build a strong bull fence (see chapter 22) 2. Select last desired calving date – remove bull according 3. Preg check 60 days later and cull opens 4. Put bulls back in first year so breeding season is 6 months 5. Start breeding replacements 20 – 30 days ahead of planned date for cows

14. Starting a Controlled Calving Season (continued) 6. Repeat same system 2nd year but leave bulls in breeding pasture 4 ½ months 7. Repeat same system 3rd year but leave bulls in 2 ½ months (75 days) 8. Continue to preg check 60 days later and cull opens 9. Shorten breeding season even more if desired

15. Alternativesin Spring Calving Programs

16. Spring Calving Early (Feb - Mar) Late (May- June) Severe calving weather Milder calving May-June breeding July-August breeding Calves can utilize forage Calves may grow slower Wean at down market Wean at slightly higher Cows winter in better BCS Cows thinner in winter No spring grass before calf May have green grass

17. Nebraska Research Sandhills (Gudmundson) Station

18. Move Calving Season to June • Wean at 4 months • Winter cows without supplement

19. Advantages • Lower feed costs • Calve in nice weather Disadvantages • August breeding • Care of early weaned calves • Relies on early spring to regain lost body condition

20. Differences in Nebraska and Oklahoma Nebraska Oklahoma Historic Averages in July High 88° F 93° F Low 65° F 71° F July 1998 High/Low Averages for Oklahoma―101/75 Historic Averages in August High 86° F 93° F Low 62° F 70° F August 1998 High/Low Averages for Oklahoma―97/ 71

22. Effects of Imposed Heat Stress on Reproduction in Beef Cows Biggers, 1986; OSU

24. Month of Breeding Season Influence on Pregnancy Rate Northern States Montana Month %Pregnant Apr. - May 80 June - July 85 Aug - Sept 88 South Dakota June - July 92 Aug - Sept. 89 -90 Sprott, Selk, and Adams. 2001

25. Month of Breeding Season Influence on Pregnancy Rate Midwestern States Illinois Month %Pregnant May – June +14 July - August --- Kansas (AI first service) May 72 June 55 July 40 Sprott, Selk, and Adams. 2001

26. Month of Breeding Season Influence on Pregnancy Rate Southern States Central Texas Month % Pregnant May (AI) 82 June (AI) 58 July (bulls) 16 Four years(bulls) Nov, Dec, Jan 91 - 94 Gulf Coast Texas Month % Pregnant April 76 All bulls May 44 June 45 July - Sept 16 Sprott, Selk, and Adams. 2001

27. Month of Breeding Season Influence on Pregnancy Rate Southwestern State—High altitude New Mexico Month % Pregnant April 15 - July 1590 June 1 - Sept. 1 90 Sprott, Selk, and Adams. 2001

28. Christenson, 1980 Reviewed Literature up to 1979 “High temperatures and humidity had the most effect... Pregnancy and calving rates from 10 to 25% common in cows bred in July through September.” “High temperatures reduced conception rate, lengthened the postpartum interval...and reduced duration of estrus”

29. Alternativesin Fall Calving Programs

30. Fall Calving Early (Sept-Oct) Late (Nov-Dec) Few born in heat Few born in cold Calve in good BCS BCS???? Rebreed in Nov-Dec Rebreed in Jan-Feb Wean in June Wean July-Aug Calving & planting Calving after planting

31. Comparing Winter Supplement Costs of Fall and Spring Calving Cows

32. Fall calves Springcalves C-P-51C 8/29/2003

33. Rebreeding Performance OSU data last two years Spring: 89.5% Fall: 95% Christenson review: “……postpartum pregnancy being higher in beef cows calving in the fall than cows calving in the spring.” Body condition at calving is the key.

34. Look Before You Leap!