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Evaluation of beef cow-calf nutrition in Yucatan, Mexico: MS thesis progress report

Evaluation of beef cow-calf nutrition in Yucatan, Mexico: MS thesis progress report. Animal Science Kotaro Baba January 2006. Situation. Beef cattle farming is the main industry in Tizimín beef production systems in Yucatan are constrained by:

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Evaluation of beef cow-calf nutrition in Yucatan, Mexico: MS thesis progress report

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  1. Evaluation of beef cow-calf nutrition in Yucatan, Mexico:MS thesis progress report Animal Science Kotaro Baba January 2006

  2. Situation • Beef cattle farming is the main industry in Tizimín • beef production systems in Yucatan are constrained by: • Declining forage quality as the forage production system progresses • Low quality and amount in the dry season • Long calving intervals and percentage of cows calving each year

  3. Thesis objectives • Predict nutrient balances during each stage of the reproductive cycle with forages available during each stage of the annual forage production cycle. • Use this information to: • Identify weak links and their effect on the calving interval • Identify cost effective management strategies that can shorten the calving interval

  4. Procedures • Use panel of experts to describe current situation • Describe each group in the beef herd • Describe forage composition available during each season of the year • Predict nutrient balances for each group in the herd when consuming forages available during each forage growth season

  5. Forage growth periods

  6. Grasses grazed by forage growth periods • Season 1 grass ( June 1- July 31) • Season 2 grass ( August 1-September 30) • Season 3 grass ( October 1- January 30) • Season 4 grass ( February 1-May 31)

  7. Farm 1: Calving on June 1 Farm 2: Calving on August 1 Farm 3: Calving on October 1 Farm 4: Calving on February 1 Physiological stages -Early lactation -Mid-late lactation -Early dry -Late Dry Parity and age - 1 st lactation cows - 2nd lactation cows -Mature cows -heifers Representative farms

  8. SBW -1st =400 kg -2nd=460 kg -Mature=500 kg Calf BW -male 33 kg -female 30 kg Weaning weight -male 210 kg (dry season) -female 180 kg (dry) - male 220 kg (rainy) - female 220 kg (rainy) Inputs for the CNCPS

  9. Milk production early lactation -1 st= 4 kg -2nd=4.5 kg -mature=5kg Mid late lactation -1 st =3 kg -2 nd=3.3 kg -Mature 3.7 kg Milk fat=4 % Milk CP=3.5 % True protein=3.3 % CI -1st (rainy) 460 days -1st(dry) 500 days -The others 420 days Inputs for the CNCPS

  10. BCS change in the rainy season

  11. BCS change in the dry season

  12. Rations for simulations • Rations -season of the year and physiological period. Example, Early lactation period =90 days Farm 1 (calving on June 1) The ration ; 60 days(June1-July 31 with season 1 grass): 30 days( August 1- August 31, season 2 grass)=2:1, (6 kg:3 kg for example)

  13. Simulation 1: grazed grass composition based on CNCPS feed library

  14. Predicted composition of forages grazed during each of 4 growth periods • Assume forage quality progressively declines from beginning of growth in rainy season (season 1) to accumulated forage grazed in the dry season (season 4). • Used CNCPS feed library to estimate composition of forage grazed during each season.

  15. Estimated composition of grazed forage during each of 4 seasons1 1Based on CNCPS Feed Library

  16. Simulation 1:early lactation with Grasss 1 and 2

  17. Simulation 1:early lactation with Grasses 3 and 4

  18. Farm 1; Mature lactating cows calving on June 1

  19. Farm 1; Mature lactation cows calving on June 1

  20. Conclusions: simulation 1 • Negative energy balance through the entire calving interval; does not agree with observations of panel of experts. i) assumptions on milk amount and composition? ii) Do cows eat more than the predicted intake by the CNCPS? iii) Forage composition assumed.

  21. Simulation 2:grazed grass composition based on data collected by Juarez at Veracruz and Rueda in Western Brazil

  22. Predicted composition of grazed forages: simulation 2 • Assume forage quality progressively declines from beginning of growth in rainy season (season 1) to accumulated forage grazed in the dry season (season 4). • Used data from Mexico Gulf Coast (Juarez et al.) and Brazil Amazon region (Rueda et al.) to estimate composition of forage grazed during each season.

  23. Composition of grass grazed, Brazil Amazon region1 1Rueda et al., J. Animal Science 81:2923-2937.

  24. Grass composition, Gulf of Mexico1 1Juarez et al., J. Dairy Science 82:2136-2145. Averaged by 3 NDF ranges; 64-69, 70-72, and 73-75

  25. Simulation 2 forage composition assumptions

  26. Simulation 2 (grasses one and two)

  27. Simulation 2 (grass three and four)

  28. Simulation 2 (Farm 1; Lactating mature cows that calved on June 1)

  29. Simulation 2 (Farm 1; early and late dry Mature cows that calved on June 1)

  30. Effect of body condition score on conception • BCS 4.5-5 is needed for mature cows, 6 for heifers at calving, for conception (Herd et al, 1995 Randel, 1990) • Need BCS inputs for Farm 1 and 3 simulations whose calving time is in the beginning of the dry season.

  31. Conclusions. • The CNCPS simulations are very sensitive to forage chemical composition (Juarez et al. J. Dairy Science) • Farm 1 (Calving on June) looks closer to average of zero energy balance for the reproductive cycle than that of Farm 4(Calving on February 4) • Farm 4 has two energy balance nadirs

  32. Conclusions about forage composition for accurate simulation • Need actual values for forage consumed. • Grass samples need to represent what cows are observed to select. • Need samples for each month of year. • Analysis should include NDF, lignin, CP, and available NDF digestion rate.

  33. Goals for shortening the CI • Reach nadir as soon as possible after calving. • Have cows in optimum BCS at calving. • Need to achieve zero energy balance over the reproductive cycle.

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