1. Stocker Programs, Feedlot Performance and Carcass Merit Jim Oltjen University of California, Davis April 10, 2008

2. UC Sierra Foothills Research & Extension Center

3. UC Davis Feedlot

4. Outline Compensatory growth Using Davis Growth Model for performance and carcass traits Growing phase feed quality effects Growing phase length effects Previous nutrition effects on carcass merit and maintenance Physiology of growth and fat development Latest Research on: – Patterns of marbling – Length of stocker phase effects on fat distribution – Length of stocker phase effects on rate of marbling and subQ fat gain – Residual feed intake relationship with maintenance requirements New model to predict fat distribution

6. Compensatory growth in beef cattle From: Sainz et al., 1995

7. Sainz et al., 1995 Compensatory gain in feedlot steers

8. Sainz et al., 1995 Compensatory gain in feedlot steers

9. Sainz et al., 1995 Compensatory gain in feedlot steers

10. Davis Growth Model Net energy Protein Maintenance Fat (kg) T t rt rt tr Rt rt tr r

11. Davis Growth Model (Oltjen et al. 1986) Metabolizable Energy Intake Heat production Biological processes: Cell proliferation and hypertrophy Homeorrhetic control Biological processes: Synthesis and degradation Biological processes: maintenance Efficiency of conversion into net energy is related to both quantity and concentration of metabolizable energy in the diet

12. Effect of diet quality in growing phase to a constant BW endpoint (327 kg)

13. Stocker cattle’s rate of gain is linear from 2 to 3 Mcal ME/kg DM assuming cattle are fed ad libitum or have adequate available forage.

14. (growing phase to 327 kg BW)

15. Finishing daily gain is inversely and nearly linearly related to previous growing phase performance. This hardly varied whether cattle were fed to equal body weight or fat content endpoints.

16. (growing phase to 327 kg BW)

17. Steers fed to an equal body weight endpoint were more sensitive to previous growing phase ration energy compared to steers fed to a constant fat endpoint. Those fed higher energy diets as calves reached acceptable carcass fatness at much lighter weights.

18. Effect of growing phase length (MEC = 1.87 Mcal/kg)

19. (growing phase MEC 1.87 Mcal/kg) Finishing period performance

20. (growing phase MEC 1.87 Mcal/kg) Finishing period performance

21. (growing phase MEC 1.87 Mcal/kg)

22. Steers fed to an equal body weight endpoint were more sensitive to the length of the growing period compared to a constant fat endpoint.

23. Calf fed’s reach carcass fatness before desirable slaughter weights, confirming previous work that medium or small frame steers require a growing period before slaughter, particularly if not implanted.

24. Conversely, if we use longer growing periods due to increased cost of grain, cattle will have to be fed to larger weights for acceptable fatness, further exacerbating the progressive trend to larger carcasses in the industry.

25. Intermuscular Fat Subcutaneous FatIntramuscular Fat

26. Compensatory growth in beef cattle From: Sainz et al., 1995 a a a b b a ab c c b a b a a b

27. Compensatory growth in beef cattle From: Sainz et al., 1995 a ab a b a b b a b b

29. Sainz et al., 1995 Compensatory gain in feedlot steers

30. Sainz et al., 1995 Compensatory gain in feedlot steers

31. Sainz et al., 1995 Compensatory gain in feedlot steers SEM a b b

32. Growth curves

33. Allometric growth

34. Frame score and total body fat

35. Growth gradients among adipose depots

37. From: Bruns et al. (2004) J. Anim. Sci. 82:1315-1322

38. UC Sierra Foothills Research & Extension Center

40. From: Sainz & Vernazza-Paganini, 2004

43. UC Sierra Foothills Research & Extension Center

45. Gain in 12 th rib fat gain (BF. µm/day) in high and low growth cattle backgrounded at two ME levels

46. Gain in intramuscular fat gain (IMF. %/day) in high and low growth cattle backgrounded at two ME levels

47. UC Davis Feedlot

49. Residual Feed Intake More efficient steers with negative RFI ate less (12%). RFI was related to maintenance energy requirements (r=0.42). No ‘significant’ association with carcass traits. Myofibrillar protein degradation rates were positively related to maintenance energy requirements (r=0.76), but were not related to RFI (r=-0.14). A genetic trait related to RFI should be used in prediction models to account for differences in maintenance. Eventually adjust for protein synthesis/degration rate differences which are explicitly represented in the Davis Growth Model.

50. Intermuscular Fat Subcutaneous FatIntramuscular Fat

51. Net energy Protein Maintenance Fat Visceral (kg) Sub (kg) Intra (kg) Inter (kg) 12/13 th Rib fat (mm) Carcass characteristics Davis Growth Model KPH (kg) KPH (%) IMF (%)

52. First order differential equation Example: Subcutaneous fat (S; kg) Constraint Where j = 1 to 4 for each fat depot d dt

53. a proportional variable is a function of DNA and maximum adipocyte size Cell number (hyperplasia) ~ DNA Cell size (hypertrophy) ~ maximum adipocyte size

54. Proportion of total fat e.g. subcutaneous (S; kg) proportional fat variable Constraint ADSMAX – Maximum adipocyte size = 4.5 x 10 5 kg TG/kg DNA

55. Days on feed Proportion of total body fat Subcutaneous Visceral Intramuscular Intermuscular

56. Grid of fat depot parameter values Breed type ImplantednkFskFmkFv 1No50.30.40.2 2No290.10.40.0 3No90.20.30.1 1Yes240.20.30.1 2Yes700.20.40.1 3Yes20.30.40.1

57. Grid of fat depot parameter values Breed type ImplantednkFskFmkFv 1No50.30.40.2 2No290.10.40.0 3No90.20.30.1 1Yes240.20.30.1 2Yes700.20.40.1 3Yes20.30.40.1

58. Growth of four body fat depots

59. Model Summary Good starting point for predicting – 12/13 th rib fat (mm), IMF (%), and KPH (%) for breed type and implant status More data is required to develop fat depot parameters e.g. serial slaughter data. But data is scarce! Model needs to be evaluated

63. From: Garcia et al., 2007 Body protein Angus- Hereford steers Salers heifers Charolais bulls DGMINRA

64. From: Garcia et al., 2007 Angus- Hereford steers Salers heifers Charolais bulls Body fat DGMINRA

65. Ingredient¹LowModerateFinishing Chopped Oat Hay²75.050.05.0 Chopped Alfalfa Hay----- 5.0 Steam-Flaked Corn³15.040.080.0 Yellow Grease3.0 2.5 Molasses2.0 4.0 Trace Mineral Salt2.0 0.5 Oyster Shell Flour1.0 0.5 Monosodium-Phosphate1.00.75----- Sodium- Bicarbonate----- 1.25 Ammonium- Chloride----- 0.25 Potassium- Chloride----- 1.0 Urea (45% N)1.01.251.0 Rumensin----- Per label Formulated Values DM %7380 NEm. Mcal/kg DM1.321.592.22 Crude Protein.%DM11.06 14.75 Composition of growth and finishing diets

66. Weight gains in high (BX) and low (GX) growth cattle backgrounded at two ME levels The arrows show the beginning of the finishing phase for the BX-M (1). GX-M and BX-L (2) and GX-L (3) groups.

67. High growthLow growth P Values¹ Measurement²LowModerateLowModerateSEM³GenotypeGroup Hot carcass wt, kg325.0320.4365.6349.29.380.0060.294 Ribeye area, cm²74.9173.7784.2678.143.300.0710.303 Backfat,mm12.4613.3412.7112.810.4950.7890.354 KPH³. fat %1.161.571.821.870.2300.0710.343 Marbling score 4 3.773.963.803.650.2070.5290.913 Quality grade 5 6.346.636.386.300.2490.5640.689 Yield grade2.973.163.003.180.1520.8480.253 Backgrounding effects: carcass traits 1 Probability of a Type 1 error 2 Standard error of the mean (n=3/group) 3 Kidney.pelvic and heart fat 4 Marbling Score: ; 3 = Small 0; 4 = Modest 0. 5 Quality Grade: 0-2=Standard; 3-5=Select; 6-8= Choice; 9-11= Prime

68. Compensatory growth in beef cattle From: Sainz et al., 1995 Fat Protein

69. Compensatory growth in beef cattle From: Sainz et al., 1995 CL-CA

70. Compensatory growth in beef cattle From: Sainz et al., 1995 Slight = 7-9, Small = 10-12

71. (growing phase to 327 kg BW)

72. Backfat, mm Growing MEC, Mcal/kg BW1.873.063.06 limited MEI 2371.01.01.0 3272.06.13.3 4819.912.611.6 Growing phase to 327 kg BW

73. Marbling Score 1 Growing MEC, Mcal/kg BW1.873.063.06 limited MEI 2370.90.90.9 3272.65.23.7 4818.78.08.9 Growing phase to 327 kg BW 1 0, devoid; 1, practically devoid 0 ; 2, practically devoid 50 3, practically devoid 100 ; 4, traces 0 ; 5, traces 50 ; 6, traces 100 ; 7, slight 0 ; 8, slight 50 ; 9, slight 100

74. Table 1.Growth performance of finishing steers previously fed a forage diet (1.87 Mcal ME/kg DM) ad libitum (FA) or a high concentrate diet (3.06 Mcal ME/kg DM) at intake levels (CL) to achieve similar growing phase gains (Sainz et al., 1995). CLFA ------------------------------------------------------------------------------------------------------------------ Period length, d89111 Intake, kg DM/d10.9811.73 Gain, kg/d2.011.82 Feed/Gain5.476.45 Viscera, kg28.832.8 Relative maintenance BW -.75.831.21 Residual feed intake, kg/d-.631.05 ------------------------------------------------------------------------------------------------------------------ What about limit feeding concentrate in growing period?