TABLE 3–5 Empty Body (EB) Chemical Composition at Different Condition Scores (CS)

CS

Percent in EB

SBW, percent of CS 5a

Fat

Protein

Ash

Water

1

3.77

19.42

7.46

69.35

77

2

7.54

18.75

7.02

66.69

81

3

11.30

18.09

6.58

64.03

87

4

15.07

17.04

6.15

61.36

93

5

18.84

16.75

5.71

58.70

100

6

22.61

16.08

5.27

56.04

108

7

26.38

15.42

4.83

53.37

118

8

30.15

14.75

4.39

50.71

130

9

33.91

14.08

3.96

48.05

144

aWeight change from CS5 weight can be estimated from the difference between CS5 weight and CS5 weight * percent of CS5 weight for the CS in question. Net energy reserves provided, or required to change CS, is kg weight change * 5.82.

81.3, 86.7, 92.9, 108.3, 118.1, 129.9, and 144.3 percent of a CS 5 cow for CS 1, 2, 3, 4, 6, 7, 8, and 9, respectively. A 500 kg cow is predicted to weigh 465, 434, 407, and 383 kg at CS 4, 3, 2, and 1 with weight losses of 35, 31, 27, and 24 kg for CS 5, 4, 3 and 2, respectively. Corresponding values for a 650 kg cow are 604, 564, 528, and 497 kg SBW at CS 4, 3, 2 and 1 with weight losses per CS of 46, 40, 35 and 31 kg for CS 5, 4, 3 and 2, respectively.

Table 3–6 gives Mcal mobilized in moving to the next lower score, or required to move from the next lower score, to the one being considered for cows with different mature sizes. These cows are within the range included in the data base used to develop the regression equations (433 to 887 kg SBW). Diet NEm replaced by mobilized reserves, or required to replenish reserves, are computed by assuming 1 Mcal of mobilized tissue will replace 0.8 Mcal of diet NEm, and 1 Mcal of diet NEm will provide 1 Mcal of tissue NE, based on Moe (1981) and NRC (1989). For example, a 500 kg cow at CS 5 will mobilize 207 Mcal in declining to a CS 4. If NEm intake is deficient 3 Mcal/day, this cow will lose 1 CS in (207 * 0.8)/3=55 days. If consuming 3 Mcal NEm above daily requirements, this cow will move back to a CS 5 in 207/3=69 days.

The weakest link in this model is the prediction of body

TABLE 3–6 Energy Reserves for Cows with Different Body Sizes and Condition Scores

CS

Mcal NE Required or Provided for Each CSa at CS 5 Mature Weight

400

450

500

550

600

650

700

750

800

2

112

126

140

154

168

182

196

210

223

3

126

141

157

173

189

204

220

236

251

4

144

162

180

198

217

235

253

271

289

5

165

186

207

227

248

269

289

310

331

6

193

217

242

266

290

314

338

362

386

7

228

267

285

314

342

371

399

428

456

8

275

309

343

378

412

446

481

515

549

9

335

377

419

461

503

545

587

629

670

aRepresents the energy mobilized in moving to the next lower score, or required to move from the next lower score to this one. Each kg of SBW change contains 5.82 Mcal, and SBW at CS 1, 2, 3, 6, 1, 8, and 9 are 76.5, 81.3, 86.7, 92.9, 108.3, 118.1, 129.9, and 144.3 percent of CS 5 weight, respectively.

weight change associated with each CS change. This is a critical step because it is used to compute total energy reserves available and energy required to replenish reserves. In this model, this calculation is based on the assumption that ash mass is constant. The weights and weight changes appear to agree well with other data at CS 5 and below, but appear to be high above CS 7. A reasonable alternative would be to use the weight change and energy reserves per CS computed for CS 5 for CS categories above a 5. Additional research is needed to be able to predict more accurately the body weights and weight changes associated with each condition score on diverse cattle types.

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