NMSU: Calf Birth and Age Determination Table HTML
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Authors: Respectively, Extension Beef Cattle Specialist, Extension Veterinarian, and Extension Horse Specialist, both of the Department of Extension Animal Sciences and Natural Resources, New Mexico State University.

The table on the reverse side is designed to aid in keeping more complete and useful breeding, calving, and performance records in a beef cow herd. It can be used to determine the date when bulls should be removed from the breeding pasture, expected birth date of a calf, calving interval, and dates when calves should be weighed so that the weights can be standardized to 205- or 365-day weights.

The table itself has been reproduced from the booklet "Angus Breed Improvement," prepared by the American Angus Association. Note that it applies only to non-leap years; in leap years (2012, 2016, 2020, etc.), add one day for any date occurring after February 28.

How to Use the Table

Breeding Season. Assume bulls are turned out on May 1 (Day 121), and the breeding season is to extend for 75 days. Then, 121 + 75 = 196. So the bulls should be removed from the breeding pasture on July 15 (Day 196).

Expected Birth Date. Add 283 to the "day number" that the cow was bred. If date bred was June 5 (Day 156), the cow should calve about 283 days later, or March 15 (Day 439).

Calving Interval. If the calving interval in the herd averages more than 12 months, or 365 days, the management program should be reviewed. If a cow calves on March 15 (Day 74) and again on March 9 (Day 433) of the next year, her calving interval is 359 days.

205-Day Weight. Calves must be weighed between 160 and 250 days of age for correct adjustment to the 205-day weaning-age weight. Thus, the earliest date to weigh a calf born on March 15 (Day 74) is 160 days later, on August 22 (Day 234). November 20 (Day 324) is the last day that a March 15 calf can be weighed for a 205-day adjustment weight.

365-Day Weight. Yearlings must be weighed between 330 and 450 days of age for this adjustment. So, an animal born on March 15 (Day 74) must be weighed between February 8 (Day 404) and June 8 (Day 524) of the following year to determine the adjusted weight.

Julian Calender
Day of
Year #1
Day of
Year #2
Month Jan Feb Mar April May June July Aug Sept Oct Nov Dec Month Jan Feb Mar April May June July Aug Sept Oct Nov Dec
1
1
32
60
91
121
152
182
213
244
274
305
335
1
366
397
425
456
486
517
547
578
609
639
670
700
2
2
33
61
92
122
153
183
214
245
275
306
336
2
367
398
426
457
487
518
548
579
610
640
671
701
3
3
34
62
93
123
154
184
215
246
276
307
337
3
368
399
4274
58
488
519
549
580
611
641
672
702
4
4
35
63
94
124
155
185
216
247
277
308
338
4
369
400
428
459
489
520
550
581
612
642
673
703
5
5
36
64
95
125
156
186
217
248
278
309
339
5
370
401
429
460
490
521
551
582
613
643
674
704
 
6
6
37
65
96
126
157
187
218
249
279
310
340
6
371
402
430
461
491
522
552
583
614
644
675
705
7
7
38
66
97
127
158
188
219
250
280
311
341
7
373
403
431
462
492
523
553
584
615
645
676
706
8
8
39
67
98
128
159
189
220
251
281
312
342
8
373
404
432
463
493
524
554
585
616
646
677
707
9
9
40
68
99
129
160
190
221
252
282
313
343
9
374
405
433
464
494
525
555
586
617
647
678
708
10
10
41
69
100
130
161
191
222
253
283
314
344
10
375
406
434
465
495
526
556
587
618
648
679
709
 
11
11
42
70
101
131
162
192
223
254
284
315
345
11
376
407
435
466
496
557
557
588
619
649
680
710
12
12
43
71
102
132
163
193
224
255
285
316
346
12
377
408
436
467
497
528
558
589
620
650
681
711
13
13
44
72
103
133
164
194
225
256
286
317
347
13
378
409
437
468
498
529
559
590
621
651
682
712
14
14
45
73
104
134
165
195
226
257
287
318
348
14
379
410
438
469
499
530
560
591
622
652
683
713
15
15
46
74
105
135
166
196
227
258
288
319
349
15
380
411
439
470
500
531
561
592
623
653
684
714
 
16
16
47
75
106
136
167
197
228
259
289
320
350
16
381
412
440
471
501
532
562
593
624
654
685
715
17
17
48
76
107
137
168
198
229
260
290
321
351
17
382
413
441
472
502
533
563
594
625
655
686
716
18
18
49
77
108
138
169
199
230
261
291
322
352
18
383
414
442
473
503
534
564
595
626
656
687
717
19
19
50
78
109
139
170
200
231
262
292
323
353
19
384
415
443
474
504
535
565
596
627
657
688
718
20
20
51
79
110
140
171
201
232
263
293
324
354
20
385
416
444
475
505
536
566
597
628
658
689
719
 
21
21
52
80
111
141
172
202
233
264
294
325
355
21
386
417
445
476
506
537
567
598
629
659
690
720
22
22
53
81
112
142
173
203
234
265
295
326
356
22
387
418
446
477
507
538
568
599
630
660
691
721
23
23
54
82
113
143
174
204
235
266
296
327
357
23
388
419
447
478
508
539
569
600
631
661
692
722
24
24
55
83
114
144
175
205
236
267
297
328
358
24
389
420
448
479
509
540
570
601
632
662
693
723
25
25
56
84
115
145
176
206
237
268
298
329
359
25
390
421
449
480
510
541
571
602
633
663
694
724
 
26
26
57
85
116
146
177
207
238
269
299
330
360
26
391
422
450
481
511
541
572
603
634
664
695
725
27
27
58
86
117
147
178
208
239
270
300
331
361
27
392
423
451
482
512
543
573
604
635
665
696
726
28
28
59
87
118
148
179
209
240
271
301
332
362
28
393
424
452
483
513
544
574
605
636
666
697
727
29
29
88
119
149
180
210
241
272
302
333
363
29
394
453
484
514
545
575
606
637
667
698
728
30
30
89
120
150
181
211
242
273
303
334
364
30
395
454
485
515
546
576
607
638
668
699
729
 
31
31
90
151
212
243
304
365
31
396
455
516
577
608
669
730

Original authors: Larry Foster and Ron Parker, former Extension beef cattle specialists.


Photo of Manny Encinias


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Revised and electronically printed November 2011, Las Cruces, NM.