Calving Season and Weaning
Management

Calving time
– Spring-reasons:
1. Grasses and forages have their highest
nutritive value in the spring, and therefore most
animals in the wild have their young in the spring
2. Weather more conducive to survival of calves
3. Minimum housing needs
4. More economical to feed dry in winter
5. Tradition in U.S.
Calving Season and Weaning
Management

Calving time
– Fall-reasons:
1. Calves weaned in spring when feeder
prices are generally more favorable
2. More steady supply of feeders if also
calving in the spring
– Regardless of calving season chosen, one
should strive to calve within a 40 to 60
period- reasons:
1. More uniform calf crop resulting:
Calving Season and Weaning
Management

Creep feeding:
– Advantages:
1. Increases weaning weights by about 50 lb.
2. Eases the stress on 2, 3 and 4 year old cows
3. Eases the stress on drought-shortened and
over populated pasture
4. Lowers the stress on calves at weaning and
makes adaptation to feedlot diets easier
5. Fall born calves maintained in drylot
substitute creep feed for lack of pasture
6. Prepares calves for early weaning program
Calving Season and Weaning
Management

Creep feeding:
– Disadvantages:
1. Calves may lose some condition if going into
backgrounding program following weaning
2. Requires extra labor, equipment, feed and
management
3. Not easily adapted to large pastures or range
conditions
Calving Season and Weaning
Management

Creep feeds:
– Can start as early as about 6 weeks of age
– Many producers start at 3-4 mo. of age (~
July 1 when grass is short) 10-11% salt of
total creep DM will limit intake to about 2.5 lb.
daily DM intake
– Consideration:
 1.
 2.
 3.
Calving Season and Weaning
Management

Creep feed examples:
1. All oats – may or may not be processed
2. Cracked corn
62.5 lb
Oats
37.5 lb
a.
b.
c.
d.
Calving Season and Weaning
Management

Implanting:
– May improve weaning weight
– If implant at birth, may need to reimplant 70
to 100 days later to get full benefit of 50 lb.
weight increase
Calving Season and Weaning
Management

Implanting:
– Concerns:
1. Steer and heifer calves implanted during
nursing period, may not respond as well to
implants during feeding period – research
contradictory on this
Calving Season and Weaning
Management

Implanting:
– Concerns:
2. Reproduction:
a. Bulls implanted as calves suffer at least 50%
reduction in testicular size and similar reduction in
futility
b. Recent research by Montana and Kansas
workers has shown no detrimental effects on fertility
1.) Previous research has shown lowered
conception rates and incidences of fertility
c. Conclusion: do not implant nursing calves that
are potential breeding stock
Calving Season and Weaning
Management

Early weaning:
– Considered to be any weaning age younger
than 6 to 7 months
– Situations promoting early weaning:
1.
2.
3.
4.
5.
2 and 3 yr. old cows
Cows with twins
Drought conditions or insufficient pasture
Fall calving
to accelerate rebreeding in late calving cows
Calving Season and Weaning
Management

Early weaning:
– ISU study:



Crossbred cows – 42 day. breeding season
Spring calving = late March through early May
Fall calving = late August through early
October
Postpartum Estrus Distribution
Postpartum interval
to estrus (days)
21
Calving Time
Weaning Age
Fall Spring Spring
45% 45 % 200 %
4.5
1.1
.5
42
63
84
84+
42.0
42.5
9.3
.5
14.3
62.9
17.4
3.2
14.1
31.4
29.4
17.3
No heat
1.2
1.1
7.3
Total
100.0 100.0
100.0
Effect of Season and Age of Calf at
Weaning on Reproductive
Performance of Cows
Calving Time
Weaning Age
In heat and bred during breeding
season (%)
First service conception (%)
Services per conception
Pregnancy rate of those bred (%)
Pregnancy rate of total (%)
Avg. da. of breeding season
conception occurred
Fall Spring Spring
45
45
200
97.5
98.9
88.6
66.0
1.57
69.1
1.48
65.7
1.54
80.5
78.5
16
84.0
83.2
15
79.6
70.2
17
Death Loss of Calves through 365
Days of Age
Calving Time
Weaning Age
Age at Time of Death (Days)
Fall
45
Spring
45 and 200
Dead at birth
0 – 45
46 – 90
91 – 200
4.4
1.8
2.0
5.3
6.9
8.0
.4
1.1
201 – 365
.5
.2
14.0
16.6
Total
Effect of Season and Weaning on Calf
Performance
Calving Time
Weaning Age
Wt., 45 da.
Fall
45
155
Spring
45 and 200
153
151
Wt., 90 da.
Wt., 200 da.
222
468
210
447
238
468
Wt./ da. of age
2.34
2.24
2.34