1. Developing Heifers
Earl H. Ward

2. What are the Goals? Start Cycling Early Calve at age of 24 Months
Prefer to calve in the first 21 days of calving season
Rebreed quickly
Longevity in the Herd

3. Puberty
Ideally – heifers reach puberty about 60 days prior to the beginning of the breeding season
Increases chances of becoming pregnant and calving earlier in the season
Inverse relationship between postweaning growth and age at puberty
Puberty
Postweaning Average Daily Gain

4. Nutrition
Plane of nutrition influences reproductive performance in heifers and cows
Delayed Gain = Lower Feed Cost with no adverse affect on pregnancy performance
Can’t Have Production without Reproduction
Can’t Have Reproduction without Nutrition

5. Dry Lot vs Pasture Dry lot is a “false” environment
Heifers developed in a dry lot, then turned out for breeding will have a period of weight loss, potentially due to re-learning grazing skills
SDSU research (Perry et al., 2013)
Drylot = -3.5 lbs/d ADG for first week
Range = 2.0 lbs/d ADG for first week
27 Days later = no difference in ADG

6. Pelvic Area
Calving difficulty results in major economic loss to the beef cattle industry. Estimated losses resulting from dystocia equal or exceed $750,000,000 annually.
David J. Patterson and William O. Herring - University of Missouri
Using pelvic measurements to estimate deliverable calf size (birth weight)
Time of measurement
Heifer age
Heifer weight
Pelvic area
Pelvic area per birth weight ratio
Estimated calf birth weight
Before breeding
12-13 months
600 pounds
140 cm2
2.1
67 pounds
160 cm2
76 pounds
180 cm2
86 pounds
Pregnancy exam
18-19 months
800 pounds
2.7
200 cm2
74 pounds
220 cm2
82 pounds

7. Reproductive Tract Score
Rectal Palpation or Ultrasound

8. Heifer Breeding
Decades of research set the guidelines of 60-65% of mature weight
Results have changed over time
BW has less impact now due to:
Shift from calving at 3 yo to 2 yo
Selection pressure on age of puberty (scrotal circ)
New Recommendation is 55-65%
(Funston – University of NE)

9. Heifer Size @ Breeding 55% 60% 65% 1000 550 600 650 1100 605 660 715
1200
720
780
1300
845
1400
770
840
910

10. Timeline Birth Weaning Breeding Calving 6-7 Months @ 7-8 Months

11. Questions? Ho
Heifers