Week 8

Beef: Cow-Calf

Replacement Heifers

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Yearling Heifers

• Puberty
  • Function of weight
    • Nutrition affects growth, which should be targeted so heifers have adequate weight to be pubertal by breeding
  • Heifers should reach 65% of mature body weight by the beginning of breeding as yearlings so most (90% or more) have reached puberty

Growth Worksheet

• Heifers wean at 500 lbs on Oct. 15
• Mature wt. is expected to be 1100 lbs.
• Heifer breeding season May 1st
  • Begin calving on Feb 5th
• Oct 15 to May 1 = 198 days
• (1100 x 0.65) – 500 = 715 – 500 = 215
• ADG = 215/198 = 1.1 lbs/day

Nutrient Requirements

• Target weight: 85% of mature weight at calving

Management Considerations

• Feed separate from mature cows
  • Cannot compete
  • Have higher nutrient demands
  • If mixed, heifers lower BCS at breeding, causing prolonged PPI and reduced fertility
• Do not overfeed
  • Fat deposited in pelvic area increases dystocia
  • Fat deposited in mammary gland decreases milk yield
• Do not limit nutrition during gestation to reduce birth weight
  • Small decrease in BW
  • Increase in dystocia
  • Weak calves at birth (mortality and morbidity)
  • Lower colostrum and milk production
  • Longer PPI and lower fertility

Creep Feeding Heifers

• Increase ADG of calves
• Reduce BCS loss of cows
• Poor quality forage
  • Usually done at end of grazing season

What to Supplement?

• Historical recommendation
  • Unlimited energy (grain based) creep
• Current recommendation
  • Usually a protein based supplement
    • Same reasons as supplementation of mature cows – Positive Associative Effects
  • Protein slightly lower than mature cows, around 16-20% CP
• Green creep

Should potential heifers be creep fed?

• Extra nutrition can increase fat deposition in udder, decrease future milk production
• Only creep feed heifers in forage shortage emergencies (drought) to get them to a normal weaning weight, do not exceed normal weaning weights