NutritionReproduction Interaction in Beef Cattle

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Nutrition-ReproductionInteraction in Beef Cattle

• Amin Ahmadzadeh
• AVS Department
• University of Idaho

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Introduction

• The nutrition/reproduction interaction involves
  several intricate relationships.
• From a nutrition standpoint, energy, protein,
  minerals and vitamins all affect reproduction
  through various avenues.
• The hypothalamus, pituitary, and/or the ovaries
  can be affected by a nutritional deficiency.
• Lamb, Univ. Min

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• As beef producers/ consultant/ veterinarian, we
  must understand the nutrition/reproduction
  interaction to fully understand how cows respond
  to nutritional management and produce a live
  healthy calf on a yearly basis.

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Late Gestation, Dry Period

• Increase in nutrient requirements
• establishing greater fat reserve
• energy reserve during lactation
• Problems with underfeeding
• calf growth
• calf survival
• lower milk yield, lower weaning wt.
• postpartum reproductive problem
• dystocia, retained placenta, re-breeding

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• Low energy intake during late pregnancy can
  result in
• slightly lowered birth weights
• higher death rates in newborn calves
• lower milk production
• lower weaning weights
• increased days to first heat
• reduced conception rates

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Breeding group
Postpartum group
Uterine involution
Peak lactation
0
45 d
60-90 d
Early postpartum stress
1st behavioral estrus
1st AI service
Distocia Retained placenta Uterine
infection Metabolic disorders Ovarian
cysts Mastitis
Suckling -induced gonadotropin inhibition
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Length of Postpartum intervals

• Factors with the greatest Effects

Suckling
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Nutrition and Reproduction

• Energy and Protein
• Not ignoring other nutrients
• vitamins, minerals, waters
• Not ignoring the impact of parasites or toxins

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calving
Early postpartum
Gestation (late lactation)
Dry
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The Effects of Energy During Late Gestation on
Calf Growth and Survival
Beal, 1996
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Effect of Body Condition at Calving on Rebreeding
Success
Pruitt Momont, 1990
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Effect of Energy Level on Postpartum Interval and
Conception Rate
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Milk urea nitrogen 21 mg/dl
Blood urea gt25 mg/dl ?
Excess dietary protein high rumen degradable
protein
Urea
via Blood Saliva
Ammonia
Protein
Peptides and Amino Acids
Liver
Ammonia
Rumen
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Impact of Excess Protein on Reproduction
(Summary)
Excess rumen degradable protein
Elevated ammonia, blood and tissue urea, low
uterine pH
Possible detrimental effects on sperm, egg, and
embryo development and survival
Delay clearance of uterine contaminants
AGE Energy Status
Alteration on gonadotropin and progesterone
secretion
Deficiency in metabolism
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Take Home Message

• Live weight at calving has no effect on
  reproductive performance, whereas calving
  condition score is a better indicator than
  prepartum change in either weight or condition
  score on the duration of postpartum anestrus
  (Whitman, 1975 Lalman et al., 1997).
• When cows are thin at calving or have BCS of 4 or
  less, increased postpartum level of energy
  increases percentages of females exhibiting
  estrus during the breeding season.

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University of Min
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Stage I

• Shortly after weaning, beef cows should be in mid
  gestation. This is the period at which producers
  can manipulate the diet to either increase or
  decrease a cows condition. At this point, cows
  require very little in terms of nutrients to
  maintain their metabolism. If cows are in poor
  condition there is no better stage to adjust a
  cows feed regimen to increase her condition.

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Stage II

• During stage two of the cows production cycle,
  the fetus begins to grow rapidly (up to a pound
  of gain a day shortly before parturition). In
  addition, cows also require several other
  physiological mechanisms to occur to prepare a
  cow for lactation. Therefore, adjusting a cows
  condition requires more feed and very often
  occurs during the worst part of winter when feed
  quality tends to be poorer and supplementation
  becomes expensive.

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Stage III

• The period of greatest nutritional need is stage
  three, shortly after calving. A cow is required
  to produce milk for a growing calf, she must
  regain any weight lost shortly before and after
  parturition and finally repair her reproductive
  tract in order to become pregnant within three
  months after birth.
• During this stage a cow usually is consuming as
  much feed as she can to support herself.
  Adjusting condition at this stage often is
  futile.

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Stage IV

• During stage four of a cows production cycle,
  lactation requires the majority of nutrients, but
  condition can be manipulated here with some
  innovative feeding practices.