Beef Cattle Reproduction Anatomy and Physiology

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Beef Cattle ReproductionAnatomy and Physiology

• Whitney A. Whitworth
• Associate Professor of Animal Science
• University of Arkansas at Monticello

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Improve reproductive efficiency

• Production of young is primary determinant of
  income for most livestock species
• A 3 improvement in birth rate would result in an
  additional 1 million beef calves per year

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Introduction

• Reproduction is a tremendously coordinated
  process, mainly between anatomy and endocrine
  functions
• Basis for reproduction is the gonad
• Female ovary
• Male testis

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Puberty

• Transitional state after which animals are able
  to reproduce
• Most important signals are weight and age
• Nutritional stress and season of year are also
  important
• After puberty, an animal is said to be
  reproductively competent

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Puberty

• Associated with development of secondary sex
  characteristics
• Hump on necks in males, increased musculature,
  voice changes
• Addition of body fat in females, mammary
  development

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Endocrinology

• Endocrine cues are initiated by the hypothalamus
• Small area in brain which releases GnRH
• Released in an episodic manner, travels to the
  anterior pituitary gland
• Anterior pituitary gland releases LH and FSH
• Travel to the gonads of both males and females

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• Relationship between hypothalamus and pituitary
  gland
• Bearden and Fuquay, 2000

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Endocrinology

• LH Luteinizing hormone
• Induces ovulation development of the corpus
  luteum
• Aids in the maturation of the follicle and
  spermatozoa
• Stimulates testosterone production in the male
• FSH Follicle stimulating hormone
• Induces follicular development
• Induces estrogen production
• Stimulates spermatogenesis

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Endocrinology

• After ovulation, follicle turns into corpus
  luteum (CL)
• Primary function is progesterone production
• Required for maintenance of pregnancy
• Progesterone inhibits FSH and LH production
• Reduced excitability of smooth muscle fibers
• Negative feedback to the hypothalamus

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Endocrinology

• Estrogen This follicular hormone is responsible
  for
• Estrus
• Influence mobility and secretory function in the
  reproductive tract
• Responsible for early stage development of the
  mammary gland
• Follicles produce estrogen, causing an LH surge
• LH surge causes ovulation

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Endocrinology

• Oxytocin secreted by the posterior pituitary and
  the corpus luteum causes contractions of smooth
  muscle fibers. This is involved in
• Milk