Infertility in Cattle

B) Photoperiodism

- Exposure to short photoperiods early in the life, until 3 to 5 months of age, hastens puberty.

-  Heifers born in autumn attained puberty sooner than those born in Springs.

-  In northern Latitudes, the duration of postpartum anestrus is often shorter for cows calving in the summer or Autumn than for cows calving in the winter or spring.

-  The long photoperiodism is effective on reproduction through:

-- Increase conception rates during winter by light supplementation.

-- Increase sperm motility and decrease sperm abnormality in bulls.

-- Reduce the interval to uterine involution.

- At the level of the hypothalamus-pituitary axis:

-- Secretion of LH early in life was greater for heifers born in September than those born in March.

-- Supplemental lighting in the winter increased the magnitude of estradiol-induced LH secretion.

- As in seasonally breeding species, the secretion of melatonin in cattle exhibits a diurnal pattern; the highest concentrations occur during darkness.