- 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.