“Long Day Photoperiod, LDPP (16 hours light, 8 hours dark) has a positive effect, improving milk yield by up to 2kg/day compared to a natural day length. LDPP improves natural hormonal response, calf growth and feed efficiency; reduces time to puberty; gives stronger, healthier production cows, when compared to 24-hour artificial lighting regime. It gives a lower Somatic Cell Count (SCC) in milk when compared to a 24-hour regime. Short Day Photoperiod, SDPP (8 hours light, 16 hours dark) gives increased levels of melatonin, lower levels of prolactin,and lower milk yield in production cows. Dry cows exposed to SDPP give up to 3kg/day increased production in the following lactation. 24-hour Photoperiod suppresses the natural day/night circadian rhythm of the herd. It gives a higher SCC in milk, and no increase in milk production when compared to LDPP regime. Dairies should expose production cows to a long-day photoperiod, and house dry cows in a separate area that can provide short-day photoperiod. 24-hour lighting should be avoided. “ #dairylight #cows #agriculture
