Effects of a Long Daily Photoperiod on Milk Yield and Ovarian Activity of Saanen Goats in Northern Mexico

To study the effect of a long daily photoperiod on milk yield and milk components, 38 pluriparous lactating Saanen goats were randomly exposed, after kidding, to either a natural photoperiod (<13 h) or a long photoperiod (16 h) between January and April. Long daily photoperiod increased (P<0.01) milk yield (3.0 +/- 0.1 us 2.5 +/- 0.1 l d(-1)) on d 42 to 84. From d 56 to 84 of lactation milk fat was higher (+ 0.5 percentage points; P<0.05) in goats subjected to natural photoperiod than long photoperiods. Photoperiod had no effect on milk lactose, protein or ovulation in goats. These data indicated that increased postpartum photoperiod during winter months in northern Mexico substantially increased milk production in Saanen goats, which might constitute a management strategy for dairy goat producers to increase milk yield.