2015 Volume 58 Issue 2 Pages 189-199
The aim of this experiment was to clarify the most effective cooling periods for reducing decreases in milk yield and milk composition in lactating goats in a hot environment. Fifteen Japanese Saanen lactating goats were divided into three groups (2HC, 4HC, 6HC). Each animal was given excessive amounts of crushed alfalfa hay cubes and 300g of concentrated feed twice daily. The animals were milked twice daily. From day 11 to day 16 of exposure to hot environment (32°C, 80.0%), the room in which the animals were kept was cooled to thermoneutral environment (20.0°C, 80.0%) during the morning and afternoon 2 h feeding periods. From day 11 to day 21 of hot environment exposure, the 4HC and 6HC groups were subjected to 4 and 6 hours respectively of cooling twice each day that was commenced in conjunction with each of the feeding periods. The 2 h cooling had no effect on milk yield and milk composition. The 4 h cooling significantly reduced the decreased milk yield in the hot environment but had no effect on milk composition. The 6 h cooling had significant effect on the reduction of decreases in milk composition and milk components yield.