Here is some additional data comparing 2016 to 2017. Daily yield per cow in 2018 was 4.5 Liters.
Total of fresh milk in 2016: 612,800 metric tons
Total of fresh milk in 2017: 536,400
Annual yield per cow in 2016: 1,678 kg
Annual yield per cow in 2017: 1.624 kg
Total head of cows in 2016: 1,223,000. There are a total of 4,013,900 cattle in Cuba.
Total head of cows in 2017: 1,172,000. There are a total of 3,886,500 total cattle in 2017.
Source: ONEI, Cuba