The objective of the study was to investigate milk yield and quality in small-scale dairy cow operations
and to assess milk production affected by subclinical mastitis. The study was conducted in the highlands and southern
Vietnam, including Lam Dong, Long An, Tien Giang province, and Ho Chi Minh City. A total of 1,347 small
dairy farms were surveyed over 12 months in 2022. The average number of dairy cows per smallholder farm was
approximately 9 cows with 11.52 ± 4.56 kg/cow/day. Milk yield was measured for the total number of dairy cows per
smallholder, and 10 milk quality parameters included somatic cell count (SCC) and others (total solid, fat, solid-nonfat,
crude protein, pH, free fatty acids, lactose, temperature, true protein), and examined by Foss–Milkoscan machines
in dairy centers. SCC was classified into 5 levels (milk). The milk yield was highest at 16.76 ± 7.86 kg/cow/day, and SCC was lowest at 356.54 ± 191.43 (103 cell/ml
milk) in Lam Dong province (the highlands region), and different from that of other provinces in southern Vietnam
(10.92 ± 3.50 kg/cow/day and 360.85 ± 187.24x103 cell/ml milk in Long An; 11.56 ± 3.00 kg/cow/day and 399.82 ±
175.35x103 cell/ml milk in Tien Giang; and 10.90 ± 3.73 kg/cow/day and 465.46 ± 222.68x103 cell/ml milk in Ho Chi
Minh City) (P < 0.05). The results indicated that seasonality affected milk production in all provinces for months and
highlighted a negative relationship between milk production, milk quality, and SCC levels in smallholder dairy farms
in the highlands and the south of Vietnam.