Melatonin concentration in cow’s milk and sources of its variation

Figures & data

Figure 1. Means (column) and 95% confidence intervals (lines) for melatonin concentration (pg/mL) in night milk and the total milk of individual cows in the low and high production groups during winter and summer.

Table 1. Means of nutrient and urea compositions, and the somatic cells count (SCC) in the total daily milk from cows in the low (Low) and high (High) production groups during winter and summer.

	Winter		Summer
Parameter	High	Low	High	Low	CV^a
Number in group	15	15	15	15	–
Milk, kg/cow/day	49.53	31.09	57.67	14.95	45.66
Fat, %	2.95	3.96	2.74	3.96	25.02
Protein, %	2.97	3.43	2.73	3.41	12.59
Lactose, %	4.50	4.66	4.62	4.45	5.97
Total solids, %	11.36	13.07	11.05	12.88	10.19
Urea, mg/dL	15.60	12.90	13.12	13.02	18.35
SCC, × 1000/mL^b	59.12	44.62	72.80	158.88	–

^aCV = coefficient of variation; ^bGeometric means.

Figure 2. Means (column) and 95% confidence intervals (lines) for illuminance levels (lux) inside the free-stall for the transition between day and night during winter and summer.

Figure 3. Means (column) and 95% confidence intervals (lines) for melatonin concentration (pg/mL) in the UHT processed milk from 12 different brands (n = 12/season), daily total milk from individual cows (n = 30/season), and bulk tank milk from 16 farms (n = 16/season) during winter and summer.

Table 2. Means of nutrient composition of milk collected from the bulk tanks and UHT processed milk during winter and summer.

	Winter		Summer
Parameter	Tanks	UHT	Tanks	UHT	CV^a
N	16	12	16	12	–
Fat, %	3.63	3.21	3.30	2.99	12.44
Protein, %	3.11	2.90	3.10	2.82	8.49
Lactose, %	4.97	4.79	4.53	4.83	7.45
Total solids, %	12.52	12.18	11.91	12.50	7.51

^aCV = coefficient of variation.