. 2019 Dec 17;9(12):305. doi: 10.3390/metabo9120305

Table 1.

Average total nitrogen and nonprotein nitrogen content of skim milk powder, rennet whey, ideal whey, and acid whey, as determined by Kjeldahl analysis.

Sample Type	Total Protein (% w/w)			Nonprotein Nitrogen (% w/w)
Sample Type	GRS	CLV	TMR	GRS	CLV	TMR
Skim milk powder	37.2 (±0.57) ^b	37.5 (±0.06) ^d	36.1 (±0.61) ^c	0.27 (±0.01) ^b,A	0.32 (±0.06) ^b,A,B	0.37 (±0.00) ^c,B
Sweet whey powder	9.27 (±0.29) ^a	9.41 (±0.68) ^b,c	9.64 (±0.17) ^b	0.25 (±0.01) ^a,b	0.27 (±0.04) ^a,b	0.32 (±0.01) ^a,b,c
Ideal whey powder	8.07 (±0.45) ^a	6.98 (±0.61) ^a	8.23 (±0.86) ^a,b	0.21 (±0.01) ^a,b	0.23 (±0.04) ^a	0.28 (±0.03) ^a,b
Acid whey powder	7.64 (±0.17) ^a	7.98 (±0.17) ^a,b	7.50 (±0.47) ^a	0.19 (±0.01) ^a	0.21 (±0.04) ^a	0.25 (±0.01) ^a

GRS—cows fed perennial ryegrass only. CLV—cows fed perennial ryegrass/20% white clover sward. TMR—cows fed indoor total mixed ration ad-libitum. ^a,b,c,d indicates values within a column not sharing a common lower-case superscript letter differed significantly (p < 0.05). ^A,B indicates values within a row not sharing a common upper-case superscript letter differed significantly (p < 0.05).