Table 1.

Pearson correlation coefficients among hepatic cystathionine β-synthase (CBS), betaine homocysteine methyltransferase (BHMT) and 5-methyltetrahydrofolate-homocysteine methyltransferase (MTR) activity, liver triacylglycerol (TAG), dry matter intake (DMI), milk yield (MY), plasma methionine (Met), liver glutathione (GSH) and liver Met in periparal dairy cows^a

Variable	CBS activity	MTR activity	BHMT activity	Liver TAG	DMI	MY	Plasma Met	Total liver GSH	Liver Met
MTR activity	−0.17*
BHMT activity	0.50*	−0.002
Liver TAG	0.31*	0.09	0.29*
DMI	0.29*	−0.28*	−0.12+	0.16*
MY	0.66*	−0.36*	0.13+	0.05	0.78*
Plasma Met	0.12+	−0.31*	−0.07	−0.09	0.26*	0.24*
Total liver GSH	−0.06	0.10	0.05	−0.06	−0.06	− 0.06	−0.21*
Liver Met	0.83*	−0.35*	0.84*	0.20	0.40*	0.88*	−0.13	−0.14
Liver betaine	0.83*	−0.34*	0.84*	0.27	−0.11	0.87*	0.08	0.28+	0.97*

^aData from three transition cow studies were used for analysis [27, 28, 64]. In the study by Zhou et al. cows were fed a total mixed ration with or without rumen-protected Met (RPM) at 0.08% DM for 21 d prepartum and 30 d postpartum. Vailati-Riboni et al. fed diets with or without RPM at 0.10% DM for 28 d prepartum and 60 d postpartum. In the last study, a 2 × 2 factorial design of body condition score (BCS) and energy level during the peripartal period was used: 2 prepartum BCS categories [4.0 (thin, BCS 4) and 5.0 (optimal, BCS 5); 10-point scale] and 2 levels of energy intake during the 3 weeks. preceding calving (75% or 125% of estimated requirements) obtained via allowance (m²/cow) of fresh pasture composed of mostly perennial ryegrass and white clover. Due to the large range and distribution of the metabolomics data variables for liver Met and betaine, they were log-transformed. Values reported in the graphs are log values

^*P ≤ 0.05; ⁺P ≤ 0.10