Table 5.

Main effects of experiments including betaine, vitamin B₁₂ and folic acid supplementation in dairy cows according to stage of lactation. ↑ = increase effect; ↓ decrease effect

Stage	Dietary manipulationa	Main effectsb	Reference
Transition period	CON or Bet from close-up until 8 weeks postpartum vs. CON or Bet from dry off until 8 weeks postpartum	↑ Milk yield and milk fat in Bet cows enrolled at dry off ↑ NEFA and BHBA postpartum Bet in cows enrolled at dry off	[103]
	CON or RP-Bet at 20 g/d from 4 weeks prepartum until 6 weeks postpartum	↑ Feed efficiency (ECM/DMI) with RP-Bet ↑ BW loos postpartum with RP-Bet ↑ BHB at d 7 postpartum with RP-Bet ↑ TPP and plasma globulin with RP-Bet ↓ Plasma glucose with RP-Bet	[104]
	FA at 0, 120 or 240 mg/500 kg of BW from 1 week prepartum to 1 week postpartum	↑ Milk yield with FA 120 mg/500 kg of BW	[105]
	FA at 0 or 2.6 g/d and B12 at 0 or 0.5 g/d in 2 × 2 factorial design from 3 weeks prepartum to 8 weeks postpartum	↑ Milk yield and milk protein with FA ↓ Milk urea N with B12 ↑ Liver phospholipids with B12	[106]
	Basal diet with restricted Met or basal diet + RP-Met. In each group half received weekly vitamin injections of FA 160 mg + B12 10 mg	↑ Milk and plasma level of FA and B12 with vitamin ↑ Milk yield with vitamin ↑ Milk lactose, milk protein and total solids with vitamin	[107]
Mid lactation	Bet at 0, 50, 100 or 150 g/d during 30 d	↑ Milk yield and milk fat linearrly with Bet	[108]
	Bet at 0, 25, 50, or 100 g/d during 16 d	↑ Milk yield with Bet 100 g/d ↓ Milk protein in Bet cows compared with CON	[109]
	CON, 20 g/d of RP-Met, 45 g/d RP-Bet, or 40 g/d of RP-Chol in limited Met diet during 70 d	↑ Milk yield in RP-Chol ↑ Milk protein in RP-Chol vs. CON or RP-Bet ↑ Milk fat in RP-Chol vs. RP-Met	[110]
	Bet at 0, 10, 15 or 20 g/d for 8 weeks during heat stress period	↑ DMI with Bet ↑ Milk yield, milk lactose and milk protein with Bet ↑ Plasma cortisol, GPX, SOD and MDA with Bet ↓ Plasma HSP70 with Bet	[111]
	Bet at 0, 57 or 114 mg/kg of BW for 2 weeks in thermoneutral and 2 weeks in heat stress conditions	↑ Milk yield with Bet 114 mg/kg of BW in thermoneutral conditions ↓ Respiration rate with Bet in heat stress ↑ Rectal temperature with Bet in heat stress ↑ Plasma glucose with Bet 114 mg/kg of BW in heat stress	[112]
	Basal diet with RP-Met and FA with or without weekly B12 10 mg injections from 4 to 18 weeks of lactation	↑ ECM, milk yield of solids, fat and lactose with B12 ↑ Blood hemoglobin and serum vitamin B12 with B12	[113]
	RP-FA at 0 or 118 mg/d during 90 d	↑ Milk yield, FCM and milk protein with RP-FA ↑ Plasma albumin with RP-FA	[114]
Whole lactation	FA at 0, 2, or 4 mg/kg of BW from 4 weeks prepartum to 305 d of lactation	↑ Serum and milk folate level with FA ↑ Multiparous milk yield with FA	[115]

^aRP rumen-protected, Bet Betaine, Met methionine, Chol choline, FA folic acid, B₁₂ vitamin B₁₂, BW body weight, CON control without supplement

^bBHBA β-hydroxybutyrate, DMI dry matter intake, ECM energy-corrected milk, FCM fatty-corrected milk, GPX glutathione peroxidase, HSP70 heat shock protein 70, MDA malondialdehyde, NEFA non-esterified fatty acids, SOD superoxide dismutase, TPP total plasmatic protein