Effects of rumen-protected methionine supplementation on dairy cows during early postpartum

Figures & data

Table 1. Ingredient composition of diets fed during close-up (−21 d relative to calving) and early lactation (+29 d relative to calving) periods.

Ingredient (% of DM)	Diet
		Early lactation
	Close-up	Control	RPM
Corn silage	49.39	42.51	42.49
Grass hay	15.28	2.86	2.86
Cottonseed	–	6.82	6.81
Corn grain	4.82	21.16	21.15
Soybean meal	12.18	16.17	16.16
Soybean hulls	15.27	7.28	7.28
Rumen-protected Met^a	–	–	0.05
Mineral-vitamin mix lactating cows^b	–	3.20	3.20
Mineral-vitamin mix prepartum cows^c	3.06	–	–

^a Smartamine M, Adisseo.

^b On a DM basis, mineral-vitamin mix for lactating cows contained 9.34% urea, 16.57% Ca, 3.03% Cl, 4.41% Mg, 8.80% Na, 2.59% P, 0.15% S, 6.8 mg/kg of Co, 384 mg/kg of Cu, 24.2 mg/kg of I, 372 mg/kg of Mn, 13.5 mg/kg of Se, 1,400 mg/kg of Zn, 145 kIU/kg of vitamin A, 27 kIU/kg of vitamin D, 1,460 IU/kg of vitamin E, 26.7 mg/kg of biotin, and 400 mg/kg of monensin.

^c On a DM basis, mineral-vitamin mix for prepartum cows contained 21.21% urea, 16.21% Ca, 9.30% Cl, 7.00% Mg, 4.07% Na, 17.4 mg/kg of Co, 1,619 mg/kg of Cu, 49.3 mg/kg of I, 1,961 mg/kg of Mn, 28.2 mg/kg of Se, 3,178 mg/kg of Zn, 821 kIU/kg of vitamin A, 33 kIU/kg of vitamin D, 10,450 IU/kg of vitamin E, and 773 mg/kg of monensin.

Table 2. Nutrient composition and evaluation of diets fed during the close-up (−21 d relative to calving) and early lactation (+29 d relative to calving) periods.

Nutrient Component^a	Diet
		Early lactation
	Close-up	Control	RPM
NEL, Mcal/kg of DM	1.59	1.59	1.59
NDF, %DM	42.07	31.03	31.01
ADF, %DM	24.29	18.38	18.38
Starch, %DM	20.61	30.31	30.29
CP, %DM	15.96	17.15	17.19
RDP, %DM	11.68	10.70	10.71
RUP, %DM	4.28	6.45	6.48
MP, g/d	1,193	2,527	2,536
Lys, %MP	7.31	6.40	6.37
Met, %MP	2.01	1.87	2.20
Lys, g/d	87	162	162
Met, g/d	24	47	56
Lys:Met ratio	3.63:1	3.41:1	2.89:1

^a Estimates using NRC (2001) based on 12.8 and 23.8 kg/d of dry matter intake on the close-up and early lactation periods, respectively.

Figure 1. Milk yield until 30 DIM (A), milk energy output (B), milk fat (C), milk protein (D), milk casein (E), milk fat-to-protein ratio (F), milk total solids (G), and milk urea nitrogen (H) in RPM-supplemented or Control cows. Values are means, with standard errors represented by vertical bars.

Table 3. Adjusted mean, respective standard error, and statistical significance of milk yield, milk energy output, and milk composition between experimental groups.

Parameter	Treatment			p value
	Control	RPM^a	SEM^b	Treatment	Time	T × T^c
Milk yield (kg/d)	32.9	31.6	1.43	0.51	<0.01	<0.01
Milk energy output (Mcal/d)	22.5	24.8	1.08	0.14	0.18	0.15
Milk fat (%)	3.67	4.15	0.09	<0.01	0.07	0.09
Milk fat-to-protein ratio	1.06	1.15	0.03	0.03	0.18	0.05
Milk total protein (%)	3.48	3.61	0.05	0.10	<0.01	0.08
Milk casein (%)	2.75	2.85	0.05	0.14	<0.01	0.07
Milk lactose (%)	4.60	4.64	0.03	0.31	<0.01	0.64
Milk total solids (%)	12.73	13.39	0.11	<0.01	<0.01	0.40
Milk urea nitrogen (mg/dL)	16.96	16.15	0.41	0.18	<0.01	0.31

^a RPM = rumen-protected methionine supplemented cows; ^bSEM = standard error of the mean; ^cT × T = treatment × time interaction.

Figure 2. Serum urea (A), aspartate aminotransferase (B), triglycerides (C), cholesterol (D), glucose (E), total protein (F), albumin (G), calcium (H), total bilirubin (I), β–hydroxybutyrate (J), and non-esterified fatty acids (K) in RPM-supplemented or Control cows. Values are means, with standard errors represented by vertical bars.

Table 4. Adjusted mean, respective standard error, and statistical significance of blood metabolites in the experimental groups.

Parameter	Treatment			p value
	Control	RPM^a	SEM^b	Treatment	Time	T × T^c
Urea (mg/dL)	29.06	29.66	0.77	0.60	<0.01	0.89
AST^d (U/L)	76.27	85.13	3.61	0.10	<0.01	0.68
Triglyceride (mg/dL)	9.27	10.69	0.51	0.07	<.0001	0.15
Cholesterol (mg/dL)	75.09	76.86	2.22	0.58	<.0001	0.79
Glucose (mg/dL)	62.87	65.31	1.37	0.22	<.0001	0.98
Total protein (g/dL)	7.10	7.21	0.14	0.57	<.0001	0.35
Albumin (g/dL)	3.29	3.39	0.05	0.17	<0.01	0.74
Calcium (mg/dL)	8.07	7.89	0.17	0.48	<0.01	0.70
Total bilirubin (mg/dL)	0.17	0.21	0.02	0.17	<0.01	0.50
BHBA^e (mmol/L)	0.52	0.61	0.04	0.15	<.0001	0.33
NEFA^f (mmol/L)	0.23	0.30	0.02	0.03	0.34	0.32

^a RPM = rumen-protected methionine supplemented cows; ^bSEM = standard error of the mean; ^cT × T = treatment × time interaction; ^dAST = aspartate aminotransferase; ^eBHBA = β–hydroxybutyrate; ^fNEFA = non-esterified fatty acids.

NRC. 2001. Nutrient requirements of dairy cattle, 7th Revised Edition. Washington, D.C: Subcommittee on Dairy Cattle Nutrition, Committee on Animal Nutrition, Board on Agriculture and Natural Resources, National Research Council, National Academy Press.

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