Effects of rumen-protected methionine or methionine analogs in starter on plasma metabolites, growth, and efficiency of Holstein calves from 14 to 91 d of age.

During weaning, methionine (Met) supply decreases as liquid feed intake is reduced and ruminal function is developing. During this transition, the calf starter should both promote ruminal development and provide adequate nutrients post-ruminally. In mature ruminants, rumen-protected Met (RPM) and the Met analogs, 2-hydroxy-4-(methylthio)-butanoic acid (HMTBa) and HMTBa isopropyl ester (HMBi), are used to increase Met supply, stimulate ruminal fermentation, or exert both effects, respectively. To evaluate the effects of these forms of Met on calf performance during development of ruminal function, 74 Holstein calves were raised until 91 d of age, in 2 enrollment periods. Calves were individually housed from birth and, at 14 d of age, balanced for sex and randomly assigned to receive a starter with no added Met (CTRL, n = 20) or one supplemented with RPM (Smartamine M, Adisseo USA Inc., Alpharetta, GA; n = 16), HMTBa (RumenSmart, Adisseo; n = 19), or HMBi (MetaSmart, Adisseo; n = 19). Milk replacer [28% crude protein (CP), 15% fat] was offered up to 1.6 kg of dry matter (DM)/d and fed 3 times daily. Weaning was facilitated from d 49 to 63. The 4 starters (25% CP, 2.5 Mcal of metabolizable energy/kg of DM) were offered ad libitum, and supplement inclusion was set to provide an additional 0.16% DM of Met equivalents, and equal amounts of HMTBa within the analogs. Body weight and stature were measured, and blood was collected and analyzed for plasma urea nitrogen, ß-hydroxybutyrate, and free AA on a weekly basis. Supplementation of RPM and HMBi increased free plasma Met, but no differences in growth or feed efficiency compared with calves fed the CTRL starter could be attributed to the additional Met supply alone. The addition of HMBi in the starter increased feed intake and body weight during the last weeks of the experiment. On the contrary, HMTBa failed to increase plasma Met and depressed intake and growth after weaning, likely because the level included in the diet was too high and intake was greater than previous studies, exacerbating the level of HMTBa ingested. No differences were observed in stature, feed efficiency, or non-AA plasma measurements among groups. These results demonstrate that RPM and HMBi are effective sources of metabolizable Met; however, Met was apparently not limiting calves fed the basal diet in this study. The increased feed intake observed with the inclusion of HMBi in the starter during the weaning and early postweaning period might be mediated by its metabolism in the rumen, and further research is needed to determine the mechanisms involved.

Effects of rumen-protected methionine and choline supplementation on vaginal discharge and uterine cytology of Holstein cows.

Methionine is one of the most limiting amino acids in dairy diets and low feed intake around the time of calving could lead to decreased synthesis of phosphatidylcholine. An alternative pathway for phosphatidylcholine is to have choline as a precursor. The objective of this study was to determine the effects of feeding rumen-protected methionine and choline pre - and postpartum on reproduction of Holstein cows. Seventy-two Holstein cows were randomly assigned to four treatments from 21 days before calving to 30 days in milk (DIM): supplementation with rumen-protected methionine (MET; n = 20, received 0.08% of the dry matter (DM) of the diet/d as methionine, Smartamine M® to a Lys:Met = 2.9:1), rumen-protected choline (CHO; n = 17, received 60 g/d choline, Reassure), both rumen protected methionine and choline (MIX; n = 19, received 0.08% of the DM of the diet/d as methionine to a Lys:Met = 2.9:1 and 60 g/d choline), or no supplementation to serve as control (CON; n = 16, fed total mixed ration with a Lys:Met = 3.5:1). Cows were evaluated at 4, 7, 10, 13, 15, 17, and 30 d after calving for the presence of secretion using the Metricheck® device. On 15, 30, and 72 d after calving, the uterine endometrium of all cows was sampled using a cytological brush and streaked onto slides for analysis of the presence of polymorphonuclear neutrophils (PMN). We hypothesized that cows supplemented with methionine would have lower metricheck smell scores and lower rates of PMN than non-supplemented cows. On d 30, a treatment difference was detected using the metricheck score and smell (P < 0.04), with treatment MIX (score = 0.38) having a lower score than CHO (score = 2.11). Supplementing cows with rumen-protected methionine may have a beneficial effect on cows' uterine health.

Hepatic Activity and Transcription of Betaine-Homocysteine Methyltransferase, Methionine Synthase, and Cystathionine Synthase in Periparturient Dairy Cows Are Altered to Different Extents by Supply of Methionine and Choline.

BACKGROUND: Compared with choline, Met enhances milk yield and feed intake, and elicits a better immuno-metabolic status in periparturient cows. It is unknown whether hepatic activity and transcription of betaine-homocysteine methyltransferase (BHMT), 5-methyltetrahydrofolate-homocysteine methyltransferase (MTR), and cystathionine ß-synthase (CBS) are responsive to Met and choline supply. OBJECTIVE: This study sought to characterize hepatic BHMT, MTR, and CBS transcription and activity in response to Met and choline supplementation. METHODS: Forty multiparous cows were used in a 2 × 2 factorial design from -21 d through 30 d around parturition to assess effects of dietary rumen-protected Met (0% or 0.08% dry matter basis) or rumen-protected choline (0 or 60 g · cow-1 · d-1). Liver tissue obtained on days -10, 7, 20, and 30 was used for analyses. RESULTS: Met-supplemented cows had greater methionine adenosyltransferase 1A (MAT1A) (0.38 compared with 0.27; SEM = 0.05; P = 0.02) and phosphatidylethanolamine methyltransferase (PEMT) (0.74 compared with 0.58; SEM = 0.08; P = 0.05) expression. Greater S-adenosylhomocysteine hydrolase (SAHH) (0.93 compared with 0.74; SEM = 0.05; P = 0.01) and CBS (1.16 compared with 1.02; SEM = 0.07; P = 0.04), as well as lower MTR activity (23.4 compared with 29.7 nmol product · h-1 · mg protein-1; SEM = 2.9; P = 0.04), also were detected in Met- but not choline-supplemented cows. Although BHMT and MTR expression and BHMT enzyme activity did not change (P > 0.05), MTR enzyme activity was lower in choline-supplemented cows (23.5 compared with 29.6 nmol product · h-1 · mg protein-1; SEM = 2.9; P = 0.05). CONCLUSIONS: These findings indicate that greater synthesis of phosphatidylcholine and antioxidants contribute to the better performance and immuno-metabolic status in Met-supplemented cows. Failure to generate a comparable amount of endogenous Met from choline could be one reason that choline-fed cows fail to achieve comparable performance and health benefits during the periparturient period.

Methionine and Choline Supply during the Periparturient Period Alter Plasma Amino Acid and One-Carbon Metabolism Profiles to Various Extents: Potential Role in Hepatic Metabolism and Antioxidant Status.

The objective of this study was to profile plasma amino acids (AA) and derivatives of their metabolism during the periparturient period in response to supplemental rumen-protected methionine (MET) or rumen-protected choline (CHOL). Forty cows were fed from -21 through 30 days around parturition in a 2 × 2 factorial design a diet containing MET or CHOL. MET supply led to greater circulating methionine and proportion of methionine in the essential AA pool, total AA, and total sulfur-containing compounds. Lysine in total AA also was greater in these cows, indicating a better overall AA profile. Sulfur-containing compounds (cystathionine, cystine, homocystine, and taurine) were greater in MET-fed cows, indicating an enriched sulfur-containing compound pool due to enhanced transsulfuration activity. Circulating essential AA and total AA concentrations were greater in cows supplied MET due to greater lysine, arginine, tryptophan, threonine, proline, asparagine, alanine, and citrulline. In contrast, CHOL supply had no effect on essential AA or total AA, and only tryptophan and cystine were greater. Plasma 3-methylhistidine concentration was lower in response to CHOL supply, suggesting less tissue protein mobilization in these cows. Overall, the data revealed that enhanced periparturient supply of MET has positive effects on plasma AA profiles and overall antioxidant status.