Rumen-protected Methionine Supplementation Research Articles

Peripartal rumen-protected methionine supplementation to higher energy diets elicits positive effects on blood neutrophil gene networks, performance and liver lipid content in dairy cows.

BackgroundMain objectives were to determine to what extent Smartamine M (SM) supplementation to a prepartal higher-energy diet could alter neutrophil (PMN) and liver tissue immunometabolic biomarkers, and whether those responses were comparable to those in cows fed a prepartal lower-energy diet (CON).ResultsTwenty-eight multiparous Holstein cows were fed CON (NEL = 1.24 Mcal/kg DM) during d −50 to d −22 relative to calving. From d −21 to calving, cows were randomly assigned to a higher-energy diet (OVE, n = 9; NEL = 1.54 Mcal/kg DM), OVE plus SM (OVE + SM, n = 10; SM = 0.07 % of DM) or remained on CON (n = 9). All cows received the same basal lactation diet (NEL = 1.75 Mcal/kg DM). Supplementation of SM (OVE + SM) continued until 30 d postpartum. Liver biopsies were harvested at d −10, 7, and 21 relative to parturition. Blood PMN isolated at −10, 3, and 21 d relative to calving was used to evaluate gene expression. As expected, OVE increased liver lipid content postpartum; however, cows fed OVE + SM or CON had lower concentrations than OVE. Compared with OVE, cows in CON and OVE + SM had greater DMI postpartum and milk production. Furthermore, cows fed OVE + SM had the greatest milk protein and fat percentage and lowest milk SCC despite having intermediate PMN phagocytic capacity. Adaptations in PMN gene expression in OVE + SM cows associated with the lower SCC were gradual increases from −10 to 21 d in genes that facilitate migration into inflammatory sites (SELL, ITGAM), enzymes essential for reducing reactive oxygen metabolites (SOD1, SOD2), and a transcription factor(s) required for controlling PMN development (RXRA). The greater expression of TLR4 on d 3, key for activation of innate immunity due to inflammation, in OVE compared with CON cows suggests a more pronounced inflammatory state. Feeding OVE + SM dampened the upregulation of TLR4, despite the fact that these cows had similar expression of the pro-inflammatory genes NFKB1 and TNF as OVE. Cows in CON had lower overall expression of these inflammation-related genes and GSR, which generates reduced glutathione, an important cellular antioxidant.ConclusionsAlthough CON cows appeared to have a less stressful transition into lactation, SM supplementation was effective in alleviating negative effects of energy-overfeeding. As such, SM was beneficial in terms of production and appeared to boost the response of PMN in a way that improved overall cow health.Electronic supplementary materialThe online version of this article (doi:10.1186/s40104-016-0077-9) contains supplementary material, which is available to authorized users.

Effects of rumen-protected methionine and choline supplementation on the preimplantation embryo in Holstein cows

Our objective was to determine the effects of supplementing methionine and choline during the prepartum and postpartum periods on preimplantation embryos of Holstein cows. Multiparous cows were assigned in a randomized complete-block design into four treatments from 21 days before calving to 30 days in milk (DIM). Treatments (TRT) were MET (n = 9, fed the basal diet + rumen-protected methionine at a rate of 0.08% [w:w] of the dry matter [DM], Smartamine M), CHO (n = 8, fed the basal diet + choline 60 g/d, Reashure), MIX (n = 11, fed the basal diet + Smartamine M and 60 g/d Reashure), and CON (n = 8, no supplementation, fed the close-up and fresh cow diets). Cows were randomly reassigned to two new groups (GRP) to receive the following diets from 31 to 72 DIM; control (CNT, n = 16, fed a basal diet) and SMT (n = 20, fed the basal diet + 0.08% [w:w] of the dry matter intake as methionine). An progesterone intravaginal insert (CIDR) device was inserted in all cows after follicular aspiration (60 DIM) and superovulation began at Day 61.5 using FSH in eight decreasing doses at 12-hour intervals over a 4-day period. On Days 63 and 64, all cows received two injections of PGF2α, and CIDR was removed on Day 65. Twenty-four hours after CIDR removal, ovulation was induced with GnRH. Cows received artificial insemination at 12 hours and 24 hours after GnRH. Embryos were flushed 6.5 days after artificial insemination. Global methylation of the embryos was assessed by immunofluorescent labeling of 5-methylcytosine, whereas lipid content was assessed by staining with Nile red. Nuclear staining was used to count the total number of cells per embryo. There was no difference between TRT, GRP, or their interaction (P > 0.05) for embryo recovery, embryos recovered, embryo quality, embryo stage, or cells per embryo. Methylation of the DNA had a TRT by GRP interaction (P = 0.01). Embryos from cows in CON-CNT had greater (P = 0.04) methylation (0.87 ± 0.09 arbitrary units [AU]) than embryos from cows in MET-CNT (0.44 ± 0.07 AU). The cytoplasmic lipid content was not affected (P > 0.05) by TRT or their interaction, but lipid content was greater (P = 0.04) for SMT (7.02 ± 1.03 AU) than that in CNT (3.61 ± 1.20 AU). In conclusion, cows in MET-CNT had embryos with lower methylation, and SMT cows had a higher lipid content than CNT. Methionine supplementation seems to impact the preimplantation embryo in a way that enhances its capacity for survival because there is strong evidence that endogenous lipid reserves serve as an energy substrate.

Effect of pre-partum supplementation of rumen protected methionine plus lysine and choline on the performance of crossbred cows

The study was conducted to determine rumen escape potential (REP) of commercial rumen protected methionine (RPM), lysine (RPL) and choline (RPC) products and to examine the effect of supplementing RPM plus RPL and RPC on the performance of preparturient crossbred cows. Crossbred cows (27; 2nd to 4th lactation) were randomly assigned to 3 groups of 9 animals each, on the basis of most probable production ability (MPPA). Cows in control group (T1), were fed basal diet as per NRC (2001). The cows in second group (T2), were supplemented with 5 g RPM and 20 g RPL, and those in third group (T3), were fed 54 g RPC per cow/day for 40 days pre-partum. In sacco study revealed that REP of RPM, RPL and RPC was 75.20, 54.97 and 72.89%, respectively. Supplementation of RPM plus RPL and RPC resulted in higher body condition score (BCS) in crossbred cows on the day of parturition. Nutrient intake was similar among the groups, except that duodenal supply of methionine and lysine was higher in T2 group. Plasma triglycerides, VLDL (very low density lipoproteins) and phosphatidylcholine levels were higher in T2 and T3 groups while vitamin E level was higher in T3 group, on the day of parturition, indicating better immune status. It was concluded that fortification of ration with RPM plus RPL and RPC resulted in improved body condition score, duodenal supply of methionine and lysine and better immune status in cows during prepartum period.

Dietary Supplementation of Rumen-Protected Methionine, Lysine and Choline Improves Lactation Performance and Blood Metabolic Profile of Karan-Fries Cows

Twenty seven crossbred (Karan-Fries) cows between second and fourth lactation with most probable production ability of around 4500 kg milk were divided into three similar groups. Animals in the Control group were offered with a basal diet consisting of threshed wheat straw, chopped green maize forage and compounded concentrate mixture as per their requirements. In addition to basal diet, animals in second group (rpMetLys) were fed with 5 g of rumen-protected methionine and 20 g of rumen-protected lysine, and in third group (rpCholine), 54 g of rumen-protected choline was supplemented 40 days before and 120 days after calving. Results revealed higher (P < 0.01) intake of various nutrients along with better body condition score in rpMetLys group. Furthermore, milk yield and milk component (fat, protein and lactose) yield were higher (P < 0.01) in both the treatment groups with higher (P < 0.01) milk choline concentration in rpCholine group. Monounsaturated fatty acids and unsaturated fatty acids in milk tended to be higher (P < 0.05) in rpCholine group. Plasma metabolites like glucose, non-esterified fatty acids, cholesterol and plasma urea nitrogen were similar among all groups. Concentration of triglycerides and very low density lipoproteins was lower (P < 0.01) in rpMetLys and rpCholine than Control group. However, phosphatidylcholine and vitamin E levels were higher (P < 0.01) in rpCholine than other two groups. Methionine levels were higher (P < 0.01) in rpMetLys and rpCholine groups, whereas lysine was increased (P < 0.01) only in the former. Moreover, days open (service period) was decreased (P < 0.01) in animals belonging to rpCholine group. It was concluded from the present study that supplementation of rpMetLys and rpCholine to high-yielding crossbred cows was beneficial in terms of improving milk yield, composition as well as metabolic health status during early lactation period under Indian situation.

Rumen-protected methionine supplementation and fibre production in alpacas (Vicugna pacos )

Sulphur-containing amino acids are a crucial requirement for fibre production and may be supplemented in the diet of fibre-producing animals to stimulate fibre growth. The alpaca fibre industry is a developing industry in Australia with high variability in fibre production. To date, there is no evidence whether supplementing the diet of alpacas with sulphur amino acids improves fibre production. We hypothesised that supplementation with the rumen-protected sulphur amino acid, methionine would increase fibre growth in alpacas. Three groups of eight huacaya alpaca wethers were fed daily a maintenance diet supplemented with 0, 2 or 4 g of rumen-protected methionine for 7 weeks. Fibre samples were taken at the beginning and end of the study with a blood sample taken by jugular venipuncture prior to feeding on the first day of each week. Methionine supplementation had no effect on fibre diameter (p = 0.92), fibre length (p = 0.91) or fibre yield (p = 0.33). The change of season over the study affected plasma glucose (p < 0.001), plasma urea nitrogen (p < 0.001) and fibre diameter (p < 0.001). The indifference between groups may be due to the maintenance diet supplying sufficient levels of methionine, the lack of genetic potential of the experimental animals to respond to additional methionine or that the supplemental methionine was not protected in alpacas and deaminated for glucose production.

Effects of metabolizable protein supply and amino acid supplementation on nitrogen utilization, milk production, and ammonia emissions from manure in dairy cows

Two experiments were conducted with the objective of investigating the effects of rumen-protected methionine (RPMet) supplementation of metabolizable protein (MP)-deficient or MP-adequate but Met-deficient diets on dairy cow performance. Experiment (Exp.) 1 utilized 36 Holstein dairy cows blocked in 12 blocks of 3 cows each. Cows within block were assigned to one of the following dietary treatments: (1) MP-adequate diet [AMP; positive MP balance according to the National Research Council (2001) dairy model]; (2) an MP-deficient diet supplemented with 100g of rumen-protected Lys (RPLys)/cow per day (DMPL); and (3) DMPL supplemented with 24g of RPMet/cow per day (DMPLM). Experiment 2 utilized 120 Holstein cows assigned to 6 pens of 20 cows each. Pens (3 per treatment) were assigned to one of the following dietary treatments: (1) AMP diet supplemented with 76g of RPLys/cow per day (AMPL); and (2) AMPL (74g of RPLys/cow per day) supplemented with 24g of RPMet/cow per day (AMPLM). Each experiment lasted for 10wk (2-wk adaptation and 8-wk experimental periods) following a 2-wk covariate period (i.e., a total of 12wk). In Exp. 1, the MP-deficient diets decreased apparent total-tract nutrient digestibility but had no statistical effect on dry matter intake (DMI), milk yield, or milk fat percentage and yield. Compared with AMP, DMPL decreased milk protein content; both DMPL and DMPLM diets decreased milk protein yield. Urinary N losses and milk urea-N concentration were decreased by the MP-deficient diets compared with AMP. The ammonia emitting potential of manure from the MP-deficient diets was decreased by about 37% compared with that of AMP manure. Plasma Lys and Met concentrations were not affected by treatment, but concentrations of His, Thr, and Val were lower for the MP-deficient diets compared with AMP. In Exp. 2, the AMPLM diet had lower milk yield than AMPL due to numerically lower DMI; no other effects were observed in Exp. 2. In conclusion, feeding MP-deficient diets supplemented with RPLys and RPMet did not statistically decrease milk yield in dairy cows in Exp. 1. However, without RPMet supplementation, milk protein content was decreased compared with the MP-adequate diet. Other amino acids, possibly His, may limit milk production in MP-deficient, corn or corn silage-based diets. A summary of 97 individual cow data from trials in which MP-deficient diets were fed suggested the National Research Council (2001) model under-predicts milk yield in cows fed MP-deficient diets (MP balance of –20 to –666g/d) in a linear manner: milk yield under-prediction [National Research Council (2001) MP-allowable milk yield, kg/d – actual milk yield, kg/d] = 0.0991 (±0.0905) + 0.0230 (±0.0003) × MP balance, g/d (R2=0.99).

Effect of Selenium Depletion on Oxidative Stress in Mature Horses

s / Journal of Equine Veterinary Science 31 (2011) 230-356 257 [5] Bryden WL. Amino acid requirements of horses estimated from tissue composition. Proc Nutr Soc 1991;16:53. [6] Wilson JA, Graham-Thiers PM. Muscle and plasma amino acids in pregnant/lactating mares and their weanling foals. J Equine Vet Sci 2009;29:370. [7] Nutrient Requirements of Horses. 6th ed. Washington, DC: The National Academies Press; 2007. [8] Waggoner JW, LOxest CA, Mathis CP, Hallford DM, Petersen MK. Effects of rumen-protected methionine supplementation and bacterial lipopolysaccharide infusion on nitrogen metabolism and hormonal responses of growing beef steers. J Anim Sci 2009;87:681. Effect of Selenium Depletion on Oxidative Stress in Mature Horses M. Brummer, S. Hayes, J.E. Earing, S.M. McCown, and L.M. Lawrence University of Kentucky, Lexington, KY, USA Introduction: Glutathione peroxidase (GPx) plays an important role in the neutralization of hydroperoxides andhydrogenperoxide. Hydrogen peroxide can generate hydroxyl radicals which are regarded as a very harmful reactive oxygen species [1]. Selenium (Se) deficiency can result in decreased GPx activity; therefore our aim was to investigate the effect of low Se status on oxidative stress in mature idle horses. We hypothesized that Se depletion would result in a decrease in GPx activity, serum total antioxidant capacity (TAC) and an increase in oxidative stress, measured as serum malondialdehyde concentration (MDA). Type I deiodinase, is a selenoenzyme responsible for the conversion of inactive T4 to active T3. Therefore as additional indicators of Se status we measured triiodothyronine (T3), thyroxine (T4), and the T3:T4 ratio as changes in these hormones or in their ratio has been evaluated in horses fed varying levels of Se before [2]. Materials and Methods: Twenty eight mature horses (6 24 yr) were used in this study. The 28 horses included 8 geldings and 20 mares that had resided on the farm for at least 60 days prior to the study. The study period was 28 wks. Horses were kept on pasture ( .05). MDA concentrationwas not different between AS and LS at the initial or final time point, howeverMDAdid increaseover time (P< .05) in LS (from3.40 .86 nmol/mL to 4.04 .89 nmol/mL) while it remained similar in AS (4.68 1.78 nmol/mL to 5.09 1.09 nmol/mL). Two traditional indicators of Se status were measured: whole blood Se concentration and GPx activity. In addition the serum T3/ T4 ratio was determined. Type I deiodinase, the enzyme responsible for converting T4 to T3, has a greater ranking in terms of priority of Se supply than cytosolic GPx [2]. A change in this ratio is generally not observed during a marginal Se deficiency [2], so the increased ratio of T3/T4 in the LS horses along with the changes in whole blood Se and GPx suggests that the LS horses were at, or approaching, deficient Se status. TAC was expected to decrease in LS horses, but it was unaffected. The lack of change in TAC may point towards a compensatory mechanism within the antioxidant system, or lack of sensitivity of the assay as a measure of the GPx-associated antioxidant capacity in serum. GPx is only one of several compounds that contribute to total antioxidant capacity. MDA is a byproduct of lipid peroxidation [4]. We hypothesized that MDA concentrations would increase with decreasing Se status. Although MDA concentrations increased over time in the LS horses, the magnitude of the changes were relatively small. Much larger changes in MDA have been reported in response to exercise or disease in other studies [4] and some type of oxidative challenge might be necessary to produce more marked differences in MDA in the horses studied here. Conclusion: In this study feeding a low Se diet for 28 wks altered indicators of Se status, but appears to have hadminimal effects on the indicator of oxidative damage. However, more marked effects might have been observed if the horses had been challenged with an oxidative stressor such as exercise or disease. Further research in this area may provide better insight into the importance of Se in oxidative stress.

Effect of rumen-protected choline and methionine on physiological and metabolic disorders and reproductive indices of dairy cows

The objective of this study was to investigate the effect of feeding different levels of ruminally protected methionine and choline on the incidence of physiological and metabolic disorders, production, and some of the reproductive indices of Holstein dairy cows. Forty Holstein dairy cows in their first and second lactation were used from 4-week pre-partum through 20-week post-partum and randomly assigned to receive one of the following treatments: 18 g/day of rumen-protected methionine (RPM), 60 g/day of rumen-protected choline (RPC), 18 g/day of RPM + 60 g/day of RPC, and neither supplement (control). The treatments significantly affected services per conception and open days of lactating dairy cows (p < 0.05), but did not affect significantly on days to first oestrus and number of pregnant cows. RPM + RPC-fed cows had the lowest open days, days to first oestrus and services per conception compared with other groups. The effect of treatments was significant on the incidence of metabolic and physiological problems except for foot/leg problems. Cows fed RPM+RPC had the lowest health problems compared with other groups (p < 0.05). Results indicate that the supplementation of RPM and RPC can improve reproductive performance and health status of dairy cows.

Effects of fat and rumen-protected methionine supplementation on production response of first-lactation cows

To determine whether supplementation of rumen-protected methionine (RPM) and fat, from 0 to 150 days in milk, improves milk production, milk quality, and energy balance (EB), in a completely randomized design, 32 first-lactation cows fed diets with 0 or 3.5% added fat and 0 or 0.15% added RPM. Fat, RPM, and fat plus RPM increased milk yield. Supplemental RPM increased milk protein (%) and decreased milk fat (%). Fat, RPM, and fat plus RPM increased (kg) milk fat, milk protein, and milk lactose. Cows fed fat and RPM alone had greater negative EB values than cows non-supplemented. Cows fed fat plus RPM had similar EB to cows non-supplemented. Supplemental RPM induced higher plasma glucose and lower urea-N. Fat induced higher plasma cholesterol. In conclusion, supplemental fat or RPM, and fat plus RPM increased milk production, but fat plus RPM enhanced EB as compared to fat or RPM alone.

Effect of rumen-protected methionine on feed intake, milk production, true milk protein concentration, and true milk protein yield, and the factors that influence these effects: A meta-analysis

A meta-analysis of published studies was used to investigate the effect of rumen-protected methionine (RPM) added to the diets of lactating dairy cattle on dry matter intake, milk production, true milk protein (TMP) production, and milk fat yield. Differences in responses between 2 commonly used RPM products, Mepron (Evonik Industries, Hanau, Germany) and Smartamine (Adisseo, Antony, France), were investigated as well as dietary and animal factors that could influence responses. Diets were coded with respect to the amino acid (AA) deficiency of the control diet as predicted by the AminoCow model (version 3.5.2, http://www.makemilknotmanure.com/aminocow.php; 0=no AA deficiency, 1=Met deficiency, 2=Met and Lys deficiency, 3=Met and Lys plus at least 1 other AA deficiency) to test the effect of AA deficiencies on RPM response. Thirty-five studies were identified, 17 studies evaluating Mepron, 18 studies evaluating Smartamine, and 1 study evaluating both. This permitted 75 dietary comparisons between control and RPM-added diets. Diets were entered into the AminoCow and the 2001 National Research Council models to compare predictions of Met, Lys, and metabolizable protein (MP) flow. Mean Met and Lys in diets where RPM was fed were estimated to be 2.35 and 6.33% of MP, respectively. Predictions of flows between models were similar. Overall, RPM addition to diets increased production of TMP, both as percentage (0.07%) and yield (27 g/d). Dry matter intake and milk fat percentage were slightly decreased, whereas milk production was slightly increased. Differences between products were detected for all production variables, with Mepron-fed cows producing less TMP percentage but greater milk production, resulting in twice as much TMP yield. Milk protein response to RPM was not related to predicted AA deficiency, calculated Met deficiency, or Met as a percentage of MP. Other dietary factors, including Lys flow (g/d), Lys as percentage of MP, neutral detergent fiber percentage, crude protein percentage, or energy balance, had no detectable effects on TMP response. When cows with a predicted positive AA balance were fed RPM, milk production increased, but when AA balance was negative, milk production decreased. Amount of RPM added to the diet was not correlated to TMP response. This study does not support the necessity of a high Lys level as a prerequisite to obtaining a TMP response to feeding RPM or the MP requirement suggested by the National Research Council model (2001). However, more dose–response studies over a wide range of milk production and dietary regimens will be required to more clearly establish AA requirements and to predict responses to RPM supplementation.

Influence of methionine supply on the response of lactational performance of dairy cows to supplementary folic acid and vitamin B12

The present experiment was undertaken to determine if the effects of supplementary folic acid on lactational performance were caused by improved methylneogenesis and if the supply in vitamin B12 could affect this metabolic pathway. In this eventuality, supplementary Met, a major source of preformed methyl groups, should reduce the requirements for these vitamins. Sixty multiparous Holstein cows were assigned to 10 blocks of 6 cows each according to their previous milk production. Within each block, 3 cows were fed a diet estimated to supply Met as 1.83% metabolizable protein and 3 cows were fed the same diet supplemented with 18g of rumen-protected methionine (RPM) to supply Met as 2.23% of metabolizable protein. Within each level of Met, cows received no vitamin supplement or weekly intramuscular injections of 160mg of folic acid alone or combined with 10mg of vitamin B12 from 3 wk before to 16 wk after calving. There was no treatment effect on dry matter intake during pre- and postcalving periods: 13.4±0.4 and 21.8±0.4kg/d, respectively. Milk production was not affected by RPM supplementation. Folic acid and vitamin B12 given together tended to increase milk production during the 16 wk of lactation. This effect was more pronounced during the first 4 wk of lactation: 37.5, 37.7, and 40.3±0.9kg/d for cows receiving no vitamin supplement, folic acid alone, or folic acid combined with vitamin B12, respectively. Milk fat yield was not affected by treatments. Lactose, crude protein, and total solid yields were greater, in early lactation, in cows injected with folic acid and vitamin B12 together but this effect diminished as lactation progressed. Intramuscular injections of folic acid alone or combined with vitamin B12 tended to decrease plasma concentrations of homocysteine from 5.51 μM with no vitamin supplement to 4.54 and 4.77±0.37 μM, respectively. Results of the present experiment suggest that the effects of the combined supplement of folic acid and vitamin B12 on lactational performance of dairy cows were not due to an improvement in methyl groups supply, because RPM supplement, a source of preformed methyl groups, did not alter the cow responsiveness to vitamin supplements.

Investigation on the Effect of Supplementing Rumen-Protected Forms of Methionine and Choline on Health Situation and Reproductive Performance of Holstein Dairy Cows

Twenty Holstein dairy cows in their first and second lactation were used from 4-week prepartum through 20-week postpartum. The aim was to investigate the effect of feeding different levels of ruminally protected methionine and choline on health situation and reproductive indices of Holstein dairy cows. Cows were randomly assigned to receive one of the following treatments: 18 g day(-1) of rumen protected methionine (RPM), 60 g day(-1) of rumen protected choline (RPC), 18 g day(-1) of RPM + 60 g day(-1) of RPC and neither supplement (control). The treatments significantly affected services per conception and open days of lactating dairy cows, but did not significantly affect on days to first estrus and number of pregnant cows. RPM + RPC-fed cows had the lowest open days, days to first estrus and services per conception compared with other groups. Although no statistical differences were noted for any given health category, the overall incidence of health-related disorders was numerically lowest for cows fed RPM + RPC. Results indicate that the supplementation of RPM and RPC have been improved reproductive performance and health situation of dairy cows.

Effects of rumen-protected methionine supplementation and bacterial lipopolysaccharide infusion on nitrogen metabolism and hormonal responses of growing beef steers1

Metabolic demand for sulfur-containing AA increases during inflammation in nonruminants. Therefore, Met supplementation may alleviate the negative effects of infection on N balance. Effects of gram-negative bacterial lipopolysaccharide (LPS) and supplemental dietary Met on N balance, serum hormones and haptoglobin, and plasma urea-N and AA were evaluated in 20 Angus-cross steers (BW = 262 +/- 6.3 kg). Treatments (2 x 2 factorial) were infusion of no LPS (-LPS) or a prolonged low dose of LPS (+LPS) and dietary supplementation of no (-MET) or 14 g/d (+MET) of rumen-protected Met (providing 7.9 g/d of dl-Met). Steers were adapted to a roughage-based diet (DMI = 1.4% of BW daily) and supplemental Met for 14 d, and were then infused (1 mL/min via intravenous catheter) with LPS on d 1 (2 microg/kg of BW) and 3 (1 microg/kg of BW) of a 5-d collection period. Blood was collected on d 1, before LPS infusion, and at 2, 4, 6, 8, 10, 12, and 24 h after LPS challenge. Diet samples, feed refusals, feces, and urine were collected daily for 5 d. Rectal temperature and serum concentrations of cortisol, prolactin, tumor necrosis factor-alpha, and haptoglobin increased, whereas thyroxine and triiodothyronine decreased for +LPS vs. -LPS steers (LPS x h; P < 0.01). Plasma urea-N was greater for +LPS than -LPS steers (LPS; P = 0.03), and serum IGF-1 was not affected (P > or = 0.26) by LPS or Met. Plasma concentrations of Thr, Lys, Leu, Ile, Phe, Trp, Asn, Glu, and Orn decreased, plasma Ala increased, and Gly and Ser initially increased, then declined in +LPS vs. -LPS steers (LPS x h; P < or = 0.04). Plasma Met was greater for +MET than -MET steers before LPS infusion, but declined in +MET steers after LPS infusion (LPS x Met x h; P < 0.01). By design, DMI was not different, but DM digested was less (P = 0.04) for +LPS than -LPS steers. Infusion of LPS did not affect (P > or = 0.24) N intake, fecal N excretion, or N digested, but resulted in greater (P < 0.01) urinary N excretion and less (P < 0.01) N retention. The absence of an LPS x Met interaction (P = 0.26) for N retention indicates that supplemental Met does not improve the N utilization of growing beef steers exposed to a gram-negative bacterial endotoxin. Decreases in plasma concentrations of several essential AA in +LPS steers suggest that metabolic demand for these AA likely increased in steers exposed to endotoxin.

Response of lactating cows to supplemental rumen protected methionine and Niacin

Eight Chinese Holstein cows were used in a 4 × 4 Latin square design to determine the effects of rumen protected methionine (RPMet) and Niacin on milk yield and milk composition of lactating cows with 14 d adaptation and 6-d sampling periods. The cows were fed the control diet or the control diet plus RPMet (25 g·−1), niacin (6 g·−1), or RPMet (25 g·−1) + niacin (6 g·−1). The results showed that RPMet supplementation in the diet increased 4% fat corrected milk (FCM) yield (P 0.05) and lactose percentage (P > 0.05). Dietary niacin supplementation increased milk yield (P 0.05) and SNF (P > 0.05). RPMet supplementation in the diet of lactating cows significantly decreased serum urea nitrogen (P 0.05). Niacin supplementation influenced the contents of glucose and NEFA in serum, but had no effects on the urea nitrogen, total cholesterol and triglyceride (P > 0.05).

Effect of rumen protected methionine supplementation on early lactational responses of dairy cows fed a grass silage and cereals diet.

To investigate the milk production limiting potential of a diet based on grass silage (40%), hay (15%), dried sugar beet pulp (13%) and grain compound mixture (32%), 28 multiparous cows in early lactation were randomly assigned to two treatment groups: a control group and a group receiving supplementary rumen protected methionine (RPMet) treatment (12 g intestinally available methionine/cow/day, given 1-120 days postpartum; Smartamine; RPAN's technology). The diet was formulated to meet the requirements for protein and net energy. RPMet supplementation had no significant effect on DMI (kg/cow/day), milk dry mass, milk lactose and milk urea contents. Responses for mean daily milk yield, mean milk fat and milk protein yields were significantly higher (P < 0.05) in cows supplied with RPMet than in controls. Mean daily milk yield, milk protein and milk fat yields increased by 2.4 kg, 108 g and 124 g, respectively. The mean daily milk protein and casein contents were increased by 1.8 g and 0.9 g and milk fat content by 1.2 g in 1 kg of milk, respectively. The results suggest that in cows fed grass silage and a grain compound mixture milk production is limited by methionine insufficiency, but milk production performance can be increased significantly by the addition of RPMet to the diet.

Rumen-protected methionine or lysine supplementation of Comisana ewes' diets: effects on milk fatty acid composition.

The effect of graded levels of dietary rumen-protected methionine (rp-Met) or lysine (rp-Lys) on the fatty acid composition of Comisana ewes' milk was investigated. The animals lambed in autumn and were separated from their lambs 7 weeks after parturition; they were divided into five groups of nine which were given different rations. The control group was fed on a mixture of vetch and oat hay with a pelleted concentrate; the other groups were given the control ration supplemented with rp-Met (3.5 or 7.0 g/kg) or rp-Lys (10.5 or 21.0 g/kg). Milk fatty acid composition was determined by gas chromatography, and these values were subjected to principal components analysis. A correlation was found between fatty acid composition and diet. We demonstrated that giving the experimental diets significantly affected milk fat, to an extent that was independent of the levels of the supplementary amino acids. The milk fat of the control group contained largely caprylic, capric and lauric acids, whereas that of the groups given the supplementary amino acids contained largely palmitic, palmitoleic, stearic and oleic acids. Thus supplementation resulted in an increase in the proportion of 16:0-18:3 (primarily palmitic and stearic) and a reduction in the proportion of 4:0-12:0 fatty acids. There was also a modest increase in the unsaturated:saturated fatty acid ratio.

Effects of energy and amino acid supply to the small intestine on amino acid metabolism

Effects of increasing the supply of starch and amino acids in the small intestine on absorption of nutrients and concentration of plasma metabolites were determined. A 2 × 2 × 2 factorial arrangement of treatments was used and dietary factors were as follows: 1) 25% versus 50% dietary corn, 2) formaldehyde-treated (rumen-protected) versus untreated corn, and 3) supplemental rumen-protected methionine and lysine versus no supplemental amino acids. Treatments were randomly allotted to 40 individually fed steers for the trial. Feeding formaldehyde-treated corn resulted in increased plasma glucose and insulin concentrations. Plasma insulin and glucose concentrations were also directly proportional to dietary corn level. The plasma concentrations of urea and most individual amino acids were markedly decreased when steers were fed treated corn compared with those fed untreated corn. Increased postruminal nutrient supply enhanced metabolic utilization of amino acids in these steers.

Effects of rumen-protected amino acids on ruminant nitrogen balance, plasma amino acid concentrations and performance.

A series of trials was conducted to determine the effects of supplemental rumen-protected methionine (RPMet) and lysine (RPLys) on nutrient metabolism and performance. In situ RPMet N disappearance was less than 4% following 48 h of incubation and was not affected (P greater than .05) by diet or resultant ruminal pH differences, indicating that RPMet was well protected from ruminal microbial degradation. Thirty-five Dorset-sired crossbred wether lambs (avg wt 28 kg) fed ground corn-soybean hull diets supplemented with urea were randomly assigned to one of the following treatments: 1) 0% RPMet, 2) .03% RPMet, 3) .06% RPMet, 4) .09% RPMet or 5) .12% RPMet. Dry matter, fiber and N digestibilities and N retention were not affected (P greater than .05) by treatment. Plasma methionine concentration tended to increase linearly (P less than .07) with dietary RPMet level. Six Simmental X Angus steers (avg wt 427 kg) were fed a corn grain-corn silage diet supplemented with urea and five levels of RPMet: 1) 0%, 2) .04%, 3) .08%, 4) .12% and 5) .16%. The plasma methionine concentration increased linearly (P less than .01) with dietary RPMet level. In a steer performance trial, no improvements in feedlot performance resulted due to these RPMet levels (P greater than .05), suggesting that the control diet (0% RPMet) was meeting the methionine requirement of these steers. The effects of RPMet and RPLys on growing and finishing steer feedlot performance also were evaluated. Treatments were 1) urea control, 2) soybean meal positive control, 3) .09% RPMet + .06% RPLys, 4) .12% RPMet + .08% RPLys and 5) .15% RPMet + .10% RPLys. In the growing trial, added RPMet and RPLys did not improve steer feedlot performance. In the finishing trial, only steers fed .09% RPMet + .06% RPLys had higher (P less than .05) gains than those fed the urea control diet. These trials indicate that postruminal methionine and lysine supplies were not limiting feedlot steer performance.