• Asian-Australasian Journal of Animal Sciences
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• v.2 no.3
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• pp.544-545
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• 1989

• Asian-Australasian Journal of Animal Sciences
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• v.27 no.12
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• pp.1705-1711
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• 2014

The objective of this study was to evaluate the effect of ruminally protected amino acids (RPAAs) and ruminally protected fat (RPF) supplementation on ruminal fermentation characteristics (in vitro) and milk yield and milk composition (in vivo). Fourteen mid-lactating Holstein dairy cows (mean weight $653{\pm}62.59kg$) were divided into two groups according to mean milk yield and number of days of postpartum. The cows were then fed a basal diet during adaptation (2 wk) and experimental diets during the treatment period (6 wk). Dietary treatments were i) a basal diet (control) and ii) basal diet containing 50 g of RPAAs (lysine and methionine, 3:1 ratio) and 50 g of RPF. In rumen fermentation trail (in vitro), RPAAs and RPF supplementation had no influence on the ruminal pH, dry matter digestibility, total volatile fatty acid production and ammonia-N concentration. In feeding trial (in vivo), milk yield (p<0.001), 4% fat corrected milk (p<0.05), milk fat (p<0.05), milk protein (p<0.001), and milk urea nitrogen (p<0.05) were greater in cows fed RPAAs and RPF than the corresponding values in the control group. With an index against as 0%, the rates of decrease in milk yield and milk protein were lower in RPAAs and RPF treated diet than those of basal diet group (p<0.05). In conclusion, diet supplemented with RPAAs and RPF can improve milk yield and milk composition without negatively affecting ruminal functions in Holstein dairy cows at mid-lactating.

• Korean Journal of Agricultural Science
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• v.48 no.4
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• pp.669-679
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• 2021

This study was conducted to evaluate the effects of rumen-protected amino acid (RPAA) prototypes, which were chemically synthesized, on in vitro rumen fermentation and protection rate outcomes. Several RPAA prototypes were incubated with timothy hay and concentrate. Treatments consisted of 1) control (CON; no RPAA prototype supplement), and prototypes of 2) 0.5% RP-methionine (RPMet), 3) 0.5% RP-tryptophan (RPTrp), 4) 0.5% RP-valine (RPVal), 5) 0.5% RP-phenylalanine (RPPhe), 6) 0.5% RP-leucine (RPLeu), 7) 0.5% RP-histidine (RPHis), 8) 20% RPMet, and 9) 20% RPTrp (w·w^-1 feed). The inoculum (50 mL) prepared with rumen fluid and McDougall's buffer (1 : 4) was dispensed in individual serum bottles and was anaerobically incubated for 0, 6, and 24 h at 39℃ in triplicate. The dry matter degradability did not differ among the groups, except for the 20% RPMet and the 20% RPTrp treatments at 6 and 24 h. The total volatile fatty acid concentration in the 20% RPMet was higher (p < 0.05) than the rest of the groups at 6 h, and 20% RPMet showed the highest molar proportion of acetate, whereas the lowest proportion of propionate was found at 6 h (p < 0.05). The protection rate of the RPAA prototypes ranged from 29.85 to 109.21%. at 24 h. In conclusion, the chemically synthesized RPAA prototypes studied here had no detrimental effects on rumen fermentation parameters. Further studies using animal models are needed for more accurate evaluations of the effectiveness of RPAA.

• Asian-Australasian Journal of Animal Sciences
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• v.9 no.3
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• pp.309-313
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• 1996

This experiment was carried out to investigate the effect of rumen-protected lysine (RPLys) on growth rate, feed efficiency and plasma amino acid concentrations in sheep. RPLys was supplemented at the level of 0% ($T_1$), 0.2% ($T_2$) and 0.4% ($T_3$) of total DMI with 24 sheep in a 56 day feeding trial. The results are summarized as follows: 1. live weight gain of sheep in groups $T_1$, $T_2$ and $T_3$ was 219, 216 and 244 g/d, and was significantly (p < 0.05) higher for $T_3$ through the entire experiment. 2. Feed intake was not affected by RPLys supplementation. 3. The group fed $T_3$ had a significantly (p < 0.05) better feed efficiency than the groups fed $T_1$ and $T_3$. The response of $T_3$ was higher in growing period II of feeding low protein basal diet than in period I. 4. Plasma lysine concentrations tended to be higher with supplementing RPLys, but there were no differences between $T_2$ and $T_3$. 5. Supplementing RPLys in the diets increased plasma concentrations of arginine, asparagines, threonine, serine, valine and leucine compared with sheep receiving no RPLys. In contrast, plasma histidine was lower in sheep fed the supplementing RPLys than fed the diet $T_1$ with significant (p < 0.05) difference.

• Journal of Animal Science and Technology
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• v.50 no.2
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• pp.199-208
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• 2008

This study was undertaken to investigate the effects of ruminally protected amino acids (Methionine and Lysine) on in vitro ruminal parameters, and in vivo milk yield and milk composition in mid-lactating cows. In the first in vitro experiment, there were no statistical significances between treatments in ruminal pH and dry matter digestibility during various incubation times. In the second in vivo experiment, milk yield decreased by 11.92% in control and 5.68% in the treatment respectively, but decrease rate of milk yield in the treatment was lower than control. Milk yields naturally decreased as time goes by since the DIMs(Days in milk) of the cows in experiment were in mid-lactation period. 4% FCM(Fat corrected milk) and milk protein yields also, respectively, decreased by 11.25% and 11.09% in control and 6.16% and 5.47% in the treatment as compared with the intial. Milk protein and milk fat production were higher in the treatment(0.90kg, 1.10kg) than those of control(0.66kg, 0.79kg). Milk fat content significantly increased with supplementing protected amino acids as compared to control(P<0.05). From the above results, protected amino acids were positively utilized in the performances of mid-lactating cows without inhibiting rumen fermentation. Further investigation is suggested for essential amino acid composition and intestinal digestion rate out of rumen bypass protein in dietary protein to be estimated.

• Animal Bioscience
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• v.36 no.11
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• pp.1666-1684
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• 2023

Objective: Our objective was to examine the relationships of supplemental rumen-protected lysine (RPL) or lysine + methionine (RPLM) on lactational performance, plasma amino acids (AA) concentration, and nitrogen use efficiency of lactating dairy cows by using a meta-analysis approach. Methods: A total of 56 articles comprising 77 experiments with either RPL or RPLM supplementation were selected and analyzed using a mixed model methodology by considering the treatments and other potential covariates as fixed effects and different experiments as random effects. Results: In early lactating cows, milk yield was linearly increased by RPL (β₁ = 0.013; p<0.001) and RPLM (β₁ = 0.014; p<0.028) but 3.5% fat-corrected milk (FCM) and energy-corrected milk (ECM) (kg/d) was increased by only RPL. RPL and RPLM did not affect dry matter intake (DMI) but positively increased (p<0.05) dairy efficiency (Milk yield/DMI and ECM/DMI). As a percentage, milk fat, protein, and lactose were unchanged by RPL or RPLM but the yield of all components was increased (p<0.05) by feeding RPL while only milk protein was increased by feeding RPLM. Plasma Lys concentration was linearly increased (p<0.05) with increasing supplemental RPL while plasma Met increased (p<0.05) by RPLM supplementation. The increase in plasma Lys had a strong linear relationship (R² = 0.693 in the RPL dataset and R² = 0.769 in the RPLM dataset) on milk protein synthesis (g/d) during early lactation. Nitrogen metabolism parameters were not affected by feeding RPL or RPLM, either top-dress or when supplemented to deficient diets. Lactation performance did not differ between AA-deficient or AA-adequate diets in response to RPL or RPLM supplementation. Conclusion: RPL or RPLM showed a positive linear relationship on the lactational performance of dairy cows whereas greater improvement effects were observed during early lactation. Supplementing RPL or RPLM is recommended on deficient-AA diet but not on adequate-AA diet.