Dietary Lysine Requirements of Older Adults Stratified by Age and Sex.

BACKGROUND: Current recommendation for lysine in older adults, 30 mg/kg/d, is based on young adult data. Evidence suggests that amino acid requirements may differ between young and old adults with both sex and age having an effect in the elderly. OBJECTIVES: This study aimed to define the lysine requirements in healthy older adults using the indicator amino acid oxidation (IAAO) method with L-[1-13C] phenylalanine as the indicator and to compare the derived estimates based on age: 60-69 y and >70 y. METHODS: Fourteen healthy males and 16 healthy females [>60 y, body mass index (BMI) = 26.3 kg/m2] were randomly assigned to receive 3-7 lysine intakes from 10 to 80 mg/kg/d. Subjects were adapted to a standard liquid diet providing 1.0 g/kg/d protein and adequate energy, for 2 d, with indicator oxidation measurements performed on day 3. The rate of release of 13CO2 from the oxidation of L-[1-13C] phenylalanine was measured in breath. A 2-phase linear mixed-effect model, and parametric bootstrap were used to determine mean lysine requirements and the 95% confidence intervals (CIs). The overlap of the 95% CI between the 2 age groups were used to compare the requirement estimates. The null hypothesis was accepted if the interval contained zero. RESULTS: The mean and upper 95% CI of the lysine requirement for females were 32.9 and 40.9 and 46.2 and 53.7 mg/kg/d for those aged 60-69 y and >70 y, respectively. The mean and upper 95% CI of the lysine requirement for the 2 groups of males were not different so was combined to yield a mean and 95% CI of 32.2 and 38.2 mg/kg/d. CONCLUSIONS: To our knowledge, this is the first study to report on the lysine requirement in adults aged >60 y. These results provide a basis from which the adequacy of diets to meet lysine needs of older adults can be assessed. The trial was registered at clinicaltrials.gov as NCT02008955 (https://clinicaltrials.gov/study/NCT02008955).

Feeding the modern sow to sustain high productivity.

Selection for hyper-prolific sows has increased the litter size by more than 50% during the last three decades, and proper nutrition of the female pigs has concomitantly changed due to improved prolificacy and productivity of gilts and sows. This review summarizes the physiological characteristics and nutritional challenges associated with feeding modern hyper-prolific sows during the gilt rearing period and during gestation, transition, and lactation periods. The review presents up-to-date knowledge of the energy and lysine requirements of female pigs and focuses on how nutrition may increase fat gain and limit protein and weight gain in the gilt rearing period and in early and mid-gestation. In late gestation, fetal and mammary growth should be considered and during the transition, colostrum yield and farrowing performance need to be optimized. Finally, milk production should be optimized and body mobilization should be minimized in the lactation period to achieve high feed efficiency in hyper-prolific sows.

Determination of the Optimal In-Feed Amino Acid Ratio for Japanese Quail Breeders Based on Utilization Efficiency.

The description of the genetic potential is the first step to estimating amino acid requirements and the ideal amino acid relation (IAAR). The aim of this study was to estimate the parameters that describe the daily maximum theoretical nitrogen retention (NRmaxT, mg/BWkg0.67), daily nitrogen maintenance requirement (NMR, mg/BWkg0.67), protein quality (b), dietary efficiency of the limiting amino acid (bc-1) and determine the lysine requirement and the IAAR for Japanese quail breeders. Two nitrogen balance assays were performed, one assay using 49 quails distributed in seven treatments (protein levels between 70.1 and 350.3 g/kg) and seven replicates and other assay to determine the IAAR by the use of bc-1, 12 treatments and 10 replicate, with a control diet (CD) and 11 treatments that had limited essential amino acids by providing only 60% of the CD. The values obtained for NRmaxT, NMR, b and bc-1 were 3386.61, 0.000486 and 0.000101, respectively. The daily intake of Lys was 291 mg/bird day. Lys was set at 100% for determining the IAAR: 87, 67, 21, 117, 96, 66, 142, 39, and 133 for Met + Cys, Thr, Trp, Arg, Val, Ile, Leu, His, and Phr + Tyr, respectively, for Japanese quail breeders.

Effects of standardized ileal digestible lysine on growth performance and economic return in duroc-sired finishing pigs.

In the United States, emphasis has shifted toward improved pork quality and has resulted in greater use of Duroc-based terminal sires. Duroc sires have differences in ADG, ADFI, G:F, and carcass leanness compared to other sires. Therefore, our objective was to determine the standardized ileal digestible (SID) Lys estimates for Duroc-based sired finishing pigs. In Exp. 1, 2,124 pigs (DNA 600 ×PIC 1050, initially 48.9 kg) were used with 24-27 pigs per pen and 16 pens per treatment. Corn-soybean meal-based diets were fed in three phases (49-59, 59-71, and 71-81 kg). Pens were randomly allotted to 1 of 5 treatments based as a percentage of PIC (2016) SID Lys estimates for gilts (85%, 95%, 103%, 110%, and 120%). Phase 1 diets were formulated to 0.90%, 1.01%, 1.09%, 1.17%, and 1.27%, phase 2 to 0.79%, 0.87%, 0.94%, 1.03%, and 1.10%, and phase 3 to 0.71%, 0.78%, 0.85%, 0.92%, and 0.99% SID Lys. Increasing SID Lys increased (linear, P < 0.001) ADG and Lys intake/kg of gain. A marginally significant improvement (quadratic, P = 0.071) in G:F was observed as SID Lys increased. Feed cost, feed cost/kg of gain, revenue (linear, P < 0.01) and income over feed cost (IOFC) increased (quadratic, P = 0.045) with increasing SID Lys. In Exp. 2, 2,099 pigs (DNA 600 ×PIC 1050, initially 90.1 kg) were used with 24-27 pigs per pen and 20 pens per treatment. Corn-soybean meal-based diets were fed in 2 phases (90-106 and 106-136 kg). Pens were randomly allotted to 1 of 4 treatments based as a percentage of PIC (2016) SID Lys estimates for gilts (85%, 93%, 100%, and 110%). Phase 1 diets were formulated to 0.65%, 0.71%, 0.77%, and 0.84% and phase 2 to 0.60%, 0.66%, 0.71%, and 0.78% SID Lys. Overall, increasing SID Lys increased (linear, P < 0.05) G:F, Lys intake/kg of gain, live weight and HCW, and increased (quadratic, P = 0.020) ADG. Feed cost (linear, P < 0.01), revenue, and IOFC increased (quadratic, P ≤ 0.053) with increasing SID Lys. In conclusion, the SID Lys estimate for growth and IOFC was 1.19% or 4.63 g SID Lys/Mcal of NE, 1.05% or 4.04 g SID Lys/Mcal of NE, and 0.94% or 3.58 g SID Lys/Mcal of NE for pigs weighing 49-59 kg, 59-71 kg, and 71-81 kg, respectively. The SID Lys estimate for late finishing pigs was 0.74%-0.81% or 2.85-3.10 g SID Lys/Mcal of NE, and 0.69%-0.75% or 2.61-2.84 g SID Lys/Mcal of NE, for 90-106 kg and 106-136 kg pigs, respectively. These data provide SID Lys estimates for current Duroc-sired genetic lines raised in a commercial environment.

Assessment of digestible lysine requirements in lipopolysaccharide-challenged pigs.

To evaluate the effect of an Escherichia coli lipopolysaccharide (LPS) challenge on the digestible lysine (Lys) requirement for growing pigs, a nitrogen (N) balance assay was performed. Seventy-two castrated male pigs (19 ± 1.49 kg body weight [BW]) were allocated in a 2 × 6 factorial design composed of two immune activation states (control and LPS-challenged) and six dietary treatments with N levels of 0.94, 1.69, 2.09, 3.04, 3.23, and 3.97% N, as fed, where Lys was limiting, with six replicates and one pig per unit. The challenge consisted of an initial LPS dose of 30 µg/kg BW via intramuscular (IM) injection and a subsequent dose of 33.6 µg/kg BW after 48 h. The experimental period lasted 11 d and was composed of a 7-d adaptation and a subsequent 4-d sampling period in which N intake (NI), N excretion (NEX), and N deposition (ND) were evaluated. Inflammatory mediators and rectal temperature were assessed during the 4-d collection period. A three-way interaction (N levels × LPS challenge × time, P < 0.05) for IgG was observed. Additionally, two-way interactions (challenge × time, P < 0.05) were verified for IgA, ceruloplasmin, transferrin, haptoglobin, α-1-acid glycoprotein, total protein, and rectal temperature; and (N levels × time, P < 0.05) for transferrin, albumin, haptoglobin, total protein, and rectal temperature. LPS-challenged pigs showed lower (P < 0.05) feed intake. A two-way interaction (N levels × LPS challenge, P < 0.05) was observed for NI, NEX, and ND, with a clear dose-response (P < 0.05). LPS-challenged pigs showed lower NI and ND at 2.09% N and 1.69 to 3.97% N (P < 0.05), respectively, and higher NEX at 3.23% N (P < 0.05). The parameters obtained by a nonlinear model (N maintenance requirement, NMR and theoretical maximum N deposition, NDmaxT) were 152.9 and 197.1 mg/BWkg0.75/d for NMR, and 3,524.7 and 2,077.8 mg/BWkg0.75/d for NDmaxT, for control and LPS-challenged pigs, respectively. The estimated digestible Lys requirements were 1,994.83 and 949.16 mg/BWkg0.75/d for control and LPS-challenged pigs, respectively. The daily digestible Lys intakes required to achieve 0.68 and 0.54 times the NRmaxT value were 18.12 and 8.62 g/d, respectively, and the optimal dietary digestible Lys concentration may change depending on the feed intake levels. Based on the derived model parameters obtained in the N balance trial with lower cost and time, it was possible to differentiate the digestible Lys requirement for swine under challenging conditions.

Determining the digestible lysine requirement of 22- to 47-week-old Lohmann laying hens using an increasing protein titration methodology.

A laying hen trial was conducted from 22 to 47 wk of age to determine the digestible lysine (DLYS) requirement of laying hens by using an increasing CP titration method. A total of 896 Lohmann LSL-Lite caged layers (22 wk of age) were allotted to 8 dietary treatments and each treatment had 8 replications of 14 hens. The first 7 experimental diets initially contained DLYS levels increasing from 0.565 to 0.980% with respective protein levels increasing from 13.8 to 21.7%. Dietary treatment 8 was a control diet which was calculated to contain 18.6% CP and 0.807% DLYS. These DLYS levels were reduced from 0.468 to 0.845% for diets 1 to 7 (0.688% for diet 8) at week 12 so that greater differences in production parameters could be obtained. Increasing DLYS levels had a significant (P < 0.05) effect on egg production, egg weight, egg mass, and feed efficiency. However, DLYS levels had no significant effect on egg component measurements such as percentage of yolk, white, and solids. Broken line regression, maximum of the quadratic polynomial (QP max) regression, and the intercept of the broken line and QP regressions were used to estimate the DLYS requirement. Broken line regression yielded the lowest requirement and QP max regression yielded the highest, with the intercept of the broken line and QP regressions yielding an intermediate requirement estimate. The DLYS requirements were consistently lower for egg production than for egg mass and feed efficiency. For egg mass and feed efficiency, DLYS requirements were 655 and 690, 817 and 866, and 706 and 778 mg/hen/d for the broken line, QP max, and the intercept of the broken line and QP regressions, respectively.

Estimation of lysine requirements of growing Japanese quail during the fourth and fifth weeks of age.

A dose-response assay was conducted using broken-line regressions to estimate the lysine (Lys) requirements of quail chicks from 21 to 35 d of age. A basal diet was formulated to be adequate in all nutrients other than Lys. Incremental levels of L-Lys.HCl were added to the basal diet at the expense of a mix of cornstarch, NaHCO3, and NaCl to create 6 experimental diets containing 0.84 to 1.59% Lys. Feed intake (FI), weight gain (WG), and feed conversion ratio (FCR) responded quadratically to incremental levels of Lys (P < 0.0001). Using the linear broken-line (LBL) model, the estimated Lys requirements for WG during the fourth and fifth wk of age were 1.25 and 1.23% of diet, respectively. The corresponding values for FCR were estimated at 1.23 and 1.26% of diet, respectively. Fitting the quadratic broken-line (QBL) model, the estimated Lys requirements for WG during the fourth and fifth wk of age were 1.34 and 1.34% of diet, respectively. The corresponding values for FCR were estimated at 1.35 and 1.36% of diet, respectively. This study showed that using the QBL model as a promising way to estimate amino acids needed in the diet, the optimal Lys level to optimize performance of growing Japanese quail at the late stage of production might be 1.36% of diet, which is 105% of NRC recommendations.

Reactive lysine content in commercially available pet foods.

The Maillard reaction can occur during processing of pet foods. During this reaction, the ε-amino group of lysine reacts with reducing sugars to become unavailable for metabolism. The aim of the present study was to determine the reactive lysine (RL; the remaining available lysine) to total lysine (TL) ratio of commercial pet foods and to evaluate whether RL levels meet minimal lysine requirements (MLR). Sixty-seven extruded, canned and pelleted commercially available dog and cat foods for growth and maintenance were analysed for proximate nutrient composition, TL and RL. RL was expressed on a metabolisable energy basis and compared with the MLR for maintenance and growth. In dog foods, average RL:TL ratios were 0·87 (se 0·02) for extruded, 0·97 (se 0·02) for canned and 0·85 (se 0·01) for pelleted foods, with the lowest ratio of 0·77 in an extruded diet for growing dogs. In extruded and canned cat foods, the average ratio was 0·91 (se 0·02) and 0·90 (se 0·03), respectively, with the lowest ratio being 0·67 in an extruded diet for growing cats. Variation in the RL:TL ratio between and within processing type indicate that ingredients rather than processing might be the key factor influencing RL content in pet foods. Eight dry foods for growing dogs had RL contents between 96 and 138 % of MLR, indicating that RL has to be between 62 and 104 % digestible to meet the MLR. Considering the variability in RL digestibility, these foods could be at risk of not meeting the MLR for growing dogs. Ingredients and pet foods should be characterised with respect to the RL content and digestibility, to avoid limitations in the lysine supply to growing dogs.