Neonatal Piglets Can Synthesize Adequate Creatine, but Only with Sufficient Dietary Arginine and Methionine, or with Guanidinoacetate and Excess Methionine.

BACKGROUND: Suckling piglets synthesize most of their creatine requirement, which consumes substantial amounts of arginine in order to synthesize guanidinoacetic acid (GAA) and methionine in order to transmethylate GAA to creatine. OBJECTIVES: To determine whether supplemental GAA or creatine spare arginine and/or methionine for protein synthesis and, if GAA is supplemented, whether excess methionine is needed for conversion to creatine. METHODS: Yucatan miniature piglets (9-11 days old; both sexes) were fed 1 of 5 elemental diets for 5 days: 1) low arginine (0.3 g·kg-1·d-1) and low methionine (0.20 g·kg-1·d-1; Base); 2) Base plus GAA (0.093 g·kg-1·d-1; +GAA); 3) Base plus GAA plus excess methionine (0.5 g·kg-1·d-1; +GAA/Met); 4) Base plus creatine (0.12 g·kg-1·d-1; +Cre); or 5) excess arginine (1.8 g·kg-1·d-1) and excess methionine (+Arg/Met). Isotope tracers were infused to determine whole-body GAA, creatine, and protein synthesis; tissues were analyzed for creatine synthesis enzymes and metabolite concentrations. Data were analyzed by 1-way ANOVA. RESULTS: : GAA and creatine syntheses were 115% and 32% higher, respectively, with the +Arg/Met diet (P < 0.0001), in spite of 33% lower renal L-arginine: glycine amidinotransferase activity (P < 0.0001) compared to Base, suggesting substrate availability dictates synthesis rather than enzyme capacity. GAA or creatine supplementation reduced arginine conversion to creatine by 46% and 43%, respectively (P < 0.01), but did not spare amino acids for whole-body protein synthesis, suggesting that limited amino acids were diverted to protein at the expense of creatine synthesis. The +GAA/Met diet led to higher creatine concentrations in the kidney (2.6-fold) and liver (7.6-fold) than the +GAA diet (P < 0.01), suggesting excess methionine is needed for GAA conversion to creatine. CONCLUSIONS: Piglets are capable of synthesizing sufficient creatine from the precursor amino acids arginine and methionine, or from GAA plus methionine.

From broiler breeder hen feed to the egg and embryo: The molecular effects of guanidinoacetate supplementation on creatine transport and synthesis.

Supplementation of broiler breeder hens with beneficial additives bears great potential for affecting nutrient deposition into the fertile egg. Guanidinoacetate (GAA) is the endogenous precursor of creatine that is used as a feed additive for improving cellular energy metabolism in animal nutrition. In the present study, we have investigated whether GAA supplementation in broiler breeder feed affects creatine deposition into the hatching egg and molecular mechanisms of creatine transport and synthesis within hens and their progeny. For this, broiler breeder hens of 47 wk of age were supplemented with 0.15% GAA for 15 wk, and samples from their tissues, hatching eggs and progeny were compared with those of control, nonsupplemented hens. A significant increase in creatine content was found within the yolk and albumen of hatching eggs obtained from the GAA group, compared with the control group. The GAA group exhibited a significant increased creatine transporter gene expression compared with the control group in their small intestines and oviduct. In GAA group progeny, a significant decrease in creatine transporter expression at embryonic day 19 and day of hatch was found, compared with control group progeny. At the day of hatch, creatine synthesis genes (arginine glycine amidinotransferase and guanidinoacetate N-methyltransferase) exhibited significant decrease in expression in the GAA group progeny compared with control group progeny. These results indicate that GAA supplementation in broiler breeder feed increases its absorbance and deposition into hatching eggs, subsequently affecting GAA and creatine absorbance and synthesis within broiler progeny.

Supplementation of guanidinoacetic acid to pig diets: effects on performance, carcass characteristics, and meat quality.

Two studies were conducted to evaluate the effects of dietary supplementation of guanidinoacetic acid (GAA) on growth performance, carcass characteristics, and meat quality in pigs from wean to finish (Exp 1) and finishing pigs fed GAA at different time periods before slaughter (Exp 2). In Exp 1, a total of 360 weaned pigs (Duroc × [Landrace × Yorkshire]) with an average initial BW of 7.17 ± 0.03 kg were randomly distributed into 3 dietary treatments consisting of 10 replicates per treatment and 12 pigs (6 barrows and 6 gilts) per replicate. Dietary treatments were a control (CON; basal diet), a basal diet + 0.08% GAA (0.08% GAA); and a basal diet + 0.12% GAA (0.12% GAA). The duration of the experiment was 150 d. At the end of the experiment, 20 pigs (10 barrows and 10 gilts) from each treatment were slaughtered for measuring carcass characteristics and meat quality. In Exp 2, 1,440 finishing pigs [(Duroc × (Landrace × Yorkshire)), 56.15 ± 0.10 kg BW)] were randomly allocated to 4 treatments with 18 replicates (20 pigs per replicate). Dietary treatments were a control diet (CON; basal), a basal diet + 0.12% GAA fed 60 d before slaughter (T1), a basal diet + 0.12% GAA fed 40 d before slaughter (T2), and a basal diet + 0.12% GAA fed 25 d before slaughter (T3). Body weight was measured at the start (120 d of age) and at the end (180 d of age) of the experiment. At the end of the study, 144 pigs (72 barrows and 72 gilts) from 4 dietary treatments (36 pigs per treatment) were slaughtered for the determination of carcass and meat quality parameters. In Exp 1, 0.12 % GAA increased (P < 0.05) ADG and G:F during starter, grower, finisher, and the overall growth period (30 to 180 d of age). Pigs fed 0.12 % GAA had improved (P < 0.05) lean meat yield in comparison with CON. There was no interaction effect among GAA supplementation and sex of the pigs. Meat quality was not affected by GAA supplementation in pigs. In Exp 2, the final BW, ADG, and lean yield of the pigs fed T1 were higher (P < 0.05) than CON and those fed T3. The carcass back-fat thickness of T1 was lower (P < 0.05) than CON. In conclusion, 0.12% GAA improved the growth performance and lean meat yield in pigs from wean to finish. Finishing pigs fed diets supplemented with 0.12% GAA 60 d before slaughter improved ADG, feed efficiency, and lean meat yield and reduced back-fat thickness compared with those fed GAA unsupplemented diets.

Effect of feed intake level on ileal digestibilities of crude protein and amino acids in diets for piglets.

BACKGROUND: The study was conducted to determine the effect of graded levels of feed intake on apparent (AID) and standardized (SID) ileal digestibilities of crude protein (CP) and amino acids (AA) in diets for piglets. The piglets were surgically fitted with simple T-cannulas at the distal ileum. The cornstarch-casein-soybean meal-based diets were fed at three graded levels of feed intake corresponding to 30, 45 and 60 g kg(-1) body weight (BW) per day. RESULTS: The AID and SID of most AA were quadratically affected by the feed intake level (P≤0.05). Initially, both AID and SID of most AA increased up to 1.9 percentage units as the feed intake level was increased from 30 to 45 g kg(-1) BW. Thereafter, these AID and SID values decreased by 2.6 and 2.7 percentage units, respectively, as the feed intake level was further increased from 45 to 60 g kg(-1) BW. CONCLUSION: Because the voluntary feed intake is highly variable in piglets after weaning, comparison of ileal AA digestibilities between and within studies may be confounded by variations in feed intake level. Thus, when designing digestibility studies with piglets, a standardization of feed intake should be taken into consideration.

Estimates of dietary threshold levels for crude protein and amino acids to obtain plateau values of apparent ileal crude protein and amino acid digestibilities in newly weaned pigs.

This study was conducted to estimate dietary threshold levels for crude protein (CP) and amino acids (AA) at which apparent ileal digestibilities (AID) of CP and AA in assay diets for newly weaned pigs reach plateaus. A total of 14 (12 + 2 for replacement) three-week old barrows were fitted with simple T cannulas at the distal ileum. Corn starch-based diets containing six graded levels of CP from casein, 90, 155, 220, 285, 350, or 415 g CP/kg assay diet (as-fed), were formulated. At 28 days of age, the pigs were randomly allocated to the six dietary treatments with two pigs per CP level in four weekly repeated measurement periods. They were fed twice daily a total of 30 g (as-fed) per kg of individual body weight at 8:00 and 20:00 h. The dietary CP and AA levels affected AID of CP and most AA (p = 0.005 to p = 0.040) in the assay diets. The AID of CP and AA were higher at 155 and 220 compared to 90 g CP/kg assay diet (p < 0.001 to p = 0.047). Initially, the AID of CP and AA increased sharply then gradually reached, at individual break points (p < 0.001 to p = 0.047), their plateaus (p < 0.001), which did not change up to dietary CP levels of 415 g/kg assay diet and the AID values became independent of the dietary AA levels. The piglets' capacity to digest CP and absorb AA was not limiting under these experimental conditions. There was no effect of age on AID of CP and AA (p = 0.056 to p = 0.899) except for a linear increase (p = 0.045) in AID of glycine from Period 1 to 4. Segmented quadratic with plateau relationships between the AID of CP and AA and their dietary contents were fitted for CP and each AA. The lower end points of 95% confidence intervals of the plateau AID values were defined to represent the initial plateau AID. The dietary CP and AA contents, corresponding to the initial plateau AID values, represent the dietary threshold levels. For CP and the indispensable amino acids, the plateau AID [%] and the dietary threshold levels [g/kg DM], respectively, in casein were: CP, 94.2 and 176; arginine, 95.1 and 7; histidine, 96.0 and 5; isoleucine, 96.4 and 8; leucine, 96.8 and 16; lysine, 96.8 and 12; methionine, 97.9 and 5; phenylalanine, 96.2 and 10; threonine, 93.4 and 9; tryptophan, 94.3 and 2; valine, 95.9 and 11. For the determination of plateau AID in piglets, the crude protein and amino acid contents in the assay diets should meet or exceed the corresponding dietary threshold levels.

Standardised ileal crude protein and amino acid digestibilities in protein supplements for piglets.

Standardised ileal digestibilities (SID) of crude protein and amino acids (AA) originating from 24 different feed ingredients, including 11 feed ingredients produced from soybeans, seven by-products of starch processing, four whey products and two fish meals, were determined in piglets by means of the difference method. For the indispensable AA, the highest SID values were obtained in three out of four whey proteins (SID ≥90% for most indispensable AA), one out of two fish meals (SID ≥86%), soy protein concentrate, hydrolysed soy protein isolate (SID ≥86% for most indispensable AA), and by-products of starch processing (SID ≥84% for most indispensable AA). The lowest SID values were obtained in extruded soybeans and microbially fermented soy protein (SID ≤78% for most indispensable AA), whereas the SID values for high-protein soybean meal were intermediate (SID 80-89% for indispensable AA except for Thr). The SID values in the three enzymatically fermented soy proteins (SID 80-94% for most indispensable AA) were similar to those in high-protein soybean meal and soy protein concentrate. The results of the present study indicate that SID values of AA in feed ingredients for piglets differ considerably from those reported for grower-finisher pigs, thus there may be a need for separate feed tables for piglets.

Effect of dietary crude protein level on jejunal brush border enzyme activities in weaned pigs.

Forty weaned pigs (7.0 ± 0.5 kg, mean ± SD) were used to determine the effects of feeding a low crude protein, amino acid-supplemented diet to piglets on the activities of jejunal brush border enzymes. Pigs were randomly allotted to two diets: a 222 g crude protein (HCP) per kg diet, or a 173 g crude protein per kg diet supplemented with amino acids (LCP). Pigs fed the HCP diet had higher small intestine weight compared with those fed the LCP diet on day 7 after weaning. Diet had no effect on the specific activities of jejunal sucrase, lactase, leucine aminopeptidase, aminopeptidase A, aminopeptidase N and dipeptidyl peptidase IV. The activities of sucrase and lactase decreased (p < 0.05) from day 3 after weaning to day 7, but the activities of leucine aminopeptidase and aminopeptidase N increased. The results showed that feeding a low protein diet supplemented with amino acids according to the ideal protein ratio to piglets had no negative effect on the development of jejunal brush border enzymes.