Dietary preference for methionine sources in weaned pigs

Bioavailability of the calcium salt of dl-methionine hydroxy analog compared with dl-methionine for nitrogen retention and the preference of nursery pigs for diets based on the 2 forms of methionine

Experiments were conducted to determine the relative bioavailability (RBV) of the calcium salt of the hydroxy analog of dl-methionine (MHA-Ca, 84%) to dl-methionine (dl-Met, 99%) as Met sources fed to pigs. In experiment 1, 42 crossbred barrows (initial BW of 15.0 ± 0.7 kg) were allotted to 7 treatments in an N-balance study. The basal diet (BD) was formulated to contain 15.4% CP and 0.22% Met (70% of requirement). Diets included (1) BD, (2) BD + 0.025% dl-Met, (3) BD + 0.050% dl-Met, (4) BD + 0.075% dl-Met, (5) BD + 0.038% MHA-Ca, (6) BD + 0.077% MHA-Ca, and (7) BD + 0.115% MHA-Ca. An increase in dietary inclusion rates of both Met sources linearly increased (P < 0.01) N retained (g/d) and N retention (% of intake). Using linear slope-ratio regression, the RBV value of MHA-Ca to dl-Met for N retained (g/d) was 63.0% on a product-to-product basis (75.0% on an equimolar basis). In experiment 2, 40 crossbred barrows (initial BW of 15.5 ± 1.5 kg) were allotted to 5 treatments in another N-balance study. The BD was formulated to contain 17.0% CP and 0.22% Met (70% of requirement). Diets included (1) BD, (2) BD + 0.030% dl-Met, (3) BD + 0.060% dl-Met, (4) BD + 0.046% MHA-Ca, and (5) BD + 0.092% MHA-Ca. Increasing levels of dl-Met or MHA-Ca increased N retained (g/d) and N retention (% of intake) linearly (P < 0.001) and quadratically (P < 0.05). Using linear slope-ratio regression, a product-to-product RBV value of MHA-Ca to dl-Met was 68.4% (81.4% on an equimolar basis) for N retained (g/d). In experiment 3, 276 pigs (12 barrow and 11 gilt replicates; initial BW of 7.09 ± 1.1 kg) were used in 3 diet preference studies. Pigs were randomly allotted to 1 of 3 treatment comparisons of feed choice: (1) BD (0.23% Met) or BD + 0.07% dl-Met; (2) BD or BD + 0.0825% MHA-Ca, and (3) BD + 0.07% dl-Met or BD + 0.0825% MHA-Ca. Pigs consumed a higher percentage (55 vs. 45%; P = 0.008) of their total feed intake from the diet supplemented with 0.07% dl-Met in Comparison 1, but a lower percentage (45 vs. 55%; P = 0.003) of their total feed intake from the diet supplemented with 0.0825% MHA-Ca in Comparison 2. There was no diet preference for dl-Met or MHA-Ca in Comparison 3. The observed Met source preference differences occurred in the barrow replicates but not in the gilt replicates. These results demonstrated the mean RBV of MHA-Ca to dl-Met of 65.7% on a product-to-product (wt/wt) basis or 78.2% on an equimolar basis and that a preference for Met sources was observed in barrows but not in gilts.

The effects of dietary sulfur amino acids on growth performance, intestinal morphology, enzyme activity, and nutrient transporters in weaning piglets

Early weaning results in intestinal dysfunction in piglets, while sulfur amino acids (SAA) are involved in improving intestinal functions. We tested a hypothesis that dietary supplementation with SAA can improve intestinal functions of weaning piglets and analyzed the effects of different dietary SAA levels on intestinal functions. A total of 80 piglets (Duroc × Landrace × Yorkshire) were weaned at 21 d of age and randomly assigned to one of the five diets that contained 0.53%, 0.63%, 0.74%, 0.85%, or 0.96% SAA, which corresponded to 70%, 85%, 100%, 115%, or 130% of the SAA:Lys ratio recommended by the National Research Council (2012). The 14 d feeding experiment involved 16 pens per diet and one piglet per pen. Eight randomly selected piglets from each treatment were euthanized for tissue sampling on day 7 and 14 post weaning. Supplementation with SAA led to a rise over time in G:F (linear, P = 0.001; quadratic, P = 0.001). Between day 0 and 14 of treatment, the jejunal crypt depth decreased (linear, P = 0.018; quadratic, P = 0.015), while that of the duodenal villus (linear, P = 0.049) and ileal villus width (linear, P = 0.029; quadratic, P = 0.034) increased. The activities of jejunal alkaline phosphatase (ALP) were quadratically increased (P = 0.040) from day 0 to 14 due to dietary SAA. Dietary SAA also elevated the activities of jejunal lactase (linear, P = 0.003; quadratic, P = 0.004), jejunal sucrase (linear, P = 0.032; quadratic, P = 0.027), and jejunal contents of glutathione (GSH) from day 0 to 7, as well as the activity of jejunal maltase (linear, P = 0.014; quadratic, P = 0.001) between day 0 and 14. During the first wk, dietary SAA linearly increased the amounts of intestinal-type fatty acid-binding protein (I-FABP) (P = 0.048) and SGLT-1 (P = 0.021) and linearly decreased the amount of GLUT2 (P = 0.029) proteins in the jejunum. The abundance of jejunal I-FABP (P = 0.044) and PEPT1 (P = 0.049) protein linearly increased from day 0 to 14 in response to this supplementation. These findings indicate that there is a dose-dependent response to dietary SAA on feed efficiency and intestinal parameters of weanling pigs.