144 Bioavailability of calcium salt of hydroxy analogue of methionine relative to DL-methionine to support growth performance of 11 to 20 kg pigs

Abstract

Abstract Methionine (Met) is typically the third limiting AA in commercial swine diets and is commonly supplied as dry DL-Met (99% pure) or DL-Met hydroxy analogue. Data on the relative bioavailability (RBV) of calcium salt of hydroxy analogue of DL-Met (MHA-Ca; 84%) compared with DL-Met in weaned pigs is scarce. The objective of the experiment was to determine the RBV of MHA-Ca compared with DL-Met to support growth performance of 11 to 20 kg pigs. A total of 504 piglets [DNA x Pietrain pigs; approximately 42 d of age and 11 kg body weight (BW)] were used in two blocks of 252 pigs each with 6 pigs (3 entire males and 3 gilts) per pen and 12 replicate pens per treatment. Within each block, pigs were randomly allotted to 7 diets for 21 d. A basal diet (BD) was formulated to be adequate in all essential nutrients except for Met (0.22% standardized ileal digestible Met), which was 61% of the SID Met requirement of 0.36% recommended by NRC (2012) for 10 to 25 kg pigs. The Met-deficient BD was then supplemented with 3 graded levels of DL-Met (0.05, 0.10, and 0.15%) or MHA-Ca (0.077, 0.154, and 0.231%) at the expense of corn. Pigs had ad libitum access to feed (mash) and water. Individual pigs and pen feed disappearance were weighed on d 0 and d 21 to calculate average daily gain (ADG), average daily feed intake (ADFI) and feed conversion rate (FCR). On d 21, blood samples were collected from 1 pig per pen after 8 h fasting to determine total protein, albumin and glucose. Data were analyzed as a randomized complete block design using GLM procedure of SAS 9.4 (SAS Inst. Inc.). Orthogonal-polynomial contrasts were used to determine linear and quadratic effects of increasing levels of DL-Met and MHA-Ca, and the effect of Met sources. The final BW at d 21 and overall average daily gain (ADG; 375, 401, 429, 430, 402, 431, and 428 g/d for diets 1 to 7, respectively) increased linearly (P < 0.01) by graded additions with both Met sources. The ADFI was not different but the overall FCR (1.64, 1.55, 1.51, 1.45, 1.59, 1.46, and 1.50 for diets 1 to 7, respectively) improved linearly (P < 0.01) by supplementation with DL-Met or MHA-Ca. Pig performance responses (ADG, ADFI and FCR) was not different (P ≥ 0.15) when Met was supplemented in the Met-deficient diet at a DL-Met to MHA-Ca ratio of 65:100 on a product basis. Plasma concentrations of total protein, albumin and glucose on d 21 were not affected (P >0.05) by dietary treatments or Met sources. Based on ADG as a response of Met supplementation level, the linear and exponential regressions estimated the RBV of 64 and 65%, respectively for MHA-Ca relative to DL-Met (product-to-product basis) in 11 to 20 kg pigs.