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.

In this review, the terminology that is used to describe ileal amino acid (AA) digestibilities in piglet feed ingredients is defined. If one accepts that the determination of AA digestibilities should be based on the ileal analysis method, one should consider that ileal digesta contains variable amounts of endogenous crude protein (CP), which originates mainly from digestive secretions, sloughedoff epithelial cells and mucins. The ileal endogenous CP and AA losses are separated into basal ileal endogenous CP and AA losses (IAAL B ), which are not influenced by the feed ingredient composition, and specific ileal endogenous CP and AA losses (IAAL S ), which are induced by feed ingredient characteristics such as level and type of fiber and anti-nutritional factors (ANF). Depending how ileal endogenous CP and AA losses are considered in the measurement of CP and AA digestibilities, digestibility values are expressed as apparent (AID), standardized (SID), or true (TID) ileal digestibilities of CP and AA. The main concern associated with the use of AID values in diet formulation for pigs is that they are not additive in mixtures of feed ingredients. Consequently, the concept of standardized ileal CP and AA digestibilities was introduced by correcting AID values for basal ileal endogenous CP and AA losses (IAAL B ). The correction for both IAAL B and IAAL S yields TID values, however, routine procedures to measure IAAL S are not yet available. In principle, SID values should be preferred, because they represent the fundamental properties of the feed ingredient. There exist only few reports on SID of CP and AA in feedstuffs frequently used in piglet nutrition. These include soybeans (SB), soybean meal (SBM), soy proteins (SP), soy protein concentrate (SPC), soy protein isolate (SPI), corn gluten (CG), wheat gluten (WG), pea protein (PeaP), potato protein (PotP), fish meal (FM) and whey proteins (WP), but the results obtained are inconsistent. Differences in SID values within feed ingredients may, at least in part, be attributed to different processing conditions or inherent differences of the assay feed ingredients. Moreover, there is some evidence that the determination of SID values and IAAL B in piglets may be confounded by the dietary CP level of the assay diet, age and (or) body weight (BW), the level of feed intake or the methodological approach used to determine IAAL B .

The objective of the study was to determine standardized ileal digestibilities (SID) of crude protein (CP) and amino acids (AA) in six ingredients commonly used in weanling pigs diets. The ingredients consisted of extruded soybeans (SB e ), high-protein soybean meal (SBM hp ), soy protein concentrate (SPC), hydrolyzed wheat gluten (WG h ), conventional fish meal 1 (FM1) and extracted fish meal 2 (FM2 e ). Each assay feed ingredient was added to a purified cornstarch-based basal diet supplemented with casein and crystalline AA, and SID of CP and AA of assay ingredients were estimated using the difference method. A total of 12 3-week-old barrows were surgically fitted with T-cannulas at the distal ileum. The piglets were allocated to four simultaneous 3 3 3 Latin-square designs with three animals and three periods each, resulting in six observations per assay diet. After 3 to 5 days recovery from surgery, each assay diet was fed at a level of 30 g/kg body weight. Each experimental period consisted of 5 days for adaptation to the assay diets and 2 days for ileal digesta collection. The SID of CP, Lys, Met, Thr and Trp were 73%, 78%, 76%, 66% and 71% in SB e ; 80%, 84%, 87%, 75% and 81% in SBM hp ; 86%, 89%, 89%, 78% and 83% in SPC; 87%, 60%, 88%, 76% and 79% in WG h ; 87%, 92%, 94%, 86% and 86% in FM1; and 79%, 86%, 89%, 80% and 74% in FM2 e , respectively. The greatest SID of indispensable AA were observed for FM1 and SPC (SID > 85% for most indispensable AA), followed by WG h , FM2 e and SBM hp (SID > 80% for most indispensable AA) and the smallest SID were obtained for SB e (SID , 80% for most indispensable AA). The SID of CP and indispensable AA in both types of fish meal, SBM hp and WG h were similar to SPC ( P 5 0.063 to 0.855), except for Arg ( P 5 0.010) and Lys ( P 5 0.001) in WG h , and Phe ( P 5 0.044) and Trp ( P 5 0.037) in FM2 e . The SID of CP and indispensable AA were smaller in SB e compared with SPC ( P , 0.001 to P 5 0.017), except for Lys ( P 5 0.136). The SID of CP and indispensable AA were consistently smaller in FM2 e compared with FM1 with significant differences for CP ( P 5 0.035), Phe ( P 5 0.028) and Trp ( P 5 0.008). Digestibility values measured in the present study can be used to formulate diets for piglets based on standardized ileal digestible contents of CP and AA.

ABSTRACT:The study was performed to investigate the effect of combinations of feed additives consisting of either a combination of a probiotic and a prebiotic (synbiotic), or a combination of a probiotic and xylanase on ileal nutrient digestibility, ileal microbial metabolite concentrations, and microbial composition in ileal digesta of weaned piglets. In total, 12 six-week old barrows with an average initial body weight of 7.5 kg, fitted with an ileal T-cannula, were assigned to 3 dietary treatments. The basal diet was supplemented with a combination of 1 g probiotics (Pediococcus acidilactici, Bactocell ® ) and 20 g prebiotics (oligofructose) (Pro/Pre) or 1 g probiotics (Pediococcus acidilactici, Bactocell ® ) and 0.5 g xylanase (Pro/Xyl) per kg diet. The supplementation of Pro/Xyl increased ileal digestibility of neutral detergent fibre (NDF) by 41.6% (P < 0.05). The microbial metabolite concentrations, pH of ileal digesta as well as ileal lactobacilli populations were not affected (P > 0.05) by any of the treatments. Enterobacteriaceae were reduced (P < 0.05) upon supplementation of Pro/Pre, resulting in an increased (P < 0.05) ileal lactobacilli to Enterobacteriaceae ratio compared with piglets fed the control diet. In conclusion, NDF digestibility was increased following xylanase supplementation, while microbial activity and composition in the ileum were not affected. The synbiotic approach was effective in reducing ileal Enterobacteriaceae numbers.