Standardized ileal digestibility of amino acids in eight genotypes of barley fed to growing pigs

Abstract

To determine chemical composition, physical characteristics and standardized ileal digestibility (SID) of CP and amino acids (AA) in eight current hulled barley genotypes, an experiment with growing pigs has been conducted. These genotypes included Yool, Campanile, Lomerit, Travira, Anisette, Canberra, Metaxa and Fridericus. Growing barrows with an average initial BW of 30 ± 2 kg were surgically fitted with simple T-cannulas at the distal ileum, and allotted to an 8 × 9 Youden square design with eight periods of 6 days each and nine pigs. Barley was the sole dietary source of CP and AA. On average, the eight genotypes contained on as-fed basis 10.7% CP, 15.2% total non-starch polysaccharides (NSP), 17.1% NDF and 4.1% β-glucan, and had a mean test weight (TW) of 72.2 kg/hl. The SID of CP in the barley genotypes varied from 69% to 74%, and was greater ( P < 0.01) for genotypes Travira, Anisette and Metaxa compared to Yool and Campanile. Standardized ileal digestibility of Lys, Met and Trp ( P < 0.05) but not of Thr differed between genotypes. Moreover, barley genotypes differed in their standardized ileal digestible content (cSID) of CP and AA. Furthermore, SID and cSID of CP and most AA linearly decreased ( P < 0.05) with increasing NDF and total sugar content. Standardized ileal digestibility of CP and some AA and cSID of CP and most AA decreased linearly with increasing TW ( P < 0.05). Additionally, SID and cSID of CP and AA of most barley genotypes were lower when compared to tabulated values. In conclusion, a comprehensive database on chemical composition and SID of CP and AA in eight current barley genotypes has been made available. However, as present SID values are lower compared to feed tables, adjustments are required to minimize the risk of overestimating the actual protein value of barley for pigs.

Evaluation of analytical and statistical approaches for predicting in vitro nitrogen solubility and in vivo pre‐caecal crude protein digestibility of cereal grains in growing pigs

“…In Table , in vitro N solubility values and corresponding in vivo PCD of CP and essential AA of the genotypes used in the pig experiments are summarized. In vitro N solubility ranged from 80.7% to 83.6% in barley, 75.1 to 80.9% in rye, 82.5 to 86.1% in triticale and 83.5 to 85.9% in wheat, whereas in vivo PCD of CP determined in growing pigs amounted to 69 to 74% in barley, 70 to 74% in rye, 81 to 85% in triticale and 83 to 87% in wheat (Rosenfelder et al, ; Spindler et al, ; Strang et al, , ). Similarly, for laying hens, greater digestibility values were obtained for wheat than for rye (Rodehutscord, & Krieg et al, ).…”

“… Values for standardized pre‐caecal digestibility obtained for barley from Spindler et al (), for rye from Strang et al (), for triticale from Strang et al () and for wheat from Rosenfelder et al (). …”

“…For prediction of in vivo PCD of CP and essential AA from in vitro N solubility and/or chemical and physical characteristics of cereal grains, eight genotypes each of barley, rye, triticale and wheat were selected from the sample conglomerate of dataset A representing a great variation in CP content within grain species. The corresponding in vivo data were extracted from previous studies with growing pigs for barley (Spindler et al, ), rye (Strang et al, ), triticale (Strang et al, ) and wheat (Rosenfelder et al, ). In brief, for the determination of these PCD values, four experiments (one for each grain species) were conducted with eight (rye/triticale) or nine (barley/wheat) barrows each, fitted with simple ileal T‐cannulas.…”

“…The feed protein evaluation system for pigs in Germany is based on the standardized pre‐caecal digestibility (PCD) of CP and AA (Gesellschaft für Ernährungsphysiologie, ). According to Rosenfelder et al (), Spindler et al (), Strang et al (), Rosenfelder‐Kuon, Strang, Spindler, Eklund, and Mosenthin (), and Strang, Eklund, Rosenfelder, Htoo, and Mosenthin (), physical and chemical characteristics such as protein source and type, starch characteristics, fat source and type, non‐starch polysaccharides (NSP) and anti‐nutritional factors vary between and within grain species may influence these digestibility values. Experiments for determination of in vivo standardized pre‐caecal CP and AA digestibility values are time‐consuming and expensive and labour‐intensive and require the use of surgically modified pigs for collection of ileal digesta.…”

“…Digestibility values for cereals based on predicting equations, or NIRS calibrations could be a useful tool for the feed industry to optimize diet formulation by reducing the inclusion of protein feedstuffs, thereby decreasing both feed costs and faecal nitrogen (N) losses. In vivo studies with growing pigs have been conducted previously to determine the standardized PCD in barley, rye, triticale and wheat as commonly used grains in pig diets (Rosenfelder et al, ; Spindler et al, ; Strang et al, , ). These digestibility values were used in the present in vitro study to predict standardized pre‐caecal CP, and AA digestibility of different genotypes of barley, rye, triticale and wheat determined in pigs from in vitro N solubility values.…”