Effect of graded levels of fiber from alfalfa meal on apparent and standardized ileal digestibility of amino acids of growing pigs

Two experiments were conducted to determine the effects of fiber level from alfalfa meal and sampling time on the apparent ileal digestibility（AID） and standardized ileal digestibility（SID） of amino acids（AA） in growing pigs. A total of 24 ileal-cannulated pigs（Duroc×（Large White×Landrace） with body weight（21.4±1.5） kg） were randomly allotted to 4 treatments. The pigs were provided a corn-soybean meal diet or a diet containing 5, 10 or 20% of alfalfa meal during two 10-d experimental periods. The AID of AA was measured. Six ileal-cannulated pigs were fed a protein-free diet in order to estimate the endogenous protein losses and SID of AA. Ileal AA digestibility was not affected by inclusion of 5 or 10% alfalfa meal in the diet（P〉0.05）. The AID of His, Lys, Met, Phe, Thr, Val, Ala, Asp, Cys, Gly, Pro, Ser and Tyr reduced by 2.0–6.8% with the addition level of alfalfa meal（linear, P〈0.05）. The SID of His, Lys, Ser, Thr and Tyr decreased by 2.2–4.3% as the level of alfalfa meal in the diet increased（linear, P〈0.05）. The AID and SID of AA were not affected by the sampling time（P〉0.05）. A multiple linear regression analysis, taking into account both the soluble and insoluble fiber content in the diets, explained more than 36% of variation in SID of Ser and Thr（P〈0.05）. In conclusion, the corn-soybean meal diet containing 10% of alfalfa meal did not affect ileal AA digestion. The AID and SID of AA were similar between two sampling times. Increasing the concentration of total dietary fiber from 12.3 to 21.4% by adding graded levels of alfalfa meal（0–20%） to a corn-soybean meal control diet induced a linear reduction in AID and SID of most AA. Soluble and insoluble fibers from alfalfa meal have differential roles in the AA digestion, which may help explain the variation observed in the SID of partial AA. These findings would provide important information for dietary fiber level and composition related to AA digestion.

Effects of graded fiber level and caecectomy on metabolizable energy value and amino acid digestibility in geese

This study was carried out to evaluate the effects of graded levels of fiber from rice hull and the caecectomy on metabolizable energy（ME） and amino acid digestibility（AAD） in 42 Wuzong geese（21 intact and 21 caecectomized）. The experiment was a 3×2 factorial randomized design with 3 fiber levels and 2 treatments of geese（caecectomized and intact）. Each of the 3 diets was tube-fed（60 g） to 7 caecectomized and 7 intact adult Wuzong geese that had been fasted for 24 h. Excreta were collected for the next 48 h. The same geese were also fasted for estimation of endogenous losses of amino acids（AA） and energy after short period recovery. AA content and metabolizable energy value were determined in the excreta. In general, significant effects were found for fiber levels on apparent digestibility of Thr, Leu, Pro, Glu,Val, Ala and total AA（P〈0.05）. Apparent metabolizable energy（AME） and true metabolizable energy（TME） were both significantly influenced by increased fiber levels（P〈0.01）. Compared with caecectomized geese, markedly increases of AME and TME were found in intact geese（P〈0.01 for AME and P 〈0.05 for TME）, but no difference in the AAD were found between intact and caecectomized geese（P〉0.05）, except for Lys and Try（P〈0.05）. These observations suggested that dietary fiber level played an important role in digestibility of AAD and ME. Intact geese should be chosen for the nutrient evaluation of feedstuffs in practice, resulting from the significant difference between caecectomized and intact geese.

Disappearance and appearance of an indigestible marker in feces from growing pigs as affected by previous-and currentdiet composition

Background： Indigestible markers are commonly utilized in digestion studies, but the complete disappearance or maximum appearance of a marker in feces can be affected by diet composition, feed intake, or an animal＇s BW.The objectives of this study were to determine the impact of previous（Phase 1, P1） and current-（Phase 2, P2）diet composition on marker disappearance（Cr） and appearance（Ti） in pigs fed 3 diets differing in NDF content.Results： When pigs were maintained on the 25.1, 72.5, and 125.0 g/kg NDF diets, it took 5.1, 4.1, and 2.5 d, respectively,for Cr levels to decrease below the limit of quantitation; or 4.6, 3.7, or 2.8 d, respectively, for Ti to be maximized. These effects were not, however, independent of the previous diet as indicated by the interaction between P1 and P2 diets on fecal marker concentrations（P 〈 0.01）. When dietary NDF increased from P1 to P2, it took less time for fecal Cr to decrease or fecal Ti to be maximized（an average of 2.5 d）, than if NDF decreased from P1 to P2 where it took longer for fecal Cr to decrease or fecal Ti to be maximized（an average of 3.4 d）.Conclusions： Because of the wide range in excretion times reported in the literature and improved laboratory methods for elemental detection, the data suggests that caution must be taken in considering dietary fiber concentrations of the past and currently fed diets so that no previous dietary marker addition remains in the digestive tract or feces such that a smal amount of maker is present to confound subsequent experimental results, and that marker concentration have stabilized when these samples are col ected.

The release and catabolism of ferulic acid in plant cell wall by rumen microbes:A review

Ferulic acid(FA)is one of the most abundant hydroxycinnamic acids in the plant world,especially in the cell wall of grain bran,in comparison with forage and crop residues.Previous studies noted that FA was mainly linked with arabinoxylans and lignin in plant cell walls in ester and ether covalent forms.After forages were ingested by ruminant animals or encountered rumen microbial fermentation in vitro,these cross-linkages form physical and chemical barriers to protect cell-wall carbohydrates from microbial attack and enzymatic hydrolysis.Additionally,increasing studies noted that FA presented some toxic effect on microbial growth in the rumen.In recent decades,many studies have addressed the relationships of ester and/or ether-linked FA with rumen nutrient digestibility,and there is still some controversy whether these linkages could be used as a predicator of forage digestibility in ruminants.The authors in this review summarized the possible relationships between ester and/or ether-linked FA and fiber digestion in ruminants.Rumen microbes,especially bacteria and fungi,were found capable of breaking down the ester linkages within plant cell walls by secreting feruloyl and p-coumaroyl esterase,resulting in the release of free FA and improvement of cell wall digestibility.The increasing evidence noted that these esterases secreted by rumen microbes presented synergistic effects with xylanase and cellulase to effectively hydrolyze forage cell walls.Some released FA were absorbed through the rumen wall directly and entered into blood circulation and presented antioxidant effects on host animals.The others were partially catabolized into volatile fatty acids by rumen microbes,and the possible catabolic pathways discussed.To better understand plant cell wall degradation in the rumen,the metabolic fate of FA along with lignin decomposition mechanisms are needed to be explored via future microbial isolation and incubation studies with aims to maximize dietary fiber intake and enhance fiber digestion in ruminant animals.