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The present study aimed to evaluate acid-insoluble ash (AIA) as an internal marker for the measurement the coefficient of total tract apparent digestibility (CTTAD) in rabbits through two experiments (E1 and E2). In E1, 48 rabbits were used to calculate the CTTAD of the same basal diet according to the European reference method (ERM), the AIA and the titanium dioxide (TiO2 with 1 g of TiO2/kg diet) techniques (n=16 rabbits/method). The effect of feed sample quantity on dietary AIA content was investigated and total collection of faeces was carried out to calculate marker recovery. In E2, 48 rabbits were allotted to three groups fed diets with no sugar beet pulp (SBP0) or with 100 (SBP100) and 200 (SBP200) g sugar beet pulp/kg (n=16 rabbits/group). Each group was divided into two subgroups, ERM and AIA (n=8 rabbits/subgroup), in which CTTAD was measured using the European reference and AIA method, respectively. In AIA subgroups, only 10% of the total daily faecal output was sampled from 9:00 to 9:30 am. Feed analysis in E1 showed that increasing sample quantity from 5 to 9 g did not affect the dietary AIA content; however, the analytical error was 7 and 5 times lower (P

The effect of a polyclonal antibody preparation (PAP) against Streptococcus bovis and Fusobacterium necrophorum on ruminal fermentation and digestion in ruminally cannulated cows was investigated in two 3 × 3 Latin squares in factorial arrangement of treatments 3 × 2 regarding two feed additives (PAP in powder (PAPP) and in liquid (PAPL) presentation) plus control (CON) and two managements of diets (with or without adaptation to highly fermentable carbohydrate diets). Adapted group had greater DMI (p

The effect of a polyclonal antibody preparation (PAP) against Streptococcus bovis and Fusobacterium necrophorum on ruminal fermentation and digestion in ruminally cannulated cows was investigated in two 3 × 3 Latin squares in factorial arrangement of treatments 3 × 2 regarding two feed additives (PAP in powder (PAPP) and in liquid (PAPL) presentation) plus control (CON) and two managements of diets (with or without adaptation to highly fermentable carbohydrate diets). Adapted group had greater DMI (p < 0.0001) and DM (p < 0.0001), NDF (p = 0.03) and total carbohydrates (p < 0.0001) apparent digestibility when compared to non-adapted group. PAPL had greater DM (p = 0.02), NDF (p = 0.03) and total carbohydrates apparent digestibility when compared to PAPP or CON. Adapted animals had lower (p < 0.0001) rumen pH when compared to non-adapted animals. Moreover, PAPL group had greater (p = 0.04) rumen pH values when compared to PAPP and CON. PAPL showed potential effect as an additive by increasing apparent digestibility of DM, NDF and total carbohydrates and also for being more efficient to prevent the drop in rumen pH during the peak of fermentation. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the effect of dietary supplementation with spirulina (Arthrospira platensis) or/and thyme (Thymus vulgaris) on total tract apparent digestibility of nutrients and the performance of growing rabbits. At weaning (5 wk of age) the rabbits were randomly allotted to 7 groups (42 rabbits/group, 3 rabbits/cage). Rabbits in the control group (C-C) received a control pelleted feed throughout the experiment (5-11 wk of age) without any supplementation (crude protein: 176 g CP/kg, neutral detergent fibre: 325 g NDF/kg). In the other groups, the control diet was supplemented with 5% spirulina (S, mainly in substitution of soybean meal), or 3% thyme (T, mainly in substitution of alfalfa meal) or by both 5% S and 3% T (ST) for the whole (5-11 wk of age; groups: S-S, T-T, ST-ST) or part of the growing period (8-11 wk of age; groups: C-S, C-T, C-ST). Supplementations had no effect on apparent digestibility of dry matter, organic matter, acid detergent fibre, gross energy and digestible energy. The CP TTAD was lowest in rabbits fed the S diet, whereas it was highest in C fed rabbits, the other 2 treatments being intermediate (P

Phytogenic silica (PS) is the silicon assimilated from soil and ultimately precipitated into or onto the cell wall structure of plant tissues in an amorphous (SiO 2), non-digestible by animals, form. The PS is the major fraction of the hydrochloric acid-insoluble ash (AIA), which is used as an internal marker in feed digestibility studies; however, PS can be quantified by methods more rapid and sensitive than AIA. Therefore, the present study aimed to evaluate PS as an alternative to AIA internal marker for the measurement of total tract apparent digestibility in rabbits. Thirty rabbits were used to calculate the coefficient of total tract apparent digestibility (CTTAD) of dry matter (DM) and gross energy (GE) of the same basal diet according to the European reference method (ERM), the AIA and the PS technique (n = 10 rabbits/method). Total faecal collection was carried out in AIA and PS rabbits to determine faecal marker recovery. The concentrations of AIA in diets and faeces were 12.89 ± 0.066 and 31.58 ± 0.042, whereas those of PS were 13.98 ± 0.066 and 36.59 ± 0.059, respectively (mean±SEM). Faecal marker recovery was 100.3 ± 1.43 % and 100.8 ± 1.48 % for AIA and PS (P = 0.939), respectively. The CTTAD of DM did not differ between methods (P = 0.935) and was 0.589 ± 0.0055, 0.591 ± 0.0056 and;0.588 ± 0.0060 for ERM, AIA and PS, respectively. Also, the CTTAD of GE was similar between all methods (P = 0.914) and was 0.581 ± 0.0058, 0.585 ± 0.0060 and 0.584 ± 0.0064 for ERM, AIA and PS, respectively. The PS determination required less sample quantity (by 98 %) and reagent volumes (by 68–82 %) and had a 7-fold higher sample throughput compared to AIA. In conclusion, PS is a reliable internal marker in rabbits and offers the possibility of calculating the CTTAD of diets with the same precision as ERM. • Acid-insoluble ash (AIA) and phytogenic silica (PS) were compared in rabbits. • PS exhibited complete faecal recovery rate similar to AIA. • Digestibility did not differ between PS, AIA and the total faecal collection methods. • PS was quantified by methods more robust, rapid and sensitive when compared to AIA. • PS could be used as an alternative to AIA marker in rabbits. [ABSTRACT FROM AUTHOR]

Abstract: This review was written to summarise knowledge available on the use of markers to determine total tract apparent digestibility in horses, and to quantify differences in estimates obtained between marker techniques and total collection of faeces. Differences were quantified with a unitless standardised effect size (Hedges''s g) and effect sizes within marker, diet (all-forage, forage and concentrate) and nutrients were combined with random effects models to account for unexplained heterogeneity among experiments. Digestibility of all-forage diets estimated by total faecal collection was not different to measurements obtained with acid detergent insoluble ash, 2N HCl acid insoluble ash, or the n-alkanes C27, C29 and C31. With diets containing forage and concentrate, acid detergent insoluble ash, chromic oxide, indigestible acid detergent fibre, indigestible cellulose or n-alkanes presented similar nutrient digestibility coefficients, and 2N HCl acid insoluble ash higher dry matter digestibility, compared to total faecal collection. Acid detergent lignin resulted in lower apparent digestibility coefficients with both types of diets. However, combined effect sizes for acid detergent insoluble ash and n-alkanes were based on 2–3 experiments conducted in few (1–2) studies, and should be interpreted accordingly. It is concluded that acid insoluble ash currently presents the most reliable marker that, with certain precautions, could be applied to determine apparent total tract apparent digestibility in horses. [Copyright &y& Elsevier]

Abstract: Conventional methods to assess total tract apparent digestibility and total mean retention time (MRT) in horses are based on a total collection of faeces during 5 or 6 consecutive days. The objective of this study was to assess some adaptations to these methods when applied to athletic horses, in order to minimize disturbances in their management and training schedule. The impact of a reduction of the collection period on both total tract apparent digestibility coefficients and MRT was evaluated. The reliability of acid insoluble ash (AIA) and lignin(sa) as markers for digestibility measurements and of a partial collection for liquid and solid phase MRT measurements was also examined, in comparison with the results obtained from total faecal collection. Six Arabian horses in endurance training, fed 8.0kg meadow hay and 5.2kg pelleted feed daily, were used. The total tract apparent digestibility of dry matter (DM), organic matter (OM), neutral detergent fibre (aNDFom), acid detergent fibre (ADFom) and hemicelluloses was measured from a total collection and a partial collection of faeces using AIA and lignin(sa) as markers, for 3-, 4- and 5-day collection period. Total MRT of Cr-EDTA, Eu-labelled hay and Yb-labelled concentrate was calculated using two algebraic methods based on the quantity or the concentration of excreted markers, for 1, 1.5, 2, 3, 4 and 5 days collection periods. The digestibility coefficients obtained with a total faecal collection were not affected when the collection period was reduced to 4 or 3 days, for DM, OM and the different fibre fractions of the diet. When lignin(sa) was used as a marker, reducing the sampling period to 3 days did not affect the digestibility coefficients of any of the constituents, and total tract apparent digestibility coefficients were under-estimated (P<0.001) in comparison to those obtained by total faecal collection. When AIA was the marker, total tract apparent digestibility coefficients were lower (P<0.05) with a 3-day collection period, than with 4- or 5-day period and the digestibility coefficients were over-estimated (P<0.01) in comparison to those obtained by total faecal collection. A spot sampling faecal collection of faeces vs. a total faecal collection led to the same MRT values for both solid and liquid phases. A 1.5-day faecal collection led to the same MRT values as a 5-day faecal collection, whatever phase (liquid or solid) was considered. However, due to horses reactions to experimental conditions, a minimum faecal collection period of 3 days is recommended for assessing total MRT. [Copyright &y& Elsevier]

Abstract: The purpose of the study was to observe the effect of feeding extruded feed that contained rapeseed (that was extruded using the standard methods for large-scale production of extruded feed) on retention and coefficient of total tract apparent digestibility (CTTAD) in hens. The laying hens were divided into two groups NEX and EXT. The composition of the diets was the same in both groups (wheat 39%, rapeseed 13.5%, pea 13.5%, soya bean meal 6%, maize 14%, fish meal 3%, limestone 1%, premix 10%). But 0.45kg of 1kg of the diets EXT (wheat, pea, and rapeseed) was extruded by dry extrusion at temperature 137°C and at moisture from 12 to 18% for 16s. A balance assay was conducted with four laying hens from group NEX and eight from group EXT when they were 61 weeks old. The CTTAD of fat, calcium and amino-acids, and the retention of the nitrogen were estimated using the indicator method. The significance between the means was evaluated by a t-test. The average egg mass production during the assay was for group NEX 45 ± 3.9g/hen/day and for group EXT 50 ± 5.0g/hen/day. The extrusion process significantly increased (P < 0.001) the CTTAD of fat from 0.807 (NEX) to 0.937 (EXT). The coefficient of nitrogen retention was higher in group EXT (0.629) than in group NEX (0.584). The extrusion significantly increased the CTTAD of arginine (P < 0.05, NEX: 0.929, EXT: 0.944) and isoleucine (P < 0.05, NEX: 0.870, EXT: 0.904). The extrusion had a tendency to increase the CTTAD of leucine (P < 0.1, NEX: 0.885, EXT: 0.907), glutamic acid (P < 0.1, NEX: 0.931, EXT: 0.945), glycine (P < 0.06, NEX: 0.823, EXT: 0.859) and alanine (P < 0.1, NEX: 0.806, EXT: 0.844). CTTAD of lysine was almost the same in both groups (NEX: 0.950 and EXT: 0.949). The extrusion process had a tendency to decrease the CTTAD of histidine (P < 0.06, NEX: 0.906, EXT: 0.859) and tyrosine (P < 0.07, NEX: 0.974, EXT: 0.921). The extrusion had a positive effect on the fat CTTAD, nitrogen retention and on the CTTAD of the essential amino-acids (except lysine and histidine). The decrease in the digestibility of these two amino-acids was not significant. [Copyright &y& Elsevier]