Digestibility Trial Research Articles

The effects of supercritical carbon dioxide extraction and cold-pressed hexane extraction on the chemical composition and feeding value of rapeseed meal for broiler chickens

ABSTRACTThe chemical characteristics of rapeseed meal (RSM) produced from two cultivars of UK-grown rapeseed, by both supercritical carbon dioxide extraction (ScCO2) and cold-pressed hexane extraction (CpHe) were examined. Their nutritional value, with and without protease, was then assessed in a broiler digestibility trial. Basal feed was substituted with one of four RSM batches (200 g/kg) following adjustments for dry matter (DM) and ether extract (EE) content. Half of each diet was supplemented with a mono-component protease derived from Bacillus subtilis (Axtra®PRO, Danisco Animal Nutrition, Malborough, UK) giving a total of eight test diets. Two control diets, with and without protease were also fed. At 13 d age male Ross 308 broilers were randomly allocated to seven replicate pens (five birds per pen) and assigned to one of 10 diets. Total excreta were collected from 17 to 21 d age and feed intake was recorded. Pre-caecal protein digestibility (pcPd) was determined using TiO2 as an indigestible marker. Colourimetrically CpHe RSM was substantially darker than ScCO2 counterparts. The influence of oil recovery method (ORM) was also evident in DM, EE, ash free neutral detergent fibre (aNDFom), neutral detergent insoluble crude protein (NDICP) and glucosinolate content (GLS). The content of DM, EE and GLS was higher in ScCO2 RSM whereas aNDFom and NDICP levels were greater in CpHe RSM. Protein solubility in KOH was greater in ScCO2 RSM whilst levels of NDICP were lower. Collectively these results suggest that less heat damage was incurred to the RSM during ScCO2 extraction. There was no significant main effect of cultivar nor were any significant interactions observed between treatment factors. Rapeseed meal ScCO2 produced greater metabolisable energy, pcPd, nitrogen retention and energy metabolisability (p < 0.05). Protease supplementation increased pcPd (p < 0.05) irrespective of ORM and cultivar. The key implications of these findings are that by adopting oil recovery methods that minimise the exposure of RSM to thermal treatments and by adding a compatible protease there is scope to increase the nutritional value of RSM for broilers and increase its utilisation in modern poultry production.

Effects of Phytonutrients on Ruminal Fermentation, Digestibility, and Microorganisms in Swamp Buffaloes.

Simple SummaryFermentation in ruminants can influence greenhouse gas production, especially methane (CH4) production. Phytonutrients (PTN) and secondary metabolites (tannins, saponins) have antimicrobial activity which can be used for the inhibition of rumen methanogens and the reduction of methane emissions in ruminants. The aim of the present study was to investigate the influence of PTN containing both mangosteen peel powder and banana flower powder on feed consumption, nutrient digestibility, and rumen microorganisms in swamp buffaloes. The results suggest that supplementation of PTN can improve fiber digestibility, increase the proteolytic and cellulolytic bacteria, and alter rumen volatile fatty acids (VFAs), especially increased C3 and reduced methane production. This study shows that PTN containing either mangosteen peel powder (MSP) or banana flower powder (BFP) could be used as a rumen modifier. This experiment aimed to use dietary sources containing phytonutrients (PTN) such as mangosteen peel powder (MSP) and banana flower powder (BFP) as sources of phytonutrients. Four swamp buffalo bulls fitted with rumen fistulae were used as experimental animals. A digestion trial covering four periods was used according to a 4 × 4 Latin square design with four treatments: Treatment 1 (T1) = control (Cont), T2 = supplementation of PTN1 fed at 100 g/d, T3 = supplementation of PTN2 fed at 100 g/d, and T4 = supplementation of PTN3 fed at 100 g/d. The experiment was conducted for four periods; each period lasted for 21 days. All animals were fed a concentrate mixture at 0.5% body weight, while rice straw, water, and mineral blocks were fed ad libitum. The findings revealed significant increases in the digestibility of neutral detergent fiber (NDF) and acid detergent fiber (ADF), while no changes in dry matter feed consumption occurred due to PTN supplementation. Rumen fermentation end-products, such as total volatile fatty acids (TVFA), propionic acid (C3), and butyric acid (C4), were notably enhanced (p < 0.05) and there were the highest in PTN2 and PTN3, whilst acetic acid (C2) was significantly decreased with PTN supplementation groups. Furthermore, the rumen protozoal population was suppressed (p < 0.05), which resulted in decreased rumen methane production (p < 0.05), while the bacterial population was enhanced. Using PTN sources can improve rumen fermentation as well as mitigating rumen methane production.

Nutritional value of dry‐extruded blends of seafood processing waste and plant‐protein feedstuffs in diets for juvenile red drum ( Sciaenops ocellatus , L.)

Six thermally processed blends were manufactured by dry‐extruding mixtures of seafood processing waste with either soybean meal (SBM) or distiller's dried grains with solubles (DDGS) at three different ratios (50:50, 60:40 and 70:30; wet basis). To assess the energy and nutrient digestibility of each blend, a digestibility trial was conducted using advanced red drum juveniles (~70 g). After computing the apparent digestibility coefficients for the mixtures, a comparative feeding trial evaluated replacement of menhaden fishmeal (FM) on digestible protein (DP) and digestible energy (DE) bases with the manufactured blends. A diet formulated to derive 70% of DP from FM and 30% from SBM served as a Control. Groups of 14 fish were stocked in 21, 110‐L aquaria operating as a recirculating aquaculture system, and treatments were randomly distributed in triplicate. Weight gain and feed efficiency of fish fed SBM 50:50, DDGS 50:50 and DDGS 60:40 were significantly lower compared to that of fish fed the Control diet. However, the inclusion of SBM 60:40, SBM 70:30 and DDGS 70:30 blends succeeded in partially replacing FM and reducing fish oil inclusion in the diet of red drum without compromising production performance.

Diet, digestion and energy intake in captive common marmosets (Callithrix jacchus): research and management implications

Common marmosets (Callithrix jacchus) are susceptible to intestinal inflammation which leads to chronic diarrhea, weight loss, and vitamin D deficiency. We examined food intake and digestion in three mixed-sex groups of adult marmosets maintained on three commercial base diets. Animals underwent two consecutive 4-day digestion trials. Body mass stayed constant. Feces and diet were assayed for Mn, fat, and gross energy (GE). Apparent digestibility of dry matter (ADDM) was calculated by the total collection method and from dietary and fecal Mn; the methods produced correlated results (r = 0.658, p < 0.001). Apparent digestibility of energy (ADE) was calculated from ADDM and the GE of feces and diet; apparent digestibility of fat (ADfat) was calculated from ADDM and fecal fat. ADDM and ADE varied by diet (p < 0.001). We found poor digesters on all three diets. The concentration of fecal fat was inversely related to ADE (r = −0.729, p < 0.001). High fecal fat (>10%) was associated with ADfat of zero, consistent with lipid malabsorption. Mean digestible energy intake (DEI) was equal to 1.5 the estimated metabolic rate, but varied widely between individuals. The diet with the fewest animals with high fecal fat had the highest mean DEI and most animals above 450 g, suggesting it may be obesogenic.

Effect of a diet containing date pits on growth performance, diet digestibility, and economic evaluation of Japanese quail (Coturnix coturnix japonica).

This study was performed to investigate the effect of feeding different levels of date pits (DP) to growing Japanese quails on growth performance, diet digestibility, blood parameters, carcass traits, and economical value of the farm production. A total of 204 1-day-old quail chicks were randomly divided into 4 groups (three replicates each). DP was chemically analyzed and used as 0%, 2%, 4%, and 6% to formulate 4 balanced experimental diets (control, DP-2, DP-4, and DP-6, respectively). The feed and water were given ad libitum. Feed intake (FI) and body weight gain (BWG) were recorded weekly, and the feed conversion ratio (FCR) was calculated. A digestibility trial was conducted, and the digestion coefficient (DC) was calculated for diet dry matter (DM) and nutrients. At the end of the experiment, carcass traits were measured and blood samples were collected for blood picture analysis. Economical evaluation of the test diets was carried out to determine the net return (NR) of feeding DP to quails. Results showed significant (P < 0.05) change in FI and final body weight among treatments. FCR of DP-6 group was the best in all treatments. DC of diet DM and nutrients were reduced with increasing DP level except for nitrogen-free extract (NFE). Carcass traits and blood parameters were within the normal range with no adverse effects. From the economic point of view, quail selling return values were significantly higher (P < 0.05) for all the groups supplemented with DP than the control one. Total return (TR) and NR values showed insignificant (P > 0.05) differences among the experimental groups; they were higher for DP-fed groups compared with the control. The present results demonstrated a beneficial effect of DP inclusion in the diet of quails in terms of growth performance, blood profiles, carcass traits, and economic value.

127 Effects of Reed Sedge Peat on stress and digestibility of lambs at weaning

Abstract Fourteen lambs (age = 71.5 ± 4.15 d; BW = 24.1 ± 3.82 kg) were used to test the effects of feeding Reed Sedge Peat (RSP) during weaning. Lambs (10 females, 4 males) were randomly assigned by sex to one of two groups, they were either fed 56.8 g/d of RSP, or were not fed RSP. Both groups were fed 0.5% BW 18% show lamb grower complete feed (Ware Milling, Houston, MS) and had ad lib access to pasture [80% bermudagrass (Cynadon dactylon) and 20% dallisgrass (Paspallum dilatatum) during the day during the weaning portion of the study (14 d prior to weaning through 14 d after weaning). On d 15 after weaning, 10 of the lambs (6 females, 2 males) were randomly selected by treatment and moved to small individual pens where they underwent a digestibility trial for 8 days (3 d adjustment and 5 d collection) during which they were fed 1% BW hay/d and 4% BW/d 18% show lamb grower complete feed used during the weaning trail. At d 2 an initial blood sample was taken via jugular venipuncture, then ACTH was injected into the vein. Blood samples were taken at 15 min intervals for 1 h following synthetic ACTH injection, and analysed by conducting a cbc with differential. Reed-Sedge Peat had no effect (P &gt; 0.05) on digestibility of DM, OM, ash, protein, NDF, ADF, HC, or fat. Reed-Sedge Peat, also had no effect on intake DM (P = 0.3184), DMI per BW (P = 0.1062), hay intake (P = 0.9581), hay intake per BW (P = 0.9330), or concentrate intake (P = 0.8744). There was a tendency (P = 0.0552) for increased intake for RSP with regard to the concentrate. No difference for blood parameters between groups (P &gt; 0.05).

178 A systematic review and meta-analysis of Ca digestibility and utilisation in growing and finishing pigs

Abstract The development of dietary recommendations based on digestible Ca values is an essential step to optimize pig performance and feed conversion because the present guidelines, expressed on total dietary Ca, are inadequate, as they ignore endogenous losses and the digestion process. A systematic review and meta-analysis of digestibility trials were performed to quantify factors affecting Ca absorption and retention, and to estimate endogenous Ca losses. Forty studies, corresponding to 201 dietary treatments performed on 1,204 growing pigs, were selected. Data analysis was performed in R using weighted linear mixed effects regression. The results indicated that while Ca absorption and retention (g/kg of BW/day) increased with increasing Ca (P &lt; 0.001), with non-phytate-P (P &lt; 0.001) and with exogenous phytase intakes (P &lt; 0.001), these responses decreased with increasing phytate-P intake (P &lt; 0.05). Interactions were detected between exogenous phytase and Ca intake (P &lt; 0.001), indicating reduced efficacy of this enzyme, and between phytate-P intake and exogenous phytase (P &lt; 0.05), indicating reversing of the direct negative effect of phytate-P on Ca absorption and retention. Based on the recommended Ca and P intake for a 25 kg pig, an exogenous phytase supplementation of 1,000 FTU/day could potentially improve Ca digestibility by 20–25%. There were no effects of animal characteristics (e.g. ‘genotype’) on Ca absorption and retention. The large amount of variance explained in Ca absorption (90%) and retention (91%) supported our a priori choice of independent variables. Estimated endogenous Ca losses were 239 mg/kg of DM (95% CI 114, 364). When scaled by bodyweight, the endogenous Ca excretion on Ca-and-P-free diets was 20.5 mg/kg of BW/day (95% CI 5.46, 36.5). These outcomes should contribute to a reassessment of Ca requirements, which should lead to a more accurate formulation of pig diets.

Evaluation of untreated and urea molasses-treated finger millet (Eleusine coracana) straw and lowland bamboo (Oxytenanthera abyssinica) leaf hay on nutritive values and the performance of Gumuz sheep in Ethiopia.

The experiment was conducted to evaluate effects of untreated and urea molasses-treated finger millet straw and lowland bamboo leaf hay feeding on nutrient utilization, growth and carcass characteristics of Gumuz sheep. Twenty yearling intact male sheep with initial body weight of 21.6 ± 1.31kg (mean ± SD) were purchased from local market and were used for 7- and 90-day digestibility and feeding trials, respectively. The sheep were grouped into five blocks of four animals and randomly assigned to four dietary treatments. The treatment diets were untreated finger millet straw (UFMS) + 150g wheat bran (WB) and noug seed cake (NSC) mixture (T1), untreated lowland bamboo leaf hay (ULBLH) + 150g WB and NSC mixture (T2), urea molasses (UM)-treated finger millet straw (TFMS) + 150g WB and NSC (T3), and UM-treated lowland bamboo leaf hay (TLBLH) + 150g WB and NSC mixture (T4). Water and salt were given freely throughout the experimental period. Data were analyzed using ANOVA procedure of SAS software. The result of the experiment indicated that better CP was recorded in T4 (21.8%) than other treatments. The total DM intake of sheep was significantly (p < 0.001) higher for T2 = T4 > T3 > T1. Significantly higher (p < 0.001) CP intake was recorded in T4 than T3. Similarly, significantly higher CP digestibility was recorded in groups assigned in T4 than other treatments. UM treatment significantly improved (p < 0.05) the FMS than LBL in most of nutrients. Moreover, significantly (p < 0.001) higher ADG was recorded for T2 and T4 than T3; treatment on FMS did not show significant (p > 0.05) effect. T4 and T3 were similar and significantly higher in most of the carcass parameters except in hot carcass weight. In conclusion, UM treatment could be taken as an option to improve nutritive value of locally available lowland bamboo leaf hay and finger millet straw.

Serum Lipid Profile in Sheep Fed Diet Incorporated with Feed Additives

feeding trial to study the supplementation effect of exogenous fibrolytic enzymes (EFE) cocktail and wormwood herb on serum lipid profile was conducted for 90 days in twenty crossbred lambs that were divided into four equal groups viz. T0 (Control) and T1, T2 and T3 (treatment groups). T0 received total mixed diet (TMR) without any supplementation, while in treatments groups TMR was supplemented either with EFE cocktail alone @ 0.60% (T1) or wormwood herb alone @ 4.50% (T2) and in a combination of the two feed additives (T3). At the end of the feeding trial, 6 days of digestibility trial was carried out to assess the supplementation effect in vivo on nutritional parameters and serum total lipids and different lipoprotein fractions were carried out at the start (0 d) and subsequently at monthly intervals of the experiment (30, 60 and 90 d). Nutrient digestibility, content as well intake were significantly higher in groups fed diets supplemented with the feed additives either alone (p less than 0.05) or in-combination (p less than 0.01). No significant effect was observed on the total cholesterol level at any point of evaluation, and on total triglycerides level-up to 30 d, but significant reduction was noted in T2 at 60 (p less than 0.05) and 90 (p less than 0.01) days as compared to T1. Significant (p less than 0.01) effect on HDL level was evident as elevated in T2 while reduced in T1 at day 60 and 90. In contrast, LDL values were reduced in T2 and elevated in T1 group at day 30 (p less than 0.05), 60 and 90 (p less than 0.01). VLDL levels did not change among the groups up to 30 d, whereas reduced at day 60 (p less than 0.05) and 90 (p less than 0.01) in T2 as compared to T1. Lowest (p less than 0.01) AI value was observed in the T2 group at day 90 compared to other groups. It was concluded that dietary incorporation of wormwood herb as a feed additive for sheep improved nutritional status along with health beneficial effects when supplemented alone.

Effect of feeding rice distillers dried grain with solubles as major protein source on nutrient digestibility and growth performance of Jersey crossbred calves

Rice Distillers Dried Grains with Solubles (RDDGS) is a byproduct of alcohol industry obtained by distillation of fermented rice. In the present experiment, chemical composition of RDDGS and the effect of supplementing RDDGS replacing soybean meal (SBM) on growth performance and feed conversion efficiency of crossbred Jersey calves have been studied. The DM content of RDDGS was 89.58 ± 0.09%. The chemical composition (% DM) in terms of OM, CP, EE, CF, NFE, TA, NDF, ADF, TCHO and AIA were 94.97±0.09, 48.43± 0.69, 5.45 ± 0.16, 6.50±0.27, 34.58±1.01, 5.03 ± 0.09, 40.50 ± 0.93, 16.82 ± 0.65, 42.91 ± 1.52 and 0.95 ± 0.06, respectively. Chemical analysis indicated that it is a good source of protein and other nutrients. The effect of feeding RDDGS in crossbred cattle was studied in a growth trial of 120 days and a digestibility trial of six days collection period. The animals in control group (T0) were fed on soya bean meal based concentrate mixture with paddy straw and green fodder as per requirement. In the treatment group (T1) soya bean meal in concentrate mixture was totally replaced by RDDGS. There was no significant difference between two groups of animals in terms of average DMI, CPI and TDNI. The blood parameters such as plasma glucose, protein, albumin, globulin, enzymes (AST and ALT) and urea also remained unaffected. The digestibility of DM, CP and EE were significantly higher in treatment group fed with RDDGS. The average daily gain (ADLG) was significantly higher in RDDGS supplemented group as a result of which feed conversion efficiency improved and thus economized the ration.

In vivo digestibility of six selected fodder species by goats in northern Ghana

An in vivo digestibility trial was conducted to evaluate the digestibility of six forages. These were selected indigenous browse species and groundnut haulms in Lawra and Jirapa Districts of the Upper West Region of Ghana. Groundnut haulms served as a control due to its known good digestibility in small ruminants. Thirty West African Dwarf (WAD) young castrated billy goats with a mean age of 8 months were used. The average live body weight was 8.9 ± 0.1 kg. The animals were randomly assigned to the six treatments and replicated five times in a completely randomized design. They were confined in metabolism cages. The adaptation period was 3 weeks after which data was taken for 10 days. The treatments were the leaves and tiny twigs of T1 Annona senegalensis, T2 Ficus gnaphalocarpa, T3 Pericopsis laxiflora, T4 Pterocarpus erinaceus, T5 Afzelia africana, and T6 (control) Arachis hypogaea. Feed intake, faecal matter and urine output were measured. The results indicated that dry matter (DM) contents of the feedstuffs were less than 50% but crude protein (CP) contents were higher than the minimum required for sustaining ruminants. Neutral and acid detergent fibre contents were high, and F. gnaphalocarpa, in particular, contained a higher level of phosphorus (P). The amounts of feed intakes were typical of most fodder species with the exception of P. laxiflora and P. erinaceus, which were lower (P < 0.05). The apparent digestibility values were also typical of most fodder species but the digestibility of A. africana fibre appeared to be lower. Nitrogen retention was positive for all test species with the exception of P. laxiflora, which was negative. Mortality was recorded in animals on P. laxiflora, and the rate was high. Pericopsis laxiflora leaves, even though morphologically similar to the leaves of P. erinaceus, were not a suitable fodder. Ficus gnaphalocarpa appeared to be the overall best fodder species in terms of nutrient uptake.

Comparative evaluation of effective microbe- and urea molasses-treated finger millet (Eleusine coracana) straw on nutritive values and growth performance of Washera sheep in northwestern Ethiopia.

An experiment was carried out to comparatively evaluate the effect of effective microbe (EM)- and urea molasses (UM)-treated finger millet straw (EMTFMS and UMTFMS, respectively) on nutrient utilization and growth performance of Washera lambs. Twenty yearling intact male Washera lambs with an initial body weight of 21.13 ± 1.77kg (mean ± SE) were used for feeding and digestibility trial. These lambs were grouped into five blocks of four animals and randomly assigned to four dietary treatments. The four experimental feeds were untreated finger millet straw (control) + 150g wheat bran (WB) (T1), untreated finger millet straw + 150g WB + 150g Noug seed cake (NSC) (T2), UMTFMS + 150g WB + 150g NSC (T3), and EMTFMS + 150g WB + 150g NSC (T4). The lambs were de-wormed and vaccinated against ecto- and endo-parasites. Data were analyzed using ANOVA procedure of SAS. Results showed that crude protein (CP) content of finger millet straw (FMS) was improved from 2.13 to 9.7% in UM treatment and 2.13 to 2.39% in EM treatments. Total DM, CP, and OM intake were higher in lambs assigned in UMTFMS (P < 0.01) and EMTFMS (P < 0.01) than the control groups and significantly highest (P < 0.01) in UMTFMS. A non-significant (P > 0.05) difference was observed between treatment technologies in all nutrient apparent digestibility and average daily weight gain. Therefore, it can be concluded that both treatments could serve as an alternative measure to improve nutritive value of finger millet straw, but due to environmental effect, EM treatment could be safe.

Ruminal In Vitro Protein Degradation and Apparent Digestibility of Energy and Nutrients in Sheep Fed Native or Ensiled + Toasted Pea (Pisum sativum) Grains.

Simple SummaryPea grains may partially replace soybean or rapeseed meals and cereals in ruminant diets, but this is limited by high solubility of pea protein in the rumen. Hydro-thermic treatments such as toasting may stabilize the protein and shift digestion from the rumen to the small intestine. The effect of toasting of ensiled pea grains on rumen-undegraded protein was tested in vitro and on apparent digestibility of organic matter, gross energy, and proximate nutrients in a digestion trial with sheep. Ensiling plus toasting increased rumen-undegraded protein from 20 to 62% of crude protein, but it also increased acid detergent insoluble protein, which is unavailable for digestive enzymes in the small intestine from 0.5 to 2.6% of crude protein. Ensiling plus toasting did not, however, affect total tract apparent digestibility of organic matter, energy, crude protein, or any other nutrient fraction, nor did it alter the concentration of metabolizable energy or net energy lactation in the peas. The technique can be implemented on farms and might have a positive impact on field pea production.Pea grains may partially replace soybean or rapeseed meals and cereals in ruminant diets, but substitution by unprocessed peas is limited by high ruminal protein solubility. The effect of combined ensiling and toasting of peas using a mobile toaster (100 kg/h throughput rate, 180 to 190 °C supplied air temperature) on rumen-undegraded protein (RUP) was tested in vitro using the Streptomyces griseus protease test. The effects of ensiling plus toasting on apparent digestibility of organic matter (OM), gross energy (GE), and proximate nutrients were examined in a digestion trial. Concentrations of metabolizable energy (ME) and net energy lactation (NEL) were calculated. Native peas had 38 g RUP/kg dry matter (DM), which was 20% of crude protein (CP). Rumen-undegraded protein increased three-fold after ensiling plus toasting (p < 0.001). Acid detergent insoluble protein increased five-fold. Apparent digestibility was 0.94 (OM), 0.90 (CP), and above 0.99 (nitrogen-free extract, starch, and sugars) and was not altered by the treatment. The ME (13.9 MJ/kg DM) or the NEL (8.9 MJ/kg DM) concentration was similar in native and ensiled plus toasted peas. This technique can easily be applied on farms and may increase RUP. However, it needs to be clarified under which conditions pea protein will be damaged.

Effect of vitamin D3 supplementation on lysine utilization in growing rabbits

The effect of vitamin D3 (VD3) on lysine utilization in growing rabbits was studied in two experiments (Exp.). In Exp. 1, 162 growing rabbits (491 ± 38 g) were fed basal diets containing 16% crude protein ad libitum. The treatments were varying levels of VD3 (0, 500, and 1000 IU) and lysine (5.5, 6, and 6.5 g/kg dry matter; DM) in a 3 × 3 factorial design with six replicates in each treatment occurring for 5 weeks, and the experimental units were the cages (3 rabbits/cage). Nine experimental VD3+lysine diets, (0 + 0), (0 + 0.5), (0 + 1), (500 + 0), (500 + 0.5), (500 + 1), (1000 + 0), (1000 + 0.5) and (1000 + 1), were formulated. A basal diet (0 + 0) was formulated to be deficient in lysine (5.5 g/kg DM) and VD3 (0.0 IU). Lysine significantly (P < 0.01) affected the final body weight (FBW), average daily gain (ADG) and feed conversion ratio (FCR) but did not affect feed intake. VD3 tended (P = 0.06) to improve the FCR with no significant effect on FBW and ADG. VD3 and lysine exhibited no effect on feed intake. The highest mortality rate (38.9%, 7/18) was observed for the 0 + 0 (control) treatment, and the lowest mortality rates of 5.6% and 0.0% were observed for the 1000 + 0 and 1000 + 0.5 treatments, respectively. Exp. 2, the nutrient digestibility and nitrogen balance trial, was conducted with 45 rabbits (n = 5/treatment) randomly chosen from Exp. 1. Rabbits were housed in metabolic cages for 8 d and offered 180 g/d of each respective diet described in Exp. 1. A significant VD3 × lysine interaction was observed for N intake (P < 0.05). VD3 tended to increase N intake (P = 0.08) and improved (P < 0.05) dry matter digestibility (DMD) and organic matter digestibility (OMD). Lysine increased (P < 0.05) N intake and retained N (P < 0.01), decreased (P < 0.01) urine N, and tended to improve crude protein digestibility (CPD) (P = 0.08) and OMD (P = 0.10). Lysine increased the plasma total protein (TP), albumin (Alb; P < 0.05) and calcium (Ca; P < 0.01) contents and decreased plasma cholesterol (Cho), while VD3 and lysine decreased the urea concentration. A significant (P < 0.01) VD3 × lysine interaction was observed for plasma phosphorus (P) and growth hormones (GHs). VD3 increased P (P < 0.01) and tended (P = 0.08) to increase GHs, whereas lysine decreased (P < 0.05) P at the 1.0 g level but caused a linear and quadratic (P < 0.05) increase in GHs. Overall, the supplementation of diets with VD3 did not improve lysine utilization in growing rabbits; however, lysine increased N intake, retained N, the FBW, and the ADG and improved the FCR.

Soybean glycinin decreased growth performance, impaired intestinal health, and amino acid absorption capacity of juvenile grass carp (Ctenopharyngodon idella).

The present study evaluated the influence of dietary soybean glycinin on growth performance, intestinal morphology, free intestinal amino acid (AA) content, and intestinal AA transporter (AAT) mRNA levels in juvenile grass carp (Ctenopharyngodon idella). Results were displayed as follows: (1) 8% dietary glycinin decreased growth performance, inhibited intestinal growth, and caused intestinal histology damage of grass carp; (2) dietary glycinin decreased the content of free neutral AAs including Val, Ser, Tyr, Ala, Pro, and Gln in all intestinal segments, and Thr, Ile, Leu, Phe, and Gly in the MI and DI while downregulated the mRNA levels of corresponding transporters including SLC38A2, SLC6A19b, and SLC6A14 in all intestinal segments, and SLC7A5, SLC7A8, and SLC1A5 in the MI and DI. Dietary glycinin decreased the content of free basic AAs including Arg in the MI and DI and His in all intestinal segments while downregulated cationic AAT SLC7A1 mRNA levels in the MI and DI. Dietary glycinin decreased the content of free acidic AAs including Glu in all intestinal segments and Asp in the MI and DI while decreased mRNA levels of corresponding transporters including SLC1A2a in all intestinal segments and SLC1A3 in the MI and DI; (3) the digestion trial showed that basic subunits of glycinin was hard to digest in the intestine of grass carp; (4) co-administration of glutamine with glycinin partially alleviated the negative effects. Overall, glycinin decreased intestinal AA absorption capacity partly contributed by decreased AATs' mRNA levels and the indigestibility of glycinin.

Testing the digestibility of seabream wastes in three candidates for integrated multi-trophic aquaculture: Grey mullet, sea urchin and sea cucumber

In this study the Integrated Multi-Trophic Aquaculture (IMTA) approach was examined at a gilthead seabream, Sparus aurata, farm located in the Eastern Mediterranean Sea. To achieve this, digestibility trials were conducted with three species representing different trophic levels, the grey mullet, Mugil cephalus, the sea urchin, Paracentrotus lividus, and the sea cucumber, Actinopyga bannwarthi using the particulate farm effluents as feed. To prepare the feeds, seabream faecal waste was collected by means of a large conical bag attached below a fish cage. The farm wastes were dried and pelleted after adding chromic oxide (indigestible marker) and alginate (binder). In the ensuing trials, the pellets were offered to the mullets, sea urchins and sea cucumbers. The faecal matter of the grey mullets was collected by stripping the fish, whereas for the sea urchins and sea cucumbers trials, faecal matter was collected by siphoning the faeces from the bottom of the tanks. The farm-waste feed and faeces of each of the tested species were analysed for chromic oxide, organic matter, protein, phosphorus, lipid, ash and energy content, and the apparent digestibility coefficient was calculated for each. The digestibility trial showed that mullets do not benefit nutritionally from the freshly deposited gilthead seabream wastes. However, both the sea urchins and sea cucumbers were able to obtain energy and nutrients from the gilthead seabream wastes, emphasising their potential as IMTA species. The sea cucumber expressed higher digestibility of the farm-waste feed than the sea urchin (11.7–45.9% and 3.8–16.3% respectively), which might be sufficient for productive growth based solely on a diet of “waste” material. These results demonstrate that IMTA systems based on detritivores in warm water locations allow to extract particulate wastes from commercial aquaculture farms and convert this to valuable biomass in the process.

Indications of a negative genetic association between growth and digestibility in juvenile Atlantic salmon (Salmo salar)

Digestibility is a part of the feed efficiency complex. Improved understanding of the genetics of digestibility and its relation to the most important traits in a breeding program, such as growth rate, is important for enhanced knowledge on the biological aspects of selective breeding for growth. The aim of the study was to estimate the genetic variance and heritability of nitrogen and carbon digestibility parameters and their genetic and phenotypic correlations with growth using individually recorded phenotypes and genotypes. The fish were kept in a common tank from start-feeding until the end of the experiment. All fish were individually tagged and genotyped (56 K SNP-chip) at ~5–10 g body weight. A total of 129 fish from 14families (average initial body weight of 194g) were included in an individual digestibility trial carried out over 30 days. Individual digestibility was measured as apparent digestibility of nitrogen and carbon in fecal samples, using a fishmeal-based diet with yttrium oxide as an inert marker. To obtain enough feces per fish for digestibility analysis, the fish were stripped four times, i.e., once a week. Results showed significant differences between families with respect to digestibility. Heritabilities were 0.39 ± 0.17 and 0.51 ± 0.18 for digestibility of nitrogen and carbon, respectively. Digestibility showed adverse genetic correlations to the growth rate (−0.77 ± 0.24 to −0.85 ± 0.16). A possible explanation may be that a high growth rate is related to higher feed intake, increasing the passage rate in the gastrointestinal tract and thereby reducing the digestibility of the nutrients. This, however, does not imply that there is an adverse genetic relationship between growth and feed efficiency, as the latter is determined by a number of other factors in addition to digestibility.

Disulphide bonds and cross‐linked amino acids may affect amino acid utilization in feather meal fed to rainbow trout (Oncorhynchus mykiss)

A digestibility trial was carried to assess the apparent digestibility coefficient (ADC) of crude protein (CP) and amino acids (AA) in two feather meals (FeM) of different origin (FeM1 and FeM2) and in their enzymatically pre-treated ingredient stream (PTFeM1 and PTFeM2) in rainbow trout. The ADC of CP was 11%–17% higher (p < 0.05) in the PTFeMs than in their FeM counterparts. There was no difference (p > 0.05) of ADC of CP among FeMs and among PTFeMs. The FT-Raman analysis showed a reduction in concentration and conformational stability of disulphide bonds in the PTFeMs when compared to their FeM counterparts. Moreover, important discrepancies in disulphide concentration were observed between FeMs and between PTFeMs. These observations suggest that the ADC of CP in FeM is not only governed by disulphide bond content and other variables should be considered. Higher concentrations of the cross-linked amino acids (CLAA) lanthionine, lysinoalanine and β-aminoalanine were measured in FeM1 and PTFeM1 as compared to FeM2 and PTFeM2 respectively. Previous studies have suggested inverse relationships between CLAAs and the digestibility as well as bioavailability of AAs in feed ingredients. A previous study conducted in our laboratory showed a lower (p < 0.05) bioavailability of arginine in FeM1 and PTFeM1 than in FeM2 and PTFeM2, respectively, in rainbow trout. Our results suggest that (a) the digestibility of AAs in FeM may be affected by disulphide bond content and the presence of CLAAs, and (b) CLAA content may be indicator of bioavailability of AAs in FeM.

Effect of live yeast supplementation to gestating sows and nursery piglets on postweaning growth performance and nutrient digestibility.

The objectives of the present study were to determine the effects of live yeast (LY) supplementation of sows during gestation and lactation and to determine the effects of supplementation of their offspring after weaning on growth performance and nutrient digestibility. A total of 40 sows were assigned to 2 dietary treatments (control vs. LY) based on parity and expected farrowing date. Birth weight, weaning weight, litter size, and mortality were measured. After weaning, 128 mixed-sex piglets (64 from each sow treatment) were selected based on their source litter and initial BW, and randomly assigned to 2 treatments (control or LY) at 4 pigs per pen (total of 32 pigs per treatment) for a 6-wk growth performance study. At the end of the growth performance trial, 2 barrows from each pen were moved to metabolism crates for total fecal collection for a digestibility trial. Addition of LY to the sow diets had no effects on birth weight, weaning weight, litter size at birth, and mortality. Piglets had greater BW on days 21 and 42 post-weaning when sows were fed diets supplemented with LY, and overall ADG was greater in piglets from sows that received LY (P < 0.05). There was no effect of sow and nursery diets on overall ADFI and G:F intake. Supplementing diets with LY during the nursery phase increased apparent total tract digestibility (ATTD) of DM, GE, and phosphorus (P) during this phase. The ATTD of GE was also greater in piglets from sows that received LY. In conclusion, LY supplementation of diets during gestation and lactation and during the nursery phase could increase ADG and ATTD of DM, GE, and P in the offspring, and this may lead to a greater lifetime growth performance in the offspring.

Effect of selected feed additives to improve growth and health of dairy calves.

The aim was to evaluate the effect of different feed additives on intake, performance, and fecal consistency index (FCI) of dairy calves from 6–60 d of age and its residual effect 15 d after weaning. Fifty Holstein calves (38 ± 1.0 kg BW) were fed 5 L/d of milk plus starter feed until weaning, and corn silage and concentrate after weaning. The treatments were: control (CON), monensin (MON; 30 mg/kg of starter), probiotic E. faecium (PROB; 70 mg/kg of starter), essential oils (EO; 300 mg/kg of starter), or PROB + EO (EOPROB). Fecal score and dry matter intake (DMI) were measured daily, and animals were weighed every 15 d. A DNA extraction from feces was performed to identify the presence of microorganisms (E. coli, Hafnia, Shiguella, Lactobacillus spp, Enterococcus spp, and Enterococcus faecium NCIMB 10415) by PCR. Two 72-h digestibility trials were performed at days 20–28 and 50–56, by total fecal collection. The DMI before weaning was greater for EO (903.0 g/d) compared with MON (794.3 g/d) and EOPROB (783.1 g/d). The FCI decreased during pre-weaning for EO and MON. Average daily gain (ADG) and feed efficiency (FE) did not differ among treatments before weaning. After weaning, DMI and FCI did not differ among treatments. The EO had greater ADG (917.5 g/d) compared with CON (615.8 g/d) and PROB (592.6 g/d). The FE improved with EO (0.72 g/g) over CON (0.36 g/g), MON (0.49 g/g), and PROB (0.36 g/g). The PCR results showed absence of E. faecium NCIMB 10415 in animals fed PROB and CON. Animals fed PROB had greater intake of CP and NDF than animals fed EOPROB. The EO can be added to the dairy calf ration to improve fecal score and increase DMI. The pre-weaning FCI decrease with MON and increase with PROB.