Faecal indices predict organic matter digestibility, short chain fatty acid production and metabolizable energy content of browse-containing sheep diets

The ability of faecal composition to accurately predict nutritional characteristics of browse-containing sheep diets was investigated. Predictive regression models were developed using data derived from three feeding experiments conducted with Acacia saligna (i.e., Avena sativa control and five inclusion levels of A. saligna), Chamaecytisus palmensis (i.e., A. sativa control and five inclusion levels) and Atriplex amnicola (i.e., A. sativa control and five inclusion levels). The fourth experiment conducted to validate the predictive models included six levels of A. saligna and five levels of C. palmensis. Feed and faecal samples collected from six replicate sheep were analysed for neutral detergent fiber (NDFom), acid detergent fiber (ADFom), lignin(sa), ash and crude protein (CP) contents. Total phenolics (TP) and tannin (TT) contents and in vitro gas production of the feed samples were also measured. Organic matter digestibility (OMD), short chain fatty acid production (SCFA) and metabolizable energy (ME) content of diets were determined. Feed and faecal data of experiments 1, 2 and 3 were pooled. Correlation coefficients among feed and faecal variables were estimated. The predictive regression models of dietary characteristics were developed from faecal composition by a stepwise regression procedure. The significant (i.e., P<0.05) predictive model with the highest R² and lowest residual standard deviation (RSD) was selected (i.e., best-fit predictive model). The model was used to predict nutritional characteristics of diets in the validation experiment from respective faecal indices. The predicted nutritional characteristics were then regressed against measured nutritional characteristics. The best-fit predictive regression model for dietary CP had a very low R² (0.21). The best-fit regression models predicting dietary TP, TT, OMD, SCFA and ME from faecal N, ash and lignin(sa)/NDFom had R² greater than 0.78 and low RSD. In the validation experiment, regressions between measured and predicted TP and TT had positive intercepts (P<0.05) and low R². Slopes of these regressions were much lower than 1.0. Intercepts of the regressions between measured and predicted OMD, SCFA and ME did not different from zero. The R² of these regressions were very high and slopes were close to 1. Dietary CP content of browse-containing diets cannot be predicted from faecal fiber, lignin(sa) and ash contents. However, these faecal indices collectively can predict the OMD, SCFA production and ME contents of browse-containing diets, and these predictive models have broad application. Further research is necessary to understand the poor validity of the predictive models of TP and TT.     

Effect of fat type and lysophosphatidylcholine addition to broiler diets on performance,apparent digestibility of fatty acids,and apparent metabolizable energy content

A completely randomized design study with a 3 × 2 factorial arrangement was conducted to evaluate the effects of three different fat sources (soybean oil, tallow, and poultry fat) with or without emulsifier supplementation on performance, coefficient of total tract apparent digestibility (CTTAD) of fatty acids, and apparent metabolizable energy (AME) content in broiler chickens. Two hundred and fifty-two one-day-old male Arbor Acres broiler chickens were randomly divided into 6 different treatments: (T1) basal diet containing soybean oil without lysophosphatidylcholine (LPC) supplementation, (T2) basal diet containing soybean oil with LPC supplementation, (T3) basal diet containing tallow without LPC supplementation, (T4) basal diet containing tallow with LPC supplementation, (T5) basal diet containing poultry fat without LPC supplementation, and (T6) basal diet containing poultry fat with LPC supplementation. Body weight gains from broiler chicks fed diets containing tallow were lower (P<0.05) than the body weight gains from chicks that were fed diets containing soybean oil or poultry fat in both the starter and grower periods. Birds fed diets containing tallow had the highest FCR (P<0.05), followed by the birds that were fed diets containing poultry fat, and soybean oil. The CTTAD of C16:0, C18:2, and C18:3n3 was greater (P<0.05) for broilers fed diets containing soybean oil than for those fed diets containing tallow or poultry fat in the starter period. The addition of LPC increased (P<0.05) body weight gain of broiler chickens in the starter period and the AME of the diets in the grower period, and tended to reduce FCR (P=0.072) in the starter period. LPC supplementation increased (P<0.05) the CTTAD of C16:0, C18:1n7 and C18:1n9 in the starter period, and of C18:2, and C18:3n3 in the grower period (P<0.05). There were no significant interactions between fat sources and the addition of LPC. These data indicated that LPC supplementation can improve body weight gain of broiler chickens in the starter period. This effect may be associated with an increase of CTTAD of FA due to LPC activity.     

Nutrient digestibility and prediction of metabolizable energy in total mixed rations for ruminants

The aim of the present study was to determine equations that predict ME in total mixed rations (TMR) based on routine methods. The ME content of 30 TMR for dairy cows was determined based on digestible crude nutrients obtained with wether sheep. Concentrations in the TMR (in g/kg DM) varied between 118 and 234 for crude protein, 26 and 48 for crude lipid, 131 and 250 for crude fibre, 281 and 488 for NDF, and 173 and 304 for ADF. Gas production ranged from 40.7 to 54.1 ml/200 mg DM, and enzymatically degraded organic matter from 652 to 800 g/kg DM. Digestibility [%] ranged from 68.6 to 84.0 for organic matter, from 55.6 to 84.3 for crude lipid, from 55.0 to 77.8 for crude fibre, from 57.6 to 77.0 for NDF and from 53.1 to 79.6 for ADF. ME ranged from 9.6 to 11.9 MJ/kg DM, and NEL from 5.7 to 7.4 MJ/kg DM. ME content was highly correlated with the concentration of both crude fibre and enzymatically degradable organic matter as well as with organic matter digestibility. A multiple regression equation based on crude fibre and crude lipid predicted ME with a reasonable goodness of fit (r² = 0.81; s_y.x = 2.4%). The inclusion of other nutrients, of neutral and acid detergent fibre, neither of gas production did improve the goodness of fit. The best prediction was achieved with inclusion of enzymatically degraded organic matter (r² = 0.90; s_y.x = 1.7%).     

Concentration of nitrosodimethylamine in commercial pelleted experimental animal diets

To know the conditions of contamination by the chemicals in the experimental animal diets, the contents of nitrosodimethylamine (NDMA) were analyzed in the diets for mice and rats. The raw materials of the diets were also analyzed. In addition, NDMA levels were determined in the diets which were stored long or heated in the autoclaves. The averages of NDMA in these diets were less than 10 ppb. In the raw materials, alfalfa contained a higher levels of NDMA. There was no clear tendency of increase or decrease in NDMA levels, when the diets were stored for six months at room temperature (23-25 degrees C) or at low temperature (7-10 degrees C). Heating the diets at 121 degrees C, no remarkable changes were observed in NDMA levels. It seems that little adverse influences on the conduct of the animal experiments would be anticipated by the NDMA in the commercial diets.     

Effects of sex and dietary phosphorus level on the apparent metabolizable energy and nutrient digestibility in broiler chickens

The influence of sex of broilers and dietary phosphorus (P) level on energy utilization and apparent ileal digestibility of N, P and phytate-P were investigated. The AME(N) was determined using 3- and 6-week old broilers, while the apparent ileal digestibility were determined only with 6-week old birds. Sex of broilers had no effect on the AME(N) values determined during week 3. During week 6, the AME(N) values for male broilers were higher (P < 0.01) than those for the females. An interaction (P < 0.05) between sex and dietary P level was also observed. AME(N) values determined with male broilers were lower in the adequate-P diet compared to those in the low-P diet, whereas no effect of P level was observed in females. Female broilers tended (P < 0.10) to have a higher ileal N digestibility than the males, but a significant (P < 0.01) sex x P level interaction was observed. Males receiving the adequate-P diet had a lower N digestibility than those receiving the low-P diet, whereas the opposite was true in the females. Ileal phytate P degradation in males was higher than in females (0.282 vs. 0.234), but the differences were not significant. Increasing dietary P level increased ileal P digestibility in both the males and females, but the improvements were greater in the females, as indicated by a significant sex x P level interaction.     

Effects of sex and dietary phosphorus level on the apparent metabolizable energy and nutrient digestibility in broiler chickens

The influence of sex of broilers and dietary phosphorus (P) level on energy utilization and apparent ileal digestibility of N, P and phytate-P were investigated. The AME_N was determined using 3- and 6-week old broilers, while the apparent ileal digestibility were determined only with 6-week old birds. Sex of broilers had no effect on the AME_N values determined during week 3. During week 6, the AME_N values for male broilers were higher (P?0.01) than those for the females. An interaction (P?0.05) between sex and dietary P level was also observed. AME_N values determined with male broilers were lower in the adequate-P diet compared to those in the low-P diet, whereas no effect of P level was observed in females. Female broilers tended (P?0.10) to have a higher ileal N digestibility than the males, but a significant (P?0.01) sex ×?P level interaction was observed. Males receiving the adequate-P diet had a lower N digestibility than those receiving the low-P diet, whereas the opposite was true in the females. Ileal phytate P degradation in males was higher than in females (0.282 vs. 0.234), but the differences were not significant. Increasing dietary P level increased ileal P digestibility in both the males and females, but the improvements were greater in the females, as indicated by a significant sex × P level interaction.     

Carnivorous mammals: nutrient digestibility and energy evaluation

Estimating the energy content is the first step in diet formulation, as it determines the amount of food eaten and hence the concentration of nutrients required to meet the animal's requirements. Additionally, being able to estimate the energy content of a diet empirically known to maintain body condition in an animal will facilitate an estimation of maintenance energy requirements. We collated data on nutrient composition of diets fed to captive wild canids, felids, hyenids, mustelids, pinnipeds, and ursids and the digestibility coefficients from the literature (45 species, 74 publications) to test whether differences in protein and fat digestibility could be detected between species groups, and whether approaches suggested for the estimation of dietary metabolizable energy (ME) content in domestic carnivores (NRC [2006] Nutrient requirements of dogs and cats. Washington, DC: National Academy Press.) can be applied to wild carnivores as well. Regressions of digestible protein or fat content vs. the crude protein (CP) or fat content indicated no relevant differences in the digestive physiology between the carnivore groups. For diets based on raw meat, fish, or whole prey, applying the calculation of ME using “Atwater factors” (16.7 kJ/g CP; 16.7 kJ/g nitrogen‐free extracts; 37.7 kJ/g crude fat) provided estimates that compared well to experimental results. This study suggests that ME estimation in such diets is feasible without additional digestion trials. For comparative nutrition research, the study implicates that highly digestible diets typically fed in zoos offer little potential to elucidate differences between species or carnivore groups, but research on diets with higher proportions of difficult‐to‐digest components (fiber, connective tissues) is lacking. Zoo Biol 29:687–704, 2010. © 2010 Wiley‐Liss, Inc.     

Effect of age of growing turkeys on nutrient digestibility and energy value of cereal-soybean-based diets

Ileal and total tract digestibility of protein, total tract digestibility of fat and AME_N of cereal-based diets were assayed in growing turkeys at four, seven and 12 weeks of age. Fat digestibility and AME_N improved linearly with age. Total tract protein digestibility improved with age according to a curvilinear trend, while ileal protein digestibility improved from 4?–?7 weeks of age but decreased from 7?–?12 weeks of age. It can be concluded that higher AME_N values could be applied when formulating diets for older than for younger turkeys. Regarding protein digestibility more investigation is needed but a possible fall in values after the first weeks of age may be expected.     

Effect of age of growing turkeys on nutrient digestibility and energy value of cereal-soybean-based diets

Ileal and total tract digestibility of protein, total tract digestibility of fat and AMEN of cereal-based diets were assayed in growing turkeys at four, seven and 12 weeks of age. Fat digestibility and AMEN improved linearly with age. Total tract protein digestibility improved with age according to a curvilinear trend, while ileal protein digestibility improved from 4-7 weeks of age but decreased from 7-12 weeks of age. It can be concluded that higher AMEN values could be applied when formulating diets for older than for younger turkeys. Regarding protein digestibility more investigation is needed but a possible fall in values after the first weeks of age may be expected.     

Phytoestrogen content of purified, open- and closed-formula laboratory animal diets.

BACKGROUND AND PURPOSE: Phytoestrogens exert estrogenic effects on the central nervous system, induce estrus, and stimulate growth of the genital tract of female animals. Over 300 plants and plant products, including some used in laboratory animal diets, contain phytoestrogens. Therefore, the source and concentration of phytoestrogens in rodent diets were determined. METHODS: Twelve rodent diets and six major dietary ingredients were assayed for phytoestrogens (daidzein, genistein, formononetin, biochanin A, and coumestrol), using high-performance liquid chromatography. Three rodent diets recently formulated to reduce phytoestrogen content also were assayed. RESULTS: Formononetin, biochanin A, and coumestrol were not detected. Soybean meal was the major source of daidzein and genistein; their concentrations were directly correlated to the percentage of soybean meal in each diet. CONCLUSIONS: High, variable concentrations of daidzein and genistein are present in some rodent diets, and dietary phytoestrogens have the potential to alter results of studies of estrogenicity. Careful attention should be given to diet phytoestrogen content, and their concentration should be reported. A standardized, open-formula diet in which estrogenic substances have been reduced to levels that do not alter results of studies that are influenced by exogenous estrogens is recommended.     

Comparative digestibility of energy and nutrients in diets fed to sows and growing pigs

The objective of this research was to compare values for digestible energy (DE) and metabolisable energy (ME) and apparent total tract digestibility (ATTD) of nutrients in 11 diets fed to both growing pigs and gestating sows. Three diets were based on corn, wheat or sorghum and eight diets were based on a combination of corn and soybean meal, canola meal, conventional distillers’ dried grains with solubles, low-fat distillers’ dried grains with solubles, corn germ meal, corn bran, wheat middlings or soybean hulls. A total of 88 gestating sows (252 ± 24.2 kg BW; parity two to six) and 88 growing barrows (40 ± 4.7 kg BW) were used and randomly allotted to the 11 diets with eight replicate sows or pigs per diet. Faecal and urine samples were collected for 4 d following a 19 d adaptation period. The DE, ME and ATTD of gross energy (GE), acid detergent fibre (ADF), neutral detergent fibre (NDF) and crude protein (CP) in the 11 diets were calculated. Gestating sows had greater (p < 0.05) ATTD of GE and CP and DE values for all diets compared with growing pigs. Gestating sows also had greater (p < 0.05) ME values than growing pigs for the three grain diets and the diets containing wheat middlings and soybean hulls. No differences were observed in ATTD of ADF and NDF between gestating sows and growing pigs for any of the diets, except that gestating sows had greater (p < 0.05) ATTD of NDF than growing pigs when they were fed the four protein diets. The ATTD of GE and CP and DE values in gestating sows may be predicted by using equations generated from the values of ATTD of GE and CP and DE values obtained in growing pigs. Results of this research indicate that ATTD values of CP and GE obtained in gestating sows are greater than the values obtained in growing pigs, but values for ATTD of ADF obtained in growing pigs are not different from values in gestating sows.     

Comparison of bioavailable energy values of diets measured with poultry and swine

Two experiments were carried out to assess the relationship between apparent digestible energy (ADE) values measured with pigs, and true metabolizable energy (TME) values measured with adult cockerels. In the second experiment both chromic oxide and acid insoluble ash were used as indicators in the pig.Pooled data revealed close relationships between ileal ADE (I) and TME (T): I = ?1.113 + 1.006T (r = 0.943; P<0.01); and between faecal ADE (F) and TME: F = 4.768 + 0.755T (r = 0.929; P<0.01); the data being expressed as MJ/kg of dry matter in the feed. The results suggest that TME values may be used to predict ADE values in the formulation of pig diets.     

Conversion efficiency and nutrient digestibility of certain seaweed diets by laboratory reared Labeo rohita (Hamilton)

Impact of three different types of seaweed diets on growth, feed utilization and nutrient digestibility of L. rohita was studied for 120 days. The seaweed diet fed fishes, especially Ulva based diet showed comparatively higher growth and weight increment. Good food conversion ratio, food assimilation efficiency, protein efficiency ratio and better nutrient digestibility were recorded for seaweed diet fed fishes. The results suggests the suitability of utilizing seaweeds, Ulva fasciata, Spyridia insignis and Sargassum wightii as partial substitute for fishmeal in formulated diets of L. rohita.     

Enzyme supplementation of wheat-based diets for broilers: 2. Effect on apparent metabolisable energy content and nutrient digestibility

Two experiments were conducted to determine the effect of enzyme supplementation on the nitrogen-corrected apparent metabolisable energy (AME_n) and apparent nutrient digestibilities in ileum and excreta from male broiler chickens fed diets containing high amounts of wheat (>80%). Four different enzyme preparations were added to the wheat-based diets in varying levels and combinations. The difference between Experiments 1 and 2 consisted in the addition of different enzymes and enzyme levels. Excreta and ileal content were collected from broiler chickens at 3 and 6 weeks of age. At 3 weeks of age enzyme supplementation increased (P<0.0001) the AME_n from an average value of 13.86 MJ kg⁻¹ dry matter (DM) to an average of 14.60 MJ kg⁻¹ DM in the two experiments. The apparent digestibility of protein (APD) and fat (AFD) were improved significantly as a result of enzyme addition in both experiments. At 3 weeks of age, improvements (P<0.05) in the ileal AFD and APD were on average 13% and 6%, respectively. The effect of enzyme supplementation on AFD measured in excreta from broiler chickens showed the same pattern. The positive effect of enzyme addition on the overall nutrient digestibility and AME_n was reflected in weight gain and feed conversion efficiency (FCE). Significant improvements in AME_n, APD, and AFD were still present in most of the groups fed with enzyme-supplemented diets at 6 weeks of age. The effect of enzyme addition, however, was less pronounced, especially in Experiment 1 where the ileal APD of broiler chickens did not differ significantly from the control group. Apparent starch digestibility (ASD), measured in Experiment 2, was very high in all groups, including the control; however, enzyme supplementation increased ASD (P<0.001) in ileum and excreta at both 3 and 6 weeks of age. The digestibility of total non-starch polysaccharides (NSP) in excreta was improved significantly (P<0.01) as a result of enzyme supplementation (Experiment 2). In addition, pH of caeca content decreased (P<0.02) in broiler chickens fed with enzyme-supplemented diets when compared with the control group. Decreased pH could indicate microbial fermentation of unabsorbed NSP residues and nitrogenous compounds. Overall, the results demonstrated that the nutritive value of wheat-based diets to broiler chickens improve enzyme supplementation. The apparent digestibility of total NSP and of arabinose and xylose residues improved (P<0.02) in the enzyme-supplemented diets indicating that the enzymes were able to break down the cell wall NSP to a certain extent.     

Effect of avilamycin and tylosin on the metabolizable energy in growing and finishing pigs

In two metabolism trials with growing and finishing pigs the influence of the antibiotic feed additives Avilamycin and Tylosin on the metabolizable energy was investigated at different levels of dietary protein content. In the first experiment (growing pigs) the antibiotics were supplied at levels of 0 mg/kg, 40 mg/kg Avilamycin and 40 mg/kg Tylosin to diets containing 18.5%, 17.5%, 16.5% and 14.0% of crude protein. In the second experiment (finishing pigs) 0 mg/kg antibiotics, 20 mg/kg Avilamycin and 20 mg/kg Tylosin were used in diets containing 16.5% and 14.0% of crude protein. The body weight of the animals averaged 46 kg (growing pigs) and 68 kg (finishing pigs).

In growing pigs the supplementation of Tylosin increased the digestibility of dry matter and energy at 1 percentage unit each, while in finishing pigs no effects were observed. Since the urinary energy excretion was not affected by antibiotics, there was only in Tylosin treated growing pigs a slight rise in dietary contents of metabolizable energy by 1.6%. The reduction of the dietary protein content resulted in increased digestibility of dry matter and energy, reduced urinary energy excretions and increased dietary contents of metabolizable energy.     

Energy digestibility of giant pandas on bamboo‐only and on supplemented diets

Endangered giant pandas (Ailuropoda melanoleuca) are bears (Family Ursidae), within the order Carnivora. They specialize on an herbivorous diet of bamboo yet retain a gastrointestinal tract typical of their carnivorous ancestry. The evolutionary constraints of their digestive tract result in a low extraction efficiency from bamboo (<40% in reported studies). The goal of this study was to determine the energy digestibility of bamboo by giant pandas used in digestibility trials and through subsequent analyses with bomb calorimetry. Seven digestibility trials were conducted (three with bamboo‐only diets and four with supplemental diets). Energy digestibilities ranged from 7.5–38.9% for mixed diets and 9.2–34.0% for bamboo‐only diets. The bamboo‐only trials summarized here represent, to our knowledge, the first empirical data available for energy digestibility on a bamboo diet for giant pandas. Zoo Biol 30:121–133, 2011. © 2010 Wiley‐Liss, Inc.     

Influence of dietary fibre on nutrient digestibility and energy utilisation in growing pigs fed diets varying in soluble and insoluble fibres from co-products

The co-products from the industry are used to reduce costs in pig diets. However, the co-products used in pig diets are limited because of a high fibre content which is not digested by endogenous enzymes and is resistant to degradation in the small and large intestines. The aim of this study was to investigate digestibility of nutrients and energy, and energy utilisation in pigs fed diets with various soluble and insoluble dietary fibre (DF) from co-products. The experiment was performed as a 4 × 4 Latin square design (four diets and four periods) using four growing pigs (66.2 ± 7.8 kg) surgically fitted with a T-cannula in the end of the small intestine. The pigs were fed four experimental diets: low-fibre control (LF), high-fibre control (HF), high-soluble fibre (HFS) and high-insoluble fibre (HFI) diets. The apparent ileal digestibility (AID) and apparent total tract digestibility (ATTD) of ash, organic matter, CP, fat, carbohydrates, starch and non-starch polysaccharides (NSP) divided into cellulose and soluble and insoluble non-cellulosic polysaccharide residues were measured using chromic oxide as marker. The recovery of total solid materials, organic matter and total carbohydrates in ileal digesta in pigs fed the HF and HFS diets was higher than in pigs fed LF and HFI, whereas recovery of organic matter and total carbohydrates in faecal materials in the HFS diet was lowest (P < 0.05). AID of organic matter, total carbohydrates and starch was lowest for HFS diet (P < 0.05). ATTD of organic matter and CP was higher for LF diet compared with other diets (P < 0.05), whereas total NSP, cellulose and non-cellulosic polysaccharides residues were highest for HFS diet (P < 0.05). Lactic acid in ileal digesta was influenced by dietary composition (P < 0.05) whereas neither type nor level of DF affected short chain fatty acids. The digestible energy, metabolisable energy, net energy and retained energy intake were similar among diets without influence of DF inclusion (P > 0.05). The metabolisable energy:digestible energy ratio was lower when feeding the HFS diet because of a higher fermentative methane loss. Faecal nitrogen and carbon were positively correlated with DM intake and insoluble DF in the diets (P < 0.05), but nitrogen and carbon (% of intake) were similar among diets. The present findings suggest that high-DF co-products can be used as ingredients of pig diets when features of DF are considered.     

Effect of extrusion on trypsin inhibitor activity and nutrient digestibility of diets based on fish meal, soybean meal and white flakes

The effects of moist extrusion processing of diets containing fish meal (FM) and conventional defatted soybean meal (SBM) or untoasted defatted soybean meal (white flakes [WF]) on amino acid composition, trypsin inhibitor activity (TIA), and apparent total tract digestibility of nutrients were studied. Three diets with the nutritional characteristics of feeds for salmonid fish were formulated: one control based on FM as protein source and two others where 40% of total amino acids from FM were substituted by either SBM or WF. Each diet was fed to mink either as an unextruded mixture of the ingredients or as extruded pellets in order to determine the effect of extrusion processing. Extrusion did not change the amino acid composition of the diets significantly, but reduced the TIA of both diets containing soy products by approximately 76%. Intake of the unextruded WF diet was only one-third compared with the other diets. The dry matter concentration in faeces from mink fed diets containing soy products was significantly lower than in mink fed the FM diet. Digestibility of crude protein, all amino acids and fat was lower, but starch higher, in the unextruded WF diet than in the FM and SBM diets, whereas no significant differences were found among the extruded diets. Extrusion of the WF diet increased digestibility of protein and all amino acids. The greatest increase in digestibility after extrusion of the WF diet was observed for cysteine followed by tryptophan. Extrusion of the FM and SBM diets had no significant effect on amino acid digestibility. Digestibility of starch was, in general, increased by extrusion. It is concluded that the heat treatment involved in typical moist extrusion processing used for fish feed may be sufficient to inactivate most of the TIA in unheated soybean meal, and to increase digestibility of the protein in WF to approximately the same level as found for SBM and FM. Still, extrusion is a lenient process with minor effects on nutrient digestibility of diets containing fish meal or toasted soybean meal as major protein sources.