Dietary Digestible Energy Research Articles

Modelling changes in whole body and fillet fatty acid composition of Atlantic salmon with changing levels of dietary omega-3 intake

In this study, a fatty acid dilution model was coupled with a dynamic nutrient demand model to provide an integrated model capable of predicting the whole-body and fillet lipid and fatty acid levels of Atlantic salmon (Salmo salar) following a change in dietary fatty acid profile. Based on knowledge of the initial fish and dietary fatty acid compositions, diet digestible energy density, the water temperature and duration of feeding, the model demonstrated that it was possible to predict a range of parameters, including the growth, feed utilisation, whole-body and fillet (Norwegian Quality Cut; NQC) total lipid, and fatty acid levels of the fish. The model was validated against five separate experiments, including two farm-based trials with harvest size fish. Validation experiments involved fish ranging in size (initial weights to final weights) from 138 g/fish to 5138 g/fish and running for durations of between 66 and 323 days. For the laboratory experiments, prediction of growth, feed utilisation and fatty acid deposition proved to be highly predictable (R2 > 0.998). Fatty acid profiles from both short and long-term cage trials were also highly predictable. Despite the reduced level of weight change in the short-term cage trial, and the higher variability that was observed in growth performance, the fatty acid deposition still showed high levels of correlation (R2 > 0.996), between the modelled and measured fatty acid levels in the fish fillet. Departure from linearity was more evident in the long-term cage trial, but correlation still exceeded R2 > 0.995 for all treatments. Prediction of whole-body and NQC total lipid levels was less accurate, with correlations being R2 = 0.962 and R2 = 0.909 respectively. Model outputs were generally more accurate with greater weight change and/or experiment duration. The outcome of this study shows that the model developed here provides a useful tool for the estimation of the fatty acid composition of Atlantic salmon following a change in dietary fatty acid composition. This could help assist in the more judicious use of dietary long-chain omega-3 fatty acids for commercial salmon farming.

Efeito da inclusão de Ceratophyllum demersum cru e fermentado na dieta sobre o desempenho de crescimento e digestibilidade em juvenis de carpa capim, Cte-nopharyngodon Idella Val.

A 12-week feeding experiment was conducted to evaluate the growth performance, feed efficiency, digestibility and carcass composition of young grass carp Ctenopharyngodon idella (Val, 1844) (4.03±0.16 g) fed on a control diet and two experimental diets (38.5% crude protein). The experiment aimed to assess the utilization of raw hornwort Ceratophyllum demersum (HR) and fermented (HF) by adding 20% of each of the alternative ingredients separately to the control diet (C) to completely compensate barley, a portion of wheat bran and 20% of fish meal. Results indicated that all growth and feed efficiency parameters among groups were no significantly different (P>0.05) in specific growth rate (SGR), food conversion ratio (FCR), protein efficiency ratio (PER), and protein productive value (PPV) of fish fed HR and HF with the control diet. There was no effect (P>0.05) in stimulating digestibility (ADCtotal) when HR and HF were added to the diet. Both HR and HF produced significantly (P<0.05) higher satiation level associated with lower dietary digestible energy contents. The evacuation rate was not affected significantly (P>0.05) by the inclusion of raw or fermented hornwort. Whereas, the moisture, protein and lipid levels in carcass were similar (P>0.05) in all groups, except for the control diet (C), which recorded the highest ash level (P<0.05). In conclusion, the incorporation of raw or fermented hornwort up to 20% level was found to be not suitable, and there were adverse effects on the growth and feed efficiency of experimental fish.

Effects of betaine on growth performance and intestinal health of rabbits fed different digestible energy diets.

An experiment was conducted to determine the effects of betaine on growth performance and intestinal health in rabbits fed diets with different levels of digestible energy. During a 36-d experiment, a total of 144 healthy 35-d-old weaned New Zealand white rabbits with a similar initial body weight (771.05 ± 41.79g) were randomly distributed to a 2 × 3 factorial arrangement. Experimental treatments consisted of two levels of digestible energy (normal: 10.20 and low: 9.60MJ/kg) and three levels of betaine (0, 500, and 1,000mg/kg). Results indicated that rabbits fed the diet with low digestible energy (LDE) had reduced body gain/feed intake on days 1 to 14 and 1 to 36 (P < 0.05), increased the apparent total tract digestibility (ATTD) of neutral detergent fiber, acid detergent fiber (ADF), and n-free extract, and decreased the ATTD of gross energy (GE), crude fiber, and organic matter (OM; P < 0.05). The LDE diet upregulated the gene abundance levels of duodenum junctional adhesion molecule-3 (JAM-3) and downregulated the ileum toll-like receptor 4, myeloid differentiation factor 88, and interleukin-6 (IL-6; P < 0.05). Activities of amylase, lipase, trypsin, and the immunoglobulin M content in the jejunum were decreased in the LDE treatment group (P < 0.05). Dietary betaine supplementation increased the ATTD of GE, dry matter (DM), ADF, and n-free extract by LDE (P < 0.05). The villus height, crypt depth, and goblet cell numbers were decreased, and the villus-crypt ratio was increased in the duodenum (P < 0.05). The gene abundance levels of duodenum IL-2 were downregulated, and the duodenum JAM-2 and JAM-3 were upregulated (P < 0.05). Furthermore, the addition of betaine to the LDE diet increased the ATTD of GE, DM, and OM in rabbits (P < 0.05). Gene abundance levels of ileum IL-6 and duodenum JAM-3 were upregulated (P < 0.05). In summary, LDE diets can reduce the activity of intestinal digestive enzymes and decrease the ATTD of nutrients. However, the addition of betaine to LDE diets improved the intestinal barrier structure and nutrient ATTD in rabbits, with better results when betaine was added at an additive level of 500mg/kg.

Fecal amylase-treated neutral detergent fiber and ash contents as independent variables can predict metabolizable energy and coefficient of energy digestibility of diets for growing pigs without dietary information

The objectives of the present study were to develop prediction equations for digestible energy (DE), metabolizable energy (ME), and coefficient of energy digestibility (ED) of swine diets using fecal nutrients as independent variables without dietary information and to validate the prediction equations. A total of 262 fecal samples obtained from growing pigs fed 27 diets in 4 experiments were used to develop prediction equations for DE, ME, and ED. These equations were validated using 95 fecal samples obtained from growing pigs fed 12 diets in an additional experiment. The diets were based mainly on corn, soybean meal, and other plant-originated feed ingredients. In the digestibility experiments, feces and urine were quantitatively collected using the marker-to-marker procedure. Diet and fecal samples were analyzed for dry matter (DM), crude protein, ash, and amylase-treated neutral detergent fiber (aNDF). The DE of the 27 diets ranged from 12,164 to 18,301 kJ/kg DM and ME of 24 diets ranged from 11,603 to 16,657 kJ/kg DM. Coefficients of ED for the 27 diets ranged from 0.667 to 0.919. Fecal ash was positively correlated with DE (r = 0.81; P < 0.001), ME (r = 0.66; P < 0.001), and coefficient of ED (r = 0.67; P < 0.001) whereas fecal aNDF was negatively correlated with DE (r = –0.66; P < 0.001), ME (r = –0.74; P < 0.001), and coefficient of ED (r = –0.67; P < 0.001). The prediction equations developed using fecal nutrients were: DE (kJ/kg DM) = 15,077 + (13.72 × ash) – (4.65 × aNDF) (R2 = 0.71; P < 0.001); ME (kJ/kg DM) = 17,067 + (6.54 × ash) – (7.56 × aNDF) (R2 = 0.63; P < 0.001); and coefficient of ED = 0.881 + (0.00037 × ash) – (0.00028 × aNDF) (R2 = 0.57; P < 0.001) where nutrients are expressed as g/kg DM. Based on the regression analysis for validation of the equations, the prediction equations for DE and coefficient of ED using only fecal aNDF did not have mean bias or linear bias. In conclusion, DE values, ME values, and coefficient of ED for swine diets are correlated with fecal ash and aNDF concentrations and the energy values can be predicted using fecal ash and aNDF concentrations without dietary information.

Evaluation of multienzyme supplementation and fiber levels on nutrient and energy digestibility of diets fed to gestating sows and growing pigs.

The objective was to investigate the effect of a multienzyme blend (MEblend) and inclusion level on apparent total tract digestibility (ATTD) of energy and nutrients, as well as ileal digestibility of crude protein (CP) and amino acids (AA) in gestation diets with low (LF) or high-dietary fiber (HF) fed to gestation sows. For comparison, growing pigs were fed the same HF diets to directly compare ATTD values with the gestating sows. In experiment 1, 45 gestating sows (parity 0 to 5; 187 ± 28 kg bodyweight; BW) were blocked by parity in a 2 × 3 factorial arrangement and fed 2.2 kg/d of the HF (17.5% neutral detergent fiber; NDF) or LF (13% NDF) diet and one of three levels of MEblend (0.0%, 0.08%, and 0.1%) to determine impacts of MEblend on ATTD. Twenty-seven growing pigs (initial 35.7 ± 3.32 kg BW) were fed the same HF diet (5% of BW) and one of three MEblend inclusions. The MEblend at both 0.08% and 0.1% increased ATTD of energy, NDF, and acid detergent fiber (ADF) (P < 0.05) in gestating sows but ATTD of total non-starch polysaccharides (NSP) and its residues were not affected. Sows fed HF, regardless of MEblend, had greater ATTD of NDF, xylose, and total NSP (P < 0.05) in comparison to grower pigs. In experiment 2, ileal cannulas were placed in 12 gestating sows (parity 0 to 2; BW 159 ± 12 kg) to determine apparent and standardized ileal digestibility (AID and SID) of AA and NSP. In a crossover design, sows were fed the same six diets, as in experiment 1, and a nitrogen-free diet during five periods of seven days each to achieve eight replicates per diet. There was no interaction between diet fiber level and MEblend inclusion. Supplementation of MEblend to gestating sow diets did not impact SID of CP and AA regardless of dietary fiber level. The SID of His, Ile, Lys, Phe, Thr, Trp, and Val were 3% to 6% lower (P < 0.09) in HF than LF independent of MEblend. Supplementation of MEblend did not impact AID of NSP components, but sows fed HF had higher AID of arabinose (LF: 26.5% vs. HF: 40.6%), xylose (LF: 3.5% vs. HF: 40.9%), and total NSP (LF: 25.9% vs. HF: 40.0%) compared to sows fed LF (P < 0.05). Dietary supplementation of MEblend increased ATTD of nutrients, NSP, and energy in diets fed to gestating sows regardless of inclusion level, with MEblend having a greater incremental increase in diets with lower NDF levels. Inclusion of MEblend impacted neither SID of AA nor AID of NSP in low- or high-fiber gestation diets, but high-fiber diet, negatively affected SID of AA.

Effects of Aspergillus oryzae prebiotic on dietary energy and nutrient digestibility of growing pigs.

The objective of this study was to determine the effects of Aspergillus oryzae prebiotic (AOP) on nutrient digestibility in growing pigs fed high-fiber diets. Eighteen growing barrows (initial body weight = 50.6 ± 4.9 kg) were surgically equipped with a T-cannula at the distal ileum. Corn and soybean meal-based diets were formulated with fiber from cereal grain byproducts corn (distillers dried grains with solubles, DDGS), rice (rice bran, RB), or wheat (wheat middlings, WM) to meet or exceed all nutrient requirements for 50 to 75 kg growing pigs. Three additional diets were formulated to contain 0.05% AOP supplemented at the expense of corn in the DDGS diet (DDGS + AOP), RB diet (RB + AOP), and WM diet (WM + AOP). All diets contained 0.5% of titanium dioxide as an indigestible marker. Pigs were allotted randomly to a triplicated 6 × 2 Youden square design with six diets and two successive periods. Ileal digesta and fecal samples were collected for 2 d after a 21-d adaptation period, and dry matter (DM), gross energy (GE), crude protein (CP), ether extract (EE), neutral detergent fiber (NDF), and ash were analyzed to calculate apparent ileal digestibility (AID) and apparent total tract digestibility (ATTD). Standardized ileal digestibility (SID) of amino acids (AA) was calculated by correcting AID with basal endogenous AA losses from the same set of pigs. Pigs fed the DDGS+AOP diet had greater (P < 0.05) AID of EE compared with those fed the DDGS diet. However, supplementation of AOP did not (P > 0.05) affect AID of GE, DM, CP, NDF, ash or SID of AA of any high-fiber diet. Supplementation of 0.05% AOP increased (P < 0.05) ATTD of DM, GE, CP, NDF, and ash in DDGS, RB, and WM diets. Diet digestible energy was 35 kcal/kg greater (P < 0.05) in pigs fed AOP supplemented diets compared with those fed diets without AOP. In conclusion, supplementation of AOP increased ATTD of nutrients and energy value in high-fiber diets containing DDGS, RB, or WM.

93 Predicting Metabolizable Energy from Digestible Energy for Growing and Finishing Beef Cattle and Relationships to Prediction of Methane

Abstract Reliable predictions of metabolizable energy (ME) from digestible energy (DE) are necessary to prescribe nutrient requirements of beef cattle accurately. Our objectives were to add new data to a previously published database and re-evaluate the relationship between DE and ME and to describe and evaluate new methane prediction equations derived from the DE:ME relationship. The previous database, which included 87 treatment means from 23 respiration calorimetry studies was updated to evaluate the efficiency of converting DE to ME by adding 47 treatment means from 11 additional studies. Diets were fed to growing-finishing cattle under individual feeding conditions. A citation-adjusted linear regression equation was developed where dietary ME concentration (Mcal/kg of dry matter [DM]) was the dependent variable and dietary DE concentration (Mcal/kg) was the independent variable: ME = 1.0001 × DE – 0.3926. The slope did not differ from unity; therefore, the intercept defines the value of ME predicted from DE. For practical use, we recommend ME = DE - 0.39. Based on the relationship between DE and ME, the citation-adjusted loss of methane was calculated and yielded a citation-adjusted value of 0.2433 Mcal/kg of DMI. Recognizing that methane production decreases per unit of intake energy as DMI increases above maintenance, we also examined the relationship between multiples of maintenance intake and daily energy lost as methane. This citation-adjusted relationship was: CH4, Mcal/kg = 0.3344 – 0.05639 × multiple of maintenance. Both the 0.2433 value and the result of the intake-adjusted equation can be multiplied by DMI to yield an estimate of methane production. Further research is needed to determine whether coefficients to predict methane from DMI could be developed for specific diet types, levels of DMI relative to body weight, or other variables that affect the emission of methane.

Regression method-derived digestible and metabolizable energy concentrations of partially defatted black soldier fly larvae meal for broiler chickens and pigs

The energy value of partially defatted black soldier fly larvae meal (pBSFLM) was determined in 2 experiments with broiler chickens and growing pigs. Experiment (Exp.) 1 was conducted to evaluate the ileal digestible energy (IDE), metabolizable energy (ME), and nitrogen-corrected ME (MEn) of pBSFLM with broiler chickens, and Exp. 2 was conducted to evaluate the digestible energy (DE) and ME of pBSFLM in growing pigs. The index method using titanium dioxide was used in Exp. 1 whereas, the total collection method was used in Exp. 2, the pig study. Three experimental diets were prepared in each of the 2 studies: a corn-soybean meal basal diet (BD) and 2 test diets containing pBSFLM at either 100 or 200 g/kg to replace the energy-contributing ingredients in the BD. Eight replicate cages of broiler chickens at 16-d-old (6 birds per cage) in Exp. 1 or 8 barrows with a mean body weight of 20 kg in Exp. 2 were assigned to each diet. A linear increase (P < 0.05) was observed in the IDE concentration of the experimental diets in Exp. 1. With increasing dietary pBSFLM, linear and quadratic increases (P < 0.05) were observed in the MEn and ME concentrations in the diets, respectively. The inclusion of pBSFLM increased ME from 13.4 to 14.5 MJ/kg DM for 0 to 200 g/kg replacement of BD. When fed to broiler chickens, the regression-derived IDE, ME, and MEn concentrations in pBSFLM were 18.9, 19.8, and 17.7 MJ/kg DM, respectively. In Exp. 2, there was a linear decrease in DM digestibility and a linear increase in dietary DE concentration (P < 0.05) of experimental diets with increasing substitution of BD with pBSFLM. The metabolizability of dietary gross energy linearly decreased (P < 0.05) but the ME concentration quadratically increased (P < 0.05) as the replacement of BD with pBSFLM in the experimental diet increased from 0 to 200 g/kg. In pigs, the regression-derived DE and ME estimates were 21.0 and 19.7 MJ/kg, respectively. The results from this study showed that pBSFLM is a potential feed ingredient for inclusion in the diet formulation for broiler chickens and pigs.

92 Effects of Increasing Dose of a Novel E. coli Phytase on Total Tract Digestibility of Minerals and Energy in Pigs

Abstract The objective was to test the hypothesis that an increasing dose of a novel thermostable 6-phytase that was derived from E. coli and expressed in a Pichia Pastoris yeast (Superphy; Hanley International, LLC, Belmont, MA) increases apparent total tract digestibility (ATTD) of minerals and energy by pigs. Forty-eight barrows (initial weight: 22.61 kg) were housed in metabolism crates and fed 6 diets based on corn and soybean meal. The positive control (PC) diet contained P at the requirement. The negative control (NC) diet contained no feed phosphate, but contained 0, 250, 500, 1,000, or 2,000 phytase unit/kg. Feces were collected for 4 d after 5 d of adaptation. Dried and ground fecal samples were analyzed for dry matter, energy, Ca, P and other minerals. Data were analyzed using a model that included diet as fixed variable and contrast statements were used to compare PC and NC diets and to demonstrate linear and quadratic effects of phytase. Results indicated that ATTD of dry matter and energy and concentration of digestible energy in NC without phytase were greater (P &amp;lt; 0.05) than in PC, but ATTD of ash, K, Mg, Na, Cu, Fe, Mn, and Zn was not different between the 2 diets. There was no effect of phytase on ATTD of dry matter and energy or on digestible energy in diets. As dietary phytase increased, ATTD of ash and Mg increased (linear, P &amp;lt; 0.05) and ATTD of Ca and the standardized total tract digestibility (STTD) of P also increased (quadratic, P &amp;lt; 0.05), but ATTD of K, Na, Cu, Fe, Mn, and Zn was not affected by phytase. In conclusion, the novel enhanced E. Coli based phytase increased ATTD of Ca, P, and Mg and STTD of P if included in a diet containing Ca and P below requirements.

Predicting metabolizable energy from digestible energy for growing and finishing beef cattle and relationships to the prediction of methane.

Reliable predictions of metabolizable energy (ME) from digestible energy (DE) are necessary to prescribe nutrient requirements of beef cattle accurately. A previously developed database that included 87 treatment means from 23 respiration calorimetry studies has been updated to evaluate the efficiency of converting DE to ME by adding 47 treatment means from 11 additional studies. Diets were fed to growing-finishing cattle under individual feeding conditions. A citation-adjusted linear regression equation was developed where dietary ME concentration (Mcal/kg of dry matter [DM]) was the dependent variable and dietary DE concentration (Mcal/kg) was the independent variable: ME = 1.0001 × DE – 0.3926; r2 = 0.99, root mean square prediction error [RMSPE] = 0.04, and P < 0.01 for the intercept and slope. The slope did not differ from unity (95% CI = 0.936 to 1.065); therefore, the intercept (95% CI = −0.567 to −0.218) defines the value of ME predicted from DE. For practical use, we recommend ME = DE – 0.39. Based on the relationship between DE and ME, we calculated the citation-adjusted loss of methane, which yielded a value of 0.2433 Mcal/kg of dry matter intake (DMI; SE = 0.0134). This value was also adjusted for the effects of DMI above maintenance, yielding a citation-adjusted relationship: CH4, Mcal/kg = 0.3344 – 0.05639 × multiple of maintenance; r2 = 0.536, RMSPE = 0.0245, and P < 0.01 for the intercept and slope. Both the 0.2433 value and the result of the intake-adjusted equation can be multiplied by DMI to yield an estimate of methane production. These two approaches were evaluated using a second, independent database comprising 129 data points from 29 published studies. Four equations in the literature that used DMI or intake energy to predict methane production also were evaluated with the second database. The mean bias was substantially greater for the two new equations, but slope bias was substantially less than noted for the other DMI-based equations. Our results suggest that ME for growing and finishing cattle can be predicted from DE across a wide range of diets, cattle types, and intake levels by simply subtracting a constant from DE. Mean bias associated with our two new methane emission equations suggests that further research is needed to determine whether coefficients to predict methane from DMI could be developed for specific diet types, levels of DMI relative to body weight, or other variables that affect the emission of methane.

Animal‐defined resources reveal nutritional inadequacies for woodland caribou during summer–autumn

AbstractPopulations of woodland caribou (Rangifer tarandus caribou) are declining throughout their range and many are at risk of extirpation, yet the role of nutrition in these declines remains poorly understood, in part owing to a lack of information about available nutritional resources during summer. We quantified rates of intake of digestible protein and digestible energy by tame caribou foraging in temporary enclosures in the predominant plant communities of northeastern British Columbia, Canada, during summer–autumn and compared intake rates to daily requirements for protein and energy during lactation. We tested hypotheses related to the nutritional adequacy of the environment to support nutritional requirements during lactation (with and without replenishment of body reserves) and simulated scenarios of foraging by caribou in these plant communities to better understand how wild caribou could meet nutritional demands on these landscapes. Nutritional resources varied among plant communities across seasonal, ecological, and successional gradients; digestible energy intake per minute and per day were significantly greater in younger than older forests; dietary digestible energy and per‐minute and daily intake of digestible protein were greater, though not significantly so, in younger than older forests; and dietary digestible protein was greater in older than younger forests, though differences were not significant. Tame caribou were unable to satisfy protein and energy requirements during lactation, even without replenishment of body reserves, at most sites sampled. Further, foraging simulations suggested widespread nutritional inadequacies on ranges of wild caribou. Selection for habitats offering the best nutrition may mitigate some nutritional inadequacies, but given low availability of vegetation communities with high nutritional value, performance (e.g., calf production, growth, replenishment of body fat and protein) of caribou may be depressed at levels of nutrition documented herein. Our results, coupled with recent measurements of body fat of wild caribou in northeastern British Columbia, refute the hypothesis that the nutritional environment available to caribou during summer in northeastern British Columbia is adequate to fully support nutritional demands of lactating caribou, which has implications to productivity of caribou populations, recovery, and conservation.

Effects of corn processing and cattle size on total tract digestion and energy and nitrogen balance.

This study used 18 calves (295 ± 29 kg) and 18 yearlings (521 ± 29 kg) fed whole, cracked, or steam-flaked corn (SFC) to evaluate nutrient digestion and energy balance across different types of processed corn and sizes of cattle. Cattle were fed a diet comprised of 75% corn (dry matter [DM]-basis) from whole, cracked, or SFC to 2.5-times maintenance energy requirements. Subsequently, cattle were placed in individual stanchions, and urine and feces were collected together with measures of gas production via indirect calorimetry. Data were analyzed using the MIXED procedure of SAS. There was no interaction between corn processing and cattle size (P ≥ 0.40). Time spent ruminating (min/d) and rumination rate (min/kg DM intake [DMI]) were not affected by corn processing or cattle size. The eating rate (min/kg DMI) was faster (P < 0.01) for yearlings compared with calves. Total tract starch digestion was greatest (P = 0.01) for cattle fed SFC (97.5%), intermediate in cattle fed cracked (92.4%), and least in cattle fed whole corn (89.5%). Dietary digestible energy and metabolizable energy (Mcal/kg DMI) were greater (P ≤ 0.05) for cattle fed SFC compared with cracked or whole. A greater proportion of digestible energy was lost to heat production (P = 0.01) in cattle fed whole corn compared with cracked and tended to be greater (P = 0.08) in cattle fed SFC than cracked. Conversion of digestible energy to metabolizable energy in this study was more closely related to a dynamic model used to estimate metabolizable energy of feeds to dairy cows than to a linear model used to predict metabolizable energy of feeds to beef cattle. If library estimates of net energy for maintenance are correct, then retained energy (Mcal/d) should have been similar between each type of processed corn; however, retained energy was greater (P < 0.01) for cattle fed cracked compared with whole corn and tended to be greater (P = 0.06) compared with SFC. Yet, observed amounts of net energy based on measures of retained energy were not different (P ≥ 0.60) between cracked and SFC. Nitrogen balance was not affected (P ≥ 0.30) by corn processing or cattle size, although cattle fed cracked had numerically greater (P ≤ 035) N retention. These data indicate that physical processing of corn provides greater net energy to cattle in comparison to whole corn.

543 Late-Breaking: Development of a Model to Predict Dietary Metabolizable Energy from Digestible Energy in Beef Cattle

Abstract We aimed to assess whether predicting the metabolizable energy (ME) to digestible energy (DE) ratio (MDR), rather than a prediction of ME with DE, is feasible and to develop a model equation to predict MDR in beef cattle. For this, we constructed a literature database based on published data. A meta-analysis was conducted with 306 means from 69 studies containing both dietary DE and ME concentrations measured by calorimetry to test whether the exclusion of the y-intercept is adequate in the linear relationship between DE and ME. A random coefficient model with study as the random variable was used to develop equations to predict MDR in growing and finishing beef cattle. The developed equations were evaluated with other published equations. The no-intercept linear equation represented the relationship between DE and ME more appropriately than the equation with a y-intercept. Within our growing and finishing cattle data, the animal’s physiological stage was not a significant variable affecting MDR after accounting for the study effect (P = 0.213). The mean (± SE) of MDR was 0.849 (± 0.0063). Two linear equations with the dry matter intake and content of several dietary nutrients were developed to predict MDR. When using these equations, the observed ME was predicted with high precision (R2 = 0.92). The model accuracy was also high, as shown by the high concordance correlation coefficient (&amp;gt; 0.95) and small root mean square error of prediction (RMSEP), less than 5% of the observed mean. Moreover, a significant portion of the RMSEP was due to random bias (&amp;gt; 93%), without mean or slope bias (P &amp;gt; 0.05). We concluded that dietary ME in beef cattle could be accurately estimated from dietary DE and its conversion factor, MDR, using the two equations developed in this study.

Development of a model to predict dietary metabolizable energy from digestible energy in beef cattle.

Understanding the utilization of feed energy is essential for precision feeding in beef cattle production. We aimed to assess whether predicting the metabolizable energy (ME) to digestible energy (DE) ratio (MDR), rather than a prediction of ME with DE, is feasible and to develop a model equation to predict MDR in beef cattle. We constructed a literature database based on published data. A meta-analysis was conducted with 306 means from 69 studies containing both dietary DE and ME concentrations measured by calorimetry to test whether exclusion of the y-intercept is adequate in the linear relationship between DE and ME. A random coefficient model with study as the random variable was used to develop equations to predict MDR in growing and finishing beef cattle. Routinely measured or calculated variables in the field (body weight, age, daily gain, intake, and dietary nutrient components) were chosen as explanatory variables. The developed equations were evaluated with other published equations. The no-intercept linear equation was found to represent the relationship between DE and ME more appropriately than the equation with a y-intercept. The y-intercept (-0.025 ± 0.0525) was not different from 0 (P = 0.638), and Akaike and Bayesian information criteria of the no-intercept model were smaller than those with the y-intercept. Within our growing and finishing cattle data, the animal's physiological stage was not a significant variable affecting MDR after accounting for the study effect (P = 0.213). The mean (±SE) of MDR was 0.849 (±0.0063). The best equation for predicting MDR (n = 106 from 28 studies) was 0.9410 ( ± 0.02160) +0.0042 ( ± 0.00186) × DMI (kg) - 0.0017 ( ± 0.00024) × NDF(% DM) - 0.0022 ( ± 0.00084) × CP(% DM). We also presented a model with a positive coefficient for the ether extract (n = 80 from 22 studies). When using these equations, the observed ME was predicted with high precision (R2 = 0.92). The model accuracy was also high, as shown by the high concordance correlation coefficient (>0.95) and small root mean square error of prediction (RMSEP), <5% of the observed mean. Moreover, a significant portion of the RMSEP was due to random bias (> 93%), without mean or slope bias (P > 0.05). We concluded that dietary ME in beef cattle could be accurately estimated from dietary DE and its conversion factor, MDR, predicted by the dry matter intake and concentration of several dietary nutrients, using the 2 equations developed in this study.

Energy substrate metabolism in skeletal muscle and liver when consuming diets of different energy levels: comparison between Tibetan and Small-tailed Han sheep

The energy intake of Tibetan sheep on the harsh Qinghai–Tibetan Plateau (QTP) varies greatly with seasonal forage fluctuations and is often below maintenance requirements, especially during the long, cold winter. The liver plays a crucial role in gluconeogenesis and skeletal muscle is the primary tissue of energy expenditure in mammals. Both play important roles in energy substrate metabolism and regulating energy metabolism homeostasis of the body. This study aimed to gain insight into how skeletal muscle and liver of Tibetan sheep regulate energy substrate metabolism to cope with low energy intake under the harsh environment of the QTP. Tibetan sheep (n = 24; 48.5 ± 1.89 kg BW) were compared with Small-tailed Han sheep (n = 24; 49.2 ± 2.21 kg BW), which were allocated randomly into one of four groups that differed in dietary digestible energy densities: 8.21, 9.33, 10.45 and 11.57 MJ /kg DM. The sheep were slaughtered after a 49-d feeding period, skeletal muscle and liver tissues were collected and measurements were made of the activities of the key enzymes of energy substrate metabolism and the expressions of genes related to energy homeostasis regulation. Compared with Small-tailed Han sheep, Tibetan sheep exhibited higher capacities of propionate to glucose conversion and fatty acid oxidation and ketogenesis in the liver, higher glucose utilization efficiency in both skeletal muscle and liver, but lower activities of fatty acid oxidation and protein mobilization in skeletal muscle, especially when in negative energy balance. However, the Small-tailed Han sheep exhibited higher capacities to convert amino acids and lactate to glucose and higher levels of glycolysis and lipogenesis in the liver than Tibetan sheep. These differences in gluconeogenesis and energy substrate metabolism conferred the Tibetan sheep an advantage over Small-tailed Han sheep to cope with low energy intake and regulate whole-body energy homeostasis under the harsh environment of the QTP.

Dry matter, protein, and energy digestibility of diets for juvenile Pacific white leg shrimps (Litopenaeus vannamei) reared at different salinity levels

ABSTRACT: This study evaluated the effect of low, medium, and high-water salinity (5, 35, and 50 ppt) on the apparent dry matter, protein, and energy digestibility of two formulated and six commercial diets for juvenile whiteleg shrimp, Litopenaeus vannamei, in a 120-day trial. Digestibility was determined in vivo using chromic oxide as an inert diet marker. Hydrostability in pellets varied from 86.8% to 99.9%; dry matter digestibility varied from 49.1% to 64.1%; protein digestibility showed greater variations at all salinities (56.9%-85.8%); and energy digestibility ranged from 70.1 to 86.4%. Salinity had a significant effect on dry matter, protein, and energy digestibility. Using a principal component analysis (PCA) with a covariance matrix, our findings suggested that the E2 (fishmeal-based formulation) diet and 35 ppt salinity provided optimum hydrostability and digestibility to Pacific white leg shrimp juveniles.

Phenotypic correlation among morphometric traits in new zealand white rabbits reared under tropical condition

A total of 48 New Zealand White (NZW) rabbit was used for the phenotypic estimation study. After two weeks of birth, the kittens were introduced to commercial grower mash (CGM) and were fed solely on the commercial grower mash diets with the following characteristics; 17.5% crude protein, 16% crude fibre and 2500 kcal/kg diet digestible energy ad libitum. Morphometric traits such as Fore Limb (FL), Hind Limb (HL), Body Length (BL), Thigh Girth (TG), Abdominal Circumference (AC) and Leg Length (LL) in NZW rabbit were measured on the rabbit with the aid of measuring tape in centimetre (cm) at 4, 8 and 12 weeks of age. The first measurement was taken on the day of weaning (4 weeks). The data obtained was analysed using the simple linear correlation procedure of SAS analytical package to obtain the correlation between the various morphometric traits studied. The study lasted for 12 weeks. From the study the phenotypic correlations obtained were all positive and ranged between moderate (0.47, the lowest value) and high (0.89, the highest value) correlated value for all ages considered for the NZW rabbit. The result further showed that BL was highly correlated (&lt;70) with other morphometric trait at 4 and 12 weeks of age. Moderate correlation was recorded more at the 8 weeks of age of the rabbit when compared to 4 and 12 weeks of age. The TG and HL recorded the highest correlation value among the other morphometric traits at 4, 8 and 12 weeks of age. This shows that as the animal grows, there is a positive relationship between the various morphometric traits and further implies growth is more inclined in other part of the body than FL and LL immediately after weaning while it evened out after 4 weeks of age.

Inclusion of quebracho tannin extract in a high-roughage cattle diet alters digestibility, nitrogen balance, and energy partitioning.

Condensed tannins (CT) might improve animal and system-level efficiency due to enhanced protein efficiency and reduced CH4. This study evaluated the impact of quebracho tannin (QT) extract fed at 0%, 1.5%, 3%, and 4.5% of dry matter (DM), within a roughage-based diet on apparent digestibility of DM, organic matter (OM), fibrous fractions, and N retention and energy partitioning of growing steers (236 ± 16 kg BW). A Latin rectangle design with eight animals and four periods was used to determine the whole-animal exchange of CO2, O2, and CH4 as well as the collection of total feces and urine over a 48-h period, using two open-circuit, indirect calorimetry respiration chambers. Following the removal of steers from respiration chambers, rumen inoculum was collected to determine ruminal parameter, including volatile fatty acids (VFA) and ammonia. Animals were fed a 56.5% roughage diet at 1.7% BW (dry matter basis). Dry matter and gross energy intakes were influenced by the level of QT inclusion (P ≤ 0.036). Digestibility of DM, OM, and N was reduced with QT inclusion (P < 0.001), and fiber digestibility was slightly impacted (P > 0.123). QTs altered the N excretion route, average fecal N-to-total N ratio excreted increased 14%, and fecal N-to-urinary N ratio increased 38% (P < 0.001) without altering the retained N. Increased fecal energy with QT provision resulted in reduced dietary digestible energy (DE) concentration (Mcal/kg DM; P = 0.024). There were no differences in urinary energy (P = 0.491), but CH4 energy decreased drastically (P = 0.007) as QT inclusion increased. Total ruminal VFA concentration did not differ across treatments, but VFA concentration increased linearly with QT inclusion (P = 0.049). Metabolizable energy (ME) was not affected by the QT rate, and the conversion efficiency of DE-to-ME did not differ. Heat energy decreased (P = 0.013) with increased QT provision likely due to changes in the DE intake, but there was no difference in retained energy. There were no differences for retained energy or N per CO2 equivalent emission produced (P = 0.774 and 0.962, respectively), but improved efficiency for energy retention occurred for 3% QT. We concluded that QT provided up to 4.5% of dry matter intake (about 3.51% of CT, dry matter basis) does not affect N and energy retention within the current setting. Feeding QT reduced energy losses in the form of CH4 and heat, but the route of energy loss appears to be influenced by the rate of QT inclusion.

Prediction of the diet energy digestion using kernel extreme learning machine: A case study with Holstein dry cows

In order to effectively evaluate the diet nutritional and feeding value, it is essential to accurately predict the indicators of diet energy digestion of dairy cows, thus further optimizing feed formulation and improving feeding management. Traditional mathematical models used to predict the main indicators of diet energy digestion of dairy cows are usually based on linear regression (LR) method. However, as a typical parametric model, the LR-based method is limited by regression function assumption, and the inaccurate assumed function sometimes leads to the learned regression model biased from the ground-truth one. In this study, we propose a kernel extreme learning machine (KELM) technique to predict the indicators of Holstein dry cows' diet digestible energy (DE) and energy digestibility (ED). KELM is a typical non-parametric machine learning model, which does not require any specific assumptions about the regression function in advance. The learned modal by KELM can well fit the actual one only by learning the training sample data in most cases. To evaluate prediction accuracy effectively, we compared the KELM technique with traditional parametric prediction LR model and other commonly used non-parametric models such as radial basis function artificial neural network, support vector machine and standard extreme learning machine methods. The required sample data is obtained from actual feeding and digestion experiments. The prediction results indicate that the proposed KELM-based prediction technique is superior to other methods in most performance metrics for prediction of the DE and ED indicators of diet energy digestion of Holstein dry cows. In particular, it has higher prediction accuracy than traditional LR-based prediction method, and can predict DE and ED better under small samples conditions. The developed KELM-based prediction model may be utilized to provide key decision support information to animal nutrition experts, livestock farmers and feed suppliers. The presented model is also exploited as a potential tool for accurate evaluation of dairy cows diet feeding effect.

Feed‐based common carp farming and eutrophication: is there a reason for concern?

AbstractMetadata from 70 research articles on Cyprinus carpio digestibility published between 1973 and 2017, covering 71 feed ingredients, were analysed. Interquartile range (IR) of nitrogen (N) and phosphorus (P) content in feedstuffs was 5–8% and 0.7–1.2% of dry matter, respectively, with digestible N:P 7.2:1–44.1:1. IR of N digestibility (79–99%) was high, whereas IR of P digestibility (27–47%) was rather poor. Dietary energy digestibility (gross energy and non‐protein energy) was &gt;76%. Higher P in feedstuffs caused significant negative interferences for N digestibility. IR of nutrient content in carp faeces was estimated at 0.5–1.7% N and 0.4–0.9% P. Considering the metabolic losses, the carp excreta have an ‘eutrophic’ N:P ratio (2.1:1–5.8:1). Eutrophication potential from feeding seems linked to P digestibility followed by bad protein profile of diets. While brewery wastes, microbial protein and natural prey offer high P digestibility (75–90%), large knowledge gaps still exist in P digestibility of various ingredients. Thermal processing does not always improve P digestibility; acidic pre‐incubation with phytases (optimum: 1500–2000 IU kg−1 feed) is worth exploring. Under semi‐intensive system, digestible ‘supplementary’ nutrients (N: 3.3–4.9%, P: 0.2–0.5%; even lower) can support at least 0.6–1.2 thermal growth coefficient (reasonable growth) and be ecologically relevant. We further considered validity of data within experimental conditions; effects on N/P utilization; non‐faecal losses (IRs 17–59% of N intake; 9–18% of P intake); and controversies over eutrophication. Recent eutrophication of carp fishponds might have been rather ‘management‐driven’ than carp's biological limitations. Ameliorative measures are outlined.