Respiration Calorimetry Research Articles

Evaluating the Net Energy Requirements for Maintenance Based on Indirect Calorimetry and Heart Rate Monitoring in Gestating Sows

The objectives of this study were (1) to determine the net energy requirements for the maintenance of gestating sows based on indirect calorimetry, and (2) to explore the feasibility of predicting the net energy requirements for the maintenance of gestating sows based on daily heart rate monitoring. In Exp. 1, six Landrace × Yorkshire crossbred reproductive sows with an initial body weight of 229.5 ± 14.9 kg at d 56 of gestation were randomly assigned to six diverse energy feeding levels using a 6 × 6 Latin square design. The experimental diet was formulated using corn, soybean meal, and wheat bran as major ingredients, and the six feeding levels were set as 1.2, 1.4, 1.6, 1.8, 2.0, and 2.2 times metabolizable energy for maintenance (100 kcal ME/kg BW0.75·d−1), respectively. The animal trial lasted for six periods with 9 days per period, encompassing 5 days of adaptation, 3 days of calorimetry in fed state, and 1 day of calorimetry in fasting state. In Exp. 2, six Landrace × Yorkshire crossbred pregnant sows with an initial body weight of 232.5 ± 12.5 kg at d 64 were fed a corn–soybean meal diet. All sows were tested in a respiratory calorimetry chamber for a 4 day calorimetry test. The heat production of the gestation sows was measured every 5 min using indirect calorimetry, and the heart rate of the gestating sows was recorded every minute using a belt-shape monitor. The results showed that the net energy requirements for the maintenance of gestating sows significant increased as the gestational stage progressed (p < 0.05), and a linear regression model revealed the average net energy requirement for the maintenance of gestating sows was 410 kJ/BW0.75 d−1 during late gestation (days 70–110). Moreover, the average heart rate of the gestating sows was 84 bpm, and the mathematical model developed to predict the net energy requirements for the maintenance of gestating sows was NEm(kcal/h)=19901+exp⁡[136−HR(bpm)43]. In conclusion, the average net energy requirement for the maintenance of sows during late gestation was 410 kJ/BW0.75 d−1, and the utilization of the heart rate monitoring method was found to provide a relevant, accurate prediction for the net energy requirements of sows.

PSIX-23 Evaluation of number of goats grazing grass-based pasture for estimation of methane emission using GreenFeed system

Abstract The objective of this study was to evaluate the number of goats in pasture grazing on methane (CH4) emissions estimates using the GreenFeed system (GFS). The study involved growing meat goats, approximately 1.2 yr old and body weight (BW) of 23.9 ± 0.63 kg, over seven 2-wk periods. In periods 1, 2, and 3, 24 goats were used (Treatment 1: G-24), while periods 4 and 5 involved 18 goats (Treatment 2: G-18), and periods 6 and 7 used 12 goats (Treatment 3: G-12). The pasture area was divided into three paddocks for grazing, except during gas measurements in a stationary respiration calorimetry system (SCS) room for 2 d, where goats were fed fresh forage from the same pastureland. The GFS was programmed to dispense pellets and measured gas at specific intervals of the day (i.e., at 0700-0800 h, 1300-1400 h, 1900-2000 h, and 0100-0200 h), provided 120 g/d of concentrate pellets to attract goats for gas measurements. Statistical analysis using mixed model procedures of SAS included SCS data from preceding and succeeding periods as covariates for GFS gas data analysis. Daily dry matter (DM) intake was greater (P < 0.001) in G-12 compared with G-24 and G-18, but when expressed g/kg BW, intakes were similar (P = 0.081) across treatments. Conversely, digested DM and gross energy intakes were greater (P < 0.001) in G-24 than in G-18 and G-12 (494, 509, and 577 g/d and SE = 21.3 and 7.91, 8.10, and 9.20 MJ/d and SE = 0.359 for G-24, G-18, and G-12, respectively). Daily CH4 production was unaffected (P = 0.254) by treatment (26.6, 25.2, and 26.1 g/d; SE = 0.819), despite variations in daily GFS visits by goats (3.26, 2.61, and 2.53 visits/d and SE = 0.106 for G-24, G-18, and G-12, respectively; P < 0.001). However, CH4 emissions in g/kg DM intake or digestible DM intake differed among treatments, with G-18 intermediate between G-24 and G-12 (35.6, 33.4, and 32.0 g/kg DM intake, SE = 1.02, P = 0.024; 54.1, 51.2, and 48.9 g/kg digestible DM intake, SE = 1.71, and P < 0.001 for G-24, G-18, and G-12, respectively). Carbon dioxide production, expressed in g/d and g/kg DM intake, was greater in G-12 and G-18 compared with G-24. Heat production ranked greatest in G-12, followed by G-18 and G-24. Regardless of treatment, CH4 emissions in g/d, g/kg DM intake or g/kg digestible DM intake were greater in GFS than in SCS (25.5 and 9.56 g/d, 33.8 and 14.4 g/kg DM intake, and 51.2 and 23.8 g/kg digestible DM intake for GFS and SCS, respectively; P < 0.001). In conclusion, differences in CH4 emissions in g/kg DM intake and digestible DM intake among treatments suggests that number of animals in grazing pasture may influence CH4 emission estimates in goats.

91 Awardee Talk: Using respiration calorimetry to estimate energy balance to estimate energy balance and methane emissions

Abstract Understanding relationships between chemical components of the diet and methane production will allow nutritionists to develop formulation strategies to decrease methane emissions. Diets that produce acetate liberate hydrogen that can be used by methanogenic archaea to produce methane. Propionate is a hydrogen sink and diets that lead to increased propionate production decrease acetate and methane production. The objective was to evaluate relationships between methane emissions and dietary chemical components and feed intake using published databases and make diet formulation recommendations that could be used to decrease methane production in finishing beef cattle. A total of 263 treatment mean observations from respiration calorimetry studies with beef cattle and dairy steers and heifers were used to evaluate relationships between methane emissions, dietary chemical components, and feed intake. Among the chemical components evaluated, dietary neutral detergent fiber and starch were strongly related to methane yield. The relationship between dietary ether extract and methane yield was variable and there was no relationship between dietary crude protein concentration and methane yield. Additionally, the ratio of metabolizable energy relative to gross energy intake had a strong relationship to methane yield. Formulation strategies to increase dietary starch and decrease dietary neutral detergent fiber should allow the feedlot industry to decrease enteric methane production.

Determining Appropriate Numbers and Times of Daily Measurements Using GreenFeed System to Estimate Ruminal Methane Emission of Meat Goats.

The study was conducted to determine appropriate numbers and times of daily gas measurements to estimate total daily methane (CH4) emission of meat goats using a GreenFeed system (GFS). A replicated 4 (four measurement protocols) × 4 (four periods) Latin square design was employed with 16 Boer wethers in a confinement pen setting. Measurement protocols entailed three (G-3T; 0600-0700, 1400-1500, and 2200-2300 h), four (G-4T; 0700-0800, 1300-1400, 1900-2000, and 0100-0200 h), and six (G-6T; 0800-0900, 1200-1300, 1600-1700, 2000-2100, 0000-0100, and 0400-0500 h) times for daily measurement periods in GFS. The fourth protocol was continuous measurement over 24 h with animals in an open-circuit respiration calorimetry system (CS). Oat hay was given in individual feeders, and a small predetermined quantity of a pelleted concentrate supplement (bait) was dispensed by the GFS or manually offered for the CS. Overall, total dry matter (DM) intake (614, 625, 635, and 577 g/day for CS, G-3T, G-4T, and G-6T, respectively; SEM = 13.9) and digestible DM intake (359, 368, 374, and 320 CS, G-3T, G-4T, and G-6T, respectively; SEM = 15.9) were lower for CS than for G-3T, G-4T, and G-6T (p < 0.05), but these variables were not different among the GFS protocols. There was a significant (p < 0.001) effect of measurement protocol on CH4 emission in g/day (11.1, 25.6, 27.3, and 26.7 for CS, G-3T, G-4T, and G-6T, respectively; SEM = 1.11), g/kg DM intake (19.3, 46.4, 43.9, and 42.4 for CS, G-3T, G-4T, and G-6T, respectively; SEM = 2.03), and g/kg body weight (0.49, 1.11, 1.18, and 1.16 for CS, G-3T, G-4T, and G-6T, respectively; SEM = 0.052), with values being much lower for CS than for G-3T, G-4T and G-6T. Conversely, CH4 emission was similar among the GFS protocols despite differences in the time and number of daily visits (2.03, 2.76, and 3.75 visits for G-3T, G-4T, and G-6T, respectively; SEM = 0.114; p < 0.001). Pearson correlation (r) analysis indicated a moderate to high (p < 0.05) correlation between CS and G-3T (r = 0.62 for CH4 in g/day and r = 0.59 for CH4 in g/kg BW), CS and G-4T (r = 0.67 for CH4 in g/day and r = 0.76 for CH4 in g/kg BW), and CS and G-6T (r = 0.70 for CH4 in g/day and r = 0.75 for CH4 in g/kg BW). However, the correlation coefficient for CH4 in g/kg DM intake was low between CS and G-3T (r = 0.11) and CS and G-6T (r = 0.31) but slightly greater between CS and G-4T (r = 0.47). In conclusion, the results suggest that CH4 emissions using GFS in a confinement setting were greater compared with the CS in goats, but CH4-emission estimation using the GFS correlated with the CH4 emission in the CS system with a stronger relationship for the four times of daily measurements.

Research Note: Effect of fasting time on the fasting heat production, blood metabolites, and body components of layer-type pullets

Fasting heat production (FHP) is used to assess the maintenance net energy requirement of animals. Herein, the FHP of layer-type pullets was estimated. In trial 1, 16 40-day-old Jingfen layer-type pullets were divided into 4 groups of 4 chickens and placed in 4 respiratory chambers. Pullets had free access to feed and water. After 4-d acclimatization, feed was withdrawn, and chickens were measured for FHP for 3 consecutive days. In trial 2, twenty-four 40-day-old pullets were placed in 4 respiratory calorimetry chambers, with 6 pullets per chamber. After 4-d acclimatization, one chamber was randomly selected and all pullets in the chamber was sampled at 5, 25, 50, or 65 h after feed withdrawal. The result showed that FHP declined with fasting time and reached the lowest level between 48 and 72 h. Respiratory quotient was decreased (P < 0.05) between 24 and 48 h compared with that in the first 24 h after fasting. The FHP in the light period showed a significant to decline with fasting time (P < 0.01), whereas the FHP in the dark period was decreased (P < 0.01) 24 h after fasting. Body weight, thigh mass, and abdominal fat decreased (P < 0.05) at 25 h after fasting. Serum glucose were increased (P < 0.01) and while triglycerides were significantly decreased (P < 0.01) at 50 h compared with that at 5 and 25 h time point. The result suggests that the adequate measuring period for FHP for layer-type pullets is from 24 to 48 h after fasting. The FHP of 7-wk-old layer-type pullets was 562.20 kJ/kg of BW0.75/d under a 10-h light and 14-h dark lighting regime.

Minimum methionine requirement in adult cats as determined by indicator amino acid oxidation.

There is a lack of empirical data on the dietary Met requirement, in the presence of Cys or cystine, in adult cats. Thus, the aim of this study was to determine the Met requirement, in the presence of excess Cys, in adult cats at maintenance using the indicator amino acid oxidation (IAAO) technique. Six adult neutered male cats were initially selected and started the study. Cats were adapted to the basal diet sufficient in Met (0.24% dry matter, DM) for 14 d prior to being randomly allocated to one of eight dietary levels of Met (0.10%, 0.13%, 0.17%, 0.22%, 0.27%, 0.33%, 0.38%, and 0.43% DM). Different dietary Met concentrations were achieved by supplementing the basal diet with Met solutions. Alanine was additionally included in the solutions to produce isonitrogenous and isoenergetic diets. Cats underwent a 2-d adaptation period to each experimental diet prior to each IAAO study day. On IAAO study days, 13 meals were offered corresponding to 75% of each cat's daily food allowance. The remaining 25% of their daily food intake was offered after each IAAO study. A bolus dose of NaH13CO3 (0.44mg kg-1) and l-[1-13C]-phenylalanine (13C-Phe; 4.8mg kg-1) were provided in fifth and sixth meals, respectively, followed by a constant dose of 13C-Phe (1.04mg kg-1) in the next meals. Breath samples were collected and total production of 13CO2 was measured every 25min through respiration calorimetry chambers. Steady state of 13CO2 achieved over at least three breath collections was used to calculate oxidation of 13C-Phe (F13CO2). Competing models were applied using the NLMIXED procedure in SAS to determine the effects of dietary Met on 13CO2. Two cats were removed from the study as they did not eat all meals, which is required to achieve isotopic steady. A breakpoint for the mean Met requirement, with excess of Cys, was identified at 0.24% DM (22.63mg kg-1) with an upper 95% confidence limit of 0.40% DM (37.71 mg·kg-1), on an energy density of 4,164 kcal of metabolizable energy/kg DM calculated using the modified Atwater factors. The estimated Met requirement, in the presence of excess of Cys, is higher than the current recommendations proposed by the National Research Council's Nutrient Requirement of Dogs and Cats, the Association of American Feed Control Officials, and the European Pet Food Industry Federation.

Effects of glucose release kinetics of extruded-maize diet on energy utilization of growing pigs

The precise energy requirement of swine should not only meet the static parameters of net energy but also consider the dynamic supply of glucose release. The effects of glucose release characteristics on nitrogen and energy utilization of growing pigs were conducted by the energy metabolism in vivo using open-circuit respiratory calorimetry and the hydrolysis in vitro of glucose release. Sixteen castrated boars were randomly divided into two groups (Raw maize group and Extruded maize group, RAW and EXT). Maize in the RAW diet was completely replaced by extruded-maize in the EXT diet. In vitro studies showed that extrusion treatment had a rapid and huge glucose release of maize (P < 0.05). The metabolizable energy (ME) in EXT was higher than that in RAW (P = 0.002), but no difference in net energy (NE) was observed (P = 0.864). EXT had higher crude protein (CP) apparent digestibility (P = 0.035) but lower nitrogen deposition (P < 0.001) due to higher urinary nitrogen (UN) excretion (P < 0.001). Extrusion treatment changed the proportion of heat production of carbohydrates, fat, and protein. EXT presented higher oxidation of protein (OXP, P < 0.001) and fat (OXF, P = 0.025) and lower oxidation of carbohydrates (OXCHO, P = 0.003). There was no difference in retained energy (RE) between the two groups (P = 0.803). Extrusion treatment can accelerate the glucose release of maize, and the extruded maize fully replacing raw maize in the diet can enhance ME of growing pigs, and the ratio of nutrient oxidation to energy supply was altered, resulting in lower protein deposition and energy utilization.

Comparative study of apparent metabolizable energy and net energy values of dephenolized cottonseed proteins for laying hens

Optimizing the energy utilization of nutrients and ensuring maximum benefits are continuous goals for livestock producers. The net energy (NE) value of feed reflects its nutritional value in the precision feeding system. An experiment was conducted to determine the apparent metabolizable energy (AME) and NE values of 3 types of dephenolized cottonseed protein (DCP) for Hy Line Brown hens aged 42 to 45 weeks using the reference diet substitution method. A reference diet based on corn soybean meal was used to meet the nutritional needs of Hy Line Brown laying hens. To render the crude protein and energy values of the 3 test diets similar, 10.5%, 12%, and 16% of the gross energy yielding ingredients from the reference diet were replaced with DCP 1, DCP 2, and DCP 3, respectively. The birds were fed 4 diets during a 7-d adaptation period. After the dietary adaptation period, 2 birds per replicate from each treatment group were placed in an individual open circuit respiratory calorimetry chamber for a 3-d experimental period. Daily O2 consumption and CO2 production were recorded, and excreta samples were collected. The AME values of DCP 1, DCP 2, and DCP 3 were 3,049.05, 2,820.13, and 2,982.31kcal/kg of dry matter (DM), respectively. The NE values of DCP 1, DCP 2, DCP 3 were 1,475.77, 1,910.31, and 1,905.37kcal/kg of DM, respectively, and the NE:AME ratios were 48.40%, 67.74%, and 63.89%, respectively. Our data show that the AME value of DCP does not reflect the nutritional value of the feed. The NE value of DCP with a high ME value was not necessarily high.

Effect of live yeast supplementation on energy partitioning and ruminal fermentation characteristics of steers fed a grower-type diet in heat-stress conditions.

The objective of this trial was to determine the influence of live yeast supplementation (LY), environmental condition (ENV), and their interaction (TRT) on energy partitioning, nitrogen metabolism, and ruminal fermentation dynamics of steers receiving a grower-type diet. The effects of LY and ENV were investigated using a 2 × 2 crossover design that spanned five periods. Eight Angus-crossbred steers were randomly split into pairs and housed in four outdoor pens outfitted with an individualized feeding system. Animals were limit-fed a grower diet (DIET) at 1.2% shrunk body weight (SBW) with no live yeast supplementation (NOY) or a grower diet top-dressed with 10 g LY/d for 14 d (1.2 × 1012 CFU/d). On days 13 and 14, animals were subjected to one of two ENV conditions, thermoneutral (TN; 18.4 ± 1.1 °C, 57.6 ± 2.8% relative humidity [RH]) or heat stress (HS; 33.8 ± 0.6 °C, 55.7 ± 2.7% RH), in two side-by-side, single-stall open-circuit, indirect respiration calorimetry chambers. Data were analyzed using a random coefficients model. Carryover effects were examined and removed from the model if not significant. Gross (GE), digestible, metabolizable, heat, and retained energies were not influenced by DIET, ENV, or TRT (P ≥ 0.202). Gaseous energy, as a percentage of GE, tended to increase during HS (P = 0.097). The only carryover effect in the study was for oxygen consumption (P = 0.031), which could be attributed to the tendency of NOY (P = 0.068) to have greater oxygen consumption. DIET, ENV, or TRT (P ≥ 0.154) had no effects on total animal methane or carbon dioxide emissions. Similarly, DIET, ENV, or TRT (P ≥ 0.157) did not affect ruminal pH, redox, protozoa enumeration, ruminal ammonia concentrations, and acetate-to-propionate ratio. Propionate concentrations were the greatest in animals in TN conditions receiving LY (P = 0.034) compared to the other TRT. This effect is mirrored by TN-LY tending to have greater acetate concentrations (P = 0.076) and total VFA concentrations (P = 0.065). Butyrate concentrations tended to be greater for animals fed LY (P = 0.09). There was a tendency for LY to have elevated numbers of Fusobacterium necrophorum (P = 0.053). Although this study lacked effects of LY on energy partitioning, nitrogen metabolism, and some ruminal parameters during HS, further research should be completed to understand if LY is a plausible mitigation technique to enhance beef animals' performance in tropical and sub-tropical regions of the world.

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.

Prediction of methane per unit of dry matter intake in growing and finishing cattle from the ratio of dietary concentrations of starch to neutral detergent fiber alone or in combination with dietary concentration of ether extract.

Previous research demonstrated that a fixed value of 0.2433 (SE = 0.0134) Mcal of CH4/kg of dry matter intake (DMI) could be used to predict CH4 production with accuracy and precision on par with similar equations in the literature. Slope bias was substantially less for the fixed-coefficient equation than noted for the other DMI- or gross energy intake (GEI)-based equations, but mean bias was substantially greater, presumably reflecting the failure of the fixed-coefficient approach to account for dietary factors that affect CH4 production. In this article, we report on the use of the dietary ratio of concentrations of starch to neutral detergent fiber (NDF) and dietary ether extract (EE) concentration to improve the accuracy and precision of the fixed-coefficient equation. The same development data set used to create the fixed-coefficient equation was used in the present study, which included 134 treatment means from 34 respiration calorimetry studies. Based on stepwise regression with dietary NDF, starch, crude protein, EE, and the starch:NDF ratio as possible dependent variables, the starch:NDF ratio and EE were the only dietary variables selected (P ≤ 0.15). The study-adjusted relationship with the starch:NDF ratio (r2 = 0.673; root mean square error [RMSE] = 0.0327) was: Mcal of CH4/kg of DMI = 0.2883 − 0.03474 × starch:NDF; whereas the relationship with a model that included both starch:NDF ratio and dietary EE (r2 = 0.738; RMSE = 0.0315) was: Mcal of CH4/kg of DMI = 0.3227 − 0.0334 × starch:NDF − 0.00868 × % EE. A previously published independent data set with 129 treatment means from 30 respiration calorimetry studies was used to evaluate these two equations, along with two additional equations in which g/d of CH4 was predicted directly from DMI, starch:NDF ratio, and/or dietary EE. The two Mcal of CH4/kg of DMI equations had superior fit statistics to the previously published 0.2433 Mcal of CH4/kg of DMI equation, with a substantial decrease in mean bias and improved concordance correlation coefficients. Moreover, the Mcal of CH4/kg of DMI equations resulted in improved fit relative to direct prediction of g/d of CH4 from DMI, the starch:NDF ratio, and % EE. Based on these results, further evaluation of the dietary ratio of starch-to-NDF concentrations and EE concentration to predict methane production per unit DMI in beef cattle is warranted.

Comparison of the accuracy of resting energy expenditure assessment using bioimpedance analysis and indirect respiratory calorimetry in children with simple obesity

Background: Assessment of resting energy expenditure (REE) is necessary for the formation of a diet for obesity patients. The «gold standard» for assessment of resting energy expenditure (REE) is indirect respiratory calorimetry. Currently, bioimpedance analyzers are increasingly being used in clinical practice to assess energy consumption at rest, including in obese children. However, the accuracy of such an assessment remains unclear.Aims: To determine the accuracy of the assessment of resting energy expenditure using bioimpedance analysis in children with simple obesity compared with indirect respiratory calorimetry.Materials and methods: Resting energy expenditure was assessed by bioimpedance analysis, Harris-Benedict formula and indirect respiratory calorimetry in all obese children. Comparability of methods was assessed using the Bland-Altman analysis.Results: The study included 320 children aged 7 to 17 years with simple obesity.Resting energy expenditure assessed by bioimpedance analysis was on average 232 kcal lower than the actual. A significant CI (-448 to 912 kcal) was revealed, as well as a large LOA from -514 to 979 kcal. REE calculated by the Harris-Benedict formula on average corresponded to the actual one, and CI varied from -38 to 27 kcal. However, large LOA from -514 to 979 kcal, indicating a high individual variability of resting energy consumption.Conclusions: Bioimpedance analyzers underestimate REE in obese children compared to indirect respiratory calorimetry and the Harris-Benedict formula. Given the significant discrepancies in the accuracy of REE assessment, bioimpedance analysis cannot be considered as an alternative to indirect respiratory calorimetry to assess resting energy in children with simple obesity.

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.

Metabolizable and Net Energy Values of Expanded Cottonseed Meal for Laying Hens and Broiler Chickens.

Three experiments were conducted to determine the metabolizable energy (ME) and net energy (NE) values of expanded cottonseed meal (ECSM) for broilers aged 14–16 days (Experiment 1), broilers aged 28–30 days (Experiment 2), and 45-week-old Hy-Line Brown hens (Experiment 3). Reference diets based on corn-soybean meal were used to meet the nutritional needs of the birds. The test diets contained ECSM as basis, which was used to replace 18.5% of the gross energy-yielding ingredients from the reference diet. The birds were fed a commercial feed before the experimental period. After the dietary adaptation period, six birds per replicate (Experiment 1) and two birds per replicate (Experiments 2 and 3) for each treatment group were placed in an individual open-circuit respiratory calorimetry chamber for 3 days. Daily O2 consumption and CO2 production were recorded, and excreta samples were collected. The ME and NE values of ECSM were determined using the substitution method. The apparent metabolizable energy (AME) values of ECSM for experiments 1, 2, and 3 were 2605.85, 2178.31, and 2782.60 kcal/kg of dry matter (DM), respectively. The NE values were 1655.23, 1196.64, and 1538.19 kcal/kg of DM, respectively. The NE:AME ratios of ECSM were 63.52%, 54.93%, and 55.29%, respectively. Our data showed that the ME and NE values of ECSM differed across various growth stages and types of chickens. These results demonstrate that the appropriate ME and NE should be used in the design of different feed formulas for specific growth stages and types of chickens.

Effects of an array of dietary treatments and length of feeding on ruminal methane emission and other variables in hair sheep

Eighteen Katahdin sheep ewes (initial body weight [BW] = 73.7 ± 1.76 kg and age = 5.2 ± 0.56 yr) and 18 St. Croix ewes (54.7 ± 1.33 kg BW and 4.1 ± 0.42 yr) were used in an experiment to determine effects of dietary level of Sericea lespedeza (Lespedeza cuneata; 5.8% condensed tannins and 10.3 % crude protein, dry matter [DM] basis) and other supplemental ingredients on BW, feed intake, digestion, energy metabolism, ruminal methane emission, and levels of blood and ruminal fluid constituents. Diets were consumed ad libitum and included a concentrate supplement at approximately 0.45 % BW (DM). Alfalfa (Medicago sativa) was the basal forage for control (CON), ionophore (ION; lasalocid at 33 mg/kg DM), coconut oil (3%; CCO), and soybean oil (3%; SBO) diets, and forage in moderate- and high-lespedeza diets was a 1:1 mixture of alfalfa and lespedeza and all lespedeza, respectively (ALF:LES and LES, respectively). There were four 6-wk periods, with digestion assessed in wk 4 and measures with a respiration calorimetry system in wk 5. Although there was a three-way interaction involving dietary treatment, breed, and period, average forage intake was greater for LES than for CON, ION, CCO, SBO (P < 0.05), and ALF:LES (P = 0.062; 988, 1072, 1265, 987, 951, and 1057 g/day for CON, ALF:LES, LES, ION, CCO, and SBO, respectively; standard error of the mean [SEM] = 69.4). Dietary level of lespedeza had marked effects (P < 0.05) on digestion of organic matter [OM] (69.2, 57.6, 50.3, 66.3, 66.0, and 68.7 %; SEM = 1.57) and nitrogen (78.3, 65.3, 46.8, 71.4, 73.9, and 75.7 %; SEM = 1.81), with digestible OM intake numerically lower (P > 0.05) for diets with lespedeza and for ION (697, 607, 589, 598, 635, and 690 g/day for CON, ALF:LES, LES, ION, CCO, and SBO, respectively; SEM = 50.4). There was a treatment by period interaction (P < 0.05) in ruminal methane emission relative to digestible energy intake, but overall, emission was greatest among treatments (P < 0.05) for CON (12.33, 9.92, 10.24, 10.41, 8.91, and 8.66 % for CON, ALF:LES, LES, ION, CCO, and SBO, respectively; SEM = 0.730). Average daily gain (ADG) was greatest among treatments (P < 0.05) for SBO (54, 28, 18, 40, 56, and 98 g; SEM = 13.2). Many findings are not closely aligned with those of previous studies with goats. For example, effects of lespedeza on feed intake and ruminal methane emission were greater in the first than second half of the experiment, though interactions observed could not be clearly attributed to factors such as microbial adaptation. The effect of the SBO diet on ADG with the alfalfa-based diet deserves future research attention.

PSX-B-4 Effect of live yeast on the ruminal fermentation characteristics of growing steers in heat-stress conditions

Abstract The objective of this trial was to determine the influence of live yeast supplementation (LY) and temperature exposure (TEMP) on the ruminal fermentation characteristics of steers receiving a grower diet. The effects of LY and TEMP were investigated using a 2 x 2 crossover design that spanned five periods. Eight Angus crossbred steers (365 ± 32 kg) were randomly split into pairs and housed in four outdoor pens outfitted with an individualized feeding system. Animals were limit fed a grower diet (DIET) at 1.2% SBW with no live yeast supplementation (NOY) or a grower diet top-dressed with 10 g live yeast/d for 14 days (1.2 × 1012 CFU/d). On days 13 and 14, animals were subjected to one of two TEMP conditions, thermoneutral (TN; 18.4 ± 1.1°C, 57.6 ± 2.8 % RH) or heat stress (HS; 33.8 ± 0.6°C, 55.7 ± 2.7 % RH), in two side-by-side, single-stall open-circuit, indirect respiration calorimetry chambers. Data were analyzed using a random coefficients model. Carryover effects were examined and removed from the model if not significant (P &amp;gt; 0.05). There was no effect of DIET, TEMP, or DIET×TEMP (P &amp;gt; 0.05) on ruminal pH, redox, ciliated protozoa count, acetate, butyrate, total VFA, and ruminal ammonia concentrations. Similarly, the acetate to propionate ratio was not influenced by DIET, TEMP, or DIET × TEMP (P ≥ 0.190). Propionate concentration was the greatest in animals in TN conditions receiving LY (P = 0.008). Compared to HS+NOY, HS+LY (P = 0.003) and TN+LY (P = 0.043) had greater ruminal enumerations of Fusobacterium necrophorum. This suggests LY (P = 0.010) provided a favorable environment for F. necrophorum during heat stress. Live yeast supplementation did not improve overall ruminal fermentation during heat stress. Additional research is required to better understand the dynamic relationship between live yeast and temperature exposure.

Nutritional status of children with undernutrition

Objective. To assess nutritional status of children with undernutrition without chronic diseases.Patients and methods. Eighty one children without chronic diseases and with undernutrition aged 3 months to 17 years and 2 months, 41 boys (50.6 %), 40 girls (49.4 %), were examined. The anthropometry was assessed by WHO criteria. The complete blood count (n = 69), blood biochemistry (n = 62), insulin level and vitamin status were examined. Bioelectric impedance analysis (n = 58) and indirect respiratory calorimetry (n = 28) were performed. The food intake was assessed in 28 patients.Results. Mild undernutrition was diagnosed in 35 (43.2 %) children, moderate - in 30 (37 %), severe - in 16 (19,8 %) children. The stunting (Z-score height to age &lt; -2) was revealed in 3 (3,7 %) children. Anemia was found in 4 (5.8 %) children, absolute lymphopenia - in 2 (2.9 %), hypoproteinemia in 8 (12.9 %), hypoalbuminemia - in 1 (1.5 %), hypocholesterolemia - in 7 (11.3 %), hypercholesterolemia - in 6 (9.7 %) children. None of children had hypoglycemia. Insulin was decreased in 9 (15.5 %) children. Deficiency of vitamin D was found in 11 (13.6 %) patients. Decrease of fat mass was found in 52 (89,7 %) patients, muscle mass - in 42 (72.4 %), active cell mass - in 18 (31 %), protein - in 37 (63.8 %), minerals - in 41 (70.7 %), total body water - in 36 (62.1 %) patients. Decrease of the phase angle (&lt;4.4) was recorded in 13 (22,4 %) children. Resting energy expenditure was normal in 12 (42,8 %) patients. Carbohydrate oxidation rate was decreased in 20 (71,4 %) children, fat oxidation rate was increased in 15 (53,6 %), protein oxidation rate was normal in 15 (53,6 %) children. The food intake was characterized by low energy intake in 21 (75 %) children. Deficiency of protein, fat and carbohydrate intake were found in 42.9, 60.7 and 82.1 % patients, respectively. Low energy intake due to all macronutrients deficiency was revealed in 35.7 % children.Conclusion. Most children with undernutrition without chronic diseases have a decrease in fat and muscle body components, low energy value of diet and imbalance of macronutrients. Changes in resting metabolism were also revealed.

Residual carbon dioxide as an index of feed efficiency in lactating dairy cows

High feed costs make feed conversion efficiency a desirable target for genetic improvement. Residual feed intake (RFI), calculated as the difference between observed and predicted intake, is a commonly used estimate of feed efficiency. However, determination of feed efficiency in dairy herds is challenging due to difficulties in measuring feed intake of individual animals reliably. Using residual CO2 (RCO2) production as an estimate of feed efficiency would allow ranking the cows according to feed efficiency, provided that CO2 production is closely related to heat production and feed intake. The objective of this study was to evaluate the potential of RCO2 as an index of feed efficiency using data from respiration calorimetry studies (289 cow per period observations). Heat production was precisely predicted from CO2 production [root mean square error (RMSE)] adjusted for random effects was 1.5% of observed mean]. Dry matter intake (DMI) was better predicted from energy-corrected milk (ECM) yield and CO2 production than from ECM yield and body weight in the model (adjusted RSME = 0.92 vs. 1.39 kg/d). Residual CO2 production estimated as the difference between actual CO2 production and that predicted from ECM yield, metabolic body weight was closely related to RFI (adjusted RMSE = 0.42) that was calculated as the difference between actual DMI and that predicted from ECM, metabolic body weight, and energy balance (EB). When the cows were categorized in 3 groups of equal sizes on the basis of RCO2 (low, medium, and high), low RCO2 cows had lower DMI, RFI, methane production and intensity (g/kg ECM), and heat production, but higher efficiency of metabolizable energy utilization for lactation than high RCO2 cows. When RFI was predicted from RCO2, the residuals (observed - predicted) were negatively related to EB and digestibility. Predicting RFI with a 2-variable model based on RCO2 and digestibility, adjusted RMSE decreased to 0.23 kg/d, and residuals were not significantly related to EB. The cows in low RCO2 group had a higher energy digestibility than the cows in the high RCO2 group, and differences in EB were observed between the groups. Error of the model predicting residual ECM production from RCO2 was 1.41 kg/d. The residuals were positively related to ECM yield and energy digestibility. Predicting residual ECM from RCO2 and ECM yield decreased adjusted RMSE to 1.07 kg/d, and further to 0.78 kg/d when digestibility was included in the 2-variable model. It is concluded that RCO2 has a potential for ranking individual cows based on feed efficiency.

Net energy, energy utilization, and nitrogen and energy balance affected by dietary pea supplementation in broilers.

Pea starch consists predominantly of C-type of amylopectin chain which is more resistant to digestive enzymes than A-type of starch thus slowly digested in poultry. It was hypothesized that the presence of slowly digested pea starch in broiler diets will increase net energy and the efficiency of energy utilization in broilers. Two experiments were performed to investigate starch digestibility of pea at different incubation times (in vitro study) and the effect of dietary pea on heat increment and net energy in broilers using an open-circuit respiratory calorimetry system (in vivo study). One-day-old Ross 308 male broilers were fed a common starter crumble from d 1 to 10 and standard grower diets thereafter. At d 21, birds were transferred to the chambers each housing 2 birds. Each treatment was replicated 6 times with 2 identical runs of 3 replicates per treatment. A wheat-soybean meal-based diet was used as a control and the treatment diet contained 500 g of pea/kg pea. In vitro study showed that pellet processing increased (P < 0.001) starch digestibility, particularly at shorter times for wheat and a much larger response for pea. Birds offered the pea-based diet had lower (P = 0.002) feed intake, lower (P = 0.020) body weight gain, but a similar (P > 0.05) FCR compared to those offered the wheat-based diet. Net energy (NE) and apparent metabolizable energy (AME) values were higher in the pea-based diet than in the wheat-based diet (P = 0.037 for NE and P = 0.018 for AME). Heat production, respiratory quotient, heat increment of feed, efficiency of utilization of gross energy for AME, and efficiency of utilization of AME for NE did not differ (P > 0.05) between the 2 treatments. There was no effect (P > 0.05) of pea on the total tract digestibilities of dry matter, crude protein and ash, but the total tract digestibility of starch was higher (P = 0.022) in the pea-based diet compared to the wheat-based diet. This study provides insight into the energy metabolism of broilers offered a pea-based diet and indicates that dietary pea supplementation increases dietary AME and NE but has no effect on heat increment of feed and the efficiency of energy utilization in broilers.

PSII-14 Effect of live yeast on greenhouse gas emissions and energy partitioning of growing steers in heat-stress conditions

Abstract The objective of this trial was to identify the influence of live yeast supplementation (LY) and temperature exposure (TEMP) on greenhouse gas emissions and energy metabolism of steers receiving a grower diet. The effects of LY and TEMP were investigated using a 2 × 2 crossover design that spanned five periods. Eight Angus crossbred steers (365 ± 32 kg; 41 mo) were randomly split into pairs and housed in four outdoor pens outfitted with an individualized feeding system. Animals were limit fed a grower diet (DIET) at 1.2% SBW with no live yeast supplementation (NOY) or a grower diet top-dressed with 10 g live yeast/d for 14 days (1.2 × 1012 CFU/d). On days 13 and 14, animals were subjected to one of two TEMP conditions, thermoneutral (TN; 18.4 ± 1.1°C, 57.6 ± 2.8 % RH) or heat stress (HS; 33.8 ± 0.6°C, 55.7 ± 2.7 % RH), in two side-by-side, single-stall open-circuit, indirect respiration calorimetry chambers. Data were analyzed using a random coefficients model. Carryover effects were examined and removed from the model if not significant (P &amp;gt; 0.05). There was no effect of DIET, TEMP, or DIET × TEMP (P ≥ 0.752) on enteric methane or carbon dioxide emissions. Similarly, GE, ME, DE, and RE were not influenced by DIET, TEMP, or DIET × TEMP (P ≥ 0.152). Gaseous energy, as a percentage of GE, tended to increase during HS (P = 0.097). Heat energy, as a percentage of GE, had a significant LY carryover effect (P = 0.045), with HS×NOY resulting in less HE than TN×NOY (P = .0495) and HS×LY (P = .084). Live yeast supplementation did not reduce enteric emissions, nor did it improve energy metabolism during heat stress. Further research is required to better understand the dynamic relationship between live yeast and temperature exposure.