Urinary Energy Losses Research Articles

Effects of Early Time-Restricted Eating on Intestinal Energy Absorption in Healthy Adults: The DIGEST Study Protocol

ObjectivesAligning energy intake with circadian rhythms and extending periods of fasting within a 24-h cycle improves whole-body metabolism. However, it is unknown if these improvements are related to changes in intestinal nutrient absorption (i.e., digestibility). The primary objective of the DIGEST study is to determine the impact of early time-restricted eating (eTRE) on energy and macronutrient digestibility, metabolizable energy, intestinal health and microbial composition, energy expenditure, glycemic variability, and circulating metabolites. A secondary objective is to identify factors that predict energy digestibility efficiency. MethodsHealthy adults (n = 16, 20–45 y) will participate in a randomized, crossover, controlled feeding trial consisting of two 9-d weight maintenance diet periods, separated by at least a 2-wk washout. Participants will be randomized to follow an eTRE schedule (i.e., all calories consumed between 0800 and 1400) and a control eating schedule (i.e., all calories consumed between 0800 and 2000). Following a 3-d acclimation to the study diet and eating schedule, participants will consume a non-absorbable blue dye capsule to mark the beginning of stool collection. This will be repeated on day 7 to mark the end of stool collection. All urinary output will be collected on days 4, 5, and 6. Energy content of the diet, stool, and urine will be measured by bomb calorimetry. Digestible energy will be calculated as the difference between dietary energy intake and stool energy loss, and metabolizable energy as the difference between digestible energy and urinary energy loss. On day 5, participants will consume a capsule that measures intestinal transit time and hydrogen gas production. On day 6, thermic effect of food, circulating metabolites, and circadian gene expression will be measured in response to a mixed meal. A continuous glucose monitor will be worn during each study period to assess glucose concentrations and variability. ResultsTo date, 10 participants have been enrolled and randomized and 3 participants have completed the study. ConclusionsThis is the first study, to our knowledge, to investigate the effects of eTRE on energy digestibility, which may provide mechanistic insight regarding the benefits of eTRE on whole-body metabolism. Funding Sources2021 Herbalife Nutrition Scholarship, FSU Council on Research & Creativity.

Effects of Time-Restricted Feeding on Energy Balance: A Cross-Over Trial in Healthy Subjects.

Time-restricted feeding (TRF) has been recently reported as an effective dietary intervention for losing body weight, implying a negative energy balance, without restricting nutrient intake. However, the detailed energy balance alteration caused by TRF remains unclear. This study was a randomized controlled clinical trial using a within-subject cross-over design. Twelve healthy, normal-weighted volunteers (age: 24 ± 2.3 years; BMI: 21.9 ± 1.71 kg/m2; 7 females) were studied under a rigorous control for calorie intakes, physical activities as well as sleep-wake cycle to evaluate the energy balance systematically. Each participant consumed an isocaloric diet within either a 5.5-hour TRF or 11-hour control schedule. All energy intake and excretion were traced and collected and accessed by bomb calorimetry. Energy expenditure and substrates oxidation were monitored in a metabolic chamber. TRF compared with control schedule is associated with a 22.7% increase in fecal energy loss (Δ = 32.25 ± 9.33 Kcal, p = 0.005) and a trend in increasing 14.5% urine energy loss (Δ = 6.67 ± 3.14 Kcal, p = 0.058) without change energy expenditure. In total, a negative energy balance (Δ = -45.95 ± 19.00 Kcal, p = 0.034), which was equal to -2.6% of total energy intake, has been observed during TRF interventions. In the meantime, glycemic profiles, heart rate, respiration rate as well as metabolic flexibility were also improved during TRF intervention. Taken together, our findings unravel the mystery of how TRF regulates energy balance, supporting the use of TRF as an alternative dietary strategy for weight loss.

Methodologies for energy evaluation of pig and poultry feeds: A review

The cost of feed represents an important part of the total cost in swine and poultry production (>60%) with energy accounting for at least 70% of feed cost. The energy value of ingredients or compound feeds can be estimated as digestible (DE), metabolisable (ME) and net energy (NE) in pigs and ME and NE in poultry. The current paper reviews the different methods for evaluating DE, ME and NE of feeds for monogastric animals and their difficulties and limits, with a focus on NE. In pigs and poultry, energy digestibility depends on the chemical characteristics of the feed, but also on technology (pelleting, for instance) and animal factors such as their health and body weight. The ME value includes the energy losses in urine that are directly dependent on the proportion of dietary N excreted in urine resulting in the concept of ME adjusted for a zero N balance (MEn) in poultry. For poultry, the concept of true ME (TME, TMEn), which excludes the endogenous fecal and urinary energy losses from the excreta energy, was also developed. The measurement of dietary NE is more complex, and NE values of a given feed depend on the animal and environmental factors and also measurement and calculation methods. The combination of NE values of diets obtained under standardised conditions allows calculating NE prediction equations that are applicable to both ingredients and compound feeds. The abundance of energy concepts, especially for poultry, and the numerous feed and animal factors of variation related to energy digestibility or ME utilisation for NE suggest that attention must be paid to the experimental conditions for evaluating DE, ME or NE content. This also suggests the necessity of standardisations, one of them being, as implemented in pigs, an adjustment of ME values in poultry for an N retention representative of modern production conditions (MEs). In conclusion, this review illustrates that, in addition to numerous technical difficulties for evaluating energy in pigs and poultry, the absolute energy values depend on feed and animal factors, the environment, and the methods and concepts. Finally, as implemented in pigs, the use of NE values should be the objective of a more reliable energy system for poultry feeds.

Energy utilization for body weight gain of ram-lambs fed differently processed breadfruit (Artocarpus altilis) meal in total mixed rations

The study was carried out to estimate the energy utilization for body weight gain in West African dwarf ram-lambs fed differently processed breadfruit meal in total mixed rations. Twenty non-castrated ram-lambs, about 7months of age with an average-initial body weight of 6.00±0.55kg, were randomly assigned to four dietary treatments with five ram-lambs per treatment group in a completely randomized design. Ficus foliage with differently processed breadfruit meals and concentrate diet were used as treatment diets. Diet A (50% unpeeled raw breadfruit meal +20% Ficus foliage + 30% concentrate diet) B (50% peeled raw breadfruit +20% Ficus foliage + 30% concentrate diet), C (50% unpeeled soaked breadfruit meal +20% Ficus foliage + 30% concentrate diet) and D (50% unpeeled boiled breadfruit meal + 20% Ficus foliage +30% concentrate diet). Results showed that faecal energy output (999.41 MJ/g/day DM) was significantly (P<0.05) highest in treatment diet A compared with other treatment diets. Ram-lambs on treatment diets B and Chad the significantly highest (P < 0.05) on digestible energy intake (1310.84 and 1295.62 MJ/g/day DM), metabolizable energy intake (1074.89 and 1062.41 MJ/g/day DM), average total weight gain (4.18 und 4.13kg) and average daily weight gain (87.08 and 86.04g) compared with treatment diets A and D. Gross energy intake (4503.00MJ/g/day), average total feed intake (13.68kg), averuge daily feed intake (285.00g) and feed conversion ratio (4.44) were significantly (P < 0.05) better in ram-lambs on treatment diet D. There were no significant (P >0.05) differences in urinary energy loss, metabolizability and initial body weight of ram-lambs. It was therefore concluded that diets B and C enhanced efficiency of energy utilization for body weight gain of ram-lambs.

Energy utilization for body weight gain of ram-lambs fed differently processed breadfruit (Artocarpus altilis) meal in total mixed rations.

The study was carried out to estimate the energy utilization for body weight gain in West African dwarf ram-lambs fed differently processed breadfruit meal in total mixed rations. Twenty non-castrated ram-lambs, about 7months of age with an average-initial body weight of 6.00 ± 0.55kg, were randomly assigned to four dietary treatments with five ram-lambs per treatment group in a completely randomized design. Ficus foliage with differently processed breadfruit meals and concentrate diet were used as treatment diets. Diet A (50% unpeeled raw breadfruit meal +20% Ficus foliage + 30% concentrate diet) B (50% peeled raw breadfruit +20% Ficus foliage + 30% concentrate diet), C (50% unpeeled soaked breadfruit meal +20% Ficus foliage + 30% concentrate diet) and D (50% unpeeled boiled breadfruit meal + 20% Ficus foliage + 30% concentrate diet). Results showed that faecal energy output (999.41MJ/g/day DM) was significantly (P< 0.05) highest in treatment diet Acompared with other treatment diets. Ram-lambs on treatment diets B and C had the significantly highest (P < 0.05) on digestible energy intake (1310.84 and 1295.62 MJ/g/day DM), metabolizable energy intake (1074.89 and 1062.41MJ/g/day DM), average total weight gain (4.18 and 4.13kg) and average daily weight gain (87.08 and 86.04g) compared with treatment diets A and D. Gross energy intake (4503.00MJ/g/day), average total feed intake (13.68kg), average daily feed intake (285.00g) and feed conversion ratio (4.44) were significantly (P < 0.05) better in ram-lambs on treatment diet D. There were no significant (P > 0.05) differences in urinary energy loss, metabolizability and initial body weight of ram-lambs. It was therefore concluded that diets B and C enhanced efficiency of energy utilization for body weight gain of ram-lambs.

15 Young Scholar Presentation: Impact of a Near Ideal Amino Acid Profile on the Efficiency of Nitrogen and Energy Utilization in Lactating Sows

Abstract The objective was to determine the efficiency of EAA and energy for lactation in sows and quantify their metabolic heat production fed a reduced protein diet. We hypothesized that feeding a reduced protein diet with near ideal AA profile (NIAA) and a leucine:lysine of 1.14 improves the dietary essential AA (EAA) and energy utilization efficiency and reduces the metabolic heat associated with lactation, compared to feeding diets containing leucine:lysine of 1.63. Three diets were formulated iso-calorically (2,580 kcal/kg net energy), including 1) control diet with a 1.63 leucine:lysine (CON; 18.75% CP), 2) optimal diet with NIAA profile and 1.14 leucine:lysine (OPT; 13.75% CP) by supplementing crystalline AA to minimum requirements; and 3) OPT diet with L-Leucine (Leu) supplementation to achieve CON Leu:Lys of 1.63 (OPTLEU; 14.25% CP). Experiment 1 was to estimate maximal biological efficiency value (MBEV) of EAA in lactating sows fed CON, OPT and OPTLEU diets. Feeding OPT diet improved efficiency of nitrogen (N) (79.1%), arginine (61.1%), His (78.3%), Ile (65.4%), Leu (75.1%), Met + Cys (78.2%), Phe (53.4%), Phe + Tyr (69.5%) and Trp (70.1%) and maximized the efficiency of Lys (63.2%), Met (67.9%), Thr (71.0%) and Val (57.0%) for milk production over a 21-day lactation. Experiment 2 was to estimate dietary energetic efficiency, energy partitioning and heat production in lactating sows fed CON, OPT and OPTLEU diets. Feeding OPT led to greater energy utilization for lactation due to less urinary energy and metabolic heat loss, and triggered dietary energy deposition into milk at the expense of maternal lipid mobilization. Feeding OPTLEU compared to OPT reduced energy utilization for lactation by directing dietary energy away from the mammary gland and towards maternal pool, in part explaining the efficacy of a NIAA diet over CON. Experiment 3 was to measure heat production in lactating sows fed CON and OPT diets and exposed to thermal neutral and HS environments. Sows fed OPT diet produced less metabolic heat and had lower body temperature when exposed to HS conditions compared to CON fed sows. In conclusion, feeding a diet with NIAA profile containing Leu:Lys of 1.14 improves EAA and energy utilization efficiency for lactation, and reduces the metabolic heat associated with lactation compared to feeding a diet with Leu:Lys of 1.63.

The effects of the forage-to-concentrate ratio on the conversion of digestible energy to metabolizable energy in growing beef steers.

Metabolizable energy (ME) is calculated from digestible energy (DE) using a constant conversion factor of 0.82. Methane and urine energy losses vary across diets and dry matter intake (DMI), suggesting that a static conversion factor fails to describe the biology. To quantify the effects of the forage-to-concentrate ratio (F:C) on the efficiency of conversion of DE to ME, 10 Angus steers were used in a 5 × 5 replicated Latin square. Dry-rolled corn was included in experimental diets at 0%, 22.5%, 45.0%, 67.5%, and 83.8% on a dry matter (DM) basis, resulting in a high F:C (HF:C), intermediate F:C (IF:C), equal F:C (EF:C), low F:C (LF:C), and a very low F:C (VLF:C), respectively. Each experimental period consisted of a 23-d diet adaption followed by 5 d of total fecal and urine collections and a 24-h gas exchange collection. Contrasts were used to test the linear and quadratic effects of the F:C. There was a tendency (P = 0.06) for DMI to increase linearly as F:C decreased. As a result, gross energy intake (GEI) increased linearly (P = 0.04) as F:C decreased. Fecal energy loss expressed as Mcal/d (P = 0.02) or as a proportion of GEI (P < 0.01) decreased as F:C decreased, such that DE (Mcal/d and Mcal/kg) increased linearly (P < 0.01) as F:C decreased. As a proportion of GEI, urine energy decreased linearly (P = 0.03) as F:C decreased. Methane energy loss as a proportion of GEI responded quadratically (P < 0.01), increasing from HF:C to IF:C then decreasing thereafter. The efficiency of DE to ME conversion increased quadratically (P < 0.01) as F:C decreased, ranging from 0.86 to 0.92. Heat production (Mcal) increased linearly (P < 0.04) as F:C decreased but was not different as a proportion of GEI (P ≥ 0.22). As a proportion of GEI, retained energy responded quadratically (P = 0.03), decreasing from HF:C to IF:C and increasing thereafter. DM, organic matter, and neutral detergent fiber digestibility increased linearly (P < 0.01) and starch digestibility decreased linearly (P < 0.01) as the F:C decreased. Total N retained tended to increase linearly as the proportion of concentrate increased in the diet (P = 0.09). In conclusion, the efficiency of conversion of DE to ME increased with decreasing F:C due to decreasing methane and urine energy loss. The relationship between DE and ME is not static, especially when differing F:C.

The effects of energy metabolism variables on feed efficiency in respiration chamber studies with lactating dairy cows

The objective of the present study was to investigate factors related to variation in feed efficiency (FE) among cows. Data included 841 cow/period observations from 31 energy metabolism studies assembled across 3 research stations. The cows were categorized into low-, medium-, and high-FE groups according to residual feed intake (RFI), residual energy-corrected milk (RECM), and feed conversion efficiency (FCE). Mixed model regression was conducted to identify differences among the efficiency groups in animal and energy metabolism traits. Partial regression coefficients of both RFI and RECM agreed with published energy requirements more closely than cofficients derived from production experiments. Within RFI groups, efficient (Low-RFI) cows ate less, had a higher digestibility, produced less methane (CH4) and heat, and had a higher efficiency of metabolizable energy (ME) utilization for milk production. High-RECM (most efficient) cows produced 6.0 kg/d more of energy-corrected milk (ECM) than their Low-RECM (least efficient) contemporaries at the same feed intake. They had a higher digestibility, produced less CH4 and heat, and had a higher efficiency of ME utilization for milk production. The contributions of improved digestibility, reduced CH4, and reduced urinary energy losses to increased ME intake at the same feed intake were 84, 12, and 4%, respectively. For both RFI and RECM analysis, increased metabolizability contributed to approximately 35% improved FE, with the remaining 65% attributed to the greater efficiency of utilization of ME. The analysis within RECM groups suggested that the difference in ME utilization was mainly due to the higher maintenance requirement of Low-RECM cows compared with Medium- and High-RECM cows, whereas the difference between Medium- and High-RECM cows resulted mainly from the higher efficiency of ME utilization for milk production in High-RECM cows. The main difference within FCE (ECM/DMI) categories was a greater (8.2 kg/d) ECM yield at the expense of mobilization in High-FCE cows compared with Low-FCE cows. Methane intensity (CH4/ECM) was lower for efficient cows than for inefficient cows. The results indicated that RFI and RECM are different traits. We concluded that there is considerable variation in FE among cows that is not related to dilution of maintenance requirement or nutrient partitioning. Improving FE is a sustainable approach to reduce CH4 production per unit of product, and at the same time improve the economics of milk production.

Reduced protein diet with near ideal amino acid profile improves energy efficiency and mitigate heat production associated with lactation in sows

BackgroundThe study objective was to test the hypothesis that 1) lowering dietary crude protein (CP) increases dietary energetic efficiency and reduces metabolic heat associated with lactation, and 2) excessive dietary leucine (Leu) supplementation in a low CP diet decreases dietary energetic efficiency and increases metabolic heat associated with lactation.MethodsFifty-four lactating multiparous Yorkshire sows were allotted to 1 of 3 isocaloric diets (10.80 MJ/kg net energy): 1) control (CON; 18.75% CP), 2) reduced CP with a near ideal or optimal AA profile (OPT; 13.75% CP) and 3) diet OPT with excessive Leu (OPTLEU; 14.25% CP). Sow body weight and backfat were recorded on day 1 and 21 of lactation and piglets were weighed on day 1, 4, 8, 14, 18, and 21 of lactation. Energy balance was measured on sows during early (day 4 to 8) and peak (day 14 to18) lactation, and milk was sampled on day 8 and 18.ResultsOver 21-day lactation, sows fed OPT lost body weight and body lipid (P < 0.05). In peak lactation, sows fed OPT had higher milk energy output (P < 0.05) than CON. Sows fed OPTLEU tended (P = 0.07) to have less milk energy output than OPT and did not differ from CON. Maternal energy retention was lower (P < 0.05) in OPT and OPTLEU compared to CON sows, and did not differ between OPTLEU and OPT sows. Sows fed OPT had higher (P < 0.05) apparent energy efficiency for milk production compared to CON. Heat production associated with lactation was lower (P < 0.05) or tended to be lower (P = 0.082), respectively, in OPT and OPTLEU compared to CON sows.ConclusionThe OPT diet, in peak lactation, improved dietary energy utilization for lactation due to less urinary energy and metabolic heat loss, and triggered dietary energy deposition into milk at the expense of maternal lipid mobilization. Leucine supplementation above requirement may reduce dietary energy utilization for lactation by decreasing the energy partitioning towards milk, partially explaining the effectiveness of OPT diet over CON diets.

Metabolisable energy of grass and red clover silages fed to sheep at maintenance level

This study investigated the effect of forage type (grass or red clover) and harvesting time (primary growth or regrowth) of silage on energy and N utilisation by sheep fed at maintenance level. Specifically, the assumption of constant loss of energy of digestible organic matter from energy losses in urine and CH4 applied in evaluation of silage metabolisable energy (ME) was investigated. Urinary excretion of high-energy phenolic compounds related to solubilisation of lignin was assumed to affect urinary energy (UE) losses from sheep fed highly digestible grass silage (GS). A total of 25 primary growth and regrowth silages of timothy (Phleum pratense) and meadow fescue (Festuca pratensis) grass mixtures and red clover (Trifolium pratense) samples collected in digestibility trials with sheep, including faecal and urine samples, were used for energy and N determinations. Urinary concentration of monophenolic compounds and CH4 emissions in vitro were also analysed. Daily faecal N output, CH4 yield (MJ/kg DM intake), proportion of CH4 energy in digestible energy (DE) and proportion of UE in DE were greater (P ≤ 0.03) in sheep fed red clover silage (RCS) than GS. Furthermore, less (P = 0.01) energy was lost as UE of DE in sheep fed primary growth GS compared with the other treatments. The relationship between UE and silage N intake or urinary N output for both silage types (i.e. grass v. red clover) was strong, but the fit of the regressions was better for GS than RCS. The CH4/DE ratio decreased (P < 0.05) and the UE/DE ratio increased (P < 0.05) with increasing organic matter digestibility in RCS. These relationships were not significant (P < 0.05) for the GS diets. The regression coefficient was higher (P < 0.05) for GS than RCS when regressing ME concentration on digestible organic matter. The results of this study imply that ME/DE ratio is not constant across first-cut GS of different maturities. The ME production response may be smaller from highly digestible first-cut GS but could not be clearly related to urinary excretion of monophenols derived from solubilisation of lignin. Furthermore, energy lost in urine was not clearly defined for RCS and was much more predictable for GS from silage N concentration.

Partition of dietary energy by sheep fed fresh ryegrass (Lolium perenne) with a wide-ranging composition and quality

Context Perennial ryegrass (Lolium perenne L.) is an important forage in temperate ruminant agricultural systems, but its quality and composition is highly variable and can become dominated by senescent material during summer and dry periods. Nutritive value is often predicted on the basis of chemical composition and calculated metabolisable energy (ME), which is rarely measured. Aim To measure the partition of energy from ryegrasses with widely varying proportions of leaf and senescent material, among faeces, urine and methane (CH4) in sheep. Methods Three experiments were undertaken with two groups of young wether sheep, fed seven diets of freshly cut ryegrass, at maintenance levels of intake to measure the partition of dietary energy among faeces, urine and CH4, enabling ME to be calculated. Across the seven diets, green leaf accounted for 16.0–87.6% of feed offered, whereas senescent material ranged from 2.8% to 65.0% and nitrogen (N) ranged between 8.6 and 31.2 g/kg DM. Measured ME was compared with predicted values based on digestible energy. Methane emissions were determined by both open-circuit respiration chambers and sulfur hexafluoride marker dilution. Key results Apparent digestibility (g/100 g) of DM ranged from 51.8 to 75.3 and N from 26.7 to 73.9. The percentage of the gross energy of feeds partitioned to CH4 (chamber) was 6.01–7.42, and 1.77–5.69 to urine. Effects of digestibility on CH4 yields (g/kg DM intake) were minor and the sum of energy losses to CH4 and urine were 13.5–17.6% of digestible energy (DE) intake, suggesting an underestimation of ME when predicted from DE. Use of sulfur hexafluoride substantially overestimated CH4 emissions when the permeation tubes had been in the sheep for 80 days. Conclusions A high proportion of senescent material in ryegrass had little effect on CH4 yields from sheep and energy losses to urine were mostly less than 3% of energy intake and were related to dietary N concentration. Implications Dietary ME calculated from DE is likely to be underestimated when ryegrass contains a high proportion of senescent material, due to reduced urinary energy losses, as CH4 yields are largely unaffected by maturity or senescence.

Systemic PPARγ deletion in mice provokes lipoatrophy, organomegaly, severe type 2 diabetes and metabolic inflexibility

BackgroundThe peroxisome proliferator-activated receptor γ (PPARγ) is a ligand-dependent transcription factor involved in many aspects of metabolism, immune response and development. Numerous studies relying on tissue-specific invalidation of the Pparg gene have shown distinct facets of its activity, whereas the effects of its systemic inactivation remain unexplored due to embryonic lethality. By maintaining PPARγ expression in the placenta, we recently generated a mouse model carrying Pparg full body deletion (PpargΔ/Δ), which in contrast to a previously published model is totally deprived of any form of adipose tissue. Herein, we propose an in-depth study of the metabolic alterations observed in this new model. MethodsYoung adult mice, both males and females analyzed separately, were first phenotyped for their gross anatomical alterations. Systemic metabolic parameters were analyzed in the blood, in static and in dynamic conditions. A full exploration of energy metabolism was performed in calorimetric cages as well as in metabolic cages. Our study was completed by expression analyses of a set of specific genes. Main findingsPpargΔ/Δ mice show a striking complete absence of any form of adipose tissue, which triggers a complex metabolic phenotype including increased lean mass with organomegaly, hypermetabolism, urinary energy loss, hyperphagia, and increased amino acid metabolism. PpargΔ/Δ mice develop severe type 2 diabetes, characterized by hyperglycemia, hyperinsulinemia, polyuria and polydispsia. They show a remarkable metabolic inflexibility, as indicated by the inability to shift substrate oxidation between glucose and lipids, in both ad libitum fed state and fed/fasted/refed transitions. Moreover, upon fasting PpargΔ/Δ mice enter a severe hypometabolic state. ConclusionsOur data comprehensively describe the impact of lipoatrophy on metabolic homeostasis. As such, the presented data on PpargΔ/Δ mice gives new clues on what and how to explore severe lipodystrophy and its subsequent metabolic complications in human.

Effects of level of intake of a 50% concentrate pelleted diet on metabolizability by mature Katahdin wethers

Ten adult Katahdin sheep wethers (74.3 ± 2.03 kg initial BW), approximately 3 yr of age, were used in a crossover experiment to study effects of a restricted feeding regime on digestibility, metabolizability, and heat energy. A 50% concentrate pelleted diet was fed near the ME requirement for maintenance (Control; DM intake = 44.4 g/kg BW0.75) and at 55% of this level (Restricted; DM intake = 24.4 g/kg BW0.75). Periods were 4 wk in length, with 3 wk for adaptation, measures in the final week when animals were situated in metabolism cages, and 2 days for gas exchange quantification via a head-box respiration calorimetry system. Apparent total tract digestibilities of DM (68.9 and 76.1%; SEM = 1.08), OM (78.3 and 83.3%; SEM = 1.57), CP (74.6 and 80.7%; SEM = 1.68), NDF (50.9 and 61.9%; SEM = 3.23), and gross energy (77.9 and 83.0%; SEM = 1.59) were greater (P < 0.05) for Restricted than for Control. Expressed in MJ/day, energy in urine (1.03 and 0.67; SEM = 0.294) and ruminally emitted methane (1.03 and 0.77; SEM = 0.076) were greater for Control vs. Restricted (P < 0.05), but as a percentage of gross energy were at least numerically greater for Restricted (urine: 5.63 and 6.48%, SEM = 2.218 and P = 0.594; methane: 5.46 and 7.16% for Control and Restricted, respectively, SEM = 0.579 and P = 0.030). As a consequence, ME intake as a percentage of gross energy intake did not differ (P = 0.354) between treatments (66.8 and 69.4% for Control and Restricted, respectively; SEM = 2.89). The treatment difference in heat energy (11.05 and 9.29 MJ/day; SEM = 0.563) was less than in ME intake (12.67 and 7.30 MJ/day for Control and Restricted, respectively; SEM = 0.508); thus, recovered energy differed from 0 (P < 0.05) and was greater for Control vs. Restricted (1.62 and −1.99 MJ/day; SEM = 0.661). In conclusion, restricted feed intake had marked influence on digestibility, although energy losses in urine and methane energy compensated so that metabolizability did not differ between treatments. With a diet of this nature a similar ME concentration could be assumed for studies with hair sheep fed near the standard maintenance requirement and restricted in intake.

Energy partition, nutritional energy requirements and methane production in F1 Holstein × Gyr bulls, using the respirometric technique

The nutritional energy requirements of animals for maintenance and weight gain, such as the energy partition of the diet, were determined in different feeding plans. Fifteen F1 Holstein × Gyr, non-castrated male bovines with a mean initial liveweight of 302 kg were used. The diets were corn silage and concentrate, formulated to enable gains of 100, 500 and 900 g/day, called low, medium and high weight gains, respectively. Tests of digestibility and metabolism were conducted to determine energy losses through faeces, urine and methane emissions. Heat production was determined using respirometry chamber. Net energy for maintenance was calculated as the antilogarithm of the intercept of the regression of the logarithm of the heat production, as a function of the metabolisable energy intake. Retained energy was obtained by subtracting the heat production from the metabolisable energy intake. With the increased consumption of dry matter, there was an increase in faecal and urinary energy loss. Retained energy increased linearly with the metabolisable energy intake. The net energy for gain in the diet did not differ among the treatments, such as the efficiency of use of metabolisable energy for weight gain kg (0.34). The net energy for maintenance was 312 kJ/kg LW0.75, and the metabolisable energy for maintenance was 523 kJ/kg LW0.75. The daily methane production (g/day) increased with the dry matter level and the daily loss represented 5.31% of the gross energy consumption.

The effect of silage type on animal performance, energy utilisation and enteric methane emission in lactating dairy cows

The present study aimed to investigate the effect of silage type on dry matter (DM) intake, nutrient digestibility, energy utilisation and methane (CH4) emission. Six late lactating Holstein dairy cows were used in a replicated 3 × 3 Latin square design study with three treatments (grass silage (GS), maize silage (MS) and whole-crop wheat silage (WCWS)) and three periods (3 weeks/period). All animals were offered forage ad libitum and 5.55 kg/day of a concentrate supplement, which contained (DM basis) 66.0% rapeseed meal, 28.3% soyabean meal and 5.7% a mineral/vitamin supplement. During each period, animals were subject to digestibility, CH4 and heat production measurements during the final 6 days using calorimeter chambers. The results demonstrated that total DM intake for MS and WCWS diets were higher (P &amp;lt; 0.001) than for the GS diet. Faecal energy and heat production loss for the GS diet were lower (P &amp;lt; 0.01) than for MS and WCWS diets. In contrast, cows fed the GS diet had higher (P &amp;lt; 0.05) urine energy loss compared with MS and WCWS diets. In comparison with the GS and MS diets, WCWS diet produced a lower CH4 loss per kg DM and organic matter intake (P &amp;lt; 0.01), and CH4 energy output as a proportion of gross energy and metabolisable energy intake (P &amp;lt; 0.05). The present study demonstrates that choice of forage types affects energy utilisation and CH4 emission in dairy cows.

Evidence for increasing digestive and metabolic efficiency of energy utilization with age of dairy cattle as determined in two feeding regimes

The changes taking place with age in energy turnover of dairy cattle are largely unknown. It is unclear whether the efficiency of energy utilization in digestion (characterized by faecal and methane energy losses) and in metabolism (characterized by urine and heat energy losses) is altered with age. In the present study, energy balance data were obtained from 30 lactating Brown Swiss dairy cows aged between 2 and 10 years, and 12 heifers from 0.5 to 2 years of age. In order to evaluate a possible dependence of age effects on diet type, half of the cattle each originated from two herds kept at the same farm, which were fed either on a forage-only diet or on the same forage diet but complemented with 5 kg/day of concentrate since their first calving. During 2 days, the gaseous exchange of the animals was quantified in open-circuit respiration chambers, followed by an 8-day period of feed, faeces, urine and milk collection. Daily amounts and energy contents were used to calculate complete energy balances. Age and feeding regime effects were analysed by parametric regression analysis where BW, milk yield and hay proportion in forage as consumed were considered as covariates. Relative to intake of gross energy, the availability of metabolizable energy (ME) increased with age. This was not the result of an increasing energy digestibility, but of proportionately lower energy losses with methane (following a curvilinear relationship with the greatest losses in middle-aged cows) and urine (continuously declining). The efficiency of utilization of ME for milk production (kl) increased with age. Potential reasons include an increase in the propionate-to-acetate ratio in the rumen because of a shift away from fibre degradation and methane formation as well as lower urine energy losses. The greater kl allowed older cows to accrete more energy reserves in the body. As expected, offering concentrate enhanced digestibility, metabolizability and metabolic utilization of energy. Age and feeding regime did not interact significantly. In conclusion, older cows seem to have digestive and metabolic strategies to use dietary energy to a certain degree more efficiently than younger cows.

Effect of condensed tannin extract supplementation on growth performance, nitrogen balance, gas emissions, and energetic losses of beef steers.

Condensed tannins (CT) may decrease greenhouse gas emissions and alter the site of N excreted by ruminants. We evaluated the effect of top-dressing a steam-flaked corn-based finishing diet (14.4% CP and NEg 1.47 Mcal/kg) for beef cattle with a commercially available CT extract at 3 levels (0, 0.5, and 1.0% of diet, DM basis). Angus-crossbred steers ( = 27; 350 ± 32 kg initial BW) were individually fed via Calan gates for 126 d. Diet digestibility and N balance were estimated after 34 and 95 d on feed (Phase 1 and Phase 2, respectively) using titanium dioxide as a marker of fecal output and the creatinine:BW ratio as a marker for urine output. Ruminal CH and metabolic CO fluxes were measured using a GreenFeed system (C-Lock Inc., Rapid City, SD) for 2 sampling periods that coincided with fecal and urine sampling. Urine energy loss was estimated from urine N excretion, assuming all excreted N was urea. Oxygen consumption was estimated from CO production assuming a respiratory quotient of 1.05. Average daily gain (2.08, 2.14, and 2.08 kg/d for 0, 0.5, and 1.0% CT, respectively) and G:F did not differ ( = 0.88) among treatments. Starch intake and OM intake did not differ ( ≥ 0.42) among treatments during each phase. Apparent total tract starch digestibility during Phase 1 linearly decreased ( = 0.04) with inclusion of CT. Apparent total tract digestibility of OM and starch were not different among treatments ( ≥ 0.13) during Phase 2. Nitrogen intake did not differ ( ≥ 0.16) among treatments during each phase, but fecal N excretion linearly increased ( = 0.05) with inclusion of CT during Phase 1. Urinary N excretion was not different ( ≥ 0.39) among treatments during both phases, but urinary N as a proportion of total N excretion linearly decreased ( = 0.01) when CT was included in the diet during Phase 1. Retained N was not different ( ≥ 0.27) among treatments during each phase. Fluxes of CO were similar ( ≥ 0.37) among treatments during both phases. No differences ( ≥ 0.23) were observed for percentage of GE intake lost as CH (2.99, 3.12, and 3.09% in Phase 1 and 3.54, 3.55, and 4.35% in Phase 2) for 0, 0.5, and 1.0% CT, respectively. No difference ( ≥ 0.42) was observed for heat production lost as a percent of GE intake during both phases. Growth performance, gas emissions, and energetic losses were not affected by the inclusion CT in a steam-flaked corn-based finishing diet.

The effects of feeding increasing concentrations of corn oil on energy metabolism and nutrient balance in finishing beef steers1

The use of an added lipid is common in high-concentrate finishing diets. The objective of our experiment was to determine if feeding increasing concentrations of added dietary corn oil would decrease enteric methane production, increase the ME:DE ratio, and improve recovered energy (RE) in finishing beef steers. Four treatments were used in a replicated 4 × 4 Latin square ( = 8; initial BW = 397 kg ± 3.8). Data were analyzed using a Mixed model with the fixed effects of period and dietary treatment and random effects of square and steer within square. Treatments consisted of: (1) 0% added corn oil (Fat-0); (2) 2% added corn oil (Fat-2); (3) 4% added corn oil (Fat-4); (4) 6% added corn oil (Fat-6). Dry matter intake or GE intake did not differ across diets ( ≥ 0.39). As a proportion of GE intake, fecal energy loss, DE, and urinary energy loss did not differ by treatment ( ≥ 0.27). Additionally, methane energy produced decreased linearly as corn oil increased in the diet ( < 0.01). No differences were detected in ME loss as a proportion of GE intake ( ≥ 0.98). However, the ME:DE ratio increased linearly ( < 0.01; 93.06, 94.10, 94.64, and 95.20 for Fat-0, Fat-2, Fat-4, and Fat-6, respectively) as corn oil inclusion increased in the diet. No differences in RE or heat production as a proportion of GE intake were noted ( ≥ 0.59) and dry matter digestibility did not differ across diets ( ≥ 0.36). Digestibility of NDF as a proportion of intake responded quadratically increasing from 0% corn to 4% corn oil and decreasing thereafter ( = 0.02). Furthermore, ether extract digestibility as a proportion of intake responded quadratically, increasing from 0% to 4% corn oil inclusion before reaching a plateau ( < 0.01). As a proportion of GE intake, RE as protein decreased linearly as corn oil was increased in the diet ( < 0.01). As a proportion of total energy retained, RE as protein decreased when corn oil increased from 0% to 6% of diet DM ( < 0.01). Similarly, RE as fat and carbohydrate as a proportion of GE intake increased linearly as corn oil increased in the diet ( = 0.05). From these data, we interpret that adding dietary fat decreases enteric methane production and increases the ME:DE ratio, in addition to increasing the amount of energy retained as fat and carbohydrate.

Comparison of measured and predicted energy density of an oral care chew for dogs.

The dog chew studied here is a starch-based, twin-screw cooker extruded dog care and treat (C&T) product with oral health benefits. The manufacturing process and nutrient profile of such products are markedly different from those of main meal pet foods. Predicted metabolisable energy (PME) in pet food is calculated using equations derived from main meal feeding studies so it is unclear whether these equations can be applied to C&T products. The present study aimed to directly measure metabolisable energy (ME) content of the dog chew in dogs and compare with calculated PME. A batch of dog chews was manufactured and the product rendered micronutrient complete to allow solus feeding. Following a 3 d standard diet pre-feed phase, the test product was fed solus to a panel of seven adult dogs for a period of 8 d. Dietary intake was recorded daily and faecal matter collected for the last 5 d. Test product and pooled faecal samples were analysed for proximate nutrients, and digestibility coefficients were calculated as the difference in intake and faecal excretion (7-11 d). Digestible energy was converted to ME by correcting for energy losses in urine. PME was calculated using proximate analysis and modified Atwater factors according to National Research Council 2006. The results showed close agreement between actual ME (1272 (sd 12·1) kJ/100 g) and calculated PME (1268 (sd 12·6) kJ/100 g), indicating transferability of the NRC 2006 PME equations to the dog chew tested here.

Impact of phytogenic feed additives on growth performance, nutrient digestion and methanogenesis in growing buffaloes

Twenty growing buffalo calves were fed on a basal diet consisting of wheat straw and concentrate mixture in a randomised block design, to study the effect of feeding phytogenic feed additives on growth performance, nutrient utilisation and methanogenesis. The four groups were viz. control (no additive), Mix-1 (ajwain oil and lemon grass oil in 1 : 1 ratio @ 0.05% of dry matter intake), Mix-2 (garlic and soapnut in 2 : 1 ratio @ 2% of DMI) and Mix-3 (garlic, soapnut, harad and ajwain in 2 : 1 : 1 : 1 ratio @ 1% of DMI). The experimental feeding was continued for a period of 8 months. A metabolism trial was conducted after 130 days of feeding. Methane emission from animals was measured by open-circuit indirect respiration calorimeter. The feed conversion efficiency was higher by 9.5% in Mix-1, 7% in Mix-2 and 10.2% in Mix-3 group than in control. The digestibility of nutrients was similar except crude protein, which was improved (P &lt; 0.05) in treatment groups. All buffalo calves were in positive nitrogen balance. Comparative faecal nitrogen decreased and urinary nitrogen increased in all the supplemented groups compared with in the control group. Methane emission (in terms of L/kg dry matter intake and L/kg digestible dry matter intake) was reduced by 13.3% and 17.8% in Mix-1, 10.9% and 13.5% in Mix-2 and 5.1% and 9.8% in Mix-3 groups as compared with control. When expressed in L/kg organic matter intake and L/kg digestible organic matter intake, methane production was reduced by 13.3% and 16.7% in Mix-1, 10.9% and 12.9% in Mix-2 and 5.1% and 8.4% in Mix-3 groups compared with the control group. These feed additives inhibited methane emission without adversely affecting feed utilisation by the animals. The faecal energy, urinary energy and methane energy losses were not affected (P &gt; 0.05) due to feeding of these additives. Further, long-term feeding experiments should be conducted on a large number of animals to validate these effects before they can be recommended for use at a field level.