Metabolizable Energy Requirements For Maintenance Research Articles

Effects of diet forage proportion on maintenance energy requirement and the efficiency of metabolizable energy use for lactation by lactating dairy cows

The objective of the present study was to examine the effect of dietary forage proportion (FP) on metabolizable energy (ME) requirement for maintenance (MEm) and the efficiency of ME use for lactation (kl) in lactating dairy cows. Data used were derived from 32 calorimetric chamber experiments undertaken at our institute between 1992 and 2010, including data from 818 Holstein-Friesian cows (HF), 50 Norwegian Red cows, and 62 crossbred cows (Jersey × HF or Norwegian Red × HF). Animals were offered forage-only rations (n=66) or forage and concentrate rations (n=864) with FP ranging from 18 to 100% (dry matter basis). The effect of FP was evaluated by dividing the whole data set into 4 groups according to the FP ranges, categorized as FP <30%, FP=30 to 59%, FP=60 to 99%, and FP=100%. The MEm for individual cows was calculated from heat production minus energy losses from inefficiencies of ME use for lactation, energy retention and pregnancy, and kl was obtained from milk energy output adjusted to zero energy balance (El(0)) divided by ME available for production. Increasing FP significantly reduced ME intake and milk energy output, although the differences between the 2 low FP groups were not significant. However, increasing FP significantly increased the ratio of heat production over ME intake and MEm (MJ/kg0.75), with the exception that the increases did not reach significance in heat production/ME intake between FP <30% and FP=30 to 59%, or in MEm between FP=60 to 99% and FP=100%. However, the FP had no significant effect on the kl values, which were similar among the 4 groups of cows. The effect of FP was also evaluated using the linear mixed regression technique relating El(0) to ME intake. The results demonstrated that with a common regression coefficient (slope), the regression constants (intercepts) taken as net energy requirement for maintenance significantly increased with increasing FP. However, the increase between the 2 high FP groups did not research significance. It is concluded that increasing diet FP had no effects on kl but significantly increased maintenance energy requirement (MJ/kg0.75). These results indicate that using the current energy feeding systems to ration dairy cows managed under low input systems may underestimate their nutrient requirements, because the majority of feeding systems adopted globally do not differentiate the maintenance energy requirements between low and high forage input systems.

Maintenance energy requirements of young Holstein cattle from calorimetric measurements at 6, 12, 18, and 22 months of age

Twenty five-month old Holstein cattle (10 steers and 10 heifers) were used in a four-period (28d/period) study with measurements made at the age of 6, 12, 18, and 22 months, to evaluate effects of gender on energy utilization efficiency and maintenance energy requirement. Cattle were offered perennial ryegrass silage mixed with concentrates. In each period, the cattle were housed together in a cubicle accommodation for the first 20d, individually in metabolism units for the next 3d, and then in indirect open-circuit respiration calorimeter chambers for the final 5d with feed intake, feces and urine outputs, and gaseous exchange measured during the final 4d. There was no difference (P>0.05) in any period between gender groups in terms of growth performance, energy intake, energy output, or energetic efficiency, with the exception of period three when the steers had a greater (P<0.05) feed and energy intake than heifers. Data from the two groups were therefore pooled to develop relationships between metabolizable energy (ME) intake and retained energy (RE) for each measurement period and for the whole experimental period. Retained energy was strongly related to ME intake (P<0.001), with R2 values ranging from 0.85 to 0.93. Net energy (NE) and ME requirements for maintenance (NEm and MEm) derived from these relationships were greater for cattle at the age of 6 months than those at 12, 18, and 22 months (NEm=0.57, 0.48, 0.47, and 0.41MJ/kg0.75; and MEm=0.78, 0.62, 0.59, and 0.63MJ/kg0.75, respectively). These maintenance energy requirements were greater than those recommended in energy feeding systems currently used in Europe, North America, and Australia. The results indicate that current feeding systems may underestimate maintenance requirements for young dairy cattle, resulting in a reduced estimate of the efficiency of production.

Effect of Age on Energy Requirement for Maintenance and Growth of Dorper and Hu Crossbred F1 Ewes Weighing 20 to 50 kg.

This research aimed to define the energy requirement of Dorper and Hu Hybrid F1 ewes 20 to 50 kg of body weight, furthermore to study energy requirement changes with age and evaluate the effect of age on energy requirement parameters. In comparative slaughter trial, thirty animals were divided into three dry matter intake treatments (ad libitum, n = 18; low restricted, n = 6; high restricted, n = 6), and were all slaughtered as baseline, intermediate, and final slaughter groups, to calculate body chemical components and energy retained. In digestibility trial, twelve ewes were housed in individual metabolic cages and randomly assigned to three feeding treatments in accordance with the design of a comparative slaughter trial, to evaluate dietary energetic values at different feed intake levels. The combined data indicated that, with increasing age, the net energy requirement for maintenance (NEm) decreased from 260.62±13.21 to 250.61±11.79 kJ/kg0.75 of shrunk body weight (SBW)/d, and metabolizable energy requirement for maintenance (MEm) decreased from 401.99±20.31 to 371.23±17.47 kJ/kg0.75 of SBW/d. Partial efficiency of ME utilization for maintenance (km, 0.65 vs 0.68) and growth (kg, 0.42 vs 0.41) did not differ (p>0.05) due to age; At the similar condition of average daily gain, net energy requirements for growth (NEg) and metabolizable energy requirements for growth (MEg) for ewes during late fattening period were 23% and 25% greater than corresponding values of ewes during early fattening period. In conclusion, the effect of age upon energy requirement parameters in the present study were similar in tendency with previous recommendations, values of energy requirement for growth (NEg and MEg) for Dorper and Hu crossbred female lambs ranged between the NRC (2007) recommendation for early and later maturating growing sheep.

イネホールクロップサイレージを給与した乾乳牛の維持に要する代謝エネルギー量のエネルギー出納および行動解析に基づく推定

イネホールクロップサイレージを給与した乳牛の維持に要する代謝エネルギー要求量（MEm）を明らかにする目的で，ホルスタイン種非妊娠乾乳牛を用い，37例のエネルギー出納試験成績を収集した．MEmの推定には，代謝エネルギー摂取量に対する蓄積エネルギーの回帰式より求める従来の推定方法に加え，エネルギー出納試験の際の呼吸試験により咀嚼や起伏といった動物の行動に伴う熱発生量を測定し，重回帰分析でMEmを推定する方法を用いた．その結果，エネルギー出納成績から求められたMEm値（kcal・kgBW−0.75/day）は121.6となった．一方，行動に伴う熱発生量より重回帰分析で求めたMEm値も121.6であった．咀嚼時間および佇立時間の変動幅を加味したMEm値は118.6〜125.8の範囲にあった．以上の結果より，イネホールクロップサイレージを給与した乾乳牛のMEmは121.6程度と求められ，これは現行日本飼養標準で示されている乳牛のMEm値（116.2）と近似した．

Enteric Methane Emission, Energetic Efficiency and Energy Requirements for the Maintenance of Beef Cattle in the Tropics

This study was conducted to determine the energy balance of beef cattle by indirect animal calorimetry utilizing a ventilated head box respiration system. Fifteen native Thai bulls were randomly allocated to one of three dietary metabolizable energy intake (MEI) levels (1.1 × maintenance, 1.5 × maintenance and 1.9 × maintenance) in a completely randomized design for a 116 day feeding trial. Animals were allocated to individual metabolic cages for the determination of digestibility and energy balance. Heat production was determined from oxygen consumption, carbon dioxide and methane production. The results showed that dry matter, organic matter and crude protein intake were increased (P 0.05) by MEI levels. The energy loss in feces and urine (% of gross energy intake) were not different (P > 0.05); however, enteric methane conversion rate (% of methane energy loss per gross energy intake) and heat energy production loss (% gross energy intake) were linearly decreased (P < 0.01) with increasing MEI levels. Methane conversion rates ranged from 8.4 to 10.0% and appeared to have been underestimated by the Intergovernmental Panel on Climate Change 6.5% default values set for cattle fed low quality crop residues and by-products. The estimate of metabolizable energy requirements for maintenance was measured using linear regression analysis derived for native Thai cattle was 520 kilojoules per kilogram of metabolic body weight per day. Increased dietary intake levels reduced enteric methane emissions in beef cattle fed on tropical feedstuffs. The results of the present study indicated that greater dietary intake feeding strategy in cattle fed above the maintenance level resulted in improved energetic efficiency utilization, and thus improved energy retention because of the reduction of enteric methane energy emission and heat production. Discipline: Animal industry Additional key words: cattle, energy requirements, enteric methane, tropical This paper reports results obtained in the international project on “Establishment of feeding standard of beef cattle and feedstuff database in Indochina.” The Japan International Research Center for Agricultural Sciences, Department of Livestock Development, Ministry of Agriculture and Cooperatives, Thailand, and Khon Kaen University took responsibility for all subjects picked up in the project, implemented main subjects jointly and managed the project. Since it is essential to construct a regional research cooperation network for the efficient achievement of the targets, other research organizations such as Mahasarakham University, Ubon Ratchatanee University, Rajamangala University of Technology-Isan, Suranaree University of Technology, Chiang Mai University, Maejo University, Prince of Songkla University, National University of Laos, Lao PDR, and Royal University of Agriculture, Cambodia were also involved in the project. The project was implemented during the five-year period from 2006 to March 2011. Present address: 4 Division of Animal Sccience, Faculty of Technology, Mahasarakham University (Mahasarakham 44150, Thailand) 5 NARO Institute of Livestock and Grassland Science (Tsukuba, Ibaraki 305-0901, Japan) *Corresponding author: e-mail: kritapon@kku.ac.th Received 2 December 2014; accepted 31 March 2015.

Comparison of maintenance energy requirement and energetic efficiency between lactating Holstein-Friesian and other groups of dairy cows

The objectives of the present study were to investigate the effects of cow group on energy expenditure and utilization efficiency. Data used were collated from 32 calorimetric chamber experiments undertaken from 1992 to 2010, with 823 observations from lactating Holstein-Friesian (HF) cows and 112 observations from other groups of lactating cows including Norwegian (n=50), Jersey × HF (n=46), and Norwegian × HF (n=16) cows. The metabolizable energy (ME) requirement for maintenance (MEm) for individual cows was calculated from heat production (HP) minus energy losses from inefficiencies of ME use for lactation, energy retention, and pregnancy. The efficiency of ME use for lactation (kl) was obtained from milk energy output adjusted to zero energy balance (El(0)) divided by ME available for production. The effects of cow groups were first evaluated using Norwegian cows against HF crossbred cows (F1 hybrid, Jersey × HF and Norwegian × HF). The results indicated no significant difference between the 2 groups in terms of energy digestibility, ratio of ME intake over gross energy intake, MEm (MJ per kg of metabolic body weight, MJ/kg0.75), or kl. Consequently, their data were combined (categorized as non-HF cows) and used to compare with those of HF cows. Again, we detected no significant difference in energy digestibility, ratio of ME intake over gross energy intake, MEm (MJ/kg0.75), or kl between non-HF and HF cows. The effects were further evaluated using linear regression to examine whether any significant differences existed between HF and non-HF cows in terms of relationships between ME intake and energetic parameters. With a common constant, no significant difference was observed between the 2 groups of cows in coefficients in each set of relationships between ME intake (MJ/kg0.75) and MEm (MJ/kg0.75), El(0) (MJ/kg0.75), HP (MJ/kg0.75), MEm:ME intake, El(0):ME intake, or HP:ME intake. However, MEm values (MJ/kg0.75) were positively related to ME intake (MJ/kg0.75), irrespective of cow group. We concluded, therefore, that cow groups evaluated in the present study had no significant effects on energy expenditure or energetic efficiency. However, the maintenance energy requirement (MJ/kg0.75) was not constant (as adopted in the majority of energy rationing systems across the world) but increased with increasing feed intake.

Modeling ovarian follicle growth in commercial and heritage Single Comb White Leghorn hens

Approximately 84% of the energy in chicken eggs resides in the yolk. A robust model of ovarian follicle development is therefore valuable for estimating energy requirements of laying hens. The current experiment was designed to model the growth of ovarian follicles in 32-wk-old modern commercial line (CL) and unselected heritage line (HL) Single Comb White Leghorn hens. The volume of yolk deposited daily during the rapid growth phase (RGP) was estimated using a double dye technique. For 21 d, 8 CL and 8 HL hens were fed capsules (no. 1) containing Sudan IV (red) and Sudan Black dyes on alternate days. An additional 8 control CL hens were fed empty capsules. Eggs were collected, and the daily volume of yolk deposited was estimated. Significant differences are reported where P < 0.05. Dye had no significant effect on BW, ME intake, or egg weight. Maintenance ME requirements were 192 and 177 kcal/kg0.67 for CL and HL hens, respectively. Duration of the RGP was shorter (7.35 d) in the CL hens compared with the HL hens (7.95 d). A nonlinear Lomolino model described follicular weight, which varied between strains over d 2 to 9 of follicle development; at each day during development, follicle weights were higher where RGP were shorter. The volume of yolk deposited for the 8 d preceding oviposition in CL was 0.17, 0.28, 0.43, 0.99, 1.84, 2.47, 2.82, 2.86, and 2.51 cm3; and in HL was 0.17, 0.33, 0.72, 1.40, 2.15, 2.46, 2.48, 2.32, and 1.93 cm3. The HL had a higher rate of yolk deposition 7 to 5 d before oviposition, and CL had a higher rate of yolk deposition 3 to 1 d before oviposition with no significant difference between lines on d 4 before oviposition. Although growth patterns differed, there were no differences among lines in final follicle weights (14.1 g) or retained energy (42.4 kcal).

Effects of feeding level on methane emissions and energy utilization of Brahman cattle in the tropics

The release of methane from ruminant livestock is a problem not only because it contributes to greenhouse gas emissions but also because it affects feed energy utilization and animal production efficiency. The objective of this experiment was to determine the effects of feeding level on methane emission and energy utilization of Brahman cattle (Bos indicus). Sixteen 2-year-old Brahman steers were housed in individual pens for a 70-day feeding experiment. Dietary treatments were applied in a randomized complete block design with four replications and four feeding levels (M, 1.4×M, 1.8×M, and ad libitum; where M represents a metabolizable energy requirement for maintenance. The animals were placed in a metabolic cage equipped with a ventilated head box system to determine the total collection digestibility and energy balance. Energy partitioning in response to feeding level significantly linearly increased. Although the total tract digestibility of dry matter, organic matter, crude protein, and neutral detergent fiber were affected slightly depressed, total feed intake, nutrient intake, and energy intake increased dramatically as feeding levels increased. Methane emission rate decreased (from 11.5 to 7.3%) with increasing feeding level, yet these values are much higher than the IPCC recommended value (6.5%) for calculation of national inventory of enteric methane emissions. A daily metabolizable energy requirement for maintenance was estimated at 435 kilojoules of metabolizable energy per kilogram of metabolic body weight, and the estimated efficiency of the utilization of metabolizable energy for growth was 0.54. Our study found that increasing feeding level increased average daily gain of Brahman cattle and the observed increased energetic efficiency was attributed to reduced energy output in urine, methane and heat production.

Seasonal heat production and energy balance of grazing yaks on the Qinghai-Tibetan plateau

A study was conducted to measure the energy balance of free-ranging yak during the four annual seasons in order to elucidate the factors constraining energy utilization by grazing yak. The heat production (HP, kJ/day) of grazing non-lactating female yaks was calculated as the product of heart rate (HR, beats/min) and the amount of O2 delivered to the body at every heartbeat (O2P, μl), and by the constant value of 20.47kJ/l of O2 consumed. Heart rates were recorded continuously over 4 days, using modified heart rate monitors. Individual daily fecal output was measured using Cr2O3 as an external marker. Daily herbage dry matter (DM) intake was calculated from fecal output and digestibility of the forage determined in vitro. The greatest herbage mass was measured in August (496kg DM/ha), and the least in December and May (208 and 226kg DM/ha). However, the herbage present in both May and August had higher crude protein contents and lower NDF contents than those sampled in October and December. Daily average HR (beats/min) was greater in summer (August) than during the other three seasons (78 vs. 49–52). The greatest O2P was recorded in May. The highest metabolizable energy intake (MEI) (1120kJ/kg BW0.75 per day) was measured in August when yaks grazed on lush green forage. HP was higher in August than in October and December (715, 548 and 400kJ/kg BW0.75 per day, respectively), but did not differ significantly from that measured in May (640kJ/kg BW0.75 per day). The animals were in positive energy balance only during August (energy retention (ER)=405kJ/kg BW0.75 per day). Energy balance did not differ between the other seasons: −111 (October), −91 (December) and −13 (May) kJ/kg BW0.75 per day, respectively. HP and ER were highly correlated with MEI (R2=0.73 and 0.88, respectively). The formulas calculated through the regression of HP and ER on MEI were used to estimate fasting heat production (FHP=341kJ/kg BW0.75 per day) and maintenance ME requirements (MEm, 545kJ/kg BW0.75 per day) of the free grazing yaks. The results showed that free-ranging yaks expended much more energy to resist harsh environmental and sward conditions compared with confined yak or cattle and grazing cattle in low land area.

Estimation of the net energy requirements for maintenance in growing and finishing pigs.

The objective of this experiment was to determine the net energy requirements for maintenance of growing and finishing pigs using regression models. Thirty-six growing (27.38 ± 2.24 kg) and 36 finishing (70.25 ± 2.61 kg) barrows were used and within each phase. Pigs received a corn-soybean meal diet fed at 6 levels of feed intake, which were calculated as 0, 20, 40, 60, 80, or 100% of the estimated ad libitum ME intake (2,400 kJ ME/kg BW(0.6)·d(-1)) of the pigs. Measurements were conducted on 6 pigs per feeding level and per stage of growth. After a 5-d adjustment period, barrows in the fasted treatment were kept in respiration chambers for 2 d to measure the fasting heat production. Barrows in the other treatments were kept individually in respiration chambers for a 5-d balance trial followed by a 2-d fasting period. Heat production (HP) in the fed state was measured and feces and urine were collected in the balance trial. The total HP increased (P < 0.01) with increasing feeding levels. Fasting HP increased (P < 0.01) as previous feeding level increased and was less (P = 0.012) in finishing pigs than growing pigs if calculated per kilogram BW(0.6) per day. When using an exponential regression analysis, ME requirements for maintenance were estimated at 973 and 921 kJ/kg BW(0.6)·d(-1) and NE requirements for maintenance were estimated at 758 and 732 kJ/kg BW(0.6)·d(-1) for growing and finishing pigs, respectively. The efficiencies of using ME for growth and for maintenance were estimated at 66 and 78.7% for growing and finishing pigs, respectively. It is concluded that exponential regression between HP and a wide range of ME intake may be used as a new method to determine the NE requirement for maintenance.

Energy requirements of Dorper crossbred ewe lambs1

The ME and NE requirements of Dorper crossbred ewe lambs grown from 35 to 50 kg BW were assessed in a comparative slaughter trial. Thirty-five ewe lambs (33.5 ± 0.6 kg BW) of F1 crosses of purebred Dorper and thin-tailed Han sheep were used: 7 lambs were slaughtered at the start of the trial to provide baseline measures of body composition and 7 lambs were fed ad libitum and slaughtered when they reached 43 kg BW to provide intermediate measures of body composition. The remaining 21 lambs were divided into 3 groups of 7 lambs each and fed a pelleted mixed diet (concentrate:roughage = 44:56, DM basis) for ad libitum intake or 65 or 45% of ad libitum intake. All 3 groups were slaughtered when the ad libitum group reached 50 kg BW. Total body energy, N, fat, ash, and moisture content were measured. In a separate trial, 15 ewe lambs (39.5 ± 0.7 kg BW) of F1 crosses of purebred Dorper and thin-tailed Han sheep were housed in metabolism cages to evaluate the ME value of the diet at each of the 3 levels of feed intake. In vivo methane production was measured by open-circuit respirometry along with the collection of all feces and urine. The daily NEm requirement of the ewe lambs was 280 kJ/kg metabolic BW (BW(0.75)) or 292 kJ/kg metabolic shrunk BW (SBW(0.75)), whereas the daily ME requirement for maintenance was 418 kJ/kg BW(0.75) or 437 kJ/kg SBW(0.75), with a partial efficiency of ME utilization for maintenance of 0.67. The NEg requirement ranged from 1.37 to 3.94 MJ/d for ADG from 100 to 250 g BW, and the partial efficiency of ME utilization for gain was 0.44. The NE and ME requirements of Dorper × thin-tailed Han crossbred ewe lambs were lower than the recommendations of the United States' nutritional system.

Energy requirement of growing pigs under commercial housing conditions

Scientifically derived recommendations for the energy supply to growing pigs are generally based on estimates of the metabolisable energy (ME) requirements for maintenance (MEm) and protein (MEp) and fat (MEf) retention. It is supposed that animals are kept within the zone of thermoneutrality and that their physical activity is not elevated. These assumptions might not always be true for practical housing conditions, and it is difficult to quantify the additional energy needed for thermoregulation and physical activity. Hence, at a given ME intake, differences can occur between the actual growth rates and those predicted from the recommendations. To quantify such differences, three trials were carried out under commercial farming conditions with pigs growing from 25 to 120 kg body weight (BW). In each trial, 624 castrated male and female pigs were allocated to four feeding groups distributed over 24 double pens. The rations were provided according to the animals’ feed intake capacity and BW was recorded every three weeks. Protein, fat and energy retention (RE) was derived from carcass composition and BW gain. The difference between ME intake and MEm plus ME required for growth (MEg = RE/kpf) was calculated and seen as the ME required for purposes other than maintenance and growth (MEx). MEx accounted for 2.0%, 17.0% and 21.4% of the animals’ ME intake in Trials 1, 2 and 3, respectively, and was higher in female than in castrated male pigs when related to metabolic BW. It was concluded that total ME requirements of pigs kept under commercial housing conditions can be considerably higher than ME requirements predicted from feeding standards since they usually ignore MEx. MEx can be used as an indicator for the quality of housing systems. Further studies are needed to identify the key factors responsible for MEx to allow for more precise recommendations for the energy supply to commercially raised pigs.

Metabolisable energy requirements for maintenance and gain of liveweight of Bali cattle (Bos javanicus)

A series of liveweight gain (LWG), feed and water intake and digestibility experiments were conducted across eastern Indonesia. Thirty-six datasets of LWG, feed and water intake, and diet characteristics were used to determine the nutritional requirements of growing Bali cattle fed a wide range of diets that varied in crude protein content and apparent dry matter digestibility. Regression of average daily LWG against estimated metabolisable energy (ME) intake was conducted, and the ME requirements for maintenance of liveweight (LW, 0 kg/day) and LWG were determined. It was estimated that the ME required to maintain LW of this class of Bali cattle, across the range of diets evaluated, was 0.47 MJ ME/kg LW0.75.day and that 34 MJ ME was required for each kg LWG, or 29 g LWG/MJ ME. The relationship between estimated ME intake and LWG was not affected by the crude protein content of the diet. The data demonstrate that ME requirements for maintenance of LW of Bali cattle are comparable with values for other cattle species, but that this class of Bali cattle is generally less efficient in the use of ME for LWG across the range of diets evaluated.

Nutritional requirements of sheep, goats and cattle in warm climates: a meta-analysis

The objective of the study was to update energy and protein requirements of growing sheep, goats and cattle in warm areas through a meta-analysis study of 590 publications. Requirements were expressed on metabolic live weight (MLW=LW0.75) and LW1 basis. The maintenance requirements for energy were 542.64 and 631.26 kJ ME/kg LW0.75 for small ruminants and cattle, respectively, and the difference was significant (P<0.01). The corresponding requirement for 1 g gain was 24.3 kJ ME without any significant effect of species. Relative to LW0.75, there was no difference among genotypes intra-species in terms of ME requirement for maintenance and gain. However, small ruminants of warm and tropical climate appeared to have higher ME requirements for maintenance relative to live weight (LW) compared with temperate climate ones and cattle. Maintenance requirements for protein were estimated via two approaches. For these two methods, the data in which retained nitrogen (RN) was used cover the same range of variability of observations. The regression of digestible CP intake (DCPI, g/kg LW0.75) against RN (g/kg LW0.75) indicated that DCP requirements are significantly higher in sheep (3.36 g/kg LW0.75) than in goats (2.38 g/kg LW0.75), with cattle intermediate (2.81 g/kg LW0.75), without any significant difference in the quantity of DCPI/g retained CP (RCP) (40.43). Regressing metabolisable protein (MP) or minimal digestible protein in the intestine (PDImin) against RCP showed that there was no difference between species and genotypes, neither for the intercept (maintenance=3.51 g/kg LW0.75 for sheep and goat v. 4.35 for cattle) nor for the slope (growth=0.60 g MP/g RCP). The regression of DCP against ADG showed that DCP requirements did not differ among species or genotypes. These new feeding standards are derived from a wider range of nutritional conditions compared with existing feeding standards as they are based on a larger database. The standards seem to be more appropriate for ruminants in warm and tropical climates around the world.

Predicting feed intake and liveweight gain of Ongole (Bos indicus) cattle in Indonesia

We evaluated the precision and accuracy of equations from the Australian Ruminant Feeding Standards (ARFS) and the Large Ruminant Nutrition System (LRNS) in predicting the performance of Ongole (Bos indicus) cattle under Indonesian conditions. A database was constructed using information from 121 cattle in five different pen-feeding experiments. Cattle included mature cows and growing bulls, and they were fed a range of diets commonly used by Indonesian farmers. We compared observed and predicted dry matter intake and daily liveweight gain. Model predictions were evaluated for precision and accuracy using mean bias, mean square prediction error and regression of observed against predicted values. Across all experiments, the LRNS provided the better estimates of intake and growth. While both models included animal age, sex, weight and body condition score, the LRNS provided better estimates of metabolisable energy requirements for maintenance of liveweight, feed quality and efficiency of energy utilisation. The LRNS model also better accounted for environmental conditions by including correction factors for minimum night temperature and relative humidity, in addition to average daily temperatures. Based on our results, the LRNS model appears suitable for use in Indonesian beef-production systems.

Energy requirements for maintenance and growth of entire male Bali cattle in East Timor

The metabolisable energy (ME) requirements for maintenance and growth of entire male Bali cattle (Bos javanicus) were determined by regressing liveweight change on ME intake. Cattle were fed either a diet (DM basis) of 52.5% urea-treated rice straw plus 47.5% fresh leucaena forage (Expt 1), or fresh leucaena forage alone (Expt 2). In each experiment, liveweight change and feed intake were measured over 4 weeks, after a 1-week introductory period, and feed constituent digestibilities were measured during the final week. In Expt 1, 10 bulls between 1.5 and 3 years of age and weighing 123.7 ± 11.79 kg (mean ± s.d.) were allocated to DM intakes estimated to provide 0.75, 1.0, 1.25, 1.5, 1.75, or 2.0 times the estimated ME requirement for maintenance (based on calculations made from published CSIRO equations for tropical cattle species other than B. javanicus), with either one or two bulls per treatment. In Expt 2, the bulls were given treatments estimated to provide 0.85, 1.0, 1.4, 1.8, or 2.2 times the ME requirement for maintenance, with two bulls allocated to each treatment. The measured ME requirements for maintenance were 0.42 ± 0.369 and 0.40 ± 0.153 MJ/kg LW0.75.day (coefficient ± standard error, Expts 1 and 2, respectively). The ME requirement for ‘production’ (i.e. positive liveweight change of male Bali cattle under the specific conditions of the experiment) was calculated to be 39.2 MJ/kg liveweight gain in Expt 2. The calculated efficiency of use of dietary ME for production in Expt 2, was 0.34

&lt;b&gt;Requirement of energy and protein of beef cattle on tropical pasture&lt;/b&gt; - doi: 10.4025/actascianimsci.v35i4.21143

Protein and energy requirements of beef cattle, aged between 4 and 18 months old, on tropical pastures, were estimated. Forty-six Nellore calves (138.3 ± 3.4 kg BW and 90-150 days old), kept on pasture, were distributed in a maintenance group (restricted feeding) or in nutritional plans, receiving a supplements with different amounts of protein and carbohydrate or non-supplemented. The net energy requirement for weight gain (NE g ) was obtained by linear regression of logarithm of retained energy as a function of logarithm of empty body weight gain. The net energy requirement for maintenance (NE m ) was estimated by the exponential relation between heat production and metabolizable energy intake. Net protein requirement for weight gain (RP) was estimated by multiple linear regression of retained protein in the weight gain of empty body (EBWG) and retained energy. The efficiency of metabolizable energy (ME) used for maintenance and for weight gain was 0.55 and 0.26, respectively. The ME requirement for maintenance was 124 kcal EBW -0.75 . RP decreased in proportion to body weight increase. NE g and RP may be obtained by equations: RE (Mcal kg -1 ) = 0.044 x EBW 0.75 x EBWG 1.1302 and RP (g day -1 ) = -31.45 + 229.69 x EBWG – 8.75 x RE, respectively.

Earlier Metabolizable Energy Intake Level Influences Heat Production during a Following 3-Day Fast in Laying Hens.

The present study was conducted to estimate energy requirements for maintenance in laying hens by using indirect calorimetry and energy balance. A total of 576 28-wk-old Nongda-3 laying hens with dwarf gene were randomly allocated into four ME intake levels (86.57, 124.45, 166.63 and 197.20 kcal/kg body weight (BW)0.75 per d) with four replicates each. After a 4 d adaptation period, 36 hens from one replicate were maintained in one of the two respiration chambers to measure the heat production (HP) for 3 d during the feeding period and subsequent 3 d fast. Metabolizable energy (ME) intake was partitioned between heat increment (HI), HP associated with activity, fasting HP (FHP) and retained energy (RE). The equilibrium FHP may provide an estimate of NE requirements for maintenance (NEm). Results showed that HP, HI and RE in the fed state increased with ME intake level (p<0.05). Based on the regression of HP on ME intake, the estimated ME requirements for maintenance (MEm) was 113.09 kcal/kg BW0.75 per d when ME intake equals HP. The FHP was decreased day by day with the lowest value on the third day of starvation. Except for lowest ME intake level, the FHP increased with ME intake level on the first day of starvation (p<0.05). The FHP at the two higher ME intake levels were greater than that at the two lower ME intake levels (p<0.05) but no difference was found between the two lower ME intake levels. Linear regression of HP from the fed state to zero ME intake yielded a value of 71.02 kcal/kg BW0·75 per d, which is higher than the extrapolated FHP at zero ME intake (60.78, 65.23 and 62.14 kcal/kg BW0.75 per d for the first, second and third day of fasting, respectively). Fasting time, lighting schedules, calculation methods and duration of adaptation of hens to changes in ME intake level should be properly established when using indirect calorimetry technique to estimate dietary NE content, MEm and NEm for laying hens.

Energy Requirements for Maintenance and Growth of German Mutton Merino Crossbred Lambs

A comparative slaughter trial and a metabolism trial were conducted to determine the requirement of net energy (NE) and metabolizable energy (ME) by the crossbreed of German Mutton Merino×Inner Mongolia Merino for fattening from 35 to 50 kg of body weight (BW). 49 crossbred female lambs ((33.9±2.3) (SD) kg BW) of German Mutton Merino×Inner Mongolia Merino were used. 34 lambs were randomly chosen for comparative slaughter, which were offered an identical mixture diet (concentrate:roughage=55:45) at 100, 75 or 55% of ad libitum intake, whereas the remainders were used in the metabolism trial to evaluate the ME of the diet after methane production was measured by open-circuit respirometry. As feed intake decreased from 100 to 75 and 55% of ad libitum intake, the apparent digestibility of dry matter (DM) linearly increased (P=0.010) from 60.8 to 63.6 and 66.9%, respectively, and methane production decreased from 52.1 to 44.3 and 39.9 L d−1, respectively, but the ratio of methane energy to gross energy intake increased linearly (P=0.010) from 8.20 to 8.96 and 10.97%, respectively. Consequently, the ME values of the diet increased from 9.35 to 9.64 and 9.85 MJ kg−1 DM, respectively. The NE requirement for maintenance (NEm) was 255 kJ kg−1 BW0.75, and the ME requirement for maintenance (MEm) was 352 kJ kg−1 BW0.75, with a partial energy efficiency for maintenance (km) of 0.72. The NE requirement for growth (NEg) ranged from 1.26 to 4.66 MJ d−1 as average daily gains increased from 100 to 300 g d−1, with a partial energy efficiency for growth (kg) of 0.45. These results indicated that the NEg required by crossbred female lambs of German Mutton Merino×Inner Mongolia Merino was lower than the recommendation of the American or British nutritional system.

Requirements for zero energy balance of nonlactating, pregnant dairy cows fed fresh autumn pasture are greater than currently estimated

Fifty-three nonlactating, pregnant Holstein-Friesian and Holstein-Friesian × Jersey cross dairy cows were grouped into 4 cohorts (n=15, 12, 13, and 13) and offered 1 of 3 allowances of fresh, cut pasture indoors for 38±2d (mean ± SD). Cows were released onto a bare paddock after their meal until the following morning. Animals were blocked by age (6±2yr), day of gestation (208±17d), and body weight (BW; 526±55kg). The 3 pasture allowances [low: 7.5kg of dry matter (DM), medium: 10.1kg of DM, or high: 12.4kg of DM/cow per day] were offered in individual stalls to determine the estimated DM and metabolizable energy (ME) intake required for zero energy balance. Individual cow DM intake was determined daily and body condition score was assessed once per week. Cow BW was recorded once per week in cohorts 1 and 2, and 3 times per week in cohorts 3 and 4. Low, medium, and high allowance treatments consumed 7.5, 9.4, and 10.6kg of DM/cow per day [standard error of the difference (SED)=0.26kg of DM], and BW gain, including the conceptus, was 0.2, 0.6, and 0.9kg/cow per day (SED=0.12kg), respectively. The ME content of the pasture was estimated from in vitro true digestibility and by near infrared spectroscopy. Total ME requirements for maintenance, pregnancy, and limited activity were 1.07MJ of ME/kg of measured metabolic BW per day. This is more than 45% greater than current recommendations. Differences may be due to an underestimation of ME requirements for maintenance or pregnancy, an overestimation of diet metabolizability, or a combination of these. Further research is necessary to determine the reasons for the greater ME requirements measured in the present study, but the results are important for on-farm decisions regarding feed allocation for nonlactating, pregnant dairy cows.