scholarly journals Energy and protein requirements of crossbred Holstein x Zebu steers fed different levels of calcium and phosphorus in the diet

2016 ◽  
Vol 37 (4Supl1) ◽  
pp. 2665
Author(s):  
Diego Zanetti ◽  
Sebastião De Campos Valadares Filho ◽  
Edenio Detmann ◽  
Marcos Vinicius Carneiro Pacheco ◽  
Letícia Artuzo Godoi ◽  
...  
Keyword(s):  
Body Weight ◽  
Body Weight Gain ◽  
The Body ◽  
Metabolizable Energy ◽  
Dicalcium Phosphate ◽  
Energy Requirements ◽  
Net Energy ◽  
Protein Requirements ◽  
Two Samples ◽  
Net Protein

The aim of this study was to determine the energy and protein requirements of crossbred Holstein x Zebu steers fed with or without the supplementation of dicalcium phosphate in the diet. Thirty-two steers with an average initial body weight of 377.5 ± 49.4 kg were used, of which four were initially slaughtered to estimate the empty body weight (EBW) of the animals. Twenty-four steers were fed ad libitum and were distributed in a completely randomized design with two levels of concentrate (30 and 60 %), and diets with or without dicalcium phosphate and four steers were fed at maintenance level, so that the body weight gain was equal to zero. After 84 days the animals were slaughtered. The animal tissues were sampled, and composted by two samples, denominated by “carcass” (bone, muscle and fat) and “non-carcass” (head, limbs, blood, hide, organs and viscera) for determination of the body composition. The net energy requirements (NEm) and metabolizable energy for maintenance (MEm) were obtained while relating heat production (HP) and metabolizable energy intake (MEI); meanwhile, the net energy requirements for gain (NEg) and the net protein requirements for gain (NPg) were obtained as a function of empty body weight (EBW), empty body gain (EBG) and retained energy (RE) in EBW. The daily net and metabolizable energy requirements for maintenance were 76.90 and 119.36 kcal/EBW0.75, respectively. The net energy requirements for gain can be obtained by the following equation: NEg = 0.0568±0.0025 × EBW0.75 × EBG1.095. The efficiencies of use of metabolizable energy for maintenance and gain are 64.4 and 29.68 %, respectively. The metabolizable protein requirements for maintenance are 4.14 g/BW0.75. The net protein requirements for gain can be obtained through the following equation: NPg = 236.36±30.06 × EBG - 19.84±6.14 × RE. We recommend the use of the equations obtained in this experiment to calculate the energy and protein requirements of crossbred Holstein x Zebu steers.

scholarly journals Energy and protein requirements of crossbred cattle in feedlot

2016 ◽  
Vol 37 (2) ◽  
pp. 1029 ◽  
Author(s):  
Maria Luciana Menezes Wanderley Neves ◽  
Antonia Sherlânea Chaves Véras ◽  
Evaristo Jorge Oliveira de Souza ◽  
Marcelo De Andrade Ferreira ◽  
Sebastião De Campos Valadares Filho ◽  
...  
Keyword(s):  
Body Weight ◽  
Reference Group ◽  
The Body ◽  
Metabolizable Energy ◽  
Net Energy ◽  
Adaptation Period ◽  
Protein Requirements ◽  
Randomized Design ◽  
Dairy Bulls ◽  
Slaughter Method

The objective of this study is to predict the energy and protein requirements of crossbred dairy cattle in feedlot. The study was conducted at the Unidade Acadêmica de Serra Talhada, Universidade Federal Rural de Pernambuco, Brazil with 30 bulls with a body weight of 339.1 ± 35.4 kg. Five animals were slaughtered at the end of the adaptation period to serve as the reference group; the remainder of the animals was slaughtered after 112 days. The latter group was randomly allocated to receive five treatments: 0, 17, 34, 51 and 68% of concentrate in the feed using a completely randomized design. The dietary intake of the animals that were not given concentrate was restricted to 1.5% of their body weight; these animals composed the group fed for maintenance. The body composition and empty body weight (EBW) were estimated by means of the comparative slaughter method and full dissection of a half-carcass. The results showed that for crossbred dairy bulls in confinement, the net and metabolizable energy requirements were 86.49 and 138 kcal EBW-0.75 day-1, respectively, and the efficiency of use of metabolizable energy for maintenance and gain were 62.67% and 31.67%, respectively. The net energy (NEg) and net protein (NPg) requirements for gain can be estimated using the following equations, respectively: NEg= 0.0392*EBW0.75*EBWG1.0529 and NPg= 242.34 x EBWG - 23.09 x RE. The efficiency of use of metabolizable protein for gain was 25.8%, and the protein requirement for maintenance was 2.96 g EBW-0.75 day-1. The rumen degradable protein can supply 62.44% of the crude protein requirements of feedlot dairy crossbred bulls with a body weight of 450 kg while gaining 1 kg day-1.

scholarly journals Body composition and net protein and energy requirements for weight gain of crossbred dairy cattle in grazing

2009 ◽  
Vol 38 (4) ◽  
pp. 746-751 ◽  
Author(s):  
Dulciene Karla Bezerra de Andrade ◽  
Antonia Sherlânea Chaves Véras ◽  
Marcelo de Andrade Ferreira ◽  
Mércia Virginia Ferreira dos Santos ◽  
Wellington Samay de Melo ◽  
...  
Keyword(s):  
Body Composition ◽  
Body Weight ◽  
Weight Gain ◽  
Experimental Period ◽  
The Body ◽  
Energy Requirements ◽  
Free Access ◽  
Protein Requirements ◽  
The Relationship ◽  
Net Protein

The body composition and net protein and energy requirements for weight gain of 5/8 Hostein-Zebu crossbred cattle raised in Brachiaria decumbens Spaft pasture were evaluated. In total, 16 bulls with 10 months of age and body weight (BW) of 180 ± 19.95 kg were used. The animals were kept with free access to pasture or with restricted grazing (from 6 to 10 h). Four animals were slaughtered at the beginning of the experimental period to estimate the empty body weight (EBW) and the initial body composition of the remaining animals. The other animals were slaughtered at the end of the 84-day trial period. The logarithm equations of the protein and energy body content were adjusted according to the logarithm of the empty body weight EBW. From these equations, the net protein and energy requirements for weight gain were estimated. There was an increase in fat (from 37.17 to 59.08 g/kg EBW) and energy (from 1.68 to 1.94 Mcal/kg EBW) concentrations, with increase in body weight from 150 to 250 kg. The protein and energy requirements for gaining 1 kg of EBW increased with the increase in body weight or empty body weight. The relationship between fat concentration in gain and protein requirements also increased, indicating that as the BW or EBW increase, more fat deposition in the gain is observed.

scholarly journals Relationships of retained energy and retained protein that influence the determination of cattle requirements of energy and protein using the California Net Energy System

2018 ◽  
Vol 3 (3) ◽  
pp. 1029-1039 ◽  
Author(s):  
Luis O Tedeschi
Keyword(s):  
Body Fat ◽  
Energy System ◽  
The Body ◽  
Metabolizable Energy ◽  
Net Energy ◽  
Body Protein ◽  
Protein Requirements ◽  
Growing Cattle ◽  
Lower Correlation

Abstract Interrelationships between retained energy (RE) and retained protein (RP) that are essential in determining the efficiency of use of feeds and the assessment of energy and protein requirements of growing cattle were analyzed. Two concerns were identified. The first concern was the conundrum of a satisfactory correlation between observed and predicted RE (r = 0.93) or between observed and predicted RP when using predicted RE to estimate RP (r = 0.939), but a much lower correlation between observed and predicted RP when using observed RE to estimate RP (r = 0.679). The higher correlation when using predicted vs. observed RE is a concern because it indicates an interdependency between predicted RP and predicted RE that is needed to predict RP with a higher precision. These internal offsetting errors create an apparent overall adequacy of nutrition modeling that is elusive, thus potentially destabilizing the predictability of nutrition models when submodels are changed independently. In part, the unsatisfactory prediction of RP from observed RE might be related to the fact that body fat has a caloric value that is 1.65 times greater than body protein and the body deposition of fat increases exponentially as an animal matures, whereas body deposition of protein tends to plateau. Thus, body fat is more influential than body protein in determining RE, and inaccuracies in measuring body protein will be reflected in the RP comparison but suppressed in the RE calculation. The second concern is related to the disconnection when predicting partial efficiency of use of metabolizable energy for growth (kG) using the proportion of RE deposited as protein—carcass approach—vs. using the concentration of metabolizable energy of the diet—diet approach. The culprit of this disconnection might be related to how energy losses that are associated with supporting energy-expending processes (HiEv) are allocated between these approaches. When computing kG, the diet approach likely assigns the HiEv to the RE pool, whereas the carcass approach ignores the HiEV, assigning it to the overall heat production that is used to support the tissue metabolism. Opportunities exist for improving the California Net Energy System regarding the relationships of RE and RP in computing the requirements for energy and protein by growing cattle, but procedural changes might be needed such as increased accuracy in the determination of body composition and better partitioning of energy.

Influence of a cocktail of protease and xylanase in different energy densities of corn- and soybean-meal-based diet on growth performance, nutrient digestibility, carcass quality, and gas emission in broilers

2018 ◽  
Vol 98 (2) ◽  
pp. 271-278 ◽  
Author(s):  
D.H. Nguyen ◽  
H.N. Tran ◽  
H.M. Yun ◽  
I.H. Kim
Keyword(s):  
Body Weight ◽  
Soybean Meal ◽  
Body Weight Gain ◽  
Nutrient Digestibility ◽  
The Body ◽  
Metabolizable Energy ◽  
Gas Emission ◽  
N Retention ◽  
Nutrient Density ◽  
High Nutrient

A total of 480 one-day-old male Ross 308 broilers with an average initial body weight (BW) of 42 ± 1 g was randomly divided into four treatments (8 replicates/treatment, 15 birds/replicate) by their BW to evaluate the influence of a cocktail of protease and xylanase in different energy density of corn- and soybean-meal-based diet on broilers. This experiment lasted for 35 d and there were two phases; starter (1–18 d) and finisher (19–35 d). The experiment was a 2 × 2 factorial arrangement with two levels of metabolizable energy and the cocktail enzyme with 200 mg of protease kg−1 diet and 100 FXU xylanase kg−1 diet. Both high-nutrient density and cocktail enzyme supplementation increased (P < 0.05) the body weight gain (BWG) during day 1–18 and day 1–35 as well as dry matter retention on day 35. Broilers fed the high-nutrient-density diets had higher (P < 0.05) energy retention on day 35 and relative breast muscle weight. Broilers fed the cocktail enzyme diets significantly increased nitrogen (N) retention and decreased the levels of ammonia (NH3) and hydrogen sulphide (H2S) emission. In conclusion, dietary supplementation of the cocktail enzyme component improved BWG, N retention, and reduced excreta noxious gas emission in broilers.

scholarly journals Body composition and energy and protein requirements of grazing Nelore steers

2009 ◽  
Vol 38 (7) ◽  
pp. 1347-1354 ◽  
Author(s):  
Vitor Visintin Silva de Almeida ◽  
Augusto César de Queiroz ◽  
Fabiano Ferreira da Silva ◽  
Robério Rodrigues Silva ◽  
Aline Cardoso Oliveira ◽  
...  
Keyword(s):  
Body Weight ◽  
Reference Group ◽  
Block Design ◽  
Average Daily Gain ◽  
The Body ◽  
Net Energy ◽  
Regression Equations ◽  
Protein Requirements ◽  
Animal Body ◽  
Daily Gain

This experimentwas carried out with the objective of determining the energy and protein requirements of grazing Nellore steers. Twenty four Nellore steers (average 371 ± 14 kg of BW and 26 months old) were used. Four steers were slaughtered at the beginning of the experiment (reference group), serving as a reference for the subsequent study. The remaining 20 animals were weighed and distributed in a randomized complete block design with four levels of supplementation offers: 0.0 (mineral mixture - control), 0.3, 0.6 and 0.9% BW, with five replications. The supplements, based on ground corn, soybean meal and/or urea, were previously balanced to achieve an average daily gain of 350, 650 and 850g, respectively, for the different levels of supplementation offers. The protein, fat and energy contents retained in the animal body were determined by regression equations of the logarithm of the protein, fat and energy in the animal body contents, in function of the logarithm of empty body weight (EBW). Net requirements of protein and energy for a gain of 1kg of EBW were obtained by deriving the prediction equations of the animal body content of protein, fat, or energy in function of the EBW logarithm. The net energy requirements for weight gain of Nellore steer can be obtained by the equation: NEg = 0.05764 × EBW0,75 × DEBWG0.8328. The following equation was obtained to estimate the retained protein (RP), in function of the average daily gain (ADG) and retained energy (RE): RP = 28.9199 + 85.7301 FBWG + 8.0669 RE. The net protein requirement for Nellore steers decreased as the body weight increased, with values of 174.62 and 163.10 g/kg EBG for animals of 300 and 450 kg BW, respectively.

scholarly journals Estimation of the net energy and protein requirements for maintenance of male arctic foxes (Alopex lagopus) during the growth period12

2019 ◽  
Vol 97 (11) ◽  
pp. 4579-4587
Author(s):  
W Zhong ◽  
L L Mu ◽  
F F Han ◽  
G L Luo ◽  
X Y Zhang ◽  
...  
Keyword(s):  
Linear Relationship ◽  
Heat Production ◽  
Feed Intake ◽  
Metabolizable Energy ◽  
Net Energy ◽  
Protein Requirements ◽  
Maintenance Requirement ◽  
Arctic Foxes ◽  
Energy Maintenance ◽  
Net Protein

Abstract The maintenance requirements of net energy and net protein were assumed to represent the most accurate and important values totally for the animal’s utilization. The objective of this experiment was to determine the net energy and net protein requirements for maintenance of growing arctic foxes. The experiments was evaluated using regression models estimated from data collected by means of indirect calorimetry, nitrogen balance trials, and digestion and metabolism experiments. Thirty-six growing arctic foxes (3 487 ± 261.7 g) at the age of 85 days were randomly assigned to four groups with 9 animals in each group. Arctic foxes were fed a complete formula diet at four intake levels (100%, or 80%, 60%, and 40% of feed requirements) from 24 July 2017 to 23 September 2017. Arctic foxes in each treatment were kept individually in respiration chambers after 1-d adaptation at day 2 for a 3-d balance trial and then at day 5 followed by a 3-d fasting period. The metabolizable energy intake (MEI), heat production in the fed state (HP), and retained energy (RE) of arctic foxes significantly decreased (P < 0.01) as the feed intake level decreased. Fasting heat production (FHP) of arctic foxes was not influenced by feed intake level (P > 0.05). The metabolizable energy maintenance requirement (MEm) and net energy maintenance requirement (NEm) estimated from the linear relationship between RE and MEI were 230 and 217 kJ/kg of body weight BW0.75/d, respectively. The MEm and NEm estimated by logarithmic regression of HP on MEI were 225 and 209 kJ/kg BW0.75/d, respectively. The net N maintenance requirement (NNm) and net protein maintenance requirement (NPm) estimated from the linear relationship between retained nitrogen (RN) and daily nitrogen intake (NI) were 179.6 mg/kg BW0.75/d and 1.123 g/kg BW0.75/d, respectively. It is concluded that NEm and NPm values obtained fill the net energy and protein requirements shortage, and provide the basic data for establishing the standard of nutrition demand of breeding arctic foxes in China.

scholarly journals Detraining of exercise-trained rats: effects on energetic efficiency and brown adipose tissue thermogenesis

1987 ◽  
Vol 57 (3) ◽  
pp. 363-370 ◽  
Author(s):  
Jeff Arnold ◽  
Denis Richard
Keyword(s):  
Body Weight ◽  
Adipose Tissue ◽  
Brown Adipose Tissue ◽  
Body Weight Gain ◽  
The Body ◽  
Metabolizable Energy ◽  
Treadmill Running ◽  
Energetic Efficiency ◽  
Brown Adipose ◽  
Brown Adipose Tissue Thermogenesis

1. Complete energy balance measurements were made in exercise-trained (treadmill running) rats subjected to 27 d of exercise detraining.2. The 20% difference in body-weight that existed at the end of the training period between sedentary and trained rats was negated by detraining. Detrained rats had twice the body-weight gain of their untrained controls.3. An elevation (12%) in metabolizable energy (ME) intake (relative to body-weight) was observed in detrained rats while their gross energetic efficiency was augmented by 60%.4. Energy expenditure, excluding the estimated costs of fat and protein storage, was similar for detrained and untrained rats. Complementing the latter was the finding that thermogenesis in brown adipose tissue, a known energy buffering process, was also similar.5. Elevated ME intake (relative to body-weight) largely contributed to the increased energetic efficiency of detrained rats.

scholarly journals Energy and protein requirements during the growing phase of indigenous goats

2018 ◽  
Vol 39 (1) ◽  
pp. 241 ◽  
Author(s):  
Kléber Tomás Resende ◽  
Silvio Doria de Almeida Ribeiro ◽  
Amélia Katiane de Almeida ◽  
Marcelo Teixeira Rodrigues ◽  
José Américo Garcia ◽  
...  
Keyword(s):  
Body Weight ◽  
Energy Requirement ◽  
Allometric Equation ◽  
Metabolizable Energy ◽  
Energy Utilization ◽  
Net Energy ◽  
Protein Requirements ◽  
Ad Libitum ◽  
Indigenous Goats ◽  
The Difference

The objective of this study was to investigate both energy and protein requirements for the maintenance and growth of indigenous goats, based on data from two separate studies. Goats were weaned at 79 ± 4.4 days of age, with milk and solid diet intake recorded daily. To determine energy maintenance requirements, 32 kids of 4.90 ± 0.302 kg initial body weight (BW) were used. Ten kids were slaughtered at 5.40 ± 0.484 kg BW to estimate initial body composition, with the remaining kids randomly assigned to one of two DM intake levels: ad libitum and restricted-fed (1.2-times maintenance level). Heat production (HP) was calculated as the difference between ingested metabolizable energy (MEI) and retained energy. Net energy requirement for maintenance (NEm) was estimated as the ?0 parameter of the relationship between HP and MEI [HP = ?0 × exp (?1 × MEI)]. Metabolizable energy required for maintenance (MEm) was calculated iteratively, as HP = MEI. Efficiency of energy utilization for maintenance (km) was calculated as NEm/MEm. The intercept of the linear regression of retained CP on CP intake was used to calculate net protein requirements for maintenance (NPm). Net energy and protein requirement for gain (NEg and NPg, respectively) were obtained using 26 kids fed ad libitum and randomly slaughtered at 5.40 ± 0.484 kg BW (n = 10), 15.8 ± 0.655 kg BW (n = 10), and 26.3 ± 1.27 kg BW (n = 6). The first derivative of the allometric equation (used to calculate energy and protein contents in empty body weight (EBW)) with respect to EBW yielded estimates of NEg and NPg. A Monte Carlo-based method was employed to simulate variation in MEm, NEg, and NPg. This study indicated that the net energy required for maintenance is 310.1 ± 36.7 kJ kg-0.75 EBW, with MEm estimated at 499.1 ± 52.1 kJ kg-0.75 EBW and km equal to 0.62. This study indicated that 1.246 g CP kg-0.75 EBW is required by indigenous kids weighing from 5 to 25 kg BW to meet their NPm. In addition, indigenous goats require between 186.6 ± 2.97 and 214.3 ± 12.9 g CP, and between 5.39 ± 1.49 and 9.74 ± 2.57 MJ to gain one kilogram of EBW. This study may contribute to future adjustments in feeding system energy and protein recommendations for indigenous kids.

scholarly journals Feeding behavior, water intake, and energy and protein requirements of young Nellore bulls with different residual feed intakes

2020 ◽  
Vol 98 (9) ◽  
Author(s):  
Ana Clara B Menezes ◽  
Sebastião C Valadares Filho ◽  
Pedro D B Benedeti ◽  
Diego Zanetti ◽  
Mário F Paulino ◽  
...  
Keyword(s):  
Body Weight ◽  
Feeding Behavior ◽  
Water Intake ◽  
Feed Intake ◽  
Carcass Traits ◽  
Metabolizable Energy ◽  
Production Costs ◽  
Energy Requirements ◽  
Feed Ratio ◽  
Net Energy

Abstract This study aimed to determine feeding behavior, water intake (WI), and energy requirements of high- and low-residual feed intake (RFI) Nellore bulls. Data were collected from 42 weaned Nellore bulls (initial body weight [BW] 260 ± 8.1 kg; age 7 ± 1.0 mo) housed in a feedlot in group pens that contained electronic feeders, waterers, and a scale connected to the waterers. The individual dry matter intake (DMI), WI, and BW were recorded daily. The indexes of average daily gain (ADG), feed efficiency (gain to feed ratio), and RFI were calculated based on the data collected. The number of feeder and waterer visits and the time spent feeding or drinking water per animal per day were recorded as feeding behavior measures. Energy requirements for maintenance and gain were calculated according to the BR-CORTE system. Low-RFI bulls had lower DMI (P &lt; 0.01) than high-RFI bulls, and no differences (P &gt; 0.05) were observed between the two groups regarding WI, performance, and feeding behavior measurements. The net energy requirements for maintenance, metabolizable energy for maintenance, and efficiency of metabolizable energy utilization were 63.4, 98.6 kcal/metabolic empty body weight (EBW)0.75 daily, and 64.3%, respectively, for low-RFI bulls, and 78.1, 123.9 kcal/EBW0.75 daily, and 63.0%, respectively, for high-RFI bulls. The equations obtained for net energy for gain (NEg) were: NEg (Mcal/EBW0.75) daily = 0.0528 × EBW0.75 × EBG0.5459 for low-RFI and 0.054 × EBW0.75 × EBG0.8618 for high-RFI bulls, where EBG is the empty body gain. We did not observe any difference (P &gt; 0.05) regarding the composition of gain in terms of protein or fat deposition between the two groups. Both groups also presented similar (P &gt; 0.05) carcass and non-carcass traits. Therefore, our study shows that low-RFI Nellore bulls eat less, grow at a similar rate, and have lower maintenance energy requirements than high-RFI bulls. We also suggest that the lower feed intake did not compromise the carcass traits of more efficient animals, which would reduce production costs and increase the competitiveness of the Brazilian beef sector on the world market.

scholarly journals Animals selected for postweaning weight gain rate have similar maintenance energy requirements regardless of their residual feed intake classification

2021 ◽  
Author(s):  
Camila Delveaux Araujo Batalha ◽  
Luís Orlindo Tedeschi ◽  
Fabiana Lana de Araújo ◽  
Renata Helena Branco ◽  
Joslaine Noely dos Santos Gonçalves Cyrillo ◽  
...  
Keyword(s):  
Body Composition ◽  
Body Weight ◽  
Weight Gain ◽  
Feed Intake ◽  
Body Weight Gain ◽  
Energy Requirement ◽  
Residual Feed Intake ◽  
Breeding Program ◽  
Energy Requirements ◽  
Net Energy

Abstract Data of comparative slaughter were used to determine Nellore bulls' net energy requirements classified as efficient or inefficient according to residual feed intake (RFI) and selection lines (SL). Sixty-seven Nellore bulls from the selected (SE) and control (CO) lines of the selection program for postweaning weight gain were used. The animals underwent digestibility trials before being submitted to the finishing trial. Sixteen bulls were slaughtered at the beginning of the finishing trial, and their body composition were used as the baseline for the remaining animals. For body composition determinations, whole empty body components were weighed, ground, and subsampled for chemical analyses. Initial body composition was determined with equations developed from the baseline group using shrunk body weight, fat, and protein. The low RFI (LRFI) and CO animals had a lower dry matter (DMI) and nutrient intake (P &lt; 0.05) than high RFI (HRFI) and SE animals, without alterations in digestibility coefficients (P &gt; 0.05). During the finishing trial, DMI remained lower for LRFI and CO animals. Growth performance was similar between RFI classes, except for empty body weight gain that tended to be higher for LRFI than HRFI (P = 0.091). The SE animals had less fat content on the empty body (P = 0.005) than CO. Carcasses tended to be leaner for LRFI than HRFI (P = 0.080) and for SE than CO (P = 0.066) animals. LRFI animals retained more energy (P = 0.049) and had lower heat production (HP; P = 0.033) than the HRFI ones. Retained energy was not influenced by SL (P = 0.165), but HP tended to be higher for SE when compared to CO (P = 0.075) animals. Net energy requirement for maintenance (NEm) was lower for LRFI than HRFI (P = 0.009), and higher for SE than CO (P = 0.046) animals. There was an interaction tendency between RFI and SL (P = 0.063), suggesting that NEm was lower for LRFI+CO than HRFI+CO (P = 0.006), with no differences for SE (P = 0.527) animals. The efficiency of ME utilization for maintenance (km) of LRFI and HRFI animals were 62.6 and 58.4%, respectively, and for SE and CO were 59.0 and 62.1%, respectively. The breeding program for postweaning weight has not improved feed efficiency over the years, with RFI classification not being a promising selection tool for SE animals. Classification based on RFI seems to be useful in animals that have not undergone the breeding program, with LRFI animals having lower energy requirements than the HRFI ones.

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