scholarly journals Apparent Digestibility and Ingestive Behavior of Nellore Bulls With Low and High Residual Feed Intake

2021 ◽  
Author(s):  
Rayanne Galdino Menezes ◽  
Juliano José de Resende Fernandes ◽  
Alana Calaca ◽  
Emmanuel Arnhold ◽  
Marcia Helena Machado da Rocha Fernandes ◽  
...  
Keyword(s):  
Feed Intake ◽  
Residual Feed Intake ◽  
Individual Performance ◽  
Nutrient Digestibility ◽  
Neutral Detergent Fiber ◽  
Ingestive Behavior ◽  
Apparent Digestibility ◽  
Dry Matter Digestibility ◽  
Internal Marker ◽  
Ingestive Behaviour

Abstract The objective of this study was to determine the correlation between ingestive behaviour, apparent digestibility and residual feed intake (RFI) of finishing Nellore bulls fed a high concentrate diet. One hundred and twenty Nellore bulls, housed in individual pens, were evaluated in individual performance tests. The animals were fed a high concentrate diet (23:77roughage/concentrate ratio). The animals were classified as: low RFI, medium RFI, and high RFI. Data from ten animals from each group was used. Faecal production and nutrient digestibility were calculated using indigestible neutral detergent fiber as an internal marker. The feeding behaviour was evaluated over twenty-four hours by direct observation every five minutes. The most efficient animals (low RFI, 8.58 kg DM/day) consumed 27.62% less feed than the least efficient animals (high RFI, 10.95 kg DM/day). Animals with medium efficiency (mean RFI, 9.49 kg DM/day) consumed 15.39% less than high RFI. Nutrient digestibility coefficients were similar except for ether extract (P<0.03) which was 8% greater for the high-RFI animals. No effect was observed for ingestive behaviour (P>0.05). Animals spent, on average, three hours twenty-eight minutes feeding, seven hours thirty-two minutes ruminating and thirteen hours forty minutes in idle time. In the present study, ingestive behaviour and dry matter digestibility were not responsible for between-animal variation in residual feed intake in Nellore bulls fed a high concentrate diet.

scholarly journals Effects of source and concentration of neutral detergent fiber from roughage in beef cattle diets on feed intake, ingestive behavior, and ruminal kinetics

2020 ◽  
Vol 98 (5) ◽  
Author(s):  
Rodrigo S Goulart ◽  
Ricardo A M Vieira ◽  
Joao L P Daniel ◽  
Rafael C Amaral ◽  
Vanessa P Santos ◽  
...  
Keyword(s):  
Beef Cattle ◽  
Feed Intake ◽  
Dry Matter ◽  
Latin Square ◽  
Nutrient Digestibility ◽  
Corn Silage ◽  
Neutral Detergent Fiber ◽  
Ingestive Behavior ◽  
Rumen Content ◽  
Residence Times

Abstract The objectives of this research were to evaluate the effects of source and concentration of α-amylase-treated neutral detergent fiber (aNDF) from roughage on feed intake, ingestive behavior, and ruminal kinetics in beef cattle receiving high-concentrate diets. Six ruminally cannulated Nellore steers (408 ± 12 kg of body weight) were randomly assigned to a 6 × 6 Latin square design with six diets: 10% aNDF from corn silage (10CS); 20% aNDF from corn silage (20CS); or four diets containing 10% aNDF from corn silage and 10% aNDF from one of the following sources: sugarcane (SC), sugarcane bagasse (SCB), soybean hulls (SH), or low oil cottonseed hulls (LOCH). The parameters of passage and degradation kinetics were estimated based on a two-compartmental model with gamma- and exponential-distributed residence times. The nonlinear models were fitted by nonlinear least squares, and a linear mixed-effects model was fitted to all variables measured from the Latin square design that were related to intake, digestibility, digestion kinetic parameters, and residence times. Mean particle size (MPS) between roughage sources (CS, SCB, and SC) and coproducts (SH and LOCH) was affected (P &lt; 0.05). Dry matter intake (DMI) was not affected (P &gt; 0.05) by 20CS, SC, SH, or LOCH. Steers fed 20CS or LOCH diets had 16% and 20% greater DMI, respectively, (P &lt; 0.05) than steers fed 10CS diet. Steers fed SCB consumed the least dry matter (DM). The SH and LOCH diets had lower MPS values (about 8.77 mm) in comparison to 20CS, SCB, and SC diets (about 13.08 mm) and, consequently, affected (P &lt; 0.05) rumen content, ruminal in situ disappearance, nutrient digestibility, and solid fractional passage rate. Chewing time was affected (P &lt; 0.05) by roughage sources and concentration. Lower values of distance travel inside the rumen (min/cm) were observed (P &lt; 0.05) for the SCB and SC diets in comparison with any other diet. Except for SCB, there was no difference (P &gt; 0.05) in rumen fill, among other treatments. Mean daily ruminal pH was not affected (P &gt; 0.05) by 20CS, SCB, SC, and LOCH diets, and it ranged from 6.1 to 6.23. Total short-chain fatty acids concentration was affected (P &lt; 0.05) by roughage source and concentration. Based on our results, we recommend that under Brazilian finishing diets, replacing roughage sources, except for SCB, based on aNDF concentration of the roughage in high-concentrate diets containing finely ground flint corn does not affect DMI.

scholarly journals Ingestive behavior and temperament of Nellore cattle classified for residual feed intake

2019 ◽  
Vol 40 (1) ◽  
pp. 457 ◽  
Author(s):  
Julian Aldrighi ◽  
Renata Helena Branco ◽  
Joslaine Noely dos Santos Gonçalves Cyrillo ◽  
Elaine Magnani ◽  
Cleisy Ferreira do Nascimento ◽  
...  
Keyword(s):  
Feed Intake ◽  
Feed Efficiency ◽  
High Efficiency ◽  
Residual Feed Intake ◽  
Serum Cortisol ◽  
Individual Performance ◽  
Flight Speed ◽  
Ingestive Behavior ◽  
Composite Score ◽  
Nellore Cattle

The objective of this study was to evaluate the relationship between ingestive behavior, temperament and residual feed intake (RFI) in Nellore cattle. Sixty-two bulls and 56 heifers after weaning, housed in individual pens, were evaluated in individual performance tests. Animals were classified as low RFI ( 0.135 kg day-1; greater than mean plus 0.5 standard deviation). Ingestive behavior was evaluated for 24 h by direct observation, every 24 days in bulls or every 10 days in heifers. Temperament was assessed by flight speed, reactivity in mobile confinement, composite score, and serum cortisol measurement. The most efficient animals (low RFI, 5.6 kg DM day-1) consumed 7% less feed than animals with medium efficiency (mean RFI, 6.0 kg DM day-1) and 13% less than the least efficient animals (high RFI, 6.34 kg DM day-1). More feed efficient animals spent a longer time feeding and ruminating per kg of DM consumed. Similarly, more efficient animals consumed less DM per hour and ruminated less DM per hour, but made the same number of visits to the feed bunk. High-efficiency animals were 13% and 35% faster to walk 1.77 m after release from the scale than medium- and low-efficiency animals, respectively, suggesting a more reactive temperament without differences in reactivity, composite score, or serum cortisol. Feed efficiency is associated with ingestive behavior and temperament in Nellore cattle. More efficient animals consume and ruminate less feed over the same period of time than animals with medium and low feed efficiency. In addition, more efficient animals exhibit a faster flight speed and are more reactive than less efficient animals.

EFFECT OF STRUCTURAL AND CHEMICAL FACTORS OF FORAGES ON POTENTIALLY DIGESTIBLE FIBER, INTAKE, AND TRUE DIGESTIBILITY BY RUMINANTS

1988 ◽  
Vol 68 (3) ◽  
pp. 787-799 ◽  
Author(s):  
V. GIRARD ◽  
G. DUPUIS
Keyword(s):  
Cell Wall ◽  
Dry Matter ◽  
Plant Cell Wall ◽  
Neutral Detergent Fiber ◽  
Optimum Number ◽  
Apparent Digestibility ◽  
Cool Season ◽  
Dry Matter Digestibility ◽  
True Digestibility

In view of the large variation found in plant cell wall digestibilities with ruminants, an attempt was made to group 124 feeds into different lignification classes (clusters) on the basis of chemical characteristics. Each feed cluster was described using a structural coefficient [Formula: see text] that related the potentially digestible fiber (PDF, %) to the ratio between lignin and cell wall volume. The optimum number of clusters was determined iteratively by performing a regression of the apparent digestibility of dry matter at maintenance level (DDM1, %) against the PDF and cell soluble (SOL, %) contents of feeds. The [Formula: see text] coefficients varied from 0.05 (grains, N = 13) to 1.85 (corn silage, N = 3) and increased with the maturity of the grasses from 0.88 (legumes, vegetative cool season grasses, N = 26) to 1.33 (mature, cool season grasses, N = 19). Predicted PDF were closely correlated (r > 0.9, P < 0.01) to in vitro cell wall disappearances (IVCWD). Apparently digestible cell wall in four grasses and four legumes increased linearly with 96-h IVCWD and standard error (SE) was similar to the SE of predicted apparent digestible SOL from SOL concentrations. Assuming that similarity between SE could be also observed in larger samples, PDF and SOL were used in summative equations to predict apparent dry matter digestibility. DDM1 discounted for intake (DDM1 – 4, %) was regressed against SOL and PDF concentrations of 87 feeds:[Formula: see text]with ds and df, the true digestibilities of SOL and PDF. Estimates of ds and df were 0.98 and 0.95 for a zero-production (maintenance) level of intake, and 0.91 and 0.79 for an intake level four times maintenance. Since the true digestibility of the PDF component was only 4% – 13% lower than that of the cell soluble component, the concentration of PDF in cell wall was the major determinant in the variation in apparent digestibility of forages. Key words: lignin, neutral detergent fiber, true digestibility, cluster analysis, feeds

scholarly journals Apparent digestibility of juveniles of matrinxã Brycon amazonicus fed diets with different protein levels

2021 ◽  
Vol 43 ◽  
pp. e52236
Author(s):  
Cesar Augusto Alves Gonçalves ◽  
Jackson Pantoja-Lima ◽  
Márcia Regina Fragoso Machado-Bussons ◽  
João Paulo Ferreira Rufino
Keyword(s):  
Crude Protein ◽  
Polynomial Regression ◽  
Analysis Data ◽  
Nutrient Digestibility ◽  
Apparent Digestibility ◽  
Protein Ratio ◽  
Digestible Energy ◽  
Protein Levels ◽  
Dry Matter Digestibility ◽  
Four Levels

The objective of the present study was to determine the apparent digestibility of juveniles of matrinxã Brycon amazonicus fed diets with different levels of protein. The experimental design was completely randomized, where the treatments consisted of four levels of protein in the diets (28, 32, 36 and 40%) and five replicates (water boxes) with 10 juveniles of matrinxã each. Diets were offered four times a day, and feces were collected twice a week, along 28 days, for digestibility analysis. Data collected were subjected to polynomial regression at 5% significance. Differences (p<0.05) were observed in dry matter digestibility, with higher digestibility according to increasing levels of protein in the diets. This behavior was directly expressed in the digestibility of nutrients by juveniles of matrinxã, such as % ash, % crude protein, apparent digestible energy, % digestibility of apparent digestible energy and energy: protein ratio. However, this was not observed (p > 0.05) in the digestibility of % ether extract. Digestibility of N, P, Ca, Mg, Cu and Zn presented linear positive (p < 0.05) behavior, in which the use of these minerals increased with the increase in the level of protein in the diets. However, the digestibility of K, Fe and Mn reduced (p < 0.05) with increasing protein levels in the diets. Thus, it can be concluded that the rise in protein level in diets for juveniles of matrinxã improves nutrient digestibility. The results of this study indicated that 40% crude protein in the diets provided better results.

scholarly journals Digestibility markers of sheep diets containing hydrolyzed sugarcane-top hay

2017 ◽  
Vol 18 (1) ◽  
pp. 38-49 ◽  
Author(s):  
Miguel Arcanjo MOREIRA FILHO ◽  
Arnaud Azevêdo ALVES ◽  
Bruno Spíndola GARCEZ ◽  
Antonia Leidiana MOREIRA ◽  
Danielle Maria Machado Ribeiro AZEVÊDO ◽  
...  
Keyword(s):  
Titanium Dioxide ◽  
Chromium Oxide ◽  
Dry Matter ◽  
Live Weight ◽  
Neutral Detergent Fiber ◽  
Acid Detergent Fiber ◽  
Collection Method ◽  
Dry Matter Digestibility ◽  
Internal Marker ◽  
Male Sheep

SUMMARY This experiment evaluated the correlation between the estimates of fecal digestibility and dry matter digestibility (DMD) and nutrients obtained using internal (indigestibles dry materiDM, neutral detergent fiber-iNDF, acid detergent fiber-iADF and acid detergent ligniniADL) and external (chromium oxide-Cr2O3, titanium dioxide-TiO2, and purified and enriched lignin from eucalyptus-LIPE®) markers and the values obtained by the total feces collection method. Twenty uncastrated male sheep, with 29.64±5.53 kg average live weight; approximately 12 months old, were kept in metabolic cages and fed diets containing untreated sugarcane-top hay or sugarcane-top hay hydrolyzed with 3 and 6% urea or 1.5 and 3% calcium oxide (CaO). There was a positive correlation (P<.05) between the fecal production estimated by the markers and via total feces collection, with coefficients higher than 90% for iDM, Cr2O3, and TiO2. The DMD and nutrients estimated with the use of markers was positively correlated (P<.05) with that obtained by total feces collection. Coefficients of correlation for digestibility obtained by total collection were higher than those obtained with Cr2O3, but close to those obtained using TiO2. The coefficient of correlation between the digestibility of protein and fiber fraction estimated with iDM and iNDF and that obtained by total collection was higher than 70%. Internal marker iDM and external markers Cr2O3 and TiO2 are effective in estimating fecal production and DMD and nutrients.

scholarly journals Associations between residual feed intake and apparent nutrient digestibility, in vitro methane-producing activity, and volatile fatty acid concentrations in growing beef cattle1

2019 ◽  
Vol 97 (8) ◽  
pp. 3550-3561 ◽  
Author(s):  
Jocelyn R Johnson ◽  
Gordon E Carstens ◽  
Wimberly K Krueger ◽  
Phillip A Lancaster ◽  
Erin G Brown ◽  
...  
Keyword(s):  
Regression Analysis ◽  
Fatty Acid ◽  
Feed Intake ◽  
Volatile Fatty Acid ◽  
Stepwise Regression ◽  
Rumen Fluid ◽  
Residual Feed Intake ◽  
Nutrient Digestibility ◽  
The Relationship

Abstract The objectives of this study were to examine the relationship between residual feed intake (RFI) and DM and nutrient digestibility, in vitro methane production, and volatile fatty acid (VFA) concentrations in growing beef cattle. Residual feed intake was measured in growing Santa Gertrudis steers (Study 1; n = 57; initial BW = 291.1 ± 33.8 kg) and Brangus heifers (Study 2; n = 468; initial BW = 271.4 ± 26.1 kg) fed a high-roughage-based diet (ME = 2.1 Mcal/kg DM) for 70 d in a Calan-gate feeding barn. Animals were ranked by RFI based on performance and feed intake measured from day 0 to 70 (Study 1) or day 56 (Study 2) of the trial, and 20 animals with the lowest and highest RFI were identified for subsequent collections of fecal and feed refusal samples for DM and nutrient digestibility analysis. In Study 2, rumen fluid and feces were collected for in vitro methane-producing activity (MPA) and VFA analysis in trials 2, 3, and 4. Residual feed intake classification did not affect BW or BW gain (P &gt; 0.05), but low-RFI steers and heifers both consumed 19% less (P &lt; 0.01) DMI compared with high-RFI animals. Steers with low RFI tended (P &lt; 0.1) to have higher DM digestibility (DMD) compared with high-RFI steers (70.3 vs. 66.5 ± 1.6% DM). Heifers with low RFI had 4% higher DMD (76.3 vs. 73.3 ± 1.0% DM) and 4 to 5% higher (P &lt; 0.01) CP, NDF, and ADF digestibility compared with heifers with high RFI. Low-RFI heifers emitted 14% less (P &lt; 0.01) methane (% GE intake; GEI) calculated according to Blaxter and Clapperton (1965) as modified by Wilkerson et al. (1995), and tended (P = 0.09) to have a higher rumen acetate:propionate ratio than heifers with high RFI (GEI = 5.58 vs. 6.51 ± 0.08%; A:P ratio = 5.02 vs. 4.82 ± 0.14%). Stepwise regression analysis revealed that apparent nutrient digestibilities (DMD and NDF digestibility) for Study 1 and Study 2 accounted for an additional 8 and 6%, respectively, of the variation in intake unaccounted for by ADG and mid-test BW0.75. When DMD, NDF digestibility, and total ruminal VFA were added to the base model for Study 2, trials 2, 3, and 4, the R2 increased from 0.33 to 0.47, explaining an additional 15% of the variation in DMI unrelated to growth and body size. On the basis of the results of these studies, differences in observed phenotypic RFI in growing beef animals may be a result of inter-animal variation in apparent nutrient digestibility and ruminal VFA concentrations.

scholarly journals Effect of dietary supplementation of xylanase in a wheat-based diet containing canola meal on growth performance, nutrient digestibility, organ weight, and short-chain fatty acid concentration in digesta when fed to weaned pigs

2020 ◽  
Vol 98 (3) ◽  
Author(s):  
Gustavo A Mejicanos ◽  
Gemma González-Ortiz ◽  
Charles Martin Nyachoti
Keyword(s):  
Growth Performance ◽  
Feed Intake ◽  
Dietary Supplementation ◽  
Nutrient Digestibility ◽  
Organ Weight ◽  
Neutral Detergent Fiber ◽  
Short Chain ◽  
Canola Meal ◽  
Weaned Pigs ◽  
Main Factors

Abstract This study was designed to determine the effect of dietary supplementation of xylanase on growth performance, nutrient digestibility, organ weight, digesta pH, and concentration of short-chain fatty acids (SCFA) of weaned pigs fed wheat–canola meal (CM) diets over a 35-d period. A total of 144 piglets (72 barrows and 72 gilts) weaned at 18 ± 2 d of age, with initial body weight (BW) of 6.2 ± 0.7 kg, received one of eight dietary treatments based on randomized complete block design. BW and feed intake were recorded weekly to calculate average daily gain (ADG), average daily feed intake (ADFI), and feed efficiency (G:F). Treatments consisted of a control wheat–soybean meal-based diet and wheat-regular (RCM), dehulled (DCM), or coarse CM (CCM) without and with 16,000 BXU/kg xylanase (Econase XT). All diets contained 500 FTU/kg of phytase (Quantum Blue 5G) and titanium dioxide (0.3%). Apparent total tract digestibility (ATTD) of neutral detergent fiber (NDF), crude protein (CP), phosphorous (P), calcium (Ca), dry matter, and diet were determined. On day 35, one pig per pen was euthanized to evaluate the main factors of protein, xylanase supplementation, and sex on organ weight, ileal and colon digesta pH, and colon digesta concentrations of SCFA. The main factors did not affect growth performance. Xylanase supplementation improved nutrient digestibilities in all diets and increased ileal and colonic digesta pH without affecting the growth performance of weaned pigs fed wheat and CM-based diets. A protein–xylanase effect (P &lt; 0.05) resulted in increasing the ATTD of NDF from 28% to 32% and from 29% to 37% for RCM and DCM, respectively. The ATTD of CP was greater (P &lt; 0.05) with xylanase supplementation (75% vs. 70%). Xylanase supplementation increased ATTD of P and Ca. A three-way interaction (P &lt; 0.05) for protein–xylanase–gender for colon pH, acetic, and propionic acid in the colon digesta of pigs indicated that, in addition to the protein source, piglet sex could have influenced how xylanase works. Xylanase supplementation increased (P &lt; 0.05) the weight of the liver and spleen and tended (P &lt; 0.10) to increase the size of the kidney. In conclusion, dietary supplementation of xylanase increased nutrient digestibility and digesta pH but did not influence the growth performance of weaned pigs fed wheat and CM-based diets over a 35-d period.

Effect of vegetable oil source supplementation on feed intake, nutrients digestibility and rumen biohydrogenation bacterial population in Thai Friesian dairy cows

2018 ◽  
Author(s):  
N. Suphrap ◽  
C. Wachirapakorn ◽  
C. Thamrongyoswittayakul ◽  
C. Wongnen
Keyword(s):  
Dairy Cows ◽  
Vegetable Oil ◽  
Feed Intake ◽  
Bacterial Population ◽  
Latin Square ◽  
Nutrient Digestibility ◽  
Cellulolytic Bacteria ◽  
Dry Matter Digestibility ◽  
Dna Copy Numbers ◽  
Oil Source

The investigation aimed to study the effect of vegetable oil sources on feed intake, nutrient digestibility and biohydrogenation bacterial population in Thai Friesian dairy cows. Three fistula Thai Friesian cows with mean body weight (BW) of 600±100 kg were assigned to receive three vegetable oil sources i.e. palm oil (PO), soybean oil (SBO) and sunflower oil (SFO) included at 4 %DM in commercial concentrate. All cows were fed on different diets that contained concentrate of 1 %BW and rice straw of 1 %BW according to a 3×3 latin square design (LSD). The results revealed that dry matter digestibility (DMD) and organic matter digestibility (OMD) tended to be higher in cows fed on SBO and SFO (P=0.06). Moreover, the DNA copy numbers (copies/ml) of biohydrogenation bacteria (Ruminococcus albus) and cellulolytic bacteria (Ruminococcus flavefaciens and Prevotella ruminicola) were higher in cows fed on SBO (P less than 0.05). In summary, supplementation of SBO in diet resulted in a higher nutrient digestibility and rumen biohydrogenation bacteria population.

scholarly journals Intake, apparent nutrient digestibility and ingestive behavior of sheep fed cashew nut meal

2011 ◽  
Vol 40 (5) ◽  
pp. 1128-1133 ◽  
Author(s):  
Patrícia Guimarães Pimentel ◽  
Elzânia Sales Pereira ◽  
Augusto César de Queiroz ◽  
Ivone Yurika Mizubuti ◽  
José Gilson Louzada Regadas Filho ◽  
...  
Keyword(s):  
Organic Matter ◽  
Crude Protein ◽  
Dry Matter ◽  
Nutrient Digestibility ◽  
Ingestive Behavior ◽  
Apparent Digestibility ◽  
Acid Detergent Fiber ◽  
Cashew Nut ◽  
Linear Behavior ◽  
Total Carbohydrates

The objective of this work was to evaluate intake, nutrient apparent digestibility and ingestive behavior of sheep fed rations with cashew nut meal (CNM) at the levels of 0; 10; 20 and 30% in the concentrate ration. It was used a double 4 × 4 Latin square experimental design. Intakes of dry matter (DM), organic matter, crude protein, mineral matter, non-fibrous carbohydrates and total digestible nutrients were not influenced by the addition of CNM, however, intake of neutral detergent fiber (NDF), acid detergent fiber and total carbohydrates presented a quadratic behavior with the increase of content of lipids in the ration. Apparent digestibility of DM, organic matter, crude protein, NDF, acid detergent fiber and non-fibrous carbohydrates was not influenced by the addition of CNM in the rations; however digestibility of ether extract and total carbohydrates presented quadratic and linear behavior, respectively. It was not observed any significant differences in time spent with feeding and rumination, however, total chewing time was influenced, presenting increasing linear behavior with the levels of CNM. Concerning to intakes of dry matter and NDF per hour, feed efficiency and rumination were not affected by increase on lipid content in the rations. Ruminating chews time per rumen bolus, number of ruminated boli and the number of ruminating chews per day were not influenced by experimental rations. In sheep feeding management, it is suggested as a feeding alternative the use of up to 30% of CNM in the concentrate ration if it is available.

Methane and carbon dioxide emissions from yearling beef heifers and mature cows classified for residual feed intake under drylot conditions

2020 ◽  
Vol 100 (3) ◽  
pp. 522-535 ◽  
Author(s):  
G. Manafiazar ◽  
V.S. Baron ◽  
L. McKeown ◽  
H. Block ◽  
K. Ominski ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Feed Intake ◽  
Carbon Dioxide Emissions ◽  
Body Weight Gain ◽  
Residual Feed Intake ◽  
Individual Performance ◽  
Feed Consumption ◽  
Beef Heifers ◽  
Air Temperatures ◽  
Rapid City

This study quantified methane (CH4) and carbon dioxide (CO2) production from beef heifers and cows classified for residual feed intake adjusted for off-test backfat thickness (RFIfat) and reared in drylot during cold winter temperatures. Individual performance, daily feed intake, and RFIfat were obtained for 1068 crossbred and purebred yearling heifers (eight trials) as well as 176 crossbred mature cows (six trials) during the winters of 2015–2017 at two locations. A portion of these heifers (147 high RFIfat; 167 low RFIfat) and cows (69 high RFIfat; 70 low RFIfat) was monitored for enteric CH4 and CO2 emissions using the GreenFeed Emissions Monitoring (GEM) system (C-Lock Inc., Rapid City, SD, USA). Low RFIfat cattle consumed less feed [heifers, 7.80 vs. 8.48 kg dry matter (DM) d−1; cows, 11.64 vs. 13.16 kg DM d−1] and emitted less daily CH4 (2.5% for heifers; 3.7% for cows) and CO2 (1.4% for heifers; 3.4% for cows) compared with high RFIfat cattle. However, low RFIfat heifers and cows had higher CH4 (6.2% for heifers; 9.9% for cows) and CO2 yield (7.3% for heifers; 9.8% for cows) per kilogram DM intake compared with their high RFIfat pen mates. The GEM system performed at air temperatures between +20 and −30 °C. Feed intake of heifers and mature cows was differently affected by ambient temperature reduction between +20 and −15 °C and similarly increased their feed intake at temperatures below −15 °C. In conclusion, low RFIfat animals emit less daily enteric CH4 and CO2, due mainly to lower feed consumption at equal body weight, gain, and fatness.

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