scholarly journals Relationships between feed efficiency and puberty in Bos taurus and Bos indicus-influenced replacement beef heifers

2020 ◽  
Vol 98 (10) ◽  
Author(s):  
Luara B Canal ◽  
Pedro L P Fontes ◽  
Carla D Sanford ◽  
Vitor R G Mercadante ◽  
Nicolas DiLorenzo ◽  
...  
Keyword(s):  
Breeding Season ◽  
Feed Intake ◽  
Feed Efficiency ◽  
Bos Taurus ◽  
Average Daily Gain ◽  
Bos Indicus ◽  
Residual Feed Intake ◽  
Feed Ratio ◽  
Beef Heifers ◽  
Efficiency Test

Abstract The objective of this experiment was to investigate the relationship between residual feed intake (RFI) and parameters associated with reproductive efficiency in growing beef heifers. One hundred and seventy-nine replacement beef heifers (Bos taurus and Bos indicus-influenced) were enrolled in a retrospective cohort design. Heifers were assigned to a 70-d feed efficiency test, and results were utilized to retrospectively classify heifers into low (n = 51), medium (n = 66), or high (n = 62) RFI groups based on their individual RFI values. Blood samples were collected weekly throughout the feed efficiency test and breeding season, which were analyzed for plasma concentration of progesterone to determine age at puberty (PUB). By design, residual feed intake differed among RFI groups where high (1.21 ± 0.08 kg/d) had greater (P < 0.01) RFI than medium (0.00 ± 0.08 kg/d) and low RFI groups (–1.49 ± 0.09 kg/d), and medium had greater (P < 0.01) RFI than low RFI heifers. Yet, no differences were observed between breed types for RFI (P = 0.53). Average daily gain (ADG) differed between breed types where Bos taurus heifers had greater ADG (P = 0.02) than B. indicus-influenced heifers. Furthermore, ADG tended (P = 0.08) to differ among RFI groups, where medium RFI heifers tended to have reduced ADG compared with low and high RFI heifers. No differences were determined between breed types for gain-to-feed ratio (G:F; P = 0.20; however, G:F differed among RFI groups and was greater (P < 0.01) in low vs. high, and low vs. medium RFI heifers. The percentage of cycling heifers by the start of the breeding season differed (P = 0.03) by RFI group, where a greater percentage of low RFI heifers were cycling compared with high RFI heifers. A difference was determined on PUB between breed types (P = 0.03), where Bos taurus (393.40 ± 4.64 d) heifers had a reduced PUB compared with B. indicus-influenced (406.90 ± 5.07 d) heifers. In addition, PUB differed by RFI group where low (385.96 ± 6.20 d; P < 0.01) and medium (398.47 ± 5.47 d; P = 0.02) RFI heifers had a reduced PUB compared with High RFI heifers (416.03 ± 5.58 d). In conclusion, more feed efficient heifers attained PUB earlier than less feed efficient heifers. Therefore, selection of heifers for feed efficiency may positively impact reproductive performance of replacement beef heifers.

Expression of candidate genes for residual feed intake in tropically adapted Bos taurus and Bos indicus bulls under thermoneutral and heat stress environmental conditions

2021 ◽  
pp. 102998
Author(s):  
Bianca Vilela Pires ◽  
Nedenia Bonvino Stafuzza ◽  
Luara Afonso de Freitas ◽  
Maria Eugênia Zerlotti Mercadante ◽  
Ester Silveira Ramos ◽  
...  
Keyword(s):  
Heat Stress ◽  
Candidate Genes ◽  
Feed Intake ◽  
Environmental Conditions ◽  
Bos Taurus ◽  
Bos Indicus ◽  
Residual Feed Intake

scholarly journals PSV-18 The role of leptin in feed efficiency and behavior attributes of commercial beef heifers

2020 ◽  
Vol 98 (Supplement_3) ◽  
pp. 162-162
Author(s):  
Nayan Bhowmik ◽  
Kris A Ringwall ◽  
Carl R Dahlen ◽  
Kendall C Swanson ◽  
Jeffrey A Clapper ◽  
...  
Keyword(s):  
Feeding Behavior ◽  
Breeding Season ◽  
Feed Intake ◽  
Feed Efficiency ◽  
Repeated Measures ◽  
Fixed Effects ◽  
Beef Heifers ◽  
Frame Size ◽  
And Behavior ◽  
Plasma Leptin

Abstract Leptin is a 16-kDa-peptide hormone product of the leptin gene (LEP) that is predominantly synthesized by adipose tissues and has known involvement in regulation of feed intake, energy expenditure, reproduction, and immune functions. The objective was to determine the association of leptin genotype (LEP c.73C >T), leptin diplotype (LEPD) and plasma leptin hormone (LEPH) concentration with growth, feed intake, feed efficiency, and behavior characteristics in developing beef heifers. A total of 336 commercial beef heifers were genotyped for the LEP c.73C >T marker. Four single nucleotide polymorphism markers including LEP c.73C >T, ARS-BFGL-NGS-59298 (intron 1), BovineHD0400026029 (upstream) and BovineHD0400026063 (downstream) of LEP were considered for haplotype analysis. Eleven LEPD were identified for this study using parsimony-based analyses. Circulating levels of LEPH were measured on 333 heifers prior to their first breeding season and used to assign low or high concentration group based on population median. Data were analyzed using the mixed procedure of SAS for repeated measures, fixed effects of ancestral breed group (n = 4), dam age category (n = 4), frame size group (n = 4), project cycle nested within birth year (n = 6), week of feed trial × year, LEP (n = 3) or LEPD (n = 11) or LEPH (n = 2), as well as week × LEPH (only for LEPH). There were no significant differences between LEP genotypes (P ≥ 0.11) or LEPD (P ≥ 0.33) for any of the studied traits. Heifers with low LEPH ate fewer meals per day (P = 0.02) and had more DMI per meal (P = 0.04) compared to those with high plasma leptin. Further research is needed to better understand plasma LEPH concentration and its role in feeding behavior attributes. However, circulatory LEPH before the breeding season may serve as a predictor for feeding behavior.

scholarly journals Genetics of steer daily and residual feed intake in two tropical beef genotypes, and relationships among intake, body composition, growth and other post-weaning measures

2009 ◽  
Vol 49 (6) ◽  
pp. 351 ◽  
Author(s):  
S. A. Barwick ◽  
M. L. Wolcott ◽  
D. J. Johnston ◽  
H. M. Burrow ◽  
M. T. Sullivan
Keyword(s):  
Body Composition ◽  
Feed Intake ◽  
Bos Taurus ◽  
Body Condition Score ◽  
Serum Insulin ◽  
Average Daily Gain ◽  
Genetic Correlations ◽  
Residual Feed Intake ◽  
Genetic Evaluation ◽  
Igf I

Genetic parameters for Brahman (BRAH) and Tropical Composite (TCOMP) cattle were estimated for steer production traits recorded at weaning (WEAN), 80 days post-weaning (POSTW), feedlot entry (ENTRY) and after ∼120 days feedlot finishing (EXIT). The TCOMP was 50% Bos indicus, African Sanga or other tropically adapted Bos taurus, and 50% non-tropically adapted Bos taurus. Data involved 2216 steers, comprising 1007 BRAH by 53 sires and 1209 TCOMP by 50 sires. Individual daily feed intake (DFI) and residual feed intake (RFI) were assessed on 680 BRAH and 783 TCOMP steers over an ~70-day feedlot test. Other traits were liveweight (LWT), average daily gain (ADG), ultrasonically scanned rump (SP8) fat depth, rib (SRIB) fat depth, M. longissimus area (SEMA) and intra-muscular fat % (SIMF), body condition score (CS), hip height (HH), flight time (FT) and serum insulin-like growth factor-I concentration (IGF-I). BRAH were significantly (P < 0.05) lighter at ENTRY and EXIT, and had lower DFI (10.8 v. 13.2 kg/day) and RFI (–0.30 v. 0.17 kg/day), greater SP8 (5.8 v. 5.1 mm) but similar SRIB at ENTRY, lower SRIB (8.2 v. 8.9 mm) but similar SP8 at EXIT, and greater HH than TCOMP. Heritabilities for DFI, RFI, LWT, ADG, scanned body composition, HH and IGF-I measures, across measurement times, were generally in the 20 to 60% range for both genotypes. Genetic variance for RFI was 0.19 (kg/day)2 in BRAH and 0.41 (kg/day)2 in TCOMP, suggesting a clear potential to genetically change RFI in both genotypes. Trait variances and genetic correlations often differed between the genotypes, supporting the use of genotype-specific parameters in genetic evaluation. The genotype differences may be associated with evolutionary changes that have occurred in B. indicus as a part of their adaptation to tropical environments. Measures with potential to be used as genetic indicators of DFI were LWT measures in BRAH and TCOMP, ADG at ENTRY in TCOMP, and SP8 and SIMF at ENTRY in BRAH. Measures with potential to be genetic indicators of RFI were HH and ADG at ENTRY in BRAH, and IGF-I in both genotypes. Taller and faster-growing BRAH steers at ENTRY had genetically lower RFI. IGF-I was negatively genetically correlated with RFI whether IGF-I was measured at POSTW, ENTRY or EXIT. SRIB fatness at EXIT was strongly positively genetically correlated with RFI in TCOMP but only lowly correlated in BRAH. Fatness at ENTRY was lowly and negatively genetically correlated with RFI. The results emphasise the need for a population-specific understanding of trait relationships and of trait differences between measurement times if genetic indicator traits are to be utilised in genetic evaluation of RFI.

scholarly journals Triticale silage replaces sorghum silage in finishing of Braford heifers

2021 ◽  
Vol 73 (5) ◽  
pp. 1180-1186
Author(s):  
A.M. Oliveira ◽  
L.D.F. Silva ◽  
A.P.O. Souza ◽  
E.L.A. Ribeiro ◽  
C.C. Jobim ◽  
...  
Keyword(s):  
Feed Intake ◽  
Average Daily Gain ◽  
Carcass Characteristics ◽  
Live Weight ◽  
Feed Ratio ◽  
Beef Heifers ◽  
Fat Thickness ◽  
Sorghum Silage ◽  
Experimental Treatments ◽  
Daily Gain

ABSTRACT The aim of this study was to evaluate the effect of sorghum silage substitution with different proportions of triticale silage on the performance and carcass of Braford heifers. Twenty-four Braford heifers were randomly assigned to four diets where sorghum silage was replaced at 0%, 30%, 60%, and 100% for triticale silage in a feedlot system. During sixty-tree days of the experiment, the feed intake, feed ratio conversion, and average daily gain were measured. The heifers were slaughtered and the effects of the sorghum and triticale silage in carcass characteristics were evaluated. The replacement of sorghum silage with triticale silage did not affect the feed intake and average daily gain (P> 0.05). Feed gain ratio was higher for the heifers that received lower proportions of triticale silage (0% and 30%) in replace sorghum silage (P <0.05). Eye loin area and fat thickness were similar among treatments (P<0.05). Other carcass characteristics, such as slaughter live weight, dressing percentage, conformation and fat classification were similar among experimental treatments (P<0.005). Triticale silage can replace sorghum silage for finishing beef heifers in feedlot system and provides similar carcass characteristics.

scholarly journals Feed efficiency and meat quality of crossbred beef heifers classified according to residual feed intake

2015 ◽  
Vol 16 (3) ◽  
pp. 632-642 ◽  
Author(s):  
Simone Frotas dos REIS ◽  
Daiane Aparecida FAUSTO ◽  
Sergio Raposo de MEDEIROS ◽  
Pedro Veiga Rodrigues PAULINO ◽  
Sebastião de Campos VALADARES FILHO ◽  
...  
Keyword(s):  
Meat Quality ◽  
Feed Intake ◽  
Feed Efficiency ◽  
Residual Feed Intake ◽  
Beef Heifers ◽  
System A ◽  
Fat Thickness ◽  
Ad Libitum ◽  
Sorghum Silage

AbstractThis study aimed to evaluate feed efficiency and meat quality of 31 three-crossbred beef heifers during 84 days in a feedlot system. A 60:40 concentrate and sorghum silage ration on DM basis (ME = 2.73Mcal/kg of DM, CP = 11.90% DM) was fed ad libitum. Based on residual feed intake (RFI) calculations, the heifers were ranked in three groups of feed efficiency: High RFI (average mean = 0.776; n = 9), medium RFI (average mean = -0.010; n = 11), and low RFI (average mean = - 0.624; n = 11). High RFI heifers consumed 4.56% more DM per day than low RFI heifers (P <0.05). The ADG did not differ (P> 0.05) among RFI groups (1.40kg/day). No differences (P>0.05) were detected for digestibility of the nutrients: DM (64.00%), CP (60.01%), crude fat (72.90%), NDF (54.80%) and non-fibrous carbohydrate (NFC) (78.91%). There were no differences between low and high RFI groups for slaughter weight (475.00 vs. 479.55kg), hot carcass weight (259.09 vs. 261.44kg), Longissimus dorsi (LD) area (69.02 vs. 68.11 cm2), back-fat thickness (5.74 vs. 6.26 cm), shear force (5.45 vs. 5.19kg), sensorial traits of LD muscle, LD color (intensities L=40.47 a*=24.74 and b*=16.13) or commercial cuts yield. Low RFI heifers presented similar meat quality and carcass traits as high RFI heifers, however low RFI heifers consumed less DM (kg/d).

scholarly journals Influence of genetic markers on the feeding behavior of yearling bulls

2019 ◽  
Vol 32 (1) ◽  
pp. 14-20
Author(s):  
Estela Garza-Brenner ◽  
Ana M Sifuentes-Rincón ◽  
Felipe A Rodríguez Almeida ◽  
Ronald D Randel ◽  
G Manuel Parra-Bracamonte ◽  
...  
Keyword(s):  
Beef Cattle ◽  
Feed Intake ◽  
Feed Efficiency ◽  
Complex Traits ◽  
Performance Test ◽  
Average Daily Gain ◽  
Residual Feed Intake ◽  
Feeding Performance ◽  
Efficiency Performance ◽  
Para Determinar

Background: The search for gene and marker effects on economically important traits is aimed not only to understanding the genetic architecture of complex traits but also to applying the information to breeding schemes. Objective: To analyze the effect of two temperament-related SNPs (rs109576799 located in the DRD3 gene, and rs43696138 in the HTR2A gene) on feeding performance of Mexican beef cattle. Methods: One hundred and thirty-six young beef bulls were included in a centralized feed efficiency performance test based on residual feed intake (RFI), with 20 d for adaptation and 70 d of feed efficiency testing. In addition to feeding traits, temperament was assessed at the beginning of the trial using pen score (PS) and exit velocity (EV). All animals were genotyped with two markers located in the HTR2A and DRD3 genes, and an association analysis was conducted between these genotypes and the measured traits. Results: For Brangus breed, a significant association was obtained between average daily gain (ADG; p=0.019), and the rs43696138 marker, resulting in higher gains for homozygous genotype GG (1.69 ± 0.04 kg), when compared to the heterozygous genotype GA (1.54 ± 0.04 kg). Conclusion: The previously reported association of these markers with temperament was not confirmed in the evaluated breeds; however, the rs43696138 marker showed an effect on a feeding performance trait. Further studies are needed to determine the effect of this and other markers on both RFI and temperament.Keywords: beef cattle, feed efficiency, residual feed intake, single nucleotide polymorphism, temperament.  Resumen Antecedentes: La búsqueda de efectos genéticos y marcadores de rasgos económicamente relevantes no solo se basa en el interés biológico de comprender la arquitectura genética de rasgos complejos, sino también en aplicar la información en los esquemas prácticos de mejoramiento. Objetivo: Analizar el efecto de dos SNPs relacionados con el temperamento (rs109576799 localizado en el gen DRD3, y rs43696138 localizado en el gen HTR2A) sobre la eficiencia alimenticia en el ganado bovino mexicano. Métodos: Ciento treinta y seis toretes de carne jóvenes fueron sometidos a una prueba de comportamiento alimenticio basada en el consumo residual de alimento (RFI), con 20 d de adaptación y 70 d de prueba para la eficiencia alimenticia. Además de los rasgos de comportamiento alimenticio, se evaluó el temperamento de los animales al inicio de la prueba, mediante la evaluación de comportamiento en el corral (PS), y la velocidad de salida (EV). Todas las muestras se tipificaron con dos marcadores localizados en los genes DRD3 y HTR2A para posteriormente realizar un análisis de asociación de los genotipos con los rasgos evaluados. Resultados: En la raza Brangus, se observó una asociación significativa de la media de ganancia diaria de peso (ADG, p=0,019) con el marcador rs43696138, localizado en el gen HTR2A, resultando en mayores ganancias para el genotipo GG (1,69 ± 0,04 kg) en comparación con los toros heterocigóticos GA (1,54 ± 0,04 kg). Conclusión: No se confirmó la asociación de estos marcadores previamente reportados con el temperamento en las razas evaluadas; sin embargo, el marcador rs43696138 mostró efecto en un rasgo de comportamiento alimenticio. Se necesitan más estudios para determinar el efecto de éste y otros marcadores en el consumo residual de alimento (RFI) y el temperamento.Palabras clave: consumo residual de alimento, eficiencia alimenticia, ganado de carne, polimorfismo de un solo nucleótido, temperamento.  Resumo Antecedentes: A busca de efeitos genéticos e marcadores de características economicamente relevantes não se baseia apenas no interesse biológico de compreender a arquitetura genética de traços complexos, mas também na aplicação da informação nos esquemas práticos de melhoria. Objetivo: Analisar o efeito de dois SNPs relacionados ao temperamento (rs109576799 localizado no gene DRD3 e rs43696138 localizado no gene HTR2A) sobre a eficiência nutricional no gado mexicano. Métodos: Cento e trinta e seis touros jovens foram submetidos a um teste de comportamento alimentar com base na entrada de alimentação residual (RFI), com 20 d de adaptação e 70 d de teste para eficiência de alimentação. Além dos traços de comportamento alimentar, o temperamento dos animais foi avaliado no início do teste, através da avaliação do comportamento na caneta (PS) e da velocidade de saída (EV). Todas as amostras foram digitadas com dois marcadores localizados nos genes DRD3 e HTR2A para posteriormente realizar uma análise de associação dos genótipos com os traços avaliados. Resultados: Na raça Brangus, observou-se uma associação significativa do ganho diário médio (ADG, p = 0,019) com o marcador rs43696138, localizado no gene HTR2A, resultando em maiores ganhos para o genótipo GG (1,69 ± 0,04 kg), em comparação com os touros heterozigóticos GA (1,54 ± 0,04 kg). Conclusão: A associação destes marcadores previamente relatados com o temperamento nas raças avaliadas não foi confirmada; no entanto, o marcador rs43696138 mostrou um efeito sobre uma característica de comportamento alimentar. Mais estudos são necessários para determinar o efeito deste e outros marcadores com ingestão alimentar residual (RFI) e temperamento.Palavras-chave: consumo residual de alimentos, eficiência alimentar, gado bovino, polimorfismo de nucleotídeo único, temperamento.

Hormonal growth implants affect feed efficiency and expression of residual feed intake-associated genes in beef cattle

2014 ◽  
Vol 54 (5) ◽  
pp. 550 ◽  
Author(s):  
W. Al-Husseini ◽  
C. Gondro ◽  
K. Quinn ◽  
L. M. Cafe ◽  
R. M. Herd ◽  
...  
Keyword(s):  
Feed Intake ◽  
Feed Efficiency ◽  
Protein Turnover ◽  
Average Daily Gain ◽  
Residual Feed Intake ◽  
Gene Marker ◽  
Turnover Rates ◽  
Feed Conversion ◽  
Muscle Area ◽  
Eye Muscle

Hormonal growth promotants (HGP) have been used to improve feed conversion ratio (FCR) and growth rates of cattle by modifying protein turnover rates. Residual feed intake (RFI) is correlated with FCR and has been adopted in Australia as a measure of feed efficiency in cattle for the purpose of genetic improvement. Eight genes (AHSG, GHR, GSTM1, INHBA, PCDH19, S100A10, SERPINI2 and SOD3) have been previously reported to be highly associated with RFI and could potentially be used to predict RFI in bulls and steers. In this study, expression levels of these genes in liver tissue of 46 cattle were measured by quantitative real-time PCR. These cattle were part of a larger tenderness gene marker experiment consisting of two breeds (Angus and Brahman); two sexes (steers and heifers) and HGP treatments (implanted vs control). Cattle were measured for growth, feed efficiency, body composition and carcass traits. Results showed the expression of these eight genes was significantly correlated with RFI. However, HGP treatment did not affect RFI or the expression of the RFI-associated genes. HGP treatment increased average daily gain by 20%, improved FCR by 18%, and increased rib eye-muscle area by 7.5%. HGP treatment was effective in improving growth rate, presumably by its known action in the protein turnover mechanism. This mechanism has been hypothesised as one of the regulators of RFI. Lack of effect of HGP treatment on RFI does not support this hypothesis.

Genetic divergence in residual feed intake affects growth, feed efficiency, carcass and meat quality characteristics of Angus steers in a large commercial feedlot

2018 ◽  
Vol 58 (1) ◽  
pp. 164 ◽  
Author(s):  
R. M. Herd ◽  
P. F. Arthur ◽  
C. D. K. Bottema ◽  
A. R. Egarr ◽  
G. H. Geesink ◽  
...  
Keyword(s):  
Meat Quality ◽  
Feed Intake ◽  
Feed Efficiency ◽  
Animal Feed ◽  
Average Daily Gain ◽  
Residual Feed Intake ◽  
Quality Characteristics ◽  
Feed Conversion ◽  
Eye Muscle ◽  
Meat Samples

Growth, feed intake, feed efficiency, and carcass and meat quality characteristics of 136 Angus steers differing in genetic merit for post-weaning residual feed intake (RFIp) were measured over 251 days in a large commercial feedlot. The steers were evaluated in two groups, low (Low-RFI) and high (High-RFI) genetic RFIp, measured by estimated breeding values for RFIp (RFIp-EBV). The difference in RFIp-EBV between the Low- and High-RFI groups was 1.05 kg/day (–0.44 vs 0.61 kg/day; P < 0.05). The Low- and High-RFI steers were similar (P > 0.05) in age (445 vs 444 days) and weight (435 vs 429 kg) at induction, and at the end of the feeding period (705 vs 691 kg). Average daily gain (ADG) over 251 days had a small negative association with variation in RFIp-EBV (P < 0.05), reflecting a 3.6% greater ADG accompanying a difference of 1 kg/day in RFIp-EBV. Pen feed intake and feed conversion by the Low-RFI group were 10.4 kg/day and 9.3 kg/kg, and for the High-RFI group were 11.1 kg/day and 10.4 kg/kg, but without availability of individual animal feed-intake data it was not possible to test for significant differences. Carcass weight and dressing-percentage was similar for the Low- and High-RFI steers. High-RFI steers had a significantly (P < 0.05) greater depth of subcutaneous rib fat at induction and finished with 5 mm more (P < 0.05) fat at the 10/11th ribs on the carcass than the Low-RFI steers. Cross-sectional area of the eye-muscle and three measures of intramuscular or marbling fat did not differ (P > 0.05) between the Low- and High-RFI steers. Shear force was higher (P < 0.05) in meat samples aged for 1 day from the Low-RFI steers, but there was no difference (P > 0.05) from the High-RFI steers after 7 days of ageing. Compression values for meat samples aged for 1 day did not differ between the RFI groups but were higher in meat samples aged for 7 days from the Low-RFI steers. For these Angus steers, genetic superiority in RFI was associated phenotypically with superior weight gain, decreased rib fat depth, slightly less tender meat, and no compromise in marbling fat or other carcass and meat quality traits.

Effect of post-weaning residual feed intake classification on grazed grass intake and performance in pregnant beef heifers

2015 ◽  
Vol 95 (3) ◽  
pp. 369-381 ◽  
Author(s):  
G. Manafiazar ◽  
J. A. Basarab ◽  
V. S. Baron ◽  
L. McKeown ◽  
R. R. Doce ◽  
...  
Keyword(s):  
Body Weight ◽  
Feed Intake ◽  
Average Daily Gain ◽  
Residual Feed Intake ◽  
Backfat Thickness ◽  
Automated System ◽  
Adaptation Period ◽  
Beef Heifers ◽  
Fat Thickness ◽  
And Performance

Manafiazar, G., Basarab, J. A., Baron, V. S., McKeown, L., Doce, R. R., Swift, M., Undi, M., Wittenberg, K. and Ominski, K. 2015. Effect of post-weaning residual feed intake classification on grazed grass intake and performance in pregnant beef heifers. Can. J. Anim. Sci. 95: 369–381. There is limited knowledge of how cattle tested for feed efficiency under drylot conditions perform when they graze on summer pasture. Residual feed intake adjusted for end of test backfat thickness (RFIfat) was determined on 171 beef crossbred heifers under drylot conditions over 2 yr using an automated system. Upon completion of the test, the 10 lowest and 10 highest RFIfat (–0.54±0.17 vs. 0.58±0.15 kg DM d−1) heifers in 2012, and the 14 lowest and 14 highest RFIfat (−0.47±0.16 vs. 0.53±0.19 kg DM d−1) heifers in 2013 were selected and placed on meadow bromegrass pasture to investigate the effect of RFIfat ranking on their grass intake and performance on the pasture. The pasture adaptation period (8 d in 2012 and 19 d in 2013) was followed by a pasture feed intake experiment during which heifers were dosed twice daily (0815 and 1415) with 500 g of C32-labeled feed pellet for 13 d (day 0 to 12) and fecal sampled twice daily (0815 and 1415) from day 8 to 12. Forage DM intake on pasture for each heifer was determined using the double alkane (C31/C32) methodology. High and low RFIfat heifers were similar in body weight (BW), backfat and rump fat thickness, and average daily gain (ADG) during the grazing trial period, except backfat thickness at the end of test period. However, low RFIfat heifers consumed 5.3% less forage when expressed as kg DM d−1 (8.20±0.08 vs. 8.66±0.09, P<0.001) and 5.1% less when expressed as a percentage of body weight (1.86±0.02 vs. 1.96±0.02% of BW, P<0.001) compared with high RFIfat heifers. RFIfat measured under drylot conditions in growing heifers was positively correlated to grazed RFIfat determined in pregnant heifers (rp=0.30, P=0.04). These results suggest that beef heifers classified as low RFIfat during the post-weaning drylot period had lower dry matter intake as heifers in their first pregnancy grazing tame pasture, with no negative impact on their body weight, back-fat thickness, and ADG compared with their high RFIfat herdmates.

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