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 Genetics of heifer performance in 'wet' and 'dry' seasons and their relationships with steer performance in two tropical beef genotypes

2009 ◽  
Vol 49 (6) ◽  
pp. 367 ◽  
Author(s):  
S. A. Barwick ◽  
D. J. Johnston ◽  
H. M. Burrow ◽  
R. G. Holroyd ◽  
G. Fordyce ◽  
...  
Keyword(s):  
Bos Taurus ◽  
Body Condition Score ◽  
Serum Insulin ◽  
Meta Analysis ◽  
Bos Indicus ◽  
Genetic Correlations ◽  
Wet Season ◽  
Igf I ◽  
Dry Seasons ◽  
Wet And Dry Seasons

The genetics of heifer performance in tropical ‘wet’ and ‘dry’ seasons, and relationships with steer performance, were studied in Brahman (BRAH) and Tropical Composite (TCOMP) (50% Bos indicus, African Sanga or other tropically adapted Bos taurus; 50% non-tropically adapted Bos taurus) cattle of northern Australia. Data were from 2159 heifers (1027 BRAH, 1132 TCOMP), representing 54 BRAH and 51 TCOMP sires. Heifers were assessed after post-weaning ‘wet’ (ENDWET) and ‘dry’ (ENDDRY) seasons. Steers were assessed post-weaning, at feedlot entry, over a 70-day feed test, and after ∼120-day finishing. Measures studied in both heifers and steers were liveweight (LWT), scanned rump fat, rib fat and M. longissimus area (SEMA), body condition score (CS), hip height (HH), serum insulin-like growth factor-I concentration (IGF-I), and average daily gains (ADG). Additional steer measures were scanned intra-muscular fat %, flight time, and daily (DFI) and residual feed intake (RFI). Uni- and bivariate analyses were conducted for combined genotypes and for individual genotypes. Genotype means were predicted for a subset of data involving 34 BRAH and 26 TCOMP sires. A meta-analysis of genetic correlation estimates examined how these were related to the difference between measurement environments for specific traits. There were genotype differences at the level of means, variances and genetic correlations. BRAH heifers were significantly (P < 0.05) faster-growing in the ‘wet’ season, slower-growing in the ‘dry’ season, lighter at ENDDRY, and taller and fatter with greater CS and IGF-I at both ENDWET and ENDDRY. Heritabilities were generally in the 20 to 60% range for both genotypes. Phenotypic and genetic variances, and genetic correlations, were commonly lower for BRAH. Differences were often explained by the long period of tropical adaptation of B. indicus. Genetic correlations were high between corresponding measures at ENDWET and ENDDRY, positive between fat and muscle measures in TCOMP but negative in BRAH (mean of 13 estimates 0.50 and –0.19, respectively), and approximately zero between steer feedlot ADG and heifer ADG in BRAH. Numerous genetic correlations between heifers and steers differed substantially from unity, especially in BRAH, suggesting there may be scope to select differently in the sexes where that would aid the differing roles of heifers and steers in production. Genetic correlations declined as measurement environments became more different, the rates of decline (environment sensitivity) sometimes differing with genotype. Similar measures (LWT, HH and ADG; IGF-I at ENDWET in TCOMP) were genetically correlated with steer DFI in heifers as in steers. Heifer SEMA was genetically correlated with steer feedlot RFI in BRAH (0.75 ± 0.27 at ENDWET, 0.66 ± 0.24 at ENDDRY). Selection to reduce steer RFI would reduce SEMA in BRAH heifers but otherwise have only small effects on heifers before their first joining.

scholarly journals Erratum to: Genetics of heifer performance in 'wet' and 'dry' seasons and their relationships with steer performance in two tropical beef genotypes

2009 ◽  
Vol 49 (8) ◽  
pp. 727 ◽  
Author(s):  
S. A. Barwick ◽  
D. J. Johnston ◽  
H. M. Burrow ◽  
R. G. Holroyd ◽  
G. Fordyce ◽  
...  
Keyword(s):  
Bos Taurus ◽  
Body Condition Score ◽  
Serum Insulin ◽  
Meta Analysis ◽  
Bos Indicus ◽  
Genetic Correlations ◽  
Wet Season ◽  
Igf I ◽  
Dry Seasons ◽  
Wet And Dry Seasons

The genetics of heifer performance in tropical 'wet' and 'dry' seasons, and relationships with steer performance, were studied in Brahman (BRAH) and Tropical Composite (TCOMP) (50% Bos indicus, African Sanga or other tropically adapted Bos taurus; 50% non-tropically adapted Bos taurus) cattle of northern Australia. Data were from 2159 heifers (1027 BRAH, 1132 TCOMP), representing 54 BRAH and 51 TCOMP sires. Heifers were assessed after post-weaning 'wet' (ENDWET) and 'dry' (ENDDRY) seasons. Steers were assessed post-weaning, at feedlot entry, over a 70-day feed test, and after ~120-day finishing. Measures studied in both heifers and steers were liveweight (LWT), scanned rump fat, rib fat and M. longissimus area (SEMA), body condition score (CS), hip height (HH), serum insulin-like growth factor-I concentration (IGF-I), and average daily gains (ADG). Additional steer measures were scanned intra-muscular fat %, flight time, and daily (DFI) and residual feed intake (RFI). Uni- and bivariate analyses were conducted for combined genotypes and for individual genotypes. Genotype means were predicted for a subset of data involving 34 BRAH and 26 TCOMP sires. A meta-analysis of genetic correlation estimates examined how these were related to the difference between measurement environments for specific traits. There were genotype differences at the level of means, variances and genetic correlations. BRAH heifers were significantly (P < 0.05) faster-growing in the 'wet' season, slower-growing in the 'dry' season, lighter at ENDDRY, and taller and fatter with greater CS and IGF-I at both ENDWET and ENDDRY. Heritabilities were generally in the 20 to 60% range for both genotypes. Phenotypic and genetic variances, and genetic correlations, were commonly lower for BRAH. Differences were often explained by the long period of tropical adaptation of B. indicus. Genetic correlations were high between corresponding measures at ENDWET and ENDDRY, positive between fat and muscle measures in TCOMP but negative in BRAH (mean of 13 estimates 0.50 and ᾰ0.19, respectively), and approximately zero between steer feedlot ADG and heifer ADG in BRAH. Numerous genetic correlations between heifers and steers differed substantially from unity, especially in BRAH, suggesting there may be scope to select differently in the sexes where that would aid the differing roles of heifers and steers in production. Genetic correlations declined as measurement environments became more different, the rates of decline (environment sensitivity) sometimes differing with genotype. Similar measures (LWT, HH and ADG; IGF-I at ENDWET in TCOMP) were genetically correlated with steer DFI in heifers as in steers. Heifer SEMA was genetically correlated with steer feedlot RFI in BRAH (0.75 ± 0.27 at ENDWET, 0.66 ± 0.24 at ENDDRY). Selection to reduce steer RFI would reduce SEMA in BRAH heifers but otherwise have only small effects on heifers before their first joining.

Residual feed intake and body composition in young growing cattle

2003 ◽  
Vol 83 (2) ◽  
pp. 189-204 ◽  
Author(s):  
J. A. Basarab ◽  
M. A. Price ◽  
J. L. Aalhus ◽  
E. K. Okine ◽  
W. M. Snelling ◽  
...  
Keyword(s):  
Body Composition ◽  
Chemical Composition ◽  
Body Fat ◽  
Feed Intake ◽  
Accretion Rate ◽  
Average Daily Gain ◽  
Residual Feed Intake ◽  
Body Water ◽  
Backfat Thickness ◽  
Marbling Score

Crossbred steers (n = 176), 7–8 mo of age and from the five BeefBooster strains (M1, M2, M3, M4 and TX), were used to determine the relationships between residual feed intake (RFI) and growth rate, body composition and heat production (HP), and to quantify differences in RFI independent of differences in body composition. Animals with different RFI levels were also characterized for growth, carcass and body compositional traits. Steers from each genetic strain were selected at random and serially slaughtered on 5 pre-selected days of the finishing period. Steers grew at 1.52 (SD = 0.22) kg d-1 and had dry matter intake (DMI) of 8.5 (SD = 1.0) kg d-1 during the last 71 to 183 d before slaughter. Metabolic mid-point weight, average daily gain (ADG), gain in empty body fat and gain in empty body water accounted for 67.9, 8.6, 3.9 and 1.1%, respectively, of the variation in actual feed intake. Similarly, metabolic mid-point weight (68.5%), ADG (8.2%), gain in ultrasound backfat thickness (1.8%), gain in ultrasound marbling score (1.1%) and year (1.3%) accounted for 80.9% of the variation in actual feed intake. Residual feed intake adjusted for differences in estimated composition of gain (estimated gain in empty body fat and water; RFIII) ranged from -2.06 kg d-1 to +1.61 kg d-1 (SD = 0.60 kg d-1). Residual feed intake adjusted for live animal measures of body composition (gain in ultrasound backfat thickness and marbling score; RFIIII) ranged from -2.11 kg d-1 to +1.88 kg d-1 (SD = 0.62 kg d-1). Low RFIIII animals (efficient) had 6.0% lower metabolizable energy intake (MEI), retained 9.3% less energy and had 4.5% lower HP than medium RFIIII animals (P < 0.01). Low RFIIII animals also had 10.2% lower MEI, retained 12.0% less energy and produced 9.3% less heat than high RFIIII animals (P < 0.01). Liver (P <0.01), small and large intestine (P = 0.09) and stomach and intestine (P < 0.01) weights were less in low and medium RFIIII steers compared to high RFIIII steers. There was a trend for low RFIIII steers to have less dissectible carcass fat (P = 0.08), intermuscular fat (P = 0.06), body cavity fat in the butt and loin (P = 0.01), faster accretion rate of empty body water (P = 0.04) and a slower accretion rate of empty body fat (P < 0.01) than medium and high RFIIII steers. A portion of the greater MEI by high RFIIII steer was accounted for by differences in the chemical composition of gain. However, a greater proportion was due to a disproportionate increase in the energy required for maintenance and heat increment of feeding in high RFIIII steers. An attempt should be made to adjust RFI for changes in the chemical composition of gain, possibly by the inclusion of ultrasound backfat thickness and marbling score into the equation for determining RFI. Key words: Cattle, feed efficiency, residual feed intake, remote sensing, GrowSafe System

scholarly journals 93 Feeding behavior as predictive traits of fertility and lifetime productivity in replacement beef heifers

2019 ◽  
Vol 97 (Supplement_3) ◽  
pp. 77-78
Author(s):  
Cameron A Olson ◽  
Lisa McKeown ◽  
Hushton Block ◽  
Changxi Li ◽  
John Basarab
Keyword(s):  
Birth Weight ◽  
Feed Intake ◽  
Bos Taurus ◽  
Body Condition Score ◽  
Genetic Correlations ◽  
Beef Cows ◽  
Development Stage ◽  
Condition Score ◽  
Mating Opportunities ◽  
Positive Correlations

Abstract Fertility and longevity traits in beef cows are difficult and expensive to measure. The use of other traits to predict fertility and longevity traits in beef cows will enable selection for efficient reproduction earlier in an animal’s life. The objective of this study is to identify feeding behaviours with predictive relationships to fertility, longevity, and lifetime productivity in beef cows. This study used 421 Bos taurus commercial replacement heifers born from 2004 to 2014 and followed over 1050 mating opportunities, 11 production cycles and 5 parities. Heifers were weaned at 6–7 mo of age and developed on a 90% barley silage, 10% rolled barley diet in pens equipped with 16 electronic feed bunks to monitor feed intake and feeding behaviors. Feed intake (FI), feeding frequency (FREQ), duration (DUR), head-down time (HD) and time-to-bunk (TTB) were collected over the course of the feeding trial. Phenotypic correlations indicate that as FI increased during the heifer development stage, so did subsequent cow pre-breeding and pre-calving body condition score (BCS; r = 0.43, 0.36 respectively) and total lifetime productivity (r = 0.40). As FREQ increased, pre-breeding and pre-calving BCS decreased (r = -0.16 and -0.20, respectively), as did calf birth weight (r = -0.15). As DUR increased, weak positive correlations were observed with days in herd (r = 0.10), age at first calving (r = 0.17) and calf birth weight (0.13). Increased HD would lead to increased pre-breeding and pre-calving BCS (r = 0.16, 0.23 respectively), and greater lifetime productivity (r = 0.16). Time-to-bunk was positively correlated with days in the herd (r = 0.15), and with decreased calf birth weight (r = -0.23) and pre-calving cow weight (r = -0.33). These feeding behaviour traits, collected early in life, are worthy of further investigation into multi trait regression, genetic correlations and genomic selection.

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 &lt; 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 &lt; 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 &lt; 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 &lt; 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

Daily methane emissions and emission intensity of grazing beef cattle genetically divergent for residual feed intake

2017 ◽  
Vol 57 (4) ◽  
pp. 627 ◽  
Author(s):  
J. I. Velazco ◽  
R. M. Herd ◽  
D. J. Cottle ◽  
R. S. Hegarty
Keyword(s):  
Feed Intake ◽  
Emission Intensity ◽  
Dry Matter ◽  
Average Daily Gain ◽  
Residual Feed Intake ◽  
Conversion Ratio ◽  
Feed Conversion Ratio ◽  
Breeding Value ◽  
Dry Matter Intake ◽  
Feed Conversion

As daily methane production (DMP; g CH4/day) is strongly correlated with dry matter intake (DMI), the breeding of cattle that require less feed to achieve a desired rate of average daily gain (ADG) by selection for a low residual feed intake (RFI) can be expected to reduce DMP and also emission intensity (EI; g CH4/kg ADG). An experiment was conducted to compare DMP and EI of Angus cattle genetically divergent for RFI and 400-day weight (400dWT). In a 6-week grazing study, 64 yearling-age cattle (30 steers, 34 heifers) were grazed on temperate pastures, with heifers and steers grazing separate paddocks. Liveweight (LW) was monitored weekly and DMP of individual cattle was measured by a GreenFeed emission monitoring unit in each paddock. Thirty-nine of the possible 64 animals had emission data recorded for 15 or more days, and only data for these animals were analysed. For these cattle, regression against their mid-parent estimated breeding value (EBV) for post-weaning RFI (RFI-EBV) showed that a lower RFI-EBV was associated with higher LW at the start of experiment. Predicted dry matter intake (pDMI), predicted DMP (pDMP) and measured DMP (mDMP) were all negatively correlated with RFI-EBV (P < 0.05), whereas ADG, EI, predicted CH4 yield (pMY; g CH4/kg DMI) were not correlated with RFI-EBV (P > 0.1). Daily CH4 production was positively correlated with animal LW and ADG (P < 0.05). The associations between ADG and its dependent traits EI and pMY and predicted feed conversion ratio (kg pDMI/kg ADG) were strongly negative (r = –0.82, –0.57 and –0.85, P < 0.001) implying that faster daily growth by cattle was accompanied by lower EI, MY and feed conversion ratio. These results show that cattle genetically divergent for RFI do not necessarily differ in ADG, EI or pMY on pasture and that, if heavier, cattle with lower RFI-EBV can actually have higher DMP while grazing moderate quality pastures.

Genetic parameters and breed differences for feed efficiency, growth, and body composition traits of young beef bulls

2004 ◽  
Vol 84 (2) ◽  
pp. 177-185 ◽  
Author(s):  
F. S. Schenkel ◽  
S. P. Miller ◽  
J. W. Wilton
Keyword(s):  
Body Composition ◽  
Genetic Correlation ◽  
Feed Intake ◽  
Feed Efficiency ◽  
Fixed Effects ◽  
Residual Feed Intake ◽  
Backfat Thickness ◽  
Daily Weight Gain ◽  
Feed Conversion ◽  
Beef Bulls

Genetic associations between feed efficiency, growth, and live ultrasound measured body composition traits were studied in purebred beef bulls of six breeds in Ontario bull test stations from 1991 to 2000. Feed traits included average daily feed intake (FI), feed conversion ratio (FCR), and residual feed intake [feed intake adjusted for production alone (RFIp) or production and backfat thickness (RFIb)]. Growth traits were average daily weight gain (ADG), mid-test metabolic weight (MW), hip height (HH), and scrotal circumference (SC). Body composition traits included ultrasound backfat thickness (BF), longissimus muscle area (LMA), and predicted percentage of intramuscular fat (IFAT). Bulls were measured every 28 d for weight and individual feed intake, and at the end of test for ultrasound body composition traits. Number of records per trait ranged from 2284 (FI) to 13 319 (ADG). Fixed effects of test group, breed and end of test age (within breed), and random effects of animal and herd of origin were modeled using REML bivariate analyses for all traits. Heritability estimates were moderate for all traits (0.30 to 0.55), except for IFAT (0.14). The genetic correlation between RFIp and RFIb was high (0.99) within breeds, but breeds ranked differently with respect to RFIp and RFIb. Genetic correlations of RFIb with ADG and backfat thickness were essentially zero, which indicate that selection on residual feed intake could be implemented to reduce feed intake and improve feed conversion without compromising growth or changing levels of subcutaneous fat. Key words: Central test, genetic correlation, heritability, residual feed intake

scholarly journals Residual feed intake and relationships with performance of Nellore cattle selected for post weaning weight

2011 ◽  
Vol 40 (4) ◽  
pp. 929-937 ◽  
Author(s):  
T. Lucila Sobrinho ◽  
R.H. Branco ◽  
S.F.M. Bonilha ◽  
A.M. Castilhos ◽  
L.A. Figueiredo ◽  
...  
Keyword(s):  
Body Weight ◽  
Standard Deviation ◽  
Feed Intake ◽  
Average Daily Gain ◽  
Residual Feed Intake ◽  
Feed Conversion ◽  
Relative Growth ◽  
Kleiber Ratio ◽  
Nellore Cattle ◽  
Daily Gain

The objective of this work was to evaluate performance, efficiency parameters and phenotypic correlations among measurements of energy efficiency of Nellore cattle selected for post weaning weight and classified according to residual feed intake, calculated by the difference between observed and predicted intake, based on average metabolic body weight and average daily gain. Thus, animals were classified within three groups: high (> mean + 0.5 standard deviation, less efficient); medium (±0.5 standard deviation of the mean); and low (< mean - 0.5 standard deviation, more efficient) residual feed intake. No differences were observed at initial and final body weights, average daily gain and dry matter intake among groups. Animals with low residual feed intake also had greater feed efficiency, feed conversion and partial efficiency of growth and did not differ from the other animals regarding to relative growth rate and Kleiber ratio. Residual feed intake was significantly correlated to feed efficiency (-0.25), feed conversion (0.25), partial efficiency of growth (-0.37) and dry matter intake (0.16) but it did not present significant correlation with body weight (0.04), average daily gain (-0.02), relative growth rate (-0.03) and Kleiber ratio (-0.05). Significant correlations were found between feed conversion and initial body weight (0.34) and average daily gain (-0.46). Partial efficiency of growth presented significant correlation with all other efficiency parameters analyzed. Residual feed intake has high potential in productive efficiency, when compared to the other energy efficiency measurements, being independent of growth and size of the animals.

Maternal body composition in seedstock herds. 4. Genetic parameters for body composition of Angus and Hereford cows

2018 ◽  
Vol 58 (1) ◽  
pp. 145 ◽  
Author(s):  
K. A. Donoghue ◽  
S. J. Lee ◽  
P. F. Parnell ◽  
W. S. Pitchford
Keyword(s):  
Body Composition ◽  
Body Condition Score ◽  
Genetic Relationships ◽  
Genetic Correlations ◽  
Fat Percentage ◽  
Muscle Area ◽  
Eye Muscle ◽  
Life Traits ◽  
Condition Score ◽  
Over Time

The genetics of body composition traits measured before calving and at weaning in the first and second parities were evaluated in 5975 Angus and 1785 Hereford cows. Traits measured were liveweight, body condition score and hip height and ultrasound scanned measurements of subcutaneous P8 and 12/13th rib fat depth, loin eye muscle area and intramuscular fat percentage. Corresponding yearling measures on these animals were obtained for analyses of relationships between yearling information with later-in-life traits. There was moderate genetic variation in all body composition traits measured at pre-calving and weaning in Angus (h2 = 0.14–0.59) and Hereford (h2 = 0.14–0.64) cows. Genetic correlations between measurements of the same trait at pre-calving and weaning were consistently positive and high in both parities for both breeds, indicating animals were ranking similarly for the same trait measured over time. Genetic correlations between measurements of different traits were generally consistent over time (pre-calving and weaning) in both breeds, indicating genetic relationships between traits were not changing significantly over time. Genetic correlations with corresponding yearling measures of body composition were consistently positive and high for the first parity, and lower for the second parity. The results of this study indicate that genetic improvement in body composition traits in cows is possible, and that body composition information recorded at yearling age is a reasonably good predictor of later in life performance for these traits.

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