Selection for residual feed intake affects appetite and body composition rather than energetic efficiency

2018 ◽  
Vol 58 (1) ◽  
pp. 175 ◽  
Author(s):  
D. S. Lines ◽  
W. S. Pitchford ◽  
C. D. K. Bottema ◽  
R. M. Herd ◽  
V. H. Oddy

Residual feed intake (RFI) is the difference between an animal’s actual feed intake and that which would be expected based on production. This experiment was to test the hypothesis that part of the variation in RFI may be due to differences in energetic efficiency through changes in heat production, these being in part due to differences in protein metabolism. Following three generations of divergent selection for RFI, eight High and eight Low-RFI heifers were fed at both 105% and 180% of predicted maintenance feed requirements. Between-RFI line and feeding-level differences were assessed for energy intake, protein metabolism, heat production, body composition, energy and nitrogen balance and digestibility. The RFI lines did not differ in protein metabolism or heat production. The High-RFI heifers deposited 51% and 56% more subcutaneous fat at the P8 rump and 12/13th rib sites, respectively, with no difference in eye muscle area gain or average daily weight gain. The greater fat deposition of High-RFI heifers was due to a larger ad libitum feed consumption compared with the Low-RFI heifers. Energy and nitrogen balance did not differ between the RFI lines. The energy transactions indicated no difference in the efficiency of energy use on 105% maintenance, although when fed 180% of maintenance the differences in feed intake suggest variation in appetite as the mechanism contributing to RFI. All of the extra energy consumed by High-RFI heifers above maintenance and deposition of protein was associated with additional energy retained as fat. This study suggests that selection for RFI may not lead to improved efficiency of energy use.

2004 ◽  
Vol 84 (2) ◽  
pp. 177-185 ◽  
Author(s):  
F. S. Schenkel ◽  
S. P. Miller ◽  
J. W. Wilton

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


2018 ◽  
Vol 58 (1) ◽  
pp. 55 ◽  
Author(s):  
K. J. Copping ◽  
J. M. Accioly ◽  
M. P. B. Deland ◽  
N. J. Edwards ◽  
J. F. Graham ◽  
...  

This experiment evaluated the productivity of 500 Angus cows that differed in genetic merit for either subcutaneous rib fat depth (Fat) or residual feed intake (RFI) based on estimated breeding values (EBVs) and managed under two levels of nutrition. Reproductive rate over four calving opportunities in mature cows and growth performance of progeny to weaning was assessed. Level of nutrition significantly affected all body composition traits for both Fat and RFI line cows. Cows on High-Nutrition were 14–16% heavier (P < 0.001) than those on Low-Nutrition. Differences in EBVs for fatness were reflected in phenotypic fatness at maturity. High-RFI line cows were fatter for both scanned rump (P8) and rib (RIB) fat depth relative to their Low-RFI contemporaries. Of those cows that were lactating, there was no significant effect of line or nutrition on pregnancy rate or days to calving (DC). There was, however, a trend (P < 0.1) in the Low-Fat line cows towards longer DC compared with the High-Fat line cows. There was no significant effect of either line or nutrition on calf birthweight. Calves with mothers on High-Nutrition were 8% heavier at weaning (P < 0.001) than those on Low-Nutrition. Lower EBVs for RFI was associated with higher 200-day growth EBV and heavier calves at weaning. Current carcass BREEDPLAN EBVs can be used to select for changes in cow body composition if desired. In this experiment, Angus cows selected for lower RFI or with below-average fatness EBV and had raised a calf at every previous opportunity were not compromised in pregnancy rate or DC at maturity under varying nutrition such as can be experienced during normal seasonal conditions in southern Australia. However, selection for lower RFI was associated with lower weaning rate (P < 0.05), which warrants further investigation to confidently predict the implications for commercial cattle production.


2020 ◽  
Vol 98 (Supplement_4) ◽  
pp. 393-394
Author(s):  
Camila D A Batalha ◽  
Fabiana L De Araújo ◽  
Renata H Branco ◽  
Luis O Tedeschi ◽  
Sarah F Bonilha

Abstract Retained energy (RE) and energetic efficiency index were measured in Nellore bulls from divergent classes of residual feed intake (RFI). Thirty-four Nellore bulls (15 low RFI-LRFI and 19 high RFI-HRFI) were feedlot finished and slaughtered with 385 ± 40 kg of body weight (BW) and 520 ± 26.2 days of age. At the beginning of the experiment, five LRFI and three HRFI were slaughtered and used as base line. Individual dry matter intake was recorded daily; initial and final BW were recorded after 16 h of fasting. Eight bulls, four LRFI and four HRFI, were fed at maintenance, receiving 65 g of DM/kg0.75 BW, and 18 bulls (10 LRFI and eight HRFI) were fed ad libitum. Diet had 19:81 roughage:concentrate, 88% of DM and 15% of crude protein. Ultrasound measurements on the Longissimus muscle were performed at intervals of 28 days. When two ad libitum bulls reached 4 mm of subcutaneous fat thickness, one maintenance bull was randomly chosen and slaughtered on the same day. After slaughter, the centesimal composition of the empty body and carcass was measured. Data were analyzed using a random coefficients model, and RFI class was included as a fixed effect. Least-square means were used to compare the means, and significance was declared for P ≤ 0.05. The LRFI had greater protein retention than HRFI (248 vs. 142 g/d; P = 0.009), and same fat and energy retention (313 g/d and 4.12 Mcal/d, respectively). The energy efficiency indexes, heat production per metabolic energy intake (Mcal/Mcal) and gain-to-feed (kg/kg) ratio, did not differ between RFI classes. Though LRFI had the same energy efficiency index, they were leaner. These results indicated an association of RFI and maturity patterns. Further research is needed to estimate the net energy requirements of Nellore bulls classified according to RFI. Acknowledgments: FAPESP Processes 2017/06709-2, 2018/20080–2 and 2019/17714-2.


2011 ◽  
Vol 89 (1) ◽  
pp. 258-266 ◽  
Author(s):  
L. J. Sadler ◽  
A. K. Johnson ◽  
S. M. Lonergan ◽  
D. Nettleton ◽  
J. C. M. Dekkers

2016 ◽  
Vol 94 (suppl_2) ◽  
pp. 108-109 ◽  
Author(s):  
D. J. Hewitt ◽  
C. F. M. de Lange ◽  
T. Antonick ◽  
J. C. M. Dekkers ◽  
A. R. Pendleton ◽  
...  

2009 ◽  
Vol 49 (6) ◽  
pp. 351 ◽  
Author(s):  
S. A. Barwick ◽  
M. L. Wolcott ◽  
D. J. Johnston ◽  
H. M. Burrow ◽  
M. T. Sullivan

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.


2016 ◽  
Vol 95 (9) ◽  
pp. 1999-2010 ◽  
Author(s):  
L. Drouilhet ◽  
R. Monteville ◽  
C. Molette ◽  
M. Lague ◽  
A. Cornuez ◽  
...  

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