Phenotypic association between residual feed intake and carcass traits of young nelore bulls

The purpose of this study was to estimate the phenotypic associations between residual food intake (RFI) and carcass traits, evaluated by ultrasonography, of young Nellore bulls. Information about 53 young Nelore bulls, pure origin (PO), participants in the Individual Performance Test of Nelore Bulls, carried out at the Capim Branco experimental farm of the Federal University of Uberlândia (UFU) were used for this purpose. It was evaluated the characteristics of residual feed intake (RFI), rib eye area (REA), marbling (MAR) and fat thickness (FT). In order to estimate the Spearman and Pearson correlation coefficients, the SAS program was used. Regarding the influence of the RFI classes (low RFI, medium RFI and high RFI) on carcass traits, an out analysis of variance was carried out using the least squares method. It was verified that there was no phenotypic association between RFI and the characteristics of REA and MAR, but the relation between FT and the phenotypic association revealed a medium magnitude. However, when evaluating the RFI classes, it was observed that there were no significant differences of the RFI classes with the carcass traits (REA, FT and MAR). It is recommended that new studies are carried out to verify if the selection for RFI does not result in damages to the finishing of carcass in Nelore cattle.

Circulating Metabolites Indicate Differences in High and Low Residual Feed Intake Holstein Dairy Cows

Selection for more feed efficient dairy cows is key to improving sustainability and profitability of dairy production; however, underlying mechanisms contributing to individual animal feed efficiency are not fully understood. The objective of this study was to identify circulating metabolites, and pathways associated with those metabolites, that differ between efficient and inefficient Holstein dairy cows using targeted metabolite quantification and untargeted metabolomics. The top and bottom fifteen percent of cows (n = 28/group) with the lowest and highest residual feed intake in mid-lactation feed efficiency trials were grouped retrospectively as high-efficient (HE) and low-efficient (LE). Blood samples were collected for quantification of energy metabolites, markers of hepatic function, and acylcarnitines, in addition to a broader investigation using untargeted metabolomics. Short-chain acylcarnitines, C3-acylcarnitine, and C4-acylcarntine were lower in HE cows (n = 18/group). Untargeted metabolomics and multivariate analysis identified thirty-nine differential metabolites between HE and LE (n = 8/group), of which twenty-five were lower and fourteen were higher in HE. Pathway enrichment analysis indicated differences in tryptophan metabolism. Combined results from targeted metabolite quantification and untargeted metabolomics indicate differences in fatty acid and amino acid metabolism between HE and LE cows. These differences may indicate post-absorptive nutrient use efficiency as a contributor to individual animal variation in feed efficiency.

Common and diet-specific metabolic pathways underlying residual feed intake in fattening Charolais yearling bulls

Residual feed intake (RFI) is one of the preferred traits for feed efficiency animal breeding. However, RFI measurement is expensive and time-consuming and animal ranking may depend on the nature of the diets. We aimed to explore RFI plasma biomarkers and to unravel the underlying metabolic pathways in yearling bulls fed either a corn-silage diet rich in starch (corn diet) or a grass-silage diet rich in fiber (grass diet). Forty-eight extreme RFI animals (Low-RFI, n = 24, versus High-RFI, n = 24, balanced per diet) were selected from a population of 364 Charolais bulls and their plasma was subjected to a targeted LC-MS metabolomic approach together with classical metabolite and hormonal plasma analyses. Greater lean body mass and nitrogen use efficiency, and lower protein turnover were identified as common mechanisms underlying RFI irrespective of the diet. On the other hand, greater adiposity and plasma concentrations of branched-chain amino acids (BCAA) together with lower insulin sensitivity in High-RFI animals were only observed with corn diet. Conversely, greater plasma concentrations of BCAA and total triglycerides, but similar insulin concentrations were noted in efficient RFI cattle with grass diet. Our data suggest that there are diet-specific mechanisms explaining RFI differences in fattening Charolais yearling bulls.

Exploring Biological Impacts of Prenatal Nutrition and Selection for Residual Feed Intake on Beef Cattle Using Omics Technologies: A Review

Approximately 70% of the cost of beef production is impacted by dietary intake. Maximizing production efficiency of beef cattle requires not only genetic selection to maximize feed efficiency (i.e., residual feed intake (RFI)), but also adequate nutrition throughout all stages of growth and development to maximize efficiency of growth and reproductive capacity, even during gestation. RFI as a measure of feed efficiency in cattle has been recently accepted and used in the beef industry, but the effect of selection for RFI upon the dynamics of gestation has not been extensively studied, especially in the context of fluctuating energy supply to the dam and fetus. Nutrient restriction during gestation has been shown to negatively affect postnatal growth and development as well as fertility of beef cattle offspring. This, when combined with the genetic potential for RFI, may significantly affect energy partitioning in the offspring and subsequently important performance traits. In this review, we discuss: 1) the importance of RFI as a measure of feed efficiency and how it can affect other economic traits in beef cattle; 2) the influence of prenatal nutrition on physiological phenotypes in calves; 3) the benefits of investigating the interaction of genetic selection for RFI and prenatal nutrition; 4) how metabolomics, transcriptomics, and epigenomics have been employed to investigate the underlying biology associated with prenatal nutrition, RFI, or their interactions in beef cattle; and 5) how the integration of omics information is adding a level of deeper understanding of the genetic architecture of phenotypic traits in cattle.

338 Nitrogen Use Efficiency Is Proportionally More Improved When Young Bulls Are Ranked on Residual Body Gain Rather Than on Residual Feed Intake

Animals with superior feed efficiency (FE) may also have an improved nitrogen use efficiency (NUE), which would be beneficial to economic profitability while reducing environmental impacts. When genetically selecting animals on FE, it is preferable to use residual traits [e.g. residual feed intake (RFI) or residual body gain (RG)] rather than ratios because of their predictable genetic outcomes. We studied the relationship of RFI and RG with NUE, estimated from the validated 15N abundance in plasma, across two contrasted diets based on corn or grass silages. We evaluated FE of 588 (half by diet) Charolais bulls (545 ± 57 kg BW) from 12 experimental cohorts (different farms and periods) over 200 days. Before the end of the FE test, plasma was sampled and analyzed for δ 15N. NUE was related to FE through simple-linear models with variables previously corrected for the cohort and diet effects. The models’ slopes were standardized according to FE deviation in order to compare the response of NUE to FE between indices. Higher NUE was related to higher FE (P < 0.001), showing positive correlations with RG (r=-0.40) and negative with RFI (r=0.29). However, the standardized slope of NUE to RG was significantly higher (+28%; P < 0.05) than that of NUE to RFI. This stronger NUE relation to RG compared to RFI could reflect a higher potential of RG animals to deposit N as compared to a more conservational N metabolism in RFI individuals. Regarding diets, and despite the correction of NUE and FE for this effect, the slopes of NUE to FE were numerically (P > 0.05) higher (-16% and +36%; for RG and RFI) in corn-based diets, which agrees with superior NUE observed in corn-vs-grass diets. Results suggested that superior RG animals may present proportionally higher NUE than superior RFI animals, with even better results in corn-vs-grass diets.

PSIX-1 Canadian Vytelle technology for determining residual feed intake in raising Qazaq Aqbas bull calves

Selection for residual feed intake (RFI) allows you to reduce feed costs and increase productivity of beef cattle. An increase in feed productivity by 10% can lead to an increase in profits by 43%, raising livestock with a low RFI can reduce feed intake by 12%, reduce methane emissions by 30%, and manure reduction by 17%. To obtain reliable trial results when determining the RFI, it is necessary to ensure the following conditions: 1) the same age of animals 2) the exchange of pedigree data between users of the system, which makes it possible to compare the EPDs within Vytelle Systems. Objects of research:QazaqAqbas bull calves (n = 46) at the age of 10–12 months in ZhanaBerekeLLP in Akmola region of Kazakhstan. Trial results confirm that residual feed intake in group 1 varied from -0.81 to 1.11, in group 2 - from -0.80 to 1.09. The RFI Rank was higher in group 1 (12.5). RADG in group 1 was at the level of -0.57 ... 0.58, in group 2 - -0.58 ... 1.13. According to the numerical rating of the animal (RADG Rank), the average value in group 1 was 12.5, in group 2 - 11.5. The average live weight at the beginning (START WT.) and end (END WT.) in the first group was 254.16 and 287.62 kg, in the second group 239.99 and 273.09 kg. The ADG in two groups was at the same level - 0.70 and 0.69 kg. The average Dry Matter Intake per day by animals during the trial was higher in the first group - 4.15, in the second group it was 3.65. For the first time in Kazakhstan national QazaqAqbas breed is tested for RFI, RADG, ADG, DMI, Raw F:G, Adj F:G.

PSVII-21 Canadian Vytelle technology for determining residual feed intake epdsin raising Qazaq Aqbas bull calves

The Abstract reviews the experience of implementing Vytelle technology in ZhanaBereke LLP, Akmola region in Kazakhstan. The trial objects are Qazaq Aqbas bull calves: group 1 aged 10–11 months (n = 22), group 2 aged 11–12 months (n = 24). Data analysis showed that more reliable Residual Feed Intake calculated for each individual animal on the basis of their phenotypes and information on pedigree, were found in group 1. The average RFI EPD for group 1 is -0.0607, for group 2 is -0.0297. The RFI% Rank in terms of RFI EPD for both trial groups varied within 4 ... 96%. However, the average RFI% Rank was lower in the first group (45%) compared to the second group (56%). From which it follows that the RFI EPD is higher in group 1. Average Daily Gain EPDs (ADG EPD) higher in group 1 -0.0018. A higher ADG EPDs indicate a more cost-effective metric. The ADG% Rank in terms of ADG EPD for group 1 varied within 1 ... 62%, for group 2: 1 ... 63%. The average ADG% Rank was slightly lower in the first group (30%) compared to the second group (33%). From the presented data, it follows that the breeding valueaccording to the ADG EPD is higher in group 1. The average Dry Matter Intake by animals per day during the trial (DMI EPD) is equal to -0,0600 in the first group, and -0,0292 in the second group. The DMI% RANK in terms of DMI EPD for group 1 varied within 31 ... 93%, for group 2: 38 ... 96%. The DMI% RANK was lower in the first group (60%) compared to the second group (67%). Summarizing the above, we can conclude that selection for this characteristic is less effective, work will continue to increase this indicator.