Feed Efficiency Groups Research Articles

PSIII-15 Feeding patterns of yearling Angus bulls based on feed efficiency metrics

Abstract The study objective was to determine how feeding behavior relates to feed efficiency in yearling Angus bulls at the Cal Poly Bull test. Bulls (n = 102) were housed in four pens sorted according to initial body weight (BW; 460 ± 35, 407 ± 15, 374 ± 20, 323 ± 30; mean kg ± SD), resulting in 24 to 28 bulls/pen. Feeding behavior was monitored using an electronic feeding system (SmartFeed, C-Lock, Inc.) during an 85-d feed efficiency test. Four feeders in each pen were filled twice daily at approximately 0630 h and 1700 h. The number of visits to the feed bunk, visit duration, total feeding time, and hourly feed intake were determined from data collected from the feeding system. These data were summarized by hour in a 24-h period, across the 85-d period. Bulls were retrospectively classified into a high feed efficiency group (HIFE) and low feed efficiency group (LOFE) based on an assessment of their summed residual feed intake rank and their feed:gain ratio rank. Within each pen, 5 HIFE and 5 LOFE bulls were selected, resulting in 20 bulls/treatment used for the final analyses. Data were analyzed using the MIXED procedure in SAS 9.4. The model included the fixed effects of feed efficiency group (HIFE vs LOFE), hour (0 to 24), and the feed efficiency group × hour interaction. Bull within pen was considered a random effect and hour a repeated measure. LOFE bulls visited the bunk more frequently throughout the day during the entire testing period (P = 0.04). Differences between feed efficiency groups depended on hour and most differences were observed within 3 h of fresh feed delivery (P ≤ 0.02). A feed efficiency group × hour interaction (P < 0.001) indicated that LOFE bulls had longer feed bunk visit durations predominantly between fresh feed deliveries (P ≤ 0.048). LOFE bulls spent more time feeding throughout the entire day (P = 0.003) when compared with HIFE bulls. Feeding duration per hour was longer for LOFE bulls during the post-morning feeding period (7-h duration) and post-evening feeding period (4-h duration; P ≤ 0.045). More feed was consumed by LOFE bulls throughout the day (P < 0.001), particularly during the post-morning feeding period (P ≤ 0.05). Overall, bulls exhibiting decreased feed efficiency had different feeding behavior patterns in all behavioral categories than their more feed efficient counterparts, especially around feed delivery. Thus, more active bulls at the feed bunk were less feed efficient, and this behavioral pattern may be an important consideration in bull selection.

Intestinal microbiota was closely related to feed efficiency of Larimichthys crocea fed two fishmeal-free diets

This study examined the link between feed efficiency (FE) and intestinal microbiota in Larimichthys crocea fed on fishmeal-free diets. Two types of fishmeal-free diets were formulated: a plant protein-based feed (Group P) and a mixed-protein feed (Group M). These two types of diets were utilized to rear the two groups of L. crocea for 28 days, each consisting of individuals that were 18 months old. Initial and final weights, as well as feed consumption, of the experimental fish were documented. FE was calculated for each fish based on this data. Post-experiment, samples were taken from fish with high and low FE for 16S rRNA gene sequencing. In the Group M, the high and low FE fishes were designated as MH (proximal intestine, MHp; distal intestine, MHd) and ML (proximal intestine, MLp; distal intestine, MLd). In the Group P, the high and low FE fishes were designated as PH (proximal intestine, PHp; distal intestine, PHd) and PL (proximal intestine, PLp; distal intestine, PLd). The results indicated that in Group M, there was no significant difference in microbial community structure between MH and ML, but the microbial diversity and species richness in MH were higher than that in the corresponding ML. MHp showed a significantly higher abundance of the orders Elsterales, Frankiales, and the family Hyphomicrobiaceae compared to MLp. MHd, in comparison to the MLd, had a significant higher abundance of the order Burkholderiales. There was also no significant difference in microbial community structure between PH and PL, but the microbial diversity in PH was lower than that in the corresponding PL. PHp showed a significantly higher abundance of Proteobacteria and GammaProteobacteria compared to PLp; whereas, the significant difference between PHd and PLd was only present in PLd. Microbial functional prediction analysis showed that the intestinal microbiota was mainly involved in carbohydrate metabolism, energy metabolism and vitamin metabolism pathways. These findings of this study contribute to our further understanding of the relationship between intestinal microbiota and the FE traits of the host. The microbial markers found between the high and low FE groups can offer insights and serve as a reference for subsequent research aiming to improve FE using Nutrition and Genetic Selection Techniques.

Assessment of milk metabolites as biomarkers for predicting feed efficiency in dairy sheep

Estimating feed efficiency (FE) in dairy sheep is challenging due to the high cost of systems that measure individual feed intake. Identifying proxies that can serve as effective predictors of FE could make it possible to introduce FE into breeding programs. Here, 39 Assaf ewes in first lactation were evaluated regarding their FE by 2 metrics, residual feed intake (RFI) and feed conversion ratio (FCR). The ewes were classified into high, medium and low groups for each metric. Milk samples of the 39 ewes were subjected to untargeted metabolomics analysis. The complete milk metabolomic signature was used to discriminate the FE groups using partial least squares discriminant analysis. A total of 41 and 26 features were selected as the most relevant features for the discrimination of RFI and FCR groups, respectively. The predictive ability when utilizing the complete milk metabolomic signature and the reduced data sets were investigated using 4 machine-learning algorithms and a multivariate regression method. The Orthogonal Partial Least Square algorithm outperformed other ML algorithms for the FCR prediction in the scenarios using the complete milk metabolite signature (r2 = 0.62 ± 0.06) and the 26 selected features (0.62 ± 0.15). Regarding RFI predictions, the scenarios using the 41 selected features outperformed the scenario with the complete milk metabolite signature, where the Multilayer feedforward artificial neural network (r2 = 0.18 ± 0.14) and extreme gradient boosting (r2 = 0.17 ± 0.15) outperformed other algorithms. The functionality of the selected metabolites implied that the metabolism of glucose, galactose, fructose, sphingolipids, amino acids, insulin, and thyroid hormones was at play. Compared with the use of traditional methods, practical applications of these biomarkers might simplify and reduce costs in selecting feed-efficient ewes.

Non-invasive methods to quantify the carcass parameters of sheep: Interaction between thermal environment and residual feed intake

The thermal environment is important in unit production because the perception of thermal stress can reduce fertility, and productive performance, therefore its management is necessary. The use of non-invasive methods, such as infrared thermography and real-time ultrasonography, are widely used to evaluate indicators in animal production, without the need to slaughter the animals. Thus, we aimed to assess the effect of the thermal environment on the physiological parameters and carcass characteristics of Dorper sheep with positive and negative residual feed intake (RFI) using infrared thermography and real-time ultrasonography techniques. Twenty uncastrated male Dorper sheep (17.8 ± 2.4 kg) were confined for 40 days for RFI classification. Sheep were separated into positive RFI (n = 10) and negative RFI (n = 10). The experimental design was in randomized blocks, in a 2 × 2 factorial arrangement, with 2 thermal environments (full sun or shade) and two feed efficiency groups (positive RFI or negative RFI), with 5 replications. The sheep remained in confinement for 60 days. The animals were slaughtered at the end of the experiment and the carcasses dissected for tissue separation. Rectal temperature (RT) and respiratory rate (RR) were measured at two times (14:00 h and 18:00 h) for periods of 5 days. The RR was determined by indirect auscultation of heart sounds at the level of the laryngotracheal region. The RT was measured introduced a digital clinical thermometer into the animal's rectum. Surface temperature (ST) was obtained using a thermographic infrared camera, collecting the temperatures of the eyeball and skin surface in the regions of the head, ribs, rump, flank and shin. Sheep confined in full sun showed higher RR (P = 0.0001), ST ribs (P = 0.0020), ST rumb (P = 0.0055), ST flank (P = 0.0001) and heat tolerance coefficient (HTC) (P = 0.0010). For sheep confined in full sun, a strong correlation was observed between the RR and the mean ST (MST; r = 0.6826; P = 0.0236) and between the final loin eye area (LEAf) with the real LEA (LEAr) (r = 0.9263; P = 0.0001) and slaughter body weight (SBW) (r = 0.7532; P = 0.0325). For negative RFI sheep, a positive correlation was observed between the RR and the ST rump (r = 0.7343; P = 0.0025) and ST ribs (r = 0.6560; P = 0.0178) and the MST (r = 0.7435; P = 0.0001), between the MST and the LEAr (r = 0.6837; P = 0.0025) and the final LEA (r = 0.6771; P = 0.0144), and between the final LEA and LEAr (r = 0.9942; P = 0.0001), BW (r = 0.8415; P = 0.0277) and MST (r = 0.6771; P = 0.0045). Positive RFI sheep confined to shade showed a high correlation between final LEA and LEAr (r = 0.9372; P = 0.0001). The use of shading in confined Dorper sheep, regardless of the RFI classification, reduces the effects of heat stress on physiological parameters.

Association of feed efficiency with organ characteristics and fatty liver haemorrhagic syndrome in laying hens

Poor feed efficiency (FE) in hens impacts body weight (BW) and may reflect suboptimal health. Fatty Liver Haemorrhagic Syndrome (FLHS) is mostly observed in laying hens and affects egg production and hen performance. The aim of this study was to investigate the relationships of FE and BW with organ characteristics, liver composition and incidence of FLHS of 150 individually housed ISA Brown hens ranked on the basis of feed conversion ratio (FCR) attained from early lay. At 45 weeks, 10 birds per FE group (HFE—High feed efficient; MFE—medium feed efficient; LFE—low feed efficient) were randomly selected and euthanized. Hen BW was positively associated with feed intake and FCR. The HFE hens had a lower abdominal fat pad and liver weight compared to LFE hens. FLHS lesion score was higher (worse) in the LFE than HFE hen group and was moderately positively associated with BW and abdominal fat pad, but strongly positively associated with liver weight. Liver pathology of LFE hens showed hepatocytes with abnormal retention of lipids causing distended cytoplasmic vacuoles compared to the HFE hens. Hens which exhibited poorer FE in early lay had heavier abdominal fat pads, heavier, fatter livers and were more prone to FLHS.

Trade-off between feed efficiency and immunity in specialized high-performing chickens

Based on resource allocation theory, ignoring importance of immunity, and focus on growth and feed efficiency (FE) traits in breeding plans may lead to serious weakness in immune system performance. However, in poultry the adverse effects of selection for FE on the immune system are unclear. Therefore, an experiment was conducted to study the trade-off between FE and immunity using a total of 180 high-performing specialized male chickens from a commercial broiler line which were selected over 30 generations for growth (body weight gain, BWG) and FE (residual feed intake, RFI). Birds were reared for 42 d and 5 FE-related traits of the birds in the last week were considered including daily feed intake (DFI), feed conversion ratio (FCR), residual feed intake (RFI), residual BW gain (RG), and residual intake and gain (RIG). For all 180 chickens, immune system performance including humoral immune response, cell-mediated immunity (CMI), and the activity of lysozyme enzyme (L. activity) as innate immunity was measured. After ascending sort of each FE records, 10% of higher records (H-FE: N=18) and 10% of lower records (L-FE: N=18) were determined, and immunity between L-FE and H-FE groups were compared. Moreover, L-BWG and H-BWG were analyzed because BWG is one of components in the FE formula. Performance of the immune system was not statistically different for CMI in none of the studied FE groups. Moreover, high and low groups for DFI and BWG were not different regarding the immunity of the birds. Antibody titers against Newcastle disease virus (NDV) were different between low and high groups of FCR, RG, and RIG. Likewise, SRBC-derived antibodies were significantly different between RFI groups. Rather than humoral immunity, RIG had adversely effect on the innate immunity. Results of the present study showed that although RIG is a more appropriate indicator for FE, choosing for high RIG can weaken the performance of the both humoral and innate immune systems, while RFI had fewer adverse effects.

Taxonomic and predicted functional signatures reveal linkages between the rumen microbiota and feed efficiency in dairy cattle raised in tropical areas.

Ruminants digest plant biomass more efficiently than monogastric animals due to their symbiotic relationship with a complex microbiota residing in the rumen environment. What remains unclear is the relationship between the rumen microbial taxonomic and functional composition and feed efficiency (FE), especially in crossbred dairy cattle (Holstein x Gyr) raised under tropical conditions. In this study, we selected twenty-two F1 Holstein x Gyr heifers and grouped them according to their residual feed intake (RFI) ranking, high efficiency (HE) (n = 11) and low efficiency (LE) (n = 11), to investigate the effect of FE on the rumen microbial taxa and their functions. Rumen fluids were collected using a stomach tube apparatus and analyzed using amplicon sequencing targeting the 16S (bacteria and archaea) and 18S (protozoa) rRNA genes. Alpha-diversity and beta-diversity analysis revealed no significant difference in the rumen microbiota between the HE and LE animals. Multivariate analysis (sPLS-DA) showed a clear separation of two clusters in bacterial taxonomic profiles related to each FE group, but in archaeal and protozoal profiles, the clusters overlapped. The sPLS-DA also revealed a clear separation in functional profiles for bacteria, archaea, and protozoa between the HE and LE animals. Microbial taxa were differently related to HE (e.g., Howardella and Shuttleworthia) and LE animals (e.g., Eremoplastron and Methanobrevibacter), and predicted functions were significatively different for each FE group (e.g., K03395-signaling and cellular process was strongly related to HE animals, and K13643-genetic information processing was related to LE animals). This study demonstrates that differences in the rumen microbiome relative to FE ranking are not directly observed from diversity indices (Faith's Phylogenetic Diversity, Pielou's Evenness, Shannon's diversity, weighted UniFrac distance, Jaccard index, and Bray-Curtis dissimilarity), but from targeted identification of specific taxa and microbial functions characterizing each FE group. These results shed light on the role of rumen microbial taxonomic and functional profiles in crossbred Holstein × Gyr dairy cattle raised in tropical conditions, creating the possibility of using the microbial signature of the HE group as a biological tool for the development of biomarkers that improve FE in ruminants.

161 Effect of High- and low-Fiber Diets on Growth Performance in Growing-Finishing Pigs Selected for low or High Feed Efficiency

Abstract Understanding the effects of high- and low-fiber diets on the growth performance of pigs with different feed efficiencies will help the livestock industry develop new strategies to reduce the costs of pig production. In this study, 18 Landrace × Large White sows with high and low estimated breeding value on feed conversion ratio (EBV-FCR) were inseminated with semen from Large White with known EBV-FCR to produce 9 litters of low feed efficiency pigs and 9 litters of high feed efficiency pigs. A total of 94 growing pigs with low or high feed efficiency were fed a low-fiber (3% crude fiber) or high-fiber (6% crude fiber) content diet in a 2 × 2 factorial arrangement for 70 days. Pigs fed a high-fiber diet presented higher body weight (BW) on day 70 (P < 0.05). High feed efficiency pigs presented lower average daily feed intake (ADFI) and feed conversion ratio (FCR) than low feed efficiency pigs from day 0 to 70 (P< 0.05). There was an interaction between fiber and feed efficiency group on average daily gain (ADG;P < 0.05) and FCR (P < 0.05) from day 0 to 35. High feed efficiency pigs fed a high-fiber diet presented lower FCR than low feed efficiency pigs fed a low-fiber diet (P< 0.05). Low feed efficiency pigs fed a low-fiber diet showed the lowest ADG (P< 0.05). Regardless of efficiency groups, pigs fed a high-fiber diet presented higher ADG and lower FCR than pigs fed a low-fiber diet from day 42 to 70 (P< 0.05). These results suggest that high feed efficiency pigs can present lower FCR and ADFI without reducing final BW and ADG. Feeding a high-fiber diet can increase ADG and reduce FCR in the later stages of the experiment.

PSXV-7 Nutrient Digestibility Evaluation in Finisher Pigs from Diverse Feed Efficiency Groups

Abstract Feed efficiency (FE) is a critical trait in swine production to improve the overall production efficiency and profitability and is an important goal for pig breeding companies. FE is a complex trait involving utilization and storage of dietary nutrients in different organs, and more especially in skeletal muscles. However, whether nutrient digestibility in the pig is altered by genetic selection for FE is less clear. Thus, this study investigated the variation in apparent total tract nutrient digestibility (ATTD) in finisher boars selected for high (HFE) or low (LFE) FE within a Large White dam and sire line. A total of 130 boars were selected at 23 wk of age based on their genomic-enabled breeding value for FE and fed ad libitum a corn-soybean meal-based diet using feeding stations that recorded individual feed intake and body weight. Fecal and diet samples were analyzed for dry matter, neutral detergent fiber, acid detergent fiber, crude protein (CP), energy, ash, phosphorus, and calcium to determine ATTD using acid-insoluble ash as an indigestible marker. There was no difference in ATTD values between genetic lines (P > 0.10). However, HFE pigs had greater (P = 0.03 ATTD of CP compared with LFE pigs. Based on the estimated protein deposition and the average feed intake one week before sampling, calculated dietary digestible lysine content diet met the requirements for the average pig. However, HFE pigs had a reduced feed intake, implying that they might have experienced a shortage of lysine in the diet. It is unclear whether the improved ATTD of CP was due to a lysine-shortage or differences in genetic merit for FE.

Identification of candidate proteins regulated by long-term caloric restriction and feed efficiency in longissimus dorsi muscle in Korean native steer.

We aimed to investigate candidate proteins related to long-term caloric restriction and feed efficiency in bovine longissimus dorsi muscle (LM). A total of 31 Korean native steers were randomly distributed to ad libitum (n = 16) or caloric restriction group (n = 15) to conduct two feeding trials for 13 mon. In the first trial (10–18 mon of age), steers were fed with 100% ad libitum (NEg = 0.63 Mcal/kg) or caloric restriction (80% of the previous day’s feed intake of ad libitum group). In the second trial (18–23 mon of age), the energy value of 100% ad libitum diet was 1.13 Mcal/kg NEg and those in caloric restriction group diet was 0.72 Mcal/kg NEg. At the endpoint of this experiment, in each group, 6 animals were selected with high (n = 3) or low feed efficiency (n = 3) to collect muscle tissue samples (6 animals/group). From muscle tissues of 23 mo of age, we excavated 9 and 12 differentially expressed (two-fold or more) proteins in a nutritional group and feed efficiency group using two-dimensional electrophoresis, respectively. Of these proteins, heat shock protein beta-6 was up-regulated in both the caloric restriction and the low feed efficiency group. In bovine embryonic fibroblasts, the mRNA expression of heat shock protein beta-6 increased after adipogenic differentiation, however, decreased after myogenic differentiation. Our data provide that heat shock protein beta-6 may be an adipogenic protein involved in the mechanism of caloric restriction and feed efficiency in the LM of the steer.

Hens That Exhibit Poorer Feed Efficiency Produce Eggs with Lower Albumen Quality and Are Prone to Being Overweight.

Simple SummaryThe contemporary hybrid layer is an efficient producer of eggs, which is a source of high-quality nutrients. However, there is a lack of scientific knowledge on how feed efficiency (FE), an important measure of hen productivity, differs between individual hens during laying life and its association with other hen performance and egg quality traits. This study sought to investigate the production traits, egg composition and quality of laying hens in mid-lay when ranked based on FE in early-lay. The results showed that feed to egg conversion ratios (FCR) exhibited in early-lay were maintained until at least 40 weeks, with feed intake being the major driver of the difference in FE, not the mass of the egg. Further, hen and egg quality traits are associated during mid-lay, with high feed efficient hens having a lower body weight but producing eggs whose albumen has a higher height, Haugh unit and amino acid concentration. These results may provide important information to poultry breeders and egg producers towards improving the economics of egg production and generally improve management decision making, which is usually made based on accepting the expected average performance of a cohort of animals.Feed efficiency (FE) is an important measure of productivity in the layer industry; however, little is known about how FE differs between individual hens during the egg-laying cycle and the implications for egg quality parameters. Individual 25-week-old ISA Brown hens were observed for 42 days, ranked into three FE groups (n = 48 per High (HFE), Medium (MFE) and Low (LFE) FE groups and then monitored later in the laying cycle from 35–40 weeks. The groups exhibited different feed to egg conversion ratios (p < 0.001) from 35–40 weeks. Average daily feed intake and body weight were highest (p < 0.001) in the LFE group compared to the MFE and HFE groups, while albumen height, Haugh unit and amino acid concentrations of the albumen were significantly higher in the HFE groups compared to the LFE cohort (p < 0.001). This study concludes that FE status established in early lay is a stable variable until at least 40 weeks of age, and overweight, mid-laying hens that had poor FE produced inferior egg albumen quality measurements and composition. The distinct traits of the highly efficient hens and the poor feed efficient hens may provide important information to improving productivity in egg production.

Community composition of cecal microbiota in commercial yellow broilers with high and low feed efficiencies

The cecal microbiota plays important roles in host food digestion and nutrient absorption, which may in part affect feed efficiency (FE). To investigate the composition and functional differences of cecal microbiota between high (n = 30) and low (n = 29) feed conversion ratio (FCR; metric for FE) groups, we performed 16S rRNA gene sequencing and predicted the metagenome function using Phylogenetic Investigation of Communities by Reconstruction of Unobserved Species in yellow broilers. The results showed that the 2 groups had the same prominent microbes but with differing abundance. Firmicutes, Bacteroidetes, and Actinobacteria were 3 prominent bacterial phyla in the cecal microbial community. Although there were no differences in microbial diversity, compositional differences related to FCR were found via linear discriminant analysis (LDA) effect size; the genus Bacteroides had a significantly higher abundance (LDA >2) in the high FE (HFE) group than in the low FE group. Furthermore, genus Bacteroides had a negative FCR-associated correlation (P < 0.05). Oscillospira was positively correlated with Bacteroides in both groups, whereas Dorea was negatively correlated with Bacteroides in the HFE group. Predictive functional analysis revealed that metabolic pathways such as “starch and sucrose metabolism,” “phenylalanine, tyrosine and tryptophan biosynthesis,” and “carbohydrate metabolism” were significantly enriched in the HFE group. The relatively subtle differences in FE-associated cecal microbiota composition suggest a possible link between cecal microbiota and FE. Moreover, Bacteroides may potentially be used as biomarkers for FE to improve growth performance in yellow broilers.

PSI-37 Post-weaning feed efficiency did not influence female fertility traits of commercial or Lowline Angus heifers

Abstract Feed costs represent ~50% of beef production costs making selection for improved efficiency without affecting female reproduction critical to the cow/calf sector. Objectives were to determine the relationship between post-weaning feed efficiency and female fertility in commercial (n = 19) and half-blood Lowline-influenced Angus heifers (n = 20). Yearling heifers were delivered to the CSU, Chico Farm cattle feeding unit 45-d post weaning and randomly assigned to one of three 7 x 18 m pens, equipped with GrowSafe feeding units. Heifers were given ad libitum access to water and a forage-based diet targeting 0.68 kg gain/d (TDN: 54%, CP: 14%, and NDF: 39.7%, on a DM basis) for 72-d. Feed efficiency measures included dry matter intake (DMI), feed conversion ratio (FCR) and residual feed intake (RFI). Heifer RFI was calculated as the difference between predicted DMI and actual DMI during the trial. Feed efficiency groups were identified as: 1) low RFI (0.5 SD above the RFI mean), 2) marginal RFI (+/- 0.5 SD about the RFI mean), and 3) high RFI (0.5 SD above the RFI mean). Serial weights were taken every 14-d to calculate average daily gain (ADG) and metabolic midweight (MMWT). Heifers were synchronized using a 14-d CIDR-PG protocol. Heifers received PG injection 16-d post-CIDR removal and were equipped with an estrous detection patch. Estrous behavior was observed morning and evening for 90-h. Heifers were artificially inseminated (AI) 12-h post-standing estrus and injected with 2 mL GnRH. Pregnancy determination via rectal palpation occurred 6-mos after initial AI. Reproductive measures included: first service conception (FSC), pregnancy rate (PR), and response to estrous synchronization (RES). Reproductive traits were analyzed using the GLM procedures of SPSS with a binary logistic response. Breed type and feed efficiency group were independent variables. Relationships among reproductive measures and performance were analyzed using logistic regression of SPSS, fitting the independent variables of ADG, DMI, and RFI. Traits FSC, PR, and RES did not differ among breed types or feed efficiency groups (P &amp;gt; 0.05) and DMI, ADG and RFI were not predictors of FSC, PR, nor RES (P &amp;gt; 0.05). Cumulatively, results indicate there is no relationship between feed efficiency and reproductive performance. Producers can select for low RFI to decrease feed costs without compromising reproductive performance.

Metagenomic analysis reveals linkages between cecal microbiota and feed efficiency in Xiayan chickens

The cecal microbiota plays a critical role in energy harvest and nutrient digestion, influencing intestinal health and the performance of chickens. Feed efficiency (FE) is essential for improving economic efficiency and saving social resources in chicken production and may be affected by the cecal microbiota. Therefore, to investigate the composition and functional capacity of cecum microbes related to FE in Xiayan chicken, an indigenous breed in Guangxi province, metagenome sequencing was performed on chicken cecal contents. 173 male and 167 female chickens were divided into high and low FE groups according to the residual feed intake. The cecal microbial genome was extracted and sequenced. The results showed that the genera Bacteroides, Prevotella, and Alistipes were the 3 most abundant in each cecal microbiome. The linear discriminant analysis effect size revealed 6 potential biomarkers in male and 14 in female chickens. Notably, the relative abundance of Lactobacillus in the high FE group was higher than that of the low FE group both in the male and female chickens, and the species Limosilactobacillus oris has a higher score in the high FE group of male chickens. In contrast, some potentially pathogenic microorganisms such as Campylobacter avium in females and Helicobacter pullorum in males were enriched in the low FE group. Predictive functional analysis showed that the high FE group in male chickens had a greater ability of xenobiotics biodegradation and metabolism and signaling molecules and interaction. In addition, the host sex was found to exert effects on the cecal microbial composition and function associated with FE. These results increased our understanding of the cecal microbial composition and identified many potential biomarkers related to FE, which may be used to improve the FE of the chickens.

Relationship between feed efficiency indexes and thermography, blood, and ruminal parameters in pre-weaning dairy heifers.

The objective of this study was to evaluate whether pre-weaning heifer calves divergent for residual feed intake (RFI) or residual feed intake and body weight gain (RIG) exhibit differences in thermography, blood, and ruminal parameters. Thirty-two Gyr heifer calves were enrolled in a 63-d trial and classified into 2 feed efficiency (FE) groups based on RFI and RIG (mean ± 0.5 SD). The groups were classified as high efficiency (HE) RFI (HE RFI, n = 9), HE RIG (HE RIG, n = 10), low efficiency (LE) RFI (LE RFI, n = 10), and LE RIG (LE RIG, n = 11). The amount of whole milk provided for each calf was calculated based on their metabolic weight at birth (42% x BW0.75). The liquid diet was divided into two meals at 0700 and 1400 h. The total solid diet (TSD) was composed of 92% concentrate and 8% of Tifton 85 hay chopped in 5-cm lengths, as fed. Intake was measured daily. Blood concentrations of insulin, beta hydroxybutyrate, urea, and glucose, and ruminal pH, N-NH3, and volatile fatty acids (VFA) were evaluated at 14, 28, 42, 56, and 70 days of age. Thermal images of the calves were taken with an infrared camera (FLIR T420, FLIR Systems Inc., Wilsonville, OR) on d 56 (±3) at 0600 h, before the morning feeding. Total VFA concentration and propionate as % of total VFA were 24.2% and 22.2% lower in HE RFI compared to LE RFI calves, respectively. On the other hand, acetate as % of total VFA was 10.6% greater in HE RFI than LE RFI calves. Blood urea concentration tended to be greater in LE RFI than HE RFI calves. High efficiency HE RIG tended to have 6.8% greater acetate and 15.4% lower propionate as % of total VFA than LE RIG. Blood insulin concentration was greater and blood glucose tended to be greater for LE RIG than HE RIG group. Low efficiency RIG group had greater left rib, left flank, and anus surface temperature measured by infrared thermography than the HE RIG group. Differences in ruminal fermentation do not seem to be associated with pre-weaning calves efficiency, while differences in protein metabolism seem to affect RFI during this phase. Infrared thermography appears to be correlated to RIG in pre-weaning heifer calves.

Integrative Analysis of Metabolomic and Transcriptomic Profiles Uncovers Biological Pathways of Feed Efficiency in Pigs.

Feed efficiency (FE) is an economically important trait. Thus, reliable predictors would help to reduce the production cost and provide sustainability to the pig industry. We carried out metabolome-transcriptome integration analysis on 40 purebred Duroc and Landrace uncastrated male pigs to identify potential gene-metabolite interactions and explore the molecular mechanisms underlying FE. To this end, we applied untargeted metabolomics and RNA-seq approaches to the same animals. After data quality control, we used a linear model approach to integrate the data and find significant differently correlated gene-metabolite pairs separately for the breeds (Duroc and Landrace) and FE groups (low and high FE) followed by a pathway over-representation analysis. We identified 21 and 12 significant gene-metabolite pairs for each group. The valine-leucine-isoleucine biosynthesis/degradation and arginine-proline metabolism pathways were associated with unique metabolites. The unique genes obtained from significant metabolite-gene pairs were associated with sphingolipid catabolism, multicellular organismal process, cGMP, and purine metabolic processes. While some of the genes and metabolites identified were known for their association with FE, others are novel and provide new avenues for further research. Further validation of genes, metabolites, and gene-metabolite interactions in larger cohorts will elucidate the regulatory mechanisms and pathways underlying FE.

Identification of Microbial Genetic Capacities and Potential Mechanisms Within the Rumen Microbiome Explaining Differences in Beef Cattle Feed Efficiency.

In this study, Bos Taurus cattle offered one high concentrate diet (92% concentrate-8% straw) during two independent trials allowed us to classify 72 animals comprising of two cattle breeds as “Low” or “High” feed efficiency groups. Digesta samples were taken from individual beef cattle at the abattoir. After metagenomic sequencing, the rumen microbiome composition and genes were determined. Applying a targeted approach based on current biological evidence, 27 genes associated with host-microbiome interaction activities were selected. Partial least square analysis enabled the identification of the most significant genes and genera of feed efficiency (VIP > 0.8) across years of the trial and breeds when comparing all potential genes or genera together. As a result, limited number of genes explained about 40% of the variability in both feed efficiency indicators. Combining information from rumen metagenome-assembled genomes and partial least square analysis results, microbial genera carrying these genes were determined and indicated that a limited number of important genera impacting on feed efficiency. In addition, potential mechanisms explaining significant difference between Low and High feed efficiency animals were analyzed considering, based on the literature, their gastrointestinal location of action. High feed efficiency animals were associated with microbial species including several Eubacterium having the genetic capacity to form biofilm or releasing metabolites like butyrate or propionate known to provide a greater contribution to cattle energy requirements compared to acetate. Populations associated with fucose sensing or hemolysin production, both mechanisms specifically described in the lower gut by activating the immune system to compete with pathogenic colonizers, were also identified to affect feed efficiency using rumen microbiome information. Microbial mechanisms associated with low feed efficiency animals involved potential pathogens within Proteobacteria and Spirochaetales, releasing less energetic substrates (e.g., acetate) or producing sialic acid to avoid the host immune system. Therefore, this study focusing on genes known to be involved in host-microbiome interaction improved the identification of rumen microbial genetic capacities and potential mechanisms significantly impacting on feed efficiency in beef cattle fed high concentrate diet.

Links between the rumen microbiota, methane emissions and feed efficiency of finishing steers offered dietary lipid and nitrate supplementation.

Ruminant methane production is a significant energy loss to the animal and major contributor to global greenhouse gas emissions. However, it also seems necessary for effective rumen function, so studies of anti-methanogenic treatments must also consider implications for feed efficiency. Between-animal variation in feed efficiency represents an alternative approach to reducing overall methane emissions intensity. Here we assess the effects of dietary additives designed to reduce methane emissions on the rumen microbiota, and explore relationships with feed efficiency within dietary treatment groups. Seventy-nine finishing steers were offered one of four diets (a forage/concentrate mixture supplemented with nitrate (NIT), lipid (MDDG) or a combination (COMB) compared to the control (CTL)). Rumen fluid samples were collected at the end of a 56 d feed efficiency measurement period. DNA was extracted, multiplexed 16s rRNA libraries sequenced (Illumina MiSeq) and taxonomic profiles were generated. The effect of dietary treatments and feed efficiency (within treatment groups) was conducted both overall (using non-metric multidimensional scaling (NMDS) and diversity indexes) and for individual taxa. Diet affected overall microbial populations but no overall difference in beta-diversity was observed. The relative abundance of Methanobacteriales (Methanobrevibacter and Methanosphaera) increased in MDDG relative to CTL, whilst VadinCA11 (Methanomassiliicoccales) was decreased. Trimethylamine precursors from rapeseed meal (only present in CTL) probably explain the differences in relative abundance of Methanomassiliicoccales. There were no differences in Shannon indexes between nominal low or high feed efficiency groups (expressed as feed conversion ratio or residual feed intake) within treatment groups. Relationships between the relative abundance of individual taxa and feed efficiency measures were observed, but were not consistent across dietary treatments.

Relationship between feed efficiency indexes and performance, body measurements, digestibility, energy partitioning, and nitrogen partitioning in pre-weaning dairy heifers.

The objectives of this study were: 1) to classify animals into groups of high and low feed efficiency using two feed efficiency indexes (Residual feed intake (RFI) and residual feed intake and body weight gain (RIG)), and 2) to evaluate if pre-weaning heifer calves divergent for feed efficiency indexes exhibit differences in performance, body measurements, digestibility, energy partitioning, and nitrogen partitioning. A total of 32 Gyr heifer calves were enrolled in a 63-d trial and classified into two feed efficiency (FE) groups based on RFI and RIG (mean ± 0.5 SD). The groups were classified as high efficiency (HE) RFI (HE RFI, n = 9; HE RIG, n = 10), and low efficiency (LE) RFI (LE RFI, n = 10; LE RIG, n = 11). The remaining animals were classified as intermediate (n = 13 (RFI) and n = 11 (RIG)). HE and LE calves had RFI values of—0.052 and 0.049 kg/d (P < 0.05), respectively. The HE RFI group consumed 8.9% less solid diet than the LE RFI group. HE RFI animals exhibited an increased digestibility of crude protein and ether extract and tended to have greater total dry and organic matter digestibility. LE RFI animals had greater gross energy and nitrogen intake, though greater fecal losses resulted in a tendency to reduce energy and nitrogen use efficiency. HE and LE calves had RIG values of 0.080 and -0.077kg/d (P ≤ 0.01), respectively. HE RIG animals exhibited greater average daily gain (9.4%), body weight (BW), and heart girth, though HE RIG group exhibited narrower hip width. HE RIG animals tended to have greater ether extract digestibility but greater methane losses (% of gross energy). HE RFI in pre-weaning heifers seems to be related to differences in digestibility. Divergent animals for RIG during the assessed phase appear to differ in body measurements, which may be related to differences in the composition of the gain.

The Bacterial and Fungal Microbiota of Nelore Steers Is Dynamic Across the Gastrointestinal Tract and Its Fecal-Associated Microbiota Is Correlated to Feed Efficiency.

The ruminant gastrointestinal tract (GIT) microbiome plays a major role in the health, physiology and production traits of the host. In this work, we characterized the bacterial and fungal microbiota of the rumen, small intestine (SI), cecum and feces of 27 Nelore steers using next-generation sequencing and evaluated biochemical parameters within the GIT segments. We found that only the bacterial microbiota clustered according to each GIT segment. Bacterial diversity and richness as well as volatile fatty acid concentration was lowest in the SI. Taxonomic grouping of bacterial operational taxonomic units (OTUs) revealed that Lachnospiraceae (24.61 ± SD 6.58%) and Ruminococcaceae (20.87 ± SD 4.22%) were the two most abundant taxa across the GIT. For the fungi, the family Neocallismastigaceae dominated in all GIT segments, with the genus Orpinomyces being the most abundant. Twenty-eight bacterial and six fungal OTUs were shared across all GIT segments in at least 50% of the steers. We also evaluated if the fecal-associated microbiota of steers showing negative and positive residual feed intake (n-RFI and p-RFI, respectively) was associated with their feed efficiency phenotype. Diversity indices for both bacterial and fungal fecal microbiota did not vary between the two feed efficiency groups. Differences in the fecal bacterial composition between high and low feed efficiency steers were primarily assigned to OTUs belonging to the families Lachnospiraceae and Ruminococcaceae and to the genus Prevotella. The fungal OTUs shared across the GIT did not vary between feed efficiency groups, but 7 and 3 OTUs were found only in steers with positive and negative RFI, respectively. These results provide further insights into the composition of the Nelore GIT microbiota, which could have implications for improving animal health and productivity. Our findings also reveal differences in fecal-associated bacterial OTUs between steers from different feed efficiency groups, suggesting that fecal sampling may represent a non-invasive strategy to link the bovine microbiota with productivity phenotypes.