Efficiency Of Sheep Research Articles

Polymorphisms of PRKAA1 and FABP4 genes and their association with feed efficiency in Hu sheep

Feed efficiency (FE) is an important economic trait in the sheep industry, influenced by biological processes such as digestion and metabolism. PRKAA1 gene participates in the synthesis and oxidation of fatty acids; the FABP4 gene is closely associated with intracellular fatty acid regulation. In this study, we use Sanger sequencing, KASPar genotyping, and qRT-PCR to investigate the association between variations in PRKAA1 and FABP4 genes and feed efficiency in Hu sheep, the expression patterns of PRKAA1 and FABP4 genes in different tissues, as well as the differences in expression of different genotypes in tail fat. The association analysis results indicated that PRKAA1 gene g.35431965 C > T locus and FABP4 gene g.62829807 C > T locus were significantly associated with the feed conversion ratio (FCR) of Hu sheep aged 80–180 days, with the dominant genotypes being CC and CC, respectively. Simultaneously, there existed notable disparities among various genotype combinations. The qRT-PCR results showed PRKAA1 and FABP4 genes were widely expressed in ten tissues, of which the PRKAA1 gene was lower expression level in rumen and lung, FABP4 gene was significantly highest expression in the tail fat than the other tissues; the expression of two different genotypes in tail fat also exhibits significant differences (P ≤ 0.05). Therefore, these findings suggested that the variation of PRKAA1 and FABP4 genes might be used as novel genetic marker for improving feed efficiency in sheep.

Technical efficiency analysis in Italian sheep and goat farms using FADN dataset

The sheep and goat farms are one of the main breeding in many Italian regions located in mountainous and disadvantaged rural areas. One of the main Italian Protected Designation Origin cheese as Pecorino Romano is made by sheep milk from many regions. The main purpose of this research was to asses by a quantitative approach the technical efficiency in sheep and goat farms part of the Farm Accountancy Data Network (FADN) in all Italian regions since 2008 to 2020. By the Multi-direction Efficiency Analysis (MEA) it has been possible to overcome one of the main bottlenecks of the technical efficiency estimation analysing which is the excess in each input able to impact to the technical efficiency. Main results have pointed out that the Italian sheep and goat farms have a higher technical efficiency compared to other studies carried out in other European countries. Land capital, labour and assets have been the main inputs able to impact to the technical efficiency. Furthermore, an important role of subsidies to the sheep and goat Italian farms exists.

PSIX-28 Optimization of feeding trial length for evaluating feed efficiency in sheep

Abstract Feed efficiency tests are well established for beef cattle, but testing for sheep remains rare due to the lack of appropriate equipment and standardized protocols. To explore the optimum trial length for evaluating feed efficiency in sheep, freshly weaned Rideau Arcott ewe lambs [n = 80; 4to 5 mo of age and body weights (BW) of 16 to 25 kg] were enrolled in a 65-d feeding trial, following a 20-d adaptation period. A mixed ration containing barley gain and protein supplement pellets were offered twice daily, and lambs had ad libitum access to feed, water and bedding straw during the trial period. Daily feed intake of individual lambs was monitored with Vytelle SENSE feed bunks, BW was recorded biweekly, as well as on two consecutive days at the start and end of the trial. Lambs that had died or had abnormal growth patterns from sickness were removed, resulting in 62 lambs remaining in the final dataset. Optimum trial length for measuring feed intake (DMI) and average daily gain (ADG) were evaluated with R Software (v. 4.3.3) via a post-hoc analysis of constructing shortened trial lengths from the regular test. The DMI and ADG values from the shortened trial datasets were compared with those from regular trial days with correlation (Pearson and Spearman tests) and linear regression analyses. There were 64 shortened trial lengths for DMI by 1 d increments, and 15 sub-datasets for ADG consisting of trial lengths between every two BW measurements. Residual feed intake (RFI), residual average daily gain (RADG), and residual intake and BW gain (RIG) were calculated for and compared between the regular trial length (65 d) and favorable shortened trial lengths based on DMI and ADG evaluations. Correlation, regression and agreement analyses were used to determine the optimum trial lengths for RFI, RADG and RIG evaluations. Results showed that DMI and ADG measurements could be shortened to 42 (r > 0.95, R2 > 0.90, β > 0.95, P < 0.001) and 56 d (r > 0.96, R2 > 0.93, β > 0.96, P < 0.001), respectively. Additionally, trial length for RFI, RADG, and RG evaluations could be reduced to 56 d (r > 0.95, R2 > 0.91, β > 0.95, CCC > 0.95, P < 0.001), primarily due to the trial length requirement for accurate ADG measurement. Reducing the duration of trials for evaluating feed efficiency in sheep not only reduces testing costs, fostering greater uptake among sheep producers, but also allows for the evaluation of more lambs annually, thereby enhancing the overall productivity and profitability of the sheep industry.

In Vitro: Anthelmintic Activity of Aqueous Leaf Extract of Indigofera tintoria L Againts Haemonchus contortus

Gastrointestinal nematodes are one of the causes of reduced production efficiency in sheep and goats in Indonesia, especially the parasite abomasum Haemonchus contortus. This parasite causes the disease Haemonchosis which causes anemia and is fatal for productive sheep and goats. Economic losses caused by the morbidity and mortality of this parasite are quite high, so it can increase the cost of prevention and treatment of this disease. The aim of this study was to evaluate the inhibition of hatching eggs and mortality of adult H. contortus worms from Indigofera tintoria L leaf infusa on in vitro. Indigofera leaf infusa on was tested at five concentrations, namely 0% as negative control, 20%, 40%, 60% and 80%. Positive control used Albendazole with a concentration of 0,025 mg/ml. At the highest concentration of 80% indigofera leaf infusa on was able to inhibit egg hatching by 95,37% and had a mortality rate of 68,67% against adult H. contortus worms. The 80% concentration had the same effect when compared to the positive control using Albendazole. Phytochemical analysis of Indigofera tintoria L leaves containing condensed tannins.

Multi-omics revealed the mechanism of feed efficiency in sheep by the combined action of the host and rumen microbiota

This study was conducted to investigate potential regulatory mechanisms of feed efficiency (FE) in sheep by linking rumen microbiota with its host by the multi-omics analysis. One hundred and ninety-eight hybrid female sheep (initial body weight = 30.88 ± 4.57 kg; 4-month-old) were selected as candidate sheep. Each test sheep was fed in an individual pen for 60 days, and the residual feed intake (RFI) was calculated. The ten candidate sheep with the highest RFI were divided into the Low-FE group, and the ten with the lowest RFI were divided into the High-FE group, all selected for sample collection. The RFI, average daily gain and average daily feed intake were highly significantly different between the two experimental groups (P < 0.05). Compared with Low-FE group, the insulin-like growth factor-1 and very low-density lipoprotein in serum and the propionate in rumen significantly increased in High-FE group (P < 0.01), but the acetate:propionate ratio in rumen significantly decreased in High-FE group (P = 0.034). Metagenomics revealed Selenomonas ruminantium, Selenomonas sp. and Faecalibacterium prausnitzii were key bacteria, and increased abundance of the genes encoding the enzymes for cellulose degradation and production of propionate in High-FE group. The results of proteomics and section showed the rumen papilla length (P < 0.001) and expression of carbonic anhydrase and Na+/K+-ATPase were significantly higher in High-FE group (P < 0.05). On the other hand, the acetyl-CoA content significantly increased in the liver of High-FE group (P = 0.002). The relative expression levels of insulin-like growth factor-1 and apolipoprotein A4 genes were significantly up-regulated in the liver of High-FE group (P < 0.01), but relative expression level of monoacylglycerol O-acyltransferase 3 gene was significantly down-regulated (P = 0.037). These findings provide the mechanism by which the collaborative interaction between rumen microbiota fermentation and host uptake and metabolism of fermentation products impacts feed efficiency traits in sheep.

Identification of the FGB gene polymorphism and analysis of its association with fat deposition traits in Hu sheep

As a crucial economic trait, fat deposition is directly related to carcass quality and feed efficiency in sheep. The purpose of this study was to investigate the polymorphisms of the FGB gene related to fat deposition and detect the expression features of the FGB gene in different adipose tissues of sheep by using Sanger sequencing, MassARRAY® SNP technique, and quantitative real-time PCR (qRT-PCR). Results showed that in the intron region of the FGB gene, a SNP g. 3378953 A > T has been identified, and significant association was found between perirenal fat weight, perirenal fat relative weight, mesenteric fat weight, and mesenteric fat relative weight (P < 0.05). Moreover, qRT-PCR analysis showed that FGB was expressed in all three adipose tissues, and FGB gene expression level in the AA genotype was significantly lower than that in the AT or TT genotypes (P < 0.05). Therefore, the FGB gene can be used as a candidate gene to reduce fat deposition in Hu sheep breeding, and the selection of the AA genotype in Hu sheep in production practice is more conducive to improving production efficiency.

Eficiência alimentar de ovinos como estratégia para mitigação de gases de efeito estufa

Climate change is a very relevant and worrying topic today and is present in the agendas of different spheres of society. High concentrations of greenhouse gases (GHGs) are released into the atmosphere, causing global temperatures to rise. In agricultural production, methane (CH4) is considered one of the highest GHG emissions, causing a negative impact on natural resources and accelerating climate change. In the coming years, with the increase in the world population, food production should be implemented in self-sufficient, quality, and sustainable production systems to meet the need for high consumption. The reduction in CH4 production is related to the better efficiency of energy use of the feed by the animals; therefore, the knowledge of the ruminal fermentation parameters, identification of the ruminal microbiota, and selection of more efficient animals, with lower consumption and greater weight gain, in addition to producing less GHGs like CH4, have a less negative impact on the environment and are economically viable. This review presents some aspects of selection for feed efficiency in sheep as a strategy to mitigate GHG emission and some techniques for measuring these gases.

Energy Metabolism of Sheep Supplemented with Complete Rumen Modifier (CRM)

This study aimed to examine the effect of supplementing the Complete Rumen Modifier (CRM) which consisted of 30% Morinda citrifolia leaf flour, 30% Camellia sinensis leaf dregs flour, 30% Ipomoea batatas leaf flour, 3% S. cerevisiae, 3% metionin and 3% sulfur on the energy metabolism of 18 local male sheep aged 6-8 months. The experimental feed consisted of ammoniated rice straw and concentrate (40:60) weighing 4% DM body weight. This study was subjected to a randomized complete block design (RCBD), analyzed six groups of initial weight of sheep allotted into three treatment groups: 0%, 1%, and 2% CRM of DM feed. The measured variables were energy intake (EI), digestible energy (DE), metabolizable energy (ME), energy retention (RE), and efficiency of RE to EI, RE to DE, and RE to ME. The results showed significant effects (P&amp;lt;0.01) of supplementing CRM in the feed on EI, DE, ME, RE, and efficiency of RE to EI, RE to DE, and RE to ME. The orthogonal polynomial test revealed that a higher dose of CRM supplementation in the feed has quadraterally increased (P&amp;lt;0.01) EI, DE, ME, and RE with peak points on 0,62%; 0,80%; 1,05%; 1,09%, respectively, and linearly increased (P&amp;lt;0.01) the efficiency of RE to EI, RE to DE, and RE to ME. It was concluded that the addition of CRM at the level of 2% was able to produce optimal energy efficiency in sheep.

The effect of RORA (RAR-Related Orphan Receptor Alpha) receptors on litter size in Akkaraman sheep breed.

In this study, the relationship between RORA 23bp indel genotype and allele frequency with twin pregnancy, fertility, live weight and milk yield in 106 female Akkaraman ewes raised in Elazığ province was investigated. In the study conducted in Elâzığ province, 10ml milk was collected from 106 Akkaraman sheep and DNA was extracted from these milk. In RORA 23bp indel genotype frequency, DD genotype was found more than ID and II genotypes and RORA 23bp indel ın allele frequency, the D allele was found to be higher than the I allele. In both the first and second parity, the twinning rate was found to be lower. In both the first and second parity, the twinning rate was higher in the DD genotype, and it was observed that this genotype promınated mıddle lıvestock weıght and mılk yıeld. According to the results of our study, mutations in the RORA gene, which is a gene affecting reproductive efficiency in sheep, do not have a positive effect on fertility and twinning rate in Akkaraman sheep. To sum, this study provided theoretical references for the comprehensively research of the function of RORA gene and the breeding of Akkaraman Sheep. The 23-bp indel variants can be considered as molecular markers for litter size of sheep for marker-assisted selection breeding.

Temperature and Temperature Humidity Index Changes during Summer to Autumn in a Temperate Zone May Affect Liveweight Gain and Feed Efficiency in Sheep

Lamb finishing during summer in southern Australia faces the challenges of dry paddock feed of low nutrient value and energy concentration, combined with periods of high temperature that reduce appetite. One potential forage to overcome these challenges is camelina, a brassica with a high lipid concentration. Liveweight gain (LWG) and feed efficiency (FE) of a pelleted diet containing 15% camelina hay (CAM) were compared with an equivalent diet based on oaten hay (STD), a feed commonly used during dry seasons. The experiment was conducted under summer to autumn conditions using 56 maternal Composite (Composite) wether lambs (4 months, 28–38 kg liveweight) and 56 Merino wether yearlings (15 months, 37–43 kg liveweight). Animals were maintained in group pens (8/pen) and weekly average feed intakes per pen and liveweights per pen were determined in a shaded well-ventilated animal house. The LWG and FE for both animal types were significantly lower during weeks 5–8 compared with weeks 1–4. These changes coincided with a higher proportion of daytime maxima exceeding 28 °C (50% vs. 21%) and night-time hours exceeding 22 °C (15% vs. 9%). The experiment indicated that the LWG and FE of sheep fed the CAM diet were less affected by the elevated temperatures than sheep fed the STD diet during weeks 5–8. However, further research under controlled environmental conditions is required to further validate these results.

350 Meta-Analysis of the Effects of Dietary Inclusion of dry Distillers Grains with Solubles (Ddgs) on Performance, Fermentation, Carcass Characteristics, and Nitrogen Efficiency in Sheep

Abstract We conducted a meta-analysis to evaluate the effects of dietary supplementation of dry distillers grains with solubles (DDGS) on performance, fermentation, carcass characteristics, and nitrogen efficiency in meat sheep. A total of 36 peer-reviewed manuscripts from 1997 to 2021 met the inclusion criteria for the analysis. Data from 940 sheep (29.1±11.5 kg) were used to estimate the magnitude of the effect between DDGS and control (No DDGS) treatments weighted by inverse variance using a robust variance estimation. Categorical and continuous covariates, like breed (pure or crossbreed), CP, NDF, and DDGS inclusion rate (0 to 100%) were adjusted to a mixed model to perform a meta-regression and subset analysis. Dietary DDGS increased (P &amp;lt; 0.05) dry matter digestibility (75.9 vs.74.9 %), neutral detergent fiber digestibility (55.9 vs. 53.8%) with respect to the control. Compared with the control, dietary DDGS increased (P &amp;lt; 0.01) final body weight (51.4 vs. 50.4 kg) and tended to increase (P = 0.06) average daily gain (254.1 vs. 247.6 g/d) in sheep. Similarly, dietary DDGS tended to increase (P &amp;lt; 0.10) hot and cold carcass weight (25.5 vs. 24.6 kg; 21.1 vs. 19.8 kg), and meat redness (16.3 vs. 16.6) compared with the control. Dietary DDGS reduced acetate molar proportions (50.1 vs. 52.0%) and acetate: propionate ratio (1.63 vs. 1.87; P = 0.02). The subset analysis revealed that breed and DDGS levels in the diet influenced yield grade and carcass weight. Dietary inclusion of DDGS linearly increased (P &amp;lt; 0.05) nitrogen intake and rumen NH3-N, but also urinary nitrogen. The inclusion rate of DDGS should not exceed 30% in the diet to prevent negative effects on nitrogen metabolism, rumen fermentation, and carcass characteristics in meat sheep. Collectively, this study supports the inclusion of DDGS in meat sheep diets to increase performance and meat quality.

375 Genomic Approaches for Feed Efficiency in Sheep

Abstract United States seedstock sheep producers have selected sheep for higher weaning and post-weaning weights using estimated breeding values for approximately forty years. Despite this, little work has investigated if the increased performance has inadvertently resulted in increased feed intakes, increasing total feed costs for the producer. Eighty range-breed ewe lambs (forty Targhee and forty Rambouillet) were enrolled in a residual feed intake (RFI) trial shortly after weaning at approximately four months of age. Feed intake was recorded utilizing a GrowsafeTM feeding system modified for sheep. Following a two-week adaption period, feed intakes were recorded daily for forty-two days. Body weights were collected at the beginning, end, and weekly throughout the trial period. Residual feed intake was calculated utilizing mid-trial body weights and feed intake measurements. Six ewes were removed from the trial due to failure to adapt to the feeding system. Linear regressions were utilized to determine the association between post-weaning weight estimated breeding values and RFI and body weight. As expected, there was a significant relationship (p&amp;lt; 0.05) between post-weaning estimated breeding value and body weight during the trial. No statistically significant relationship between post-weaning weight estimated breeding value and RFI was identified, indicating selection for increased body weight has not resulted in decreased feed efficiency during the growth phase. Additional feed efficiency measures will be collected on these same ewes at a later life stage to represent the maintenance phase of production as opposed to the growth phase. In addition, genetic and rumen microbial analysis is ongoing. Together these approaches will aid in the construction of a framework for eventual genetic and genomic selection of feed efficiency in U.S. range sheep.

Supplementation of Aspergillus oryzae Culture Improved the Feed Dry Matter Digestibility and the Energy Supply of Total Volatile Fatty Acid Concentrations in the Rumen of Hu Sheep

The objective of the present study was to investigate the effects of feeding different amounts of Aspergillus oryzae culture (AOC) on the degradation rate of various feeds for 24 h, rumen fermentation parameters, microbial community, and blood cell composition of Hu sheep. Sixteen castrated and fattening adult Hu sheep with permanent rumen fistula were randomly divided into four groups (four sheep per group) based on body weight (64.62 ± 5.83 kg). The experiment was repeated for two periods to ensure eight replicates for each treatment, and each period consisted of 28 days, including a 7-d of transition, a 14-d of pre-feeding, and a 7-d of sample collection. The control group (CON) received a basal diet without AOC, and the other groups were fed basal diet supplemented with 10 g/d, 20 g/d, and 40 g/d AOC, respectively, every day before the morning feeding. Supplementation with 20 g/d and 40 g/d AOC significantly increased (P < 0.05) the total volatile fatty acids (TVFAs) content, the molar ratio of butyric acid, and the 24 h dry matter (DM) degradation rate of alfalfa hay and corn straw. When fed 40 g/d AOC, the DM degradation rate of corn germ meal and the relative abundance of Kiritimatiellaeota were significantly increased (P < 0.05), but the ratio of acetic acid to propionic acid (A/P) was significantly reduced (P = 0.04). In conclusion, supplementation with AOC for Hu sheep could improve feed DM digestibility and increase the energy supply of TVFAs concentration in the rumen. Based on the feed conditions of the present study, supplementation 40 g/d of AOC could increase the production efficiency of sheep while higher level have to further investigate.

Identification and characterization of circular RNAs in association with the feed efficiency in Hu lambs

BackgroundCircular RNA (circRNA), as a new members of noncoding RNA family, have vital functions in many biological processes by as microRNA sponges or competing endogenous RNAs (ceRNAs). However, little has been reported about the genetic mechanism of circRNAs regulation of feed efficiency in sheep.ResultsThis study aimed to explore the expression of circRNAs in the liver of Hu sheep with High-RFI (High residual feed intake) and Low-RFI (Low residual feed intake) using transcriptome sequencing. A total of 20,729 circRNAs were identified in two groups, in which 219 circRNAs were found as significantly differentially expressed. Several circRNAs were validated by using RT-PCR, sanger sequencing and RT-qPCR methods. These results demonstrated that the RNA-seq result and expression level of circRNAs identified are reliable. Subsequently, GO and KEGG enrichment analysis of the parental genes of the differentially expressed (DE) circRNAs were mainly involved in immunity response and metabolic process. Finally, the ceRNA regulatory networks analysis showed that the target binding sites for miRNA such as novel_41, novel_115, novel_171 and oar-miR-485-3p in the identified DE cirRNAs. Importantly, two metabolic (SHISA3 and PLEKHH2) and four (RTP4, CD274, OAS1, and RFC3) immune-related target mRNAs were identified from 4 miRNAs. Association analysis showed that the polymorphism (RTP4 c.399 A > G) in the target gene RTP4 were significantly associated with RFI (P < 0.05).ConclusionsAnalysis of sequencing data showed some candidate ceRNAs that may play key roles in the feed efficiency in sheep by regulating animal immune and metabolic. These results provide the basis data for further study of the biological functions of circRNAs in regulating sheep feed efficiency.

122 Evaluation of Sire FEC EBV Type andHaemonchus contortous Infection on Feed Efficiency in Katahdin Sheep

Abstract Understanding the impact of genetic resistance to internal parasitism and infection status on feed efficiency could be valuable to selection and management programs. The aim of this study was to evaluate the effect of fecal egg count (FEC) estimated breeding value (EBV) and Haemonchus contortous (H.C.) infection on intake, feed:gain (F:G), and residual feed intake (RFI). Over two years, Katahdin lambs divergently selected for FEC EBV (LowFEC, n = 86; HighFEC, n = 87) were born mid-March at the Southwest Virginia Agricultural Research and Extension Center. Mid-July, lambs were transported to West Virginia University’s Animal Science Farm and fed using a Growsafe™. Lambs were provided a complete pellet (16% CP) ad libitum while individual intake was measured. Half of the lambs from each sire FEC EBV type were infected with 5,000 H.C. L3 larvae and observed for 6 weeks alongside uninfected contemporaries. Artificial H.C. infection resulted in lambs becoming moderately infected with FEC ranging from (0 – 1208 eggs/g). RFI was calculated as the difference between actual and expected intake. Expected intake was predicted based on average daily gain and metabolic body size. Intake was not affected by sire FEC EBV type or infection status (P &amp;gt; 0.10). Infection status did not affect F:G, however HighFEC lambs tended to have greater F:G values (13.5 vs. 6.8 kg feed:kg gain; P = 0.07). RFI was not affected by sire FEC EBV type or infection status (P &amp;gt; 0.10). Individual sire (n = 9) had a significant effect on intake and RFI (P &amp;lt; 0.05). Year and year x sire interaction did not have an effect on RFI or F:G (P &amp;gt; 0.40). Sire FEC EBV type and infection status did not impact feed efficiency. However, variation between sires independent of year indicates potential sire impact on progeny feed efficiency in sheep.

Investigation of the Effectiveness of Quercetin on Acrosome Integrity of Merino Ram Sperm

To achieving high efficiency in sheep, ram sperm must have high fertilization ability. Quercetin, a potent antioxidant, has been shown to have a positive effect on semen in different species. This study aims to improve the efficiency of the Merino ram sperm using quercetin. The ejaculates collected from Merino rams were used for the dilution of the sperm (sperm density ≥ 3×109 spermatozoa/ml, motility ≥ 75%). Tris diluent was used to dilute the semen. The ejaculates were divided into 4 equal volumes at 32 °C. Three groups were formed by adding quercetin (15, 30, 45 μg/mL) at different doses. Antioxidant (quercetin) did not participate in the 4th group (the control group). Spermatozoa were diluted and frozen to approximately 4x108 spermatozoa per ml with Tris diluent. After thawing, the master mix was prepared with 60μl semen, 10μl FITC-PNA and 2.5μl PI and allowed to incubate at 37 °C for 20 minutes. The reaction was then terminated after treatment with 10μL Hancock solution. An amount of 2.5μl of the sample was taken and 200 sperm were counted at 400 magnifications on a fluorescent microscope. Sperm cells with a green color were evaluated as damaged acrosome, and no green colour was regarded as undamaged acrosome. In terms of the undamaged percentage of acrosomal integrity was assessed in the control group and quercetin groups (15, 30, and 45μg/mL). Findings: 39.16 ± 2.65b in the 15μg/mL group, 40.83 ± 0.30b in the 30μ/mL group, 20.83 ± 2.95a in the 45μg/mL group and 54.83 ± 3.38c in the control group. The percentage of the three groups formed with the quercetin substance added at different doses (15, 30, 45μg/mL) were lower than the control group. Quercetin has been shown to toxicize acrosome integrity at these doses.

Polymorphisms in ovine ME1 and CA1 genes and their association with feed efficiency in Hu sheep.

Improving feed efficiency would increase profitability for producers. The objective of this study was to detect the expression levels of ME1 and CA1 and the polymorphisms of ME1 and CA1 associated with the feed conversion ratio (FCR) and residual feed intake (RFI) of Hu sheep by using qRT-PCR, pooled DNA sequencing and KASPar assay. The qRT-PCR results indicated that the expression levels of ME1 and CA1 were significantly higher in the liver tissues of low-RFI sheep than in those of the high-RFI sheep (p<.01). Association analysis demonstrated that the polymorphism ME1 g.453 C>T was significantly associated with FCR and RFI (p<.05). The polymorphism CA1 g.199 C>T had a significantly associated with FCR (p<.05) and no association with RFI (p>.05). Significant differences were observed between the combined genotypes and FCR and RFI at different measurement periods (p<.05). Thus, we propose the use of these two polymorphisms as new candidate molecular markers for improving feed efficiency in sheep populations.

Characterization of the rumen microbiota and its relationship with residual feed intake in sheep

Feed efficiency is a highly important economic trait in sheep production and has a significant impact on the economic benefits of sheep farming. Microbial fermentation of the rumen has a vital role in the host's nutrition; the rumen microbiota might affect host feed efficiency. However, the relationship between the rumen microbiota and feed efficiency in sheep is unclear. In the present study, the microbiota of 195 Hu sheep was investigated and their residual feed intake (RFI), a commonly used measure of feed efficiency, was determined. From birth, all sheep were subjected to the same management practices. At slaughter, samples of liquid rumen contents were collected and subjected to amplicon sequencing for the 16S rDNA gene on the IonS5™XL platform. To identify the bacterial taxa differentially represented at the genus or higher taxonomy levels, we used linear discriminant analysis coupled with effect size and curve fitting. In the sheep rumen, the four most abundant phyla were Firmicutes, Bacteroidetes, Fibrobacteres, and Proteobacteria; and the dominant genera were unidentified Prevotellaceae, Fibrobacter, unidentified Lachnospiraceae, Saccharofermentans, and Succinivibrio. Pathway analysis of the 16S rDNA sequencing data from the rumen microbiota identified that carbohydrate metabolism was enriched. Using α-diversity analysis, we further identified that Observed species, ACE, Good's coverage, and Chao1 are more abundant (P < 0.01) in the low-RFI (L-RFI) group compared to the high-RFI (H-RFI) group. High-RFI sheep had a higher abundance of three bacterial taxa (Prevotellaceae, Negativicutes, and Selenomonadales), and one taxa was overrepresented in the L-RFI sheep (Succinivibrio), respectively. Furthermore, model fitting showed that Veillonellaceae, Sphaerochaeta, Negativibacillus, Saccharofermentans, and members of the Tenericutes, Kiritimatiellaeota, Deltaproteobacteria, and Campylobacterales were correlated with the sheep RFI classification and thus were indicative of a role in animal efficiency. Tax4Fun analysis revealed that metabolic pathways such as “energy metabolism,” “metabolism of cofactors and vitamins,” “poorly characterized,” and “replication recombination and repair proteins” were enriched in the rumen from H-RFI sheep, and “genetic information processing” and “lipopolysaccharide biosynthesis” were overrepresented in L-RFI sheep rumen. In addition, six Kyoto Encyclopedia of Genes and Genomes orthology pathways were identified as different between H-RFI and L-RFI groups. In conclusion, the low RFI phenotype (efficient animals) consistently (or characteristically) exhibited a more abundant and diverse microbiome in sheep.

Feed conversion efficiency in sheep genetically selected for resistance to gastrointestinal nematodes

Context It has been indicated that there might be an antagonism between selection for gastrointestinal nematode resistance and high productivity and feed conversion efficiency in ruminants. Aims This study aimed to determine whether genetic selection for resistance to gastrointestinal nematodes would alter the feed intake and feed efficiency of sheep with or without an infection of Haemonchus contortus. Methods Sixty-seven Corriedale lambs (357 ± 14 days old) derived from flocks genetically selected to be resistant (n= 29) or susceptible (n = 38) to gastrointestinal nematodes (GIN) were evaluated for individual dry-matter intake (DMI), feed conversion ratio (FCR) and residual feed intake (RFI). Considering bodyweight (BW), GIN line and sires, males were allotted to one of three outdoor pens and females to one of two, each pen being equipped with five automated feeding systems and two automatic weighing platforms to record individual feed intake and BW. Feed (lucerne haylage, crude protein 20.5%, metabolisable energy 9.2 MJ/kg DM) and water were offered ad libitum. The experiment was conducted in two periods. First, animals were maintained worm-free (14 days of acclimatisation and 44 days of records) and then, in Period 2 (42 days), animals were artificially infected with 6000 L3 of Haemonchus contortus. Worm egg counts were recorded on Days 9, 23, 27, 30, 42 post-infection. While DMI, FCR, average daily gain and BW were analysed using a generalised linear model including dams age, pen and GIN line as fixed effects, RFI was analysed including only GIN line. Key results In both periods, GIN line did not have a significant (P &gt; 0.05) effect on DMI, FCR, RFI, average daily gain or BW. Worm egg count was different (P &lt; 0.05) on Day 23 post-infection (Period 2), being higher in susceptible line. Conclusions The most important finding of this study is that breeding GIN-resistant animals would not have a negative effect on feed conversion efficiency when evaluated as FCR or RFI in 1-year old lambs fed ad libitum with a high-protein diet. Implications Breeding for resistance to internal nematodes does not affect feed efficiency or productivity.

146 Survey of residual feed intake in Katahdin and Texel lambs in a feedlot environment

Abstract Residual feed intake (RFI) is quickly becoming the preferred measurement of efficiency in many species due to its inherent independence of most other important production traits. Making meaningful improvement in feed efficiency of sheep will require a consistent methodology to accurately identify efficient individuals. Due to difficulty in measuring this trait efforts must be made to incorporate efficiency data in large-scale genetic evaluations. The aim of this study was to evaluate lambs in a feedlot with large-scale genetic evaluations for feed efficiency calculated by residual feed intake (RFI) utilizing a Growsafe™ system. RFI was calculated by subtracting expected intake from actual intake. Expected intake was determined by regressing metabolic body size of mid-test weight. Regression determined ADG on actual intake for individuals in the population. Texel (n = 58) and Katahdin (n = 118) lambs were placed in a feedlot and fed in separate feeding trials, a complete pellet ad libitum as the sole source of nutrition. In this environment Texel and Katahdin lambs had expected ADG values (0.27 kg/day, 0.32 kg/day respectively) and actual intake data (2154.17 g/day, 1909.33 g/day respectively. After a period of adaptation, Texel average intake was determined over a period of 27 consecutive days and used to calculate individual RFI within the test population. Observable ranges of RFI (-0.62 – +0.62) were seen in the Texel lambs. At the start of the Katahdin trial lambs were separated by sex and FEC treatment. After a period of adaptation, Katahdin average intake was determined over a period of 42 consecutive days and used to calculate individual RFI within the test population. Observable ranges of RFI (-0.53 – +0.50) were seen in the Katahdin lambs as well. In both feeding trials RFI appeared to be normally distributed. Use of this technology may be useful in identifying superior individuals for feed efficiency.