Fetal Programming Influence on Microbiome Diversity and Ruminal and Cecal Epithelium in Beef Cattle.

We explored the influence of maternal nutritional strategies on the development of the rumen and cecum in offspring. Additionally, we investigated the potential repercussions of prenatal nutrition on the rumen and fecal microbiota composition, utilizing metagenomic 16S techniques, to understand the effects of fetal programming (FP) in Nellore cattle. A total of 63 bulls submitted to different prenatal nutrition strategies, namely, non-programming (NP), partial programming (PP), and complete programming (CP), were evaluated. The rumen epithelium was methodically evaluated based on the presence of rumenitis and structural irregularities. The assessment of cecum lesions was conducted post-evisceration, whereby all thoroughly cleaned ceca were methodically evaluated. Samples from 15 animals of rumen fluid at slaughter and feces during the finishing phase were collected, respectively. All DNA extraction were carried out using the Macherey Nagel NucleoSpin Tissue®, and 16S sequencing was conducted using the V4 primers on the MiSeq platform. Within the ruminal ecosystem, an estimated range of 90 to 130 distinct amplicon sequence variants was discerned, as distributed across 45,000 to 70,000 sequencing reads. Our metagenomic exploration unveils microbial communities that distinctly mirror gastrointestinal tract microenvironments and dietary influences. In sum, this comprehensive study advances our comprehension of FP, highlighting the interplay of maternal nutrition, gastrointestinal development, and microbial communities, contributing significantly to the fields of animal science.

Effects of early weaning on the reproductive performance of suckled Nelore cows in the subsequent breeding season.

This study aimed to evaluate the effects of early weaning (EW) on body composition, hormone concentrations and metabolites, and reproductive performance of Nelore cows in the subsequent breeding season (BS). Suckled cows that became pregnant by timed-AI (TAI) in the 2020-BS were exposed in 2021 to early weaning at 150 d (27 primiparous [PRI] and 74 multiparous [MUL]) or conventional weaning (CW) at 240 d postpartum (30 PRI and 77 MUL). Body weight (BW) and body condition score (BCS) were determined at 2020-BS, EW, CW, prepartum, and 2021-BS. Blood samples were collected at EW, CW, prepartum (54.75 ±â€…0.56 d prepartum), and 2021-TAI and assayed for insulin-like growth factor-1 (IGF-I), non-esterified fatty acid (NEFA), and ß-hydroxybutyrate (BHB) concentrations. In 2021-BS, cows were exposed to a P4/E2-based protocol for TAI at day 0 (D0), and a second TAI was performed at D22 in females detected with luteolysis (D20) by Doppler ultrasound. The presence of corpus luteum (CL) on D10, estrous expression, and dominant follicle (DF) diameter, and blood perfusion (BP) on D2 and D0 were determined. Data were analyzed by ANOVA or logistic regression of SAS as a 2 × 2 factorial with main factors of parity (PRI or MUL) and weaning strategy (EW or CW). An interaction of parity and weaning strategy was not observed (P > 0.1), but the weight (kg) and BCS were greater (P < 0.05) in MUL cows at the five timepoints, and EW cows were heavier than CW at the moment of CW (541 vs. 493 kg; and 5.3 vs. 4.3), prepartum (551 vs. 506 kg; and 5.2 vs. 4.4) and 2021-BS (475 vs. 450 kg; and 4.5 vs. 3.7). Plasma urea concentration at 2021-BS was greater (P = 0.01) for PRI than for MUL. A parity-by-time interaction was observed (P ≤ 0.05) for concentrations of IGF-I, NEFA, and BHB. PRI cows had greater (P ≤ 0.05) concentrations of IGF-I at EW and greater (P ≤ 0.05) prepartum concentrations of NEFA and BHB than MUL cows. The proportion of cows with CL at D10 was not affected (P > 0.1) by weaning but was greater (P < 0.05) in MUL than in PRI cows (40.4 vs. 15.7%). The diameter of DF and proportion of BP on D0 were greater (P < 0.05) in EW cows than in CW cows. The pregnancy rate (P/AI, %) at the first TAI was greater (P < 0.05) in EW cows (60% vs. 45%), whereas no difference (P > 0.1) was observed at the second TAI. Cumulative P/AI (first and second TAIs) was greater (P < 0.05) in EW cows (81% vs. 63%). In conclusion, weaning at 150 d in Nelore cattle is a strategy to successfully recover the parous cow's body condition and to improve pregnancy success in the next BS, regardless of the cow's parity order.

The nutritional condition and body energy reserves at parturition are important factors that can affect the reproductive performance of suckled Nelore cows. Also, decreasing the weaning time can benefit the cow's metabolic status. The present study evaluated the effect of two periods of weaning (150 vs. 240 d) on the reproductive performance of the Nelore dam in the subsequent breeding season. The results of the present study indicate that early weaning: 1) improves the body condition, rump fat thickness, and metabolic condition of Nelore cows for the subsequent breeding season; 2) provides better ovarian follicle growth and blood perfusion during the subsequent timed artificial insemination program; 3) enhances the pregnancy rates in the subsequent breeding season.

Evaluation of Maternal Nutrition Effects in the Lifelong Performance of Male Beef Cattle Offspring.

This study aimed to evaluate the effects of different prenatal nutrition treatments on pregnant cows and their progeny. One hundred and twenty-six pregnant Nellore cows (455.3 ± 8.1 kg) were allocated in three different nutritional treatments during pregnancy: NP-control, PP-protein-energy supplementation in the last 3 months of pregnancy, and FP-the same supplementation throughout pregnancy. After parturition, all cows and calves received the same environmental and nutrition condition. The body condition score (BCS), body weight (BW), ribeye area (REA), backfat thickness (BFT), and rumpfat thickness (RFT) were collected on four occasions during pregnancy in the cows and from birth to finishing in calves. All data (cows and calves) were submitted to an analysis of variance (p < 0.05) using a linear model (MIXED procedure; SAS software). The BW, RFT, and BCS from the cows showed significant differences in the middle third of pregnancy and pre-delivery and RFT postpartum (p < 0.05). For the offspring, the weaning weight showed a tendency (NP lighter than others). In terms of gain, the PP group tended to be higher in RFT at calving (p = 0.06), in REA at finishing (p = 0.09), and in ADG in the same period (p = 0.09). The prenatal nutrition strategies had little or no effect on the beef cattle postnatal performance.

Impacts of Different Prenatal Supplementation Strategies on the Plasma Metabolome of Bulls in the Rearing and Finishing Phase.

This study investigated the effects of maternal nutrition on the plasma metabolome of Nellore bulls in the rearing and finishing phases, and metabolic differences between these phases. For this study, three nutritional approaches were used in 126 cows during pregnancy: NP-(control) mineral supplementation; PP-protein-energy supplementation in the final third; and FP-protein-energy supplementation during the entire pregnancy. We collected blood samples from male offspring in the rearing (450 ± 28 days old) and finishing phases (660 ± 28 days old). The blood was processed, and from plasma samples, we performed the targeted metabolome analysis (AbsoluteIDQ® p180 Kit). Multiple linear regression, principal component analysis (PCA), repeated measures analysis over time, and an enrichment analysis were performed. PCA showed an overlap of treatments and time clusters in the analyses. We identified significant metabolites among the treatments (rearing phase = six metabolites; finishing phase = three metabolites) and over time (21 metabolites). No significant metabolic pathways were found in the finishing phase, however, we found significant pathways in the rearing phase (Arginine biosynthesis and Histidine metabolism). Thus, prenatal nutrition impacted on plasma metabolome of bulls during the rearing and finishing phase and the different production stages showed an effect on the metabolic levels of bulls.

Metabolomics Changes in Meat and Subcutaneous Fat of Male Cattle Submitted to Fetal Programming.

This study investigated changes in meat and subcutaneous fat metabolomes and possible metabolic pathways related to prenatal nutrition in beef cattle. For this purpose, 18 Nellore bulls were used for meat sampling and 15 for fat sampling. The nutritional treatments during the gestation were: NP-not programmed or control, without protein-energy supplementation; PP-partially programmed, with protein-energy supplementation (0.3% of body weight (BW)) only in the final third of pregnancy; and FP-full programming, with protein-energy supplementation (0.3% of BW) during the entire pregnancy. The meat and fat samples were collected individually 24 h after slaughter, and the metabolites were extracted using a combination of chemical reagents and mechanical processes and subsequently quantified using liquid chromatography or flow injection coupled to mass spectrometry. The data obtained were submitted to principal component analysis (PCA), analysis of variance (ANOVA), and functional enrichment analysis, with a significance level of 5%. The PCA showed an overlap between the treatments for both meat and fat. In meat, 25 metabolites were statistically different between treatments (p ≤ 0.05), belonging to four classes (glycerophospholipids, amino acids, sphingolipids, and biogenic amine). In fat, 10 significant metabolites (p ≤ 0.05) were obtained in two classes (phosphatidylcholine and lysophosphatidylcholine). The functional enrichment analysis showed alterations in the aminoacyl-tRNA pathway in meat (p = 0.030); however, there was no pathway enriched for fat. Fetal programming influenced the meat and fat metabolomes and the aminoacyl-tRNA metabolic pathway, which is an important candidate for the biological process linked to meat quality and related to fetal programming in beef cattle.

Maternal Nutrition Affects Nitrogen Isotopic Signature in Blood Plasma of Beef Cattle Dams and Their Offspring.

This study evaluated the effects of gestational supplementation strategy on nitrogen isotopic signature in blood plasma of beef cows and their progeny. The study comprised 15 pregnant Nellore cows divided into three different supplementation protocols: NP) non-programmed group; PP) cows receiving protein−energy supplement in the last third of pregnancy; and FP) cows receiving protein−energy supplement throughout the gestational period. Blood plasma from cows was sampled at the beginning of gestation, in the prepartum, and postpartum periods as well as from their calves at 30 and 180 days of age, for the analysis of stable isotope ratios 15 N/14 N. At pre- and postpartum periods, cows fed PP and FP presented greater abundance of δ15 N compared to NP (p < 0.05) at pre- and postpartum. All three groups showed significant differences (p < 0.05) in the postpartum period. The δ15 N values of calves at 30 days of age differed between the NP group and PP and FP groups (p < 0.05), with no difference (p > 0.05) at 180 days of age. The different gestational supplementation strategies influenced isotopic fractionation of nutrients of cows and their calves after birth, indicating effects on nutritional metabolism and cumulative behavior on isotope abundance related to consumption during gestation.

Identification of eQTLs and differential gene expression associated with fetal programming in beef cattle.

This study assessed differential gene expression and identified expression quantitative trait loci (eQTLs) from samples of Longissimus lumborum muscle from bulls at 15 months of age submitted to different prenatal nutrition. Upon confirmation of pregnancy, 126 dams were separated into three diet treatments varying the period of inclusion of energy protein supplementation (NP, PP, and FP). At calving, 63 males were genotyped with GGP LD BeadChip. The skeletal muscle of 15 bulls was sequenced (RNA-seq) at 15 months of age. The EdgeR package was used for differential gene expression and principal component analysis (PCA), and the Matrix eQTL package was used for the eQTLs analysis (R statistical). The functional enrichment analysis was performed using the MetaCore® software. No genes differentially expressed were found between treatments (FDR > 0.05); nevertheless, we found 179 cis-tag-eQTLs and 20,762 trans-tag-eQTLs (FDR < 0.05) after linkage disequilibrium analysis. The functional enrichment analysis identified terms from gene ontology related to genes associated to trans-eQTLs (FDR < 0.05) as well as metabolic pathways (> gScore). Most biological pathways and genes found had been previously associated to fetal programming. The different prenatal supplementation strategies did not impact on muscle transcriptome of bulls. Additionally, there is a link between genotype and gene expression levels related to developmental traits in Nellore cattle.

Effects of Different Prenatal Nutrition Strategies on the Liver Metabolome of Bulls and Its Correlation with Body and Liver Weight.

This study investigated the effect of prenatal nutrition on liver metabolome and on body (BW) and liver weight (LW) of Nellore bulls at slaughter. Three treatments were applied in 126 cows during pregnancy: NP­control (mineral supplementation); PP­protein-energy supplementation in the third trimester; and FP­protein-energy supplementation during the entire pregnancy. Offspring BW and LW were evaluated, and a targeted metabolomics analysis was performed on their livers (n = 18, 22.5 ± 1 months of age). Data were submitted to principal component analysis (PCA), analysis of variance (ANOVA), enrichment analysis, and Pearson's correlation analysis. The phenotypes did not show differences between treatments (p > 0.05). Metabolites PCA showed an overlap of treatment clusters in the analysis. We found significant metabolites in ANOVA (p ≤ 0.05; Glycine, Hydroxytetradecadienylcarnitine, Aminoadipic acid and Carnosine). Enrichment analysis revealed some biological processes (Histidine metabolism, beta-Alanine metabolism, and Lysine degradation). Pearson's correlation analysis showed 29 significant correlated metabolites with BW and 1 metabolite correlated with LW. In summary, prenatal nutrition did not show effects on the phenotypes evaluated, but affected some metabolites and biological pathways, mainly related to oxidative metabolism. In addition, BW seems to influence the hepatic metabolome more than LW, due to the amount and magnitude of correlations found.

Prenatal Supplementation in Beef Cattle and Its Effects on Plasma Metabolome of Dams and Calves.

This study investigated the effect of different prenatal nutrition on the plasma metabolome of Nellore dams and their offspring. For that purpose, three nutritional treatments were used in 126 cows during pregnancy: NP­(control) only mineral supplementation; PP­protein-energy supplementation in the final third; and FP­protein-energy supplementation during the entire pregnancy. Targeted metabolomics were analyzed in plasma at the beginning of pregnancy and in pre-delivery of cows (n = 27) as well as in calves (n = 27, 30 ± 9.6 days of age). Data were analyzed by the analysis of variance, partial least squares discriminant analysis, and the principal component analysis (PCA). The PCA showed a clear clustering in the periods investigated only in cows (early gestation and pre-delivery). We found significant metabolites in both supervised analyses (p < 0.05 and VIP score > 1) for cows (Taurine, Glutamic acid, Histidine, and PC aa C42:2) and for calves (Carnosine, Alanine, and PC aa C26:0). The enrichment analysis revealed biological processes (p < 0.1) common among cows and calves (histidine metabolism and beta-alanine metabolism), which may be indicative of transgenerational epigenetic changes. In general, fetal programming affected mainly the metabolism of amino acids.

Effects of Maternal Nutrition on Female Offspring Weight Gain and Sexual Development.

Maternal nutrition during pregnancy influences postnatal life of animals; nevertheless, few studies have investigated its effects on the productive performance and reproductive development of heifers. This study evaluated the performance, reproductive development, and correlation between reproduction × fat thickness and performance × ribeye area (REA) traits of heifers. We also performed an exploratory genomic association during the rearing period in heifers submitted to fetal programming. The study comprised 55 Nellore heifers born to dams exposed to one of the following nutritional planes: control, without protein-energy supplementation; PELT, protein-energy last trimester, protein-energy supplementation offered in the final third of pregnancy; and PEWG, protein-energy whole gestation, protein-energy supplementation upon pregnancy confirmation. Protein-energy supplementation occurred at the level of 0.3% live weight. After weaning, heifers were submitted to periodic evaluations of weight and body composition by ultrasonography. From 12 to 18 months, we evaluated the reproductive tract of heifers to monitor its development for sexual precocity and ovarian follicle population. The treatments had no effect (p > 0.05) on average daily gain; however, the weight of the animals showed a significant difference over time (p = 0.017). No differences were found between treatments for REA, backfat, and rump fat thickness, nor for puberty age, antral follicular count, and other traits related to reproductive tract development (p > 0.05). The correlation analysis between performance traits and REA showed high correlations (r > 0.37) between REA at weaning and year versus weight from weaning until yearling; however, no correlation was found for reproductive development traits versus fat thickness (p > 0.05). The exploratory genomic association study showed one single-nucleotide polymorphism (SNP) for each treatment on an intergenic region for control and PEWG, and the one for PELT on an intronic region of RAPGEF1 gene. Maternal nutrition affected only the weight of the animals throughout the rearing period.

Carcass characteristics and non-carcass components of young ½ Purunã x ½ Canchim bulls fed rations with three concentrate contents / Características de carcaça e componentes não-carcaça de tourinhos ½ Purunã x ½ Canchim alimentados com rações contendo três teores de concentrado

Improving the quality and energy content of rations increases performance in feedlot cattle, resulting in higher weight at slaughter, better carcass quality and a higher yield of non-carcass components. The purpose of this study was to evaluate the effect of increasing concentrate content in the ration on the carcass traits and weight of non-carcass components of young bulls finished in a feedlot. Eighteen young crossbred ½ Purunã x ½ Canchim bulls were used, with an average body weight (BW) of 278 kg and 12 months of age at the start of the experiment. The experimental design was completely randomized with three treatments and six replicates, where the treatments were the contents of 0.71, 0.97 and 1.24% BW day-1 of concentrate in the ration, on a dry matter (DM) basis. Corn silage was used as roughage and was provided ad libitum during the experiment. The young bulls were kept in the feedlot for 168 days and slaughtered at 17 months of age. There was a linear effect of concentrate content on the slaughter weight (SW) and hot carcass weight (HCW), which increased from 433 to 485 kg and from 248 to 280 kg between 0.71 and 1.24% BW in DM day-1 of concentrate. This represented an increase of 9.87 kg in SW and 6.16 kg in HCW for each 0.10% BW in DM day-1 of concentrate added to the ration. The hot carcass yield, rib eye area, subcutaneous fat thickness and the proportions of bone, muscle and fat in the carcass were not affected by the concentrate content and showed mean values of 57.3%, 79.6 cm2, 3.20 mm, 14.88%, 65.21% and 20.67%, respectively. There was a linear effect of concentrate content on the carcass temperature after cooling, which increased from 8.1 to 9.0 oC between 0.71 and 1.24% BW in DM day-1 of concentrate. An increase of 0.16 oC in the post-cooling carcass temperature for each 0.10% BW in DM day-1 of concentrate added to the ration was observed.(AU)

A melhoria da qualidade e do aporte energético da ração proporciona alto desempenho aos bovinos confinados, resultando em elevado peso ao abate, melhor qualidade da carcaça e alto rendimento dos componentes não-carcaça. Objetivou-se com este estudo avaliar a influência do aumento do teor de concentrado da ração nas características de carcaça e no peso de componentes não-carcaça de tourinhos terminados em confinamento. Foram utilizados 18 tourinhos mestiços ½ Purunã x ½ Canchim, que iniciaram o experimento com 278 kg de peso corporal (PC) e 12 meses de idade, em média. O delineamento experimental foi inteiramente casualizado com três tratamentos e seis repetições, em que os tratamentos foram os teores de 0,71; 0,97 e 1,24% PC dia-1 de concentrado na ração, em base de matéria seca (MS). A silagem de milho foi utilizada como volumoso e fornecida à vontade durante o experimento. Os animais permaneceram confinados por 168 dias e foram abatidos com 17 meses de idade. Houve efeito linear dos teores de concentrado no peso ao abate (PA) e no peso de carcaça quente (PCQ), que aumentaram de 433 para 485 kg, e de 248 para 280 kg entre os teores de 0,71 e 1,24% PC em MS dia-1 de concentrado. Isso correspondeu ao aumento de 9,87 kg no PA e de 6,16 kg no PCQ dos tourinhos a cada 0,10% PC em MS dia-1 de concentrado adicionado à ração. O rendimento de carcaça quente, a área de olho de lombo, a espessura de gordura subcutânea e as proporções de osso, músculo e gordura da carcaça não foram influenciados pelos teores de concentrado, apresentando valores médios de 57,3%, 79,6 cm2, 3,20 mm, 14,88%, 65,21% e 20,67%, respectivamente. Houve efeito linear dos teores de concentrado na temperatura da carcaça após o resfriamento, que aumentou de 8,1 para 9,0 ºC entre os teores de 0,71 e 1,24% PC em MS dia-1 de concentrado.(AU)

Carcass characteristics and non-carcass components of young ½ Purunã x ½ Canchim bulls fed rations with three concentrate contents / Características de carcaça e componentes não-carcaça de tourinhos ½ Purunã x ½ Canchim alimentados com rações contendo três teores de concentrado

Improving the quality and energy content of rations increases performance in feedlot cattle, resulting in higher weight at slaughter, better carcass quality and a higher yield of non-carcass components. The purpose of this study was to evaluate the effect of increasing concentrate content in the ration on the carcass traits and weight of non-carcass components of young bulls finished in a feedlot. Eighteen young crossbred ½ Purunã x ½ Canchim bulls were used, with an average body weight (BW) of 278 kg and 12 months of age at the start of the experiment. The experimental design was completely randomized with three treatments and six replicates, where the treatments were the contents of 0.71, 0.97 and 1.24% BW day-1 of concentrate in the ration, on a dry matter (DM) basis. Corn silage was used as roughage and was provided ad libitum during the experiment. The young bulls were kept in the feedlot for 168 days and slaughtered at 17 months of age. There was a linear effect of concentrate content on the slaughter weight (SW) and hot carcass weight (HCW), which increased from 433 to 485 kg and from 248 to 280 kg between 0.71 and 1.24% BW in DM day-1 of concentrate. This represented an increase of 9.87 kg in SW and 6.16 kg in HCW for each 0.10% BW in DM day-1 of concentrate added to the ration. The hot carcass yield, rib eye area, subcutaneous fat thickness and the proportions of bone, muscle and fat in the carcass were not affected by the concentrate content and showed mean values of 57.3%, 79.6 cm2, 3.20 mm, 14.88%, 65.21% and 20.67%, respectively. There was a linear effect of concentrate content on the carcass temperature after cooling, which increased from 8.1 to 9.0 oC between 0.71 and 1.24% BW in DM day-1 of concentrate. An increase of 0.16 oC in the post-cooling carcass temperature for each 0.10% BW in DM day-1 of concentrate added to the ration was observed.

A melhoria da qualidade e do aporte energético da ração proporciona alto desempenho aos bovinos confinados, resultando em elevado peso ao abate, melhor qualidade da carcaça e alto rendimento dos componentes não-carcaça. Objetivou-se com este estudo avaliar a influência do aumento do teor de concentrado da ração nas características de carcaça e no peso de componentes não-carcaça de tourinhos terminados em confinamento. Foram utilizados 18 tourinhos mestiços ½ Purunã x ½ Canchim, que iniciaram o experimento com 278 kg de peso corporal (PC) e 12 meses de idade, em média. O delineamento experimental foi inteiramente casualizado com três tratamentos e seis repetições, em que os tratamentos foram os teores de 0,71; 0,97 e 1,24% PC dia-1 de concentrado na ração, em base de matéria seca (MS). A silagem de milho foi utilizada como volumoso e fornecida à vontade durante o experimento. Os animais permaneceram confinados por 168 dias e foram abatidos com 17 meses de idade. Houve efeito linear dos teores de concentrado no peso ao abate (PA) e no peso de carcaça quente (PCQ), que aumentaram de 433 para 485 kg, e de 248 para 280 kg entre os teores de 0,71 e 1,24% PC em MS dia-1 de concentrado. Isso correspondeu ao aumento de 9,87 kg no PA e de 6,16 kg no PCQ dos tourinhos a cada 0,10% PC em MS dia-1 de concentrado adicionado à ração. O rendimento de carcaça quente, a área de olho de lombo, a espessura de gordura subcutânea e as proporções de osso, músculo e gordura da carcaça não foram influenciados pelos teores de concentrado, apresentando valores médios de 57,3%, 79,6 cm2, 3,20 mm, 14,88%, 65,21% e 20,67%, respectivamente. Houve efeito linear dos teores de concentrado na temperatura da carcaça após o resfriamento, que aumentou de 8,1 para 9,0 ºC entre os teores de 0,71 e 1,24% PC em MS dia-1 de concentrado.

Effects of fibre digestibility and level of roughage on performance and rumen fermentation of finishing beef cattle.

The objective was to evaluate effects of neutral detergent fibre (NDF) digestibility and level of fresh sugarcane on intake, body fatness, carcass characteristics, and rumen kinetics and fermentation of beef cattle. Forty-eight Nellore young bulls were used in a complete randomized block design with a 2 × 2 factorial arrangement of treatments. Eight rumen-cannulated Nellore steers were used in a replicated 4 × 4 Latin square design. Two sugarcane genotypes divergent for stalk NDF digestibility (NDFD) were used. Experimental diets were formulated with 20 or 40% of sugarcane on a dry matter (DM) basis. High-NDFD genotype associated with the lower level of roughage in the diet promoted greater DM intake, resulting in greater body gain. Sugarcane with high-NDFD increased final body weight, hot carcass weight, and back-fat thickness. Animals receiving the genotype with high NDFD had greater rump-fat thickness only with 40% sugarcane in the diet. Animals receiving the low-NDFD genotype at 20% of the diet had lower NDF passage rate. Rumen pH was greater for diets with greater NDF content. There was greater proportion of butyrate in the rumen of animals receiving diets with greater NDF content. In conclusion, high-NDFD sugarcane increased final body and carcass weight, HCW, and fat thickness. When associated with lower inclusion of roughage in the diet, it can also increase DM intake and body weight gain of beef cattle.

Using a system of differential equations that models cattle growth to uncover the genetic basis of complex traits.

The interplay between dynamic models of biological systems and genomics is based on the assumption that genetic variation of the complex trait (i.e., outcome of model behavior) arises from component traits (i.e., model parameters) in lower hierarchical levels. In order to provide a proof of concept of this statement for a cattle growth model, we ask whether model parameters map genomic regions that harbor quantitative trait loci (QTLs) already described for the complex trait. We conducted a genome-wide association study (GWAS) with a Bayesian hierarchical LASSO method in two parameters of the Davis Growth Model, a system of three ordinary differential equations describing DNA accretion, protein synthesis and degradation, and fat synthesis. Phenotypic and genotypic data were available for 893 Nellore (Bos indicus) cattle. Computed values for parameter k1 (DNA accretion rate) ranged from 0.005 ± 0.003 and for α (constant for energy for maintenance requirement) 0.134 ± 0.024. The expected biological interpretation of the parameters is confirmed by QTLs mapped for k1 and α. QTLs within genomic regions mapped for k1 are expected to be correlated with the DNA pool: body size and weight. Single nucleotide polymorphisms (SNPs) which were significant for α mapped QTLs that had already been associated with residual feed intake, feed conversion ratio, average daily gain (ADG), body weight, and also dry matter intake. SNPs identified for k1 were able to additionally explain 2.2% of the phenotypic variability of the complex ADG, even when SNPs for k1 did not match the genomic regions associated with ADG. Although improvements are needed, our findings suggest that genomic analysis on component traits may help to uncover the genetic basis of more complex traits, particularly when lower biological hierarchies are mechanistically described by mathematical simulation models.

Estudo genético e genômico da ingestão e eficiência alimentar em bovinos da raça Nelore (Bos indicus) / Genetic and genomic study of intake and feed efficiency in Nellore (Bos indicus) cattle

O objetivo dessa pesquisa foi avaliar os parâmetros genéticos e correlações das medidas de ingestão e eficiência alimentar com desempenho e características de carcaça, além de realizar o estudo de associação de amplo genoma (GWAS) para ingestão de matéria seca (IMS), consumo alimentar residual (CAR) e ganho de peso (GMD) em bovinos da raça Nelore (Bos indicus). Foram utilizados dados de 1.058 animais com fenótipo para IMS, taxa de conversão alimentar (CA), CAR, ganho de peso residual (GPR), consumo e ganho residuais (CGR), ganho de peso diário (GMD) e características de carcaça. Os parâmetros genéticos da IMS, CA, CAR, GPR e CGR e suas as correlações com GMD e características de carcaça foram estimados utilizando abordagem bayesiana. Quatro marcadores do tipo SNP (Single Nucleotide Polymorphism), localizados em genes relacionados ao controle de apetite (NPY e PDE3B) e transporte iônico (TRPM3 e ITPR1), foram associados com o desempenho, ingestão e medidas de eficiência alimentar. Adicionalmente, os animais foram genotipados em dois chips distintos (Illumina Bovine HD e Illumina BovineSNP50) e as informações genotípicas foram combinadas por meio de estudo de imputação. As centenas de milhares de SNPs foram utilizadas para o GWAS da IMS, CAR e GMD pelo teste de associação GRAMMAR-Gamma. A herdabilidade da IMS, CAR e CGR foi de 0,40, 0,38 e 0,54, respectivamente. Não foram encontradas associações nos SNPs localizados nos genes TRPM3, NPY e ITPR1, no entanto, o SNP no gene PDE3B foi associados significativamente (P≤0,05) com IMS, CAR e CGR. Os SNPs mais associados com a IMS e CAR, no GWAS, estão localizados nos cromossomos 4, 8, 14 e 21 em regiões genômicas relacionadas com transporte iônico e regulação da ingestão. O GWAS para o GMD apontou os cromossomos 3, 6 e 10 como os que continham os marcadores com maior associação. A ingestão e eficiência alimentar são passíveis de seleção genética, principalmente o CGR. O gene PDE3B deve ser melhor estudado pois, aparenta ter relação com esses fenótipos. Por fim, esse trabalho apontou regiões genômicas, por meio de associação de amplo genoma, relacionadas com a IMS, CAR e GMD, acredita-se ser o primeiro estudo desse tipo para esses fenótipos em animais da raça Nelore.

The aim of this study was to evaluate the genetic parameters and correlations of intake and feed efficiency with performance and carcass traits, and perform the genome-wide association study (GWAS) for dry matter intake (DMI), residual feed intake (RFI) and average daily gain (ADG) in Nelore cattle (Bos indicus). Data from 1,058 animals phenotyped for DMI, feed conversion ratio (FCR), RFI, residual body weight gain (RG), residual intake and body weight gain (RIG), average daily gain (ADG) and carcass traits were used. Genetic parameters of DMI, FCR, RFI, RG and RIG and their correlations with ADG and carcass traits were estimated using Bayesian approach. Four SNPs (Single Nucleotide Polymorphism), located in genes related to appetite control (NPY and PDE3B) and ion transport (TRPM3 and ITPR1), were associated with performance, intake and feed efficiency traits. Additionally, the animals were genotyped in two different chips (Illumina Bovine HD and Illumina BovineSNP50) and genotypic information were combined by imputation. The hundreds of thousands of SNPs were used for GWAS of DMI, RFI and ADG by GRAMMAR-Gamma association test. The heritability of DMI, RFI and RIG was 0.40, 0.38 and 0.54, respectively. No associations were found in SNPs in genes TRPM3, NPY and ITPR1, however, the SNP in PDE3B gene was significantly associated (P≤0.05) with DMI, RFI and RIG. The SNPs most associated with DMI and RFI, in GWAS, are located on chromosomes 4, 8, 14 and 21 in genomic regions associated with ion transport and appetite regulation. The GWAS pointed chromosomes 3, 6 and 10 as those containing more associated markers for ADG. Feed intake and feed efficiency are amenable to genetic selection, especially the RIG. The PDE3B gene should be further studied thus appears to be related to these phenotypes. Finally, this work shows genomic regions by genome-wide association, related to DMI, RFI and ADG, believed to be the first study of its kind for these phenotypes in Nellore cattle.

Blood cell and metabolic profile of Nellore bulls and their correlations with residual feed intake and feed conversion ratio / Perfis sanguíneo e metabólico de touros Nelore e suas correlações com consumo alimentar residual e taxa de conversão alimentar

Due to the potential metabolic changes related to the residual feed intake (RFI), this study investigated the correlation of traditional RFI (RFI1), RFI adjusted for final rump fat thickness (RFI2) and feed conversion ratio (FCR) with the metabolic and blood profiles, as well as determined the possible different classes of RFI1 and RFI2. For this purpose, 46 Nellore bulls, 22 month-old and 411kg of weight at the beginning of the study were used. The animals were fed with the same diet for 84 days, and blood samples were collected every 21 days for evaluation of serum metabolites and blood cell profiles. No significant correlations were found between FCR and metabolic or blood traits, although there was a significant correlation between RFI1 and urea serum concentration. There were also differences between the RFI classes for creatinine, in which more efficient animals showed higher values. The RFI2 did not correlate with any metabolic and blood cell variable, but young bulls with smaller RFI2 had a smaller number of eosinophils when compared to animals with higher RFI2. These results suggest that animals with a high RFI can have greater energy expenditure due to protein synthesis and degradation process, resulting in a larger blood urea level.

Em função das diversas variações metabólicas relacionadas com o consumo alimentar residual (CAR), objetivou-se nesse estudo avaliar as correlações do CAR tradicional (CAR1), CAR ajustado para deposição de gordura subcutânea na garupa (CAR2) e da conversão alimentar (CA) com o perfil metabólico e sanguíneo, assim como verificar as possíveis diferenças das classes de CAR1 e CAR2. Para tanto, foram utilizados 46 touros da raça Nelore com 22 meses de idade e 411kg no início do estudo. Os animais foram alimentados com a mesma dieta durante 84 dias, nesse período foram coletadas a cada 21 dias amostras de sangue para avaliação de metabólitos no soro e do perfil celular no sangue. Não foram encontradas correlações significativas da CA com nenhuma característica metabólica ou sanguínea, já para o CAR1 foi encontrada correlação significativa para a concentração de ureia sérica, também houve diferença entre as classes com relação à creatinina, na qual animais mais eficientes apresentaram valores superiores para essa variável. O CAR2 não foi correlacionado com nenhuma variável metabólica e das células do sangue, porém animais de menor CAR2 tiveram menor quantidade de eosinófilos quando comparados com os animais de maior CAR2. Esses resultados sugerem que animais menos eficientes para CAR podem ter maior gasto energético com processos de síntese e degradação proteica corporal, devido à maior quantidade de ureia presente no sangue.

Blood cell and metabolic profile of Nellore bulls and their correlations with residual feed intake and feed conversion ratio / Perfis sanguíneo e metabólico de touros Nelore e suas correlações com consumo alimentar residual e taxa de conversão alimentar

Due to the potential metabolic changes related to the residual feed intake (RFI), this study investigated the correlation of traditional RFI (RFI1), RFI adjusted for final rump fat thickness (RFI2) and feed conversion ratio (FCR) with the metabolic and blood profiles, as well as determined the possible different classes of RFI1 and RFI2. For this purpose, 46 Nellore bulls, 22 month-old and 411kg of weight at the beginning of the study were used. The animals were fed with the same diet for 84 days, and blood samples were collected every 21 days for evaluation of serum metabolites and blood cell profiles. No significant correlations were found between FCR and metabolic or blood traits, although there was a significant correlation between RFI1 and urea serum concentration. There were also differences between the RFI classes for creatinine, in which more efficient animals showed higher values. The RFI2 did not correlate with any metabolic and blood cell variable, but young bulls with smaller RFI2 had a smaller number of eosinophils when compared to animals with higher RFI2. These results suggest that animals with a high RFI can have greater energy expenditure due to protein synthesis and degradation process, resulting in a larger blood urea level.(AU)

Em função das diversas variações metabólicas relacionadas com o consumo alimentar residual (CAR), objetivou-se nesse estudo avaliar as correlações do CAR tradicional (CAR1), CAR ajustado para deposição de gordura subcutânea na garupa (CAR2) e da conversão alimentar (CA) com o perfil metabólico e sanguíneo, assim como verificar as possíveis diferenças das classes de CAR1 e CAR2. Para tanto, foram utilizados 46 touros da raça Nelore com 22 meses de idade e 411kg no início do estudo. Os animais foram alimentados com a mesma dieta durante 84 dias, nesse período foram coletadas a cada 21 dias amostras de sangue para avaliação de metabólitos no soro e do perfil celular no sangue. Não foram encontradas correlações significativas da CA com nenhuma característica metabólica ou sanguínea, já para o CAR1 foi encontrada correlação significativa para a concentração de ureia sérica, também houve diferença entre as classes com relação à creatinina, na qual animais mais eficientes apresentaram valores superiores para essa variável. O CAR2 não foi correlacionado com nenhuma variável metabólica e das células do sangue, porém animais de menor CAR2 tiveram menor quantidade de eosinófilos quando comparados com os animais de maior CAR2. Esses resultados sugerem que animais menos eficientes para CAR podem ter maior gasto energético com processos de síntese e degradação proteica corporal, devido à maior quantidade de ureia presente no sangue.(AU)