Post-weaning Weight Gain Research Articles

Genome-wide association study considering genotype-by-environment interaction for productive and reproductive traits using whole-genome sequencing in Nellore cattle

BackgroundThe genotype-by-environment interaction (GxE) in beef cattle can be investigated using reaction norm models to assess environmental sensitivity and, combined with genome-wide association studies (GWAS), to map genomic regions related to animal adaptation. Including genetic markers from whole-genome sequencing in reaction norm (RN) models allows us to identify high-resolution candidate genes across environmental gradients through GWAS. Hence, we performed a GWAS via the RN approach using whole-genome sequencing data, focusing on mapping candidate genes associated with the expression of reproductive and growth traits in Nellore cattle. For this purpose, we used phenotypic data for age at first calving (AFC), scrotal circumference (SC), post-weaning weight gain (PWG), and yearling weight (YW). A total of 20,000 males and 7,159 females genotyped with 770k were imputed to the whole sequence (29 M). After quality control and linkage disequilibrium (LD) pruning, there remained ∼ 2.41 M SNPs for SC, PWG, and YW and ∼ 5.06 M SNPs for AFC.ResultsSignificant SNPs were identified on Bos taurus autosomes (BTA) 10, 11, 14, 18, 19, 20, 21, 24, 25 and 27 for AFC and on BTA 4, 5 and 8 for SC. For growth traits, significant SNP markers were identified on BTA 3, 5 and 20 for YW and PWG. A total of 56 positional candidate genes were identified for AFC, 9 for SC, 3 for PWG, and 24 for YW. The significant SNPs detected for the reaction norm coefficients in Nellore cattle were found to be associated with growth, adaptative, and reproductive traits. These candidate genes are involved in biological mechanisms related to lipid metabolism, immune response, mitogen-activated protein kinase (MAPK) signaling pathway, and energy and phosphate metabolism.ConclusionsGWAS results highlighted differences in the physiological processes linked to lipid metabolism, immune response, MAPK signaling pathway, and energy and phosphate metabolism, providing insights into how different environmental conditions interact with specific genes affecting animal adaptation, productivity, and reproductive performance. The shared genomic regions between the intercept and slope are directly implicated in the regulation of growth and reproductive traits in Nellore cattle raised under different environmental conditions.

Factors Affecting Post-Weaning Growth of Boer and Boer Cross Goats in a Closed Breeding Farm Population

This study aimed to analyze the factors affecting the post-weaning growth of Boer and Boer cross goats in a closed breeding farm population. A total of 1,083 female kids were selected from a record of 1,501 weaned kids produced by mating Boer bucks with Boer does, Jawarandu does, and Boer × Jawarandu does. The data collected at a private company's goat farm represent a closed breeding population from January 2013 to January 2016. The data were selected based on the weaning weight and at least one post-weaning weight at approximately 6, 9, or 12 months. Two-step linear models were applied: complete model and reduced model. The complete model factors included genetic group, buck, litter size, birth season, weaning season-year, and their interactions. The reduced model included only significant factors and two-way interactions. The results showed that the genetic group, bucks, litter size, birth season, and weaning season-year significantly affected Boer and Boer cross goats' post-weaning weight and average daily gain. Additionally, interactions between the genetic group with the buck, litter size, and birth season were observed. In conclusion, genetic and non-genetic factors significantly influence the post-weaning growth of Boer and Boer cross goats. Non-genetic factors should be considered in the model and selection to achieve optimal goat performance.

Breeding objectives for Central Highland goats using participatory and bio-economic modelling approaches.

The breeding objectives of Central Highland goats rearing under a low-input production system were defined through a participatory proportional piling method and bio-economic model. Additionally, the economic values and relative economic value of the breeding objective traits were derived. A participatory proportional piling method was used to estimate the relative weights of farmers attached to a list of goat traits identified, and the relative weights were statistically evaluated using a generalized multinomial logit model analysis. A bio-economic model was used to compute the economic values of the identified traits. The most important traits for selection of does according to farmer's preference were body size, coat colour, post-weaning growth rate and weaning rate with a relative weight (odds ratio) of 1.58, 1.38, 1.37 and 1.13, respectively. Goats with dark red followed by light red coat colour were the most preferred (p < 0.001) by goat keepers compared with white-coloured goats. Farmers were more likely (p < 0.001) to allocate higher scores for does-bearing twins than for single and triplet-bearing does. Using the bio-economic model (economic value and relative economic value), post-weaning growth rate, weaning rate, and six-month weight (body size) were identified as the most important traits and if the mean of these traits is changed by one genetic standard deviation, the change in profit will range from 2.06 to 3.03 $ doe-1 year-1 . Therefore, the most important traits for the selection of Central Highland goats according to the economic-based method were post-weaning weight gain, weaning rate and body size (six-month weight). Besides, coat colour was the second preferred trait by goat keepers next to body size. Thus, this aesthetical trait should be included in the designed breeding programme besides economically important quantitative traits. The combination of the participatory proportional piling method and bio-economic model would give better insights to explore the trait preferences of farmers and enhance profitability. The economic values of traits estimated in this study can be used for the construction of selection indices for Central Highland goats.

Evaluation of the productive performance of Colombian hair sheep based on growth traits

Contextualization: Colombian hair sheep [CHS] are animals of great importance, because their genetic material has been adapting for more than 500 years to the environment; besides, these animals have a transcendental role in Colombia for their contribution to food security and family economy. However, a great part of the sheep production in the country presents low production parameters. Knowledge gap: ignorance of Colombian hair sheep (CHS) biotypes’ productivity has led to the undervaluation of the genetic resource found in these animals, accompanied by insufficient efforts to improve sheep production systems. Purpose of the study: determine the productive performance of three biotypes of Colombian hair sheep. Methodology: this study was conducted in these biotypes of hair sheep: Ethiopian [CHSE] (40 individuals), Sudan [CHSS] (60) and Creole crossed with Pelibuey [CHSP] (60). Five growth traits [birth weight, adjusted weaning weight at 90 days, adjusted final weight at the age of 1 year, and pre-weaning and post-weaning weight gain] were evaluated. Descriptive statistical and variance analysis were performed based on variables such as sex, farm, type of birth, parent, and season of birth. Also, a Duncan's multiple range test was performed. Results and conclusions: CHSE showed low productive parameters that were mostly affected by the variables sex and farm [p ≤ 0.05]. CHSs displayed a low to moderate productive performance and many traits were also affected by sex and farm [p ≤ 0.05]. Lastly, CHSP showed moderate to high productive parameters, which were mainly affected by parent, season, and type of birth [p ≤ 0.05]. The results determined the productive performance of the three sheep biotypes, among which CHSE showed low growth parameters, CHSS showed low to moderate parameters, and CHSP displayed moderate to high parameters. In all cases, the three biotypes were mostly affected by non-genetic variables.

Genetic parameters for mouth size and their influence on growth traits in pasture-raised Nelore cattle.

Evaluating traits that allow breeders to increase production efficiency in beef production systems is important. The mouth size score is a trait easily measured and implemented by breeders. Bite size is related to mouth size in beef cattle and is a determinant of daily feed intake of pasture-raised animals, influencing their growth. The aim of this study was to estimate genetic parameters for mouth size (MS), weaning weight (WW) and postweaning weight gain (PWG) of Nelore cattle and to evaluate the influence of the interaction between MS and WW on PWG. Phenotypic records of 134,282 Nelore animals born between 1995 and 2019 were used. Variance components were estimated using multi-trait animal model with the Bayesian method. The model included the contemporary group as fixed effect, age at measurement of the trait as linear covariate, and direct additive genetic and residual effects as random effects. For WW, random maternal and maternal permanent environmental effects were added to the model. A Bayesian approach was used to analyze the interaction between WW clusters and MS. The heritability estimates were 0.24, 0.15 and 0.23 for MS, WW and PWG, respectively. The genetic correlation between variables studied ranged from 0.24 to 0.46. The results suggest that animals with a larger mouth tend to have greater PWG, demonstrating the positive influence of MS score on the postweaning performance of cattle. The direct heritability estimates confirm the possibility of selecting animals for the traits studied.

The Crowded Uterine Horn Mouse Model for Examining Postnatal Metabolic Consequences of Intrauterine Growth Restriction vs. Macrosomia in Siblings.

Differential placental blood flow and nutrient transport can lead to both intrauterine growth restriction (IUGR) and macrosomia. Both conditions can lead to adult obesity and other conditions clustered as metabolic syndrome. We previously showed that pregnant hemi-ovariectomized mice have a crowded uterine horn, resulting in siblings whose birth weights differ by over 100% due to differential blood flow based on uterine position. We used this crowded uterus model to compare IUGR and macrosomic male mice and also identified IUGR males with rapid (IUGR-R) and low (IUGR-L) postweaning weight gain. At week 12 IUGR-R males were heavier than IUGR-L males and did not differ from macrosomic males. Rapid growth in IUGR-R males led to glucose intolerance compared to IUGR-L males and down-regulation of adipocyte signaling pathways for fat digestion and absorption and type II diabetes. Macrosomia led to increased fat mass and altered adipocyte size distribution compared to IUGR males, and down-regulation of signaling pathways for carbohydrate and fat digestion and absorption relative to IUGR-R. Clustering analysis of gonadal fat transcriptomes indicated more similarities than differences between IUGR-R and macrosomic males compared to IUGR-L males. Our findings suggest two pathways to adult metabolic disease: macrosomia and IUGR with rapid postweaning growth rate.

Genotype-environment interaction effects on weight gain in cattle using reaction norms

The existence of genotype-environment interaction (GEI) using reaction norm models and their impact on the genetic evaluation of Nellore sires for body weight at 120, 210, 365 and 450 days of age was verified. Three models were used: animal model (AM) that disregards GEI and the one-step reaction norm model with homogeneous and heterogeneous residual variance (1SRNMH_het). Bayes Inference via Gibbs Sampling was used to estimate the variance components. The AM model better fits to weights at 120 and 210 days of age, while 1SRNMH_het was more adequate for body weights at 365 and 450 days of age, suggesting the existence of GEI. The posterior means of direct heritability were 0.33±0.01 and 0.36±0.01 and maternal heritability of 0.21±0.01 and 0.19±0.01 for body weights at 120 and 210 days of age, respectively. For body weights at 365 and 450 days of age, posterior means of heritability varied along the environmental gradient, but the ranking of sires based on breeding values was not changed by different environmental gradients. All rank correlations were greater than 0.80, strongly suggesting a scale effect of GEI. Despite the evidence of GEI on post-weaning weight gain, it did not change the ranking of sires. Therefore, it did not have a relevant impact on the genetic evaluation of sires because they are robust to environmental changes.

Comparison of methods for predicting genomic breeding values for growth traits in Nellore cattle

The objective of this study was to evaluate the accuracy of genomic predictions of growth traits in Nellore cattle. Data from 5064 animals belonging to farms that participate in the Conexão DeltaGen and PAINT breeding programs were used. Genotyping was performed with the Illumina BovineHD BeadChip (777,962 SNPs). After quality control of the genomic data, 412,993 SNPs were used. Deregressed EBVs (DEBVs) were calculated using the estimated breeding values (EBVs) and accuracies of birth weight (BW), weight gain from birth to weaning (GBW), postweaning weight gain (PWG), yearling height (YH), and cow weight (CW) provided by GenSys. Three models were used to estimate marker effects: genomic best linear unbiased prediction (GBLUP), BayesCπ, and improved Bayesian least absolute shrinkage and selection operator (IBLASSO). The prediction ability of genomic estimated breeding value (GEBVs) was estimated by the average Pearson correlation between DEBVs and GEBVs, predicted with the different methodologies in the validation populations. The regression coefficients of DEBVs on GEBVs in the validation population were calculated and used as indicators of prediction bias of GEBV. In general, the Bayesian methods provided slightly more accurate predictions of genomic breeding values than GBLUP. The BayesCπ and IBLASSO were similar for all traits (BW, GBW, PWG, and YH), except for CW. Thus, there does not seem to be a more suitable method for the estimation of SNP effects and genomic breeding values. Bayesian regression models are of interest for future applications of genomic selection in this population, but further improvements are needed to reduce deflation of their predictions.

Comparative Growth and Economic Performances between Indigenous Swamp and Murrah Crossbred Buffaloes in Malaysia.

Simple SummaryA buffalo breeding farm was selected to study the growth performance of Swamp and Murrah crossbred buffaloes. The farm was practicing extensive grazing system without supplementation since 2010 to 2011. In early 2012, the farm had implemented a new intervention to improve the growth performance via improving the feed and the feeding management. Farm records between 2010 to 2015 were analyzed for growth performance and partial budget analysis. So far, there is no comparative study done between Swamp and Murrah crossbred buffaloes in Malaysia. Therefore, in the present study, we aimed to study the differences in the biological and economical performances between Swamp and crossbred buffaloes in Malaysia. With a new intervention, a significant improvement was reported of the number of calves born, average birth weight, and reduced percentage of calf mortality rate, calving interval, and weaning age. Crossbred buffalo showed dominance in biological performance in terms of higher pre- and post-weaning daily weight gain and taking a shorter period to achieve market and breeding weight compared to Swamp buffaloes. Thus, reared Murrah crossbred buffaloes with new intervention management would give a farmer a higher profit return. However, with reared Swamp, the farmer potentially conserves the local indigenous breed of Swamp buffalo.This study was conducted to compare the growth and economic performances between Swamp and Murrah crossbred buffaloes. The records of 108 Swamp and 276 Murrah crossbred buffaloes born between January 2010 and December 2015 were used in this study. The farm was practicing an extensive grazing system without supplementation from January 2010 to December 2011 (pre-intervention) and a new implementation of supplement in the feeding regime from January 2012 to December 2015 (post-intervention). The birth, weaning, and body weight at three monthly intervals, number of calves born, and mortality rate of calves at different years and during pre- and post-intervention were analyzed using a general linear model procedure. The interventions in 2012 had a positive effect on increasing the number of calves born for both breeds, average birth weight, economic performance, and reduce mortality calf rate. As a result, the birth weight of Murrah crossbred buffaloes was higher (36.63 ± 0.50 kg) than Swamp buffaloes (34.69 ± 0.40 kg) (p < 0.05). The average pre-weaning daily weight gain for Swamp and Murrah crossbred buffaloes was 0.73 and 0.98 kg/day (p < 0.05), while the average post-weaning daily weight gain was 0.39 and 0.44 kg/day, respectively (p < 0.05). The Swamp and Murrah crossbred buffaloes achieved the targeted market weight of 250 kg at 18 and 15 months old, respectively, while the targeted breeding weight of 385 kg was achieved at 30 and 26 months old, respectively. In this farm, on average a total of 64 calves were born yearly, with the ratio number of born calves per number of mated dams recorded higher in Murrah crossbred buffaloes as compared to Swamp buffalo (0.64 vs. 0.37) (p < 0.05). Furthermore, the average number of calves born in the post-intervention period (January 2012–December 2015) was significantly higher than in the pre-intervention period (January 2010–December 2011), respectively (Swamp: 23 vs. 8 and Murrah crossbred: 53 vs. 31, respectively) (p < 0.05). Partial budget method was used to estimate the net gain or loss between the two breeds. The average annual revenue was 2304.14 MYR (566.13 USD) for Swamp buffaloes and 4531.50 MYR (1113.39 USD) for Murrah crossbred buffaloes. The average annual cost saving was 340.02 MYR (83.54 USD) for Swamp and 215.75 MYR (53.01 USD) for Murrah crossbred buffaloes. On the other hand, annual added cost was 84.95 MYR (20.87 USD) for Swamp and 96.76 MYR (23.77 USD) for Murrah crossbred buffaloes. Therefore, the annual net benefit was 2559.21 MYR (628.80 USD) for Swamp and 4650.49 MYR (1142.63 USD) for Murrah crossbred buffaloes. As a conclusion, this study had shown that the higher average daily weight gain contributes to better cost savings, as shown by the crossbred buffaloes.

Animals selected for postweaning weight gain rate have similar maintenance energy requirements regardless of their residual feed intake classification.

Data of comparative slaughter were used to determine Nellore bulls' net energy requirements classified as efficient or inefficient according to residual feed intake (RFI) and selection lines (SL). Sixty-seven Nellore bulls from the selected (SE) and control (CO) lines of the selection program for postweaning weight gain were used. The animals underwent digestibility trials before being submitted to the finishing trial. Sixteen bulls were slaughtered at the beginning of the finishing trial, and their body composition was used as the baseline for the remaining animals. For body composition determinations, whole empty body components were weighed, ground, and subsampled for chemical analyses. Initial body composition was determined with equations developed from the baseline group using shrunk body weight, fat, and protein. The low RFI (LRFI) and CO animals had a lower dry matter (DMI) and nutrient intake (P < 0.05) than high RFI (HRFI) and SE animals, without alterations in digestibility coefficients (P > 0.05). During the finishing trial, DMI remained lower for LRFI and CO animals. Growth performance was similar between RFI classes, except for empty body weight gain that tended to be higher for LRFI than HRFI (P = 0.091). The SE animals had less fat content on the empty body (P = 0.005) than CO. Carcasses tended to be leaner for LRFI than HRFI (P = 0.080) and for SE than CO (P = 0.066) animals. LRFI animals retained more energy (P = 0.049) and had lower heat production (HP; P = 0.033) than the HRFI ones. Retained energy was not influenced by SL (P = 0.165), but HP tended to be higher for SE when compared to CO (P = 0.075) animals. Net energy requirement for maintenance (NEm) was lower for LRFI than HRFI (P = 0.009), and higher for SE than CO (P = 0.046) animals. There was an interaction tendency between RFI and SL (P = 0.063), suggesting that NEm was lower for LRFI+CO than HRFI+CO (P = 0.006), with no differences for SE (P = 0.527) animals. The efficiency of ME utilization for maintenance (km) of LRFI and HRFI animals were 62.6% and 58.4%, respectively, and for SE and CO were 59.0% and 62.1%, respectively. The breeding program for postweaning weight has not improved feed efficiency over the years, with RFI classification not being a promising selection tool for SE animals. Classification based on RFI seems to be useful in animals that have not undergone the breeding program, with LRFI animals having lower energy requirements than the HRFI ones.

Genome-wide association study for postweaning weight traits in Lori-Bakhtiari sheep.

Marker-assisted selection is an effective method in novel animal breeding programs. This study was conducted to perform a genome-wide association study to detect candidate genes and quantitative trait loci associated with postweaning weight traits in meat-type sheep. Body weight records were collected during 29 years (1989 to 2017) in Lori-Bakhtiari sheep flock of the Shooli Breeding Station in Iran. A total of 132 animals were selected based on estimates of breeding values (EBVs) for body weight, using two-tailed and random selection strategies. Genomic DNA was extracted from whole blood samples. The samples were genotyped using Illumina OvineSNP50 BeadChip. De-regressed EBVs for postweaning body weight traits were used as pseudo-phenotypes in a genome-wide association study. One SNP on chromosome 10 (rs406324209) and two SNPs on chromosome 13 (rs401963094 and rs418761613) were significantly (Bonferroni-adjusted p-values < 0.05) associated with postweaning body weight traits. The significant variants accounted for 0.20% and 0.48% of the total genetic variances for 6- and 9-month body weights, respectively. Genomic heritabilities estimated for 6-, 9- and 12-month weights and postweaning weight gain were 0.28 ± 0.34, 0.35 ± 0.29, 0.37 ± 0.34, and 0.16 ± 0.33, respectively. Two significant SNPs were located within the ATP8A2 and PLXDC2 genes, on chromosomes 10 and 13, respectively. Based on the known gene ontologies, both ATP8A2 and PLXDC2 could be considered as candidate genes for postweaning body weight traits.

Sow behaviour and piglet weight gain after late cross-fostering in farrowing crates and pens

Determining best practices for managing free farrowing systems is crucial for uptake. Cross-fostering, the exchange of piglets between litters, is routinely performed amongst crate-housed sows. However, cross-fostering can increase fighting amongst the litter and may be more challenging within free farrowing systems as sows have more freedom to respond to cross-fostered piglets. This study compared the effect of either cross-fostering (FOS), or a control of sham-fostering (CON), of four focal piglets per litter on Day 6 postpartum in crates (CRATE) and free farrowing pens (PEN). The post-treatment behavioural responses of sows were recorded (Day 6 = 60 min; Day 7 = 300 min; n = 48), as were the average daily gain (ADG; g/day), total weight gain (TWG; kg) and body lesion scores of focal piglets and their littermates throughout lactation (Day 6, Day 8, Day 11 and Day 26; n = 539) and the post-weaning period (Day 29, Day 32 and Day 60; n = 108). On Day 6, though post-reunion latency to nursing did not differ, latency to successful nursing was longer amongst FOS than CON litters (P < 0.001), more so amongst CRATE FOS than PEN FOS (P < 0.01). On Day 7, PEN FOS sows had fewer successful nursing bouts (P < 0.05) and exhibited decreased lateral (P < 0.01) and increased ventral lying frequencies (P < 0.01) compared to all other housing and treatment combinations. Focal piglet ADG was lower for FOS than CON in the CRATE during Day 6 to Day 8 (P < 0.01) and lower in the PEN during Day 6 to Day 8 (P < 0.001), Day 8 to Day 11 (P < 0.01) and Day 11 to Day 26 (P < 0.05). The TWG of pre-weaned focal piglets (Day 6 to Day 26) was higher amongst CON than FOS litters (P = 0.01). Post-weaning, piglet ADG was higher for PEN than CRATE during Day 26 to Day 29 (P < 0.01) and higher for FOS than CON during Day 26 to Day 29 (P < 0.05), Day 29 to Day 32 (P < 0.001) and Day 32 to Day 60 (P < 0.01); thus, TWG was higher for FOS than CON during the weaner (P = 0.001) and the combined lactation and weaner periods (P = 0.09). In conclusion, sow behaviour was disrupted by cross-fostering in the crates and pens and continued to be disturbed on the following day amongst penned sows. FOS piglets exhibited reduced ADG after cross-fostering, which extended throughout lactation in the pens. However, the increased post-weaning weight gain of FOS piglets meant that their TWG was higher than CON piglets, irrespective of the farrowing system used.

PSV-24 Effect of pre-weaning, post-weaning and fattening growth rate on carcass and meat traits in feedlot Nellore cattle

Abstract The goal of this study was to evaluate the effect of contrasting growth rate in pre and post-weaning period on carcass traits and meat quality of feedlot Nellore cattle. To high weight gain, in pre and post-weaning period, were be considered management groups with mean weight gain above the third quartile of pre-weaning (PREW) or post-weaning (PROW) weight gain distribution of population to group of moderate gain were be considered management lots with daily average gains between the first and third quartiles of PREW or PROW weight gain distribution of population. In the low gain group will be considered management lots with daily average gains lower than the first quartile of PREW or PROW weight gain distribution of population. We used a total of 500 bulls, registered in the National Association of Breeders and Researchers, fed during 90 days with the same diet, confined and slaughtered. The PREW presented a weight gain rate (WGR) of 57.1, 67.3, and 77.7 kg for low, moderate and high WGR, respectively; and the PROW of 110.3, 113.4, and 119.4 kg for low, moderate and high WGR, respectively. The hot carcass weight influenced WGR in pre-weaning (297.56±11.80, 323.53±10.09, and 364.31±18.88 kg) for low, moderate and high, respectively (P = 0.03). The carcass dressing was affected by weaning period in WGR (pre-weaning: 54.18, 54.33, and 57.88 %; P = 0.034, and post-weaning 55.52, 56.23, and 54.66%; P = 0.471) for low, moderate and high WGR, respectively. The contrasting weight gain groups did not influence the marbling score in PREW (P = 0.128) and PROW (P = 0.772), back fat thickness in PREW (P = 0.719) and PROW (P = 0.833), ribeye area in PREW (P = 0.472) and PROW (P = 0.833), tenderness in PREW (P = 0.936) and PROW (P = 0.911). In general, the gain rate did not improve the carcass traits and meat quality of feedlot Nellore cattle.

Palm Fruit Bioactives augment expression of Tyrosine Hydroxylase in the Nile Grass Rat basal ganglia and alter the colonic microbiome

Tyrosine hydroxylase (TH) catalyzes the hydroxylation of L-tyrosine to L-DOPA. This is the rate-limiting step in the biosynthesis of the catecholamines – dopamine (DA), norepinephrine (NE), and epinephrine (EP). Catecholamines (CA) play a key role as neurotransmitters and hormones. Aberrant levels of CA are associated with multiple medical conditions, including Parkinson’s disease. Palm Fruit Bioactives (PFB) significantly increased the levels of tyrosine hydroxylase in the brain of the Nile Grass rat (NGR), a novel and potentially significant finding, unique to PFB among known botanical sources. Increases were most pronounced in the basal ganglia, including the caudate-putamen, striatum and substantia nigra. The NGR represents an animal model of diet-induced Type 2 Diabetes Mellitus (T2DM), exhibiting hyperglycemia, hyperinsulinemia, and insulin resistance associated with hyperphagia and accelerated postweaning weight gain induced by a high-carbohydrate diet (hiCHO). The PFB-induced increase of TH in the basal ganglia of the NGR was documented by immuno-histochemical staining (IHC). This increase in TH occurred equally in both diabetes-susceptible and diabetes-resistant NGR fed a hiCHO. PFB also stimulated growth of the colon microbiota evidenced by an increase in cecal weight and altered microbiome. The metabolites of colon microbiota, e.g. short-chain fatty acids, may influence the brain and behavior significantly.

Comparison of genomic prediction methods for evaluation of adaptation and productive efficiency traits in Braford and Hereford cattle

Various strategies to the use of genetic markers in genetic evaluations have been proposed and substantial genetic progress has been achieved in livestock breeding programs by incorporating genomic information. However, the implementation of genomic selection in beef cattle breeds, especially in composites, adapted to tropical and sub-tropical conditions, is well behind other cattle breeds. Alternative methods to perform genomic predictions for novel adaptation and productive efficiency traits in Brazilian Hereford and Braford need to be further investigated in order to improve the competitiveness of these beef cattle populations. Pedigree, phenotypes and a total of 3,680 genotypes (2,997 Braford and 683 Hereford) were used in this study to assess the predictive ability of genomic predictions for tick resistance, prepuce (navel) score, hair length, ocular pigmentation score, birth weight, pre- and post-weaning weight gain, scrotal circumference, body conformation, precocity, muscularity, and body size. Accuracies of Direct Genomic Values (DGVs) across all scenarios ranged from 0.08 to 0.66, and accuracies of Genomic Estimated Breeding Values (GEBVs) ranged from 0.08 to 0.81. In general, there were no statistical differences (P>0.05) between the DGVs and GEBVs accuracies, and the regression coefficients were not statistically different from 1 (i.e. not biased) for the large majority of traits and scenarios. Our findings indicate that accurate breeding values can be obtained at an early age for various adaptation and productive efficiency traits in Hereford and Braford. In addition, both DGVs and GEBVs predicted by single-step and two-step GBLUP methods produced similar accuracy and amount of bias. Considering the implementation's feasibility, the use the single-step GBLUP method for genetic evaluation of adaptation and productive efficiency traits in Braford and Hereford cattle is recommended.

Genome-wide associations and detection of candidate genes for direct and maternal genetic effects influencing growth traits in the Montana Tropical® Composite population

The Montana Tropical® Composite beef cattle have been developed in Brazil to serve as a genetic resource to meet the consumers’ needs for higher-quality meat while animals are raised in extensive production systems under tropical conditions. In order to optimize the selection process for economically important traits in this population, various genetic and genomic studies are still lacking. In this regard, the aim of this study was to assess genetic parameters and identify genomic regions and potential candidate genes associated with various growth traits, using the single-step Genomic Best Linear Unbiased Predictor (ssGBLUP) method. Approximately 400,000 cows, bulls and progeny had measurements for birth weight (BW), weaning weight (WW), yearling weight (YW) and post-weaning weight gain (WG). A total of 1394 animals were genotyped for 27,199 SNPs (after the quality control) to enable implementation of weighted single-step genome-wide association studies. The traits included in this study were shown to be moderately heritable (i.e. heritability estimates ranging from 0.16 ± 0.01 to 0.33 ± 0.04) and the genetic correlations ranged from 0.60 ± 0.067 (between WW and WG) to 0.88 ± 0.08 (between BW and WW). Single-trait weighted genome-wide association studies enabled the identification of 83 genomic regions for direct genetic effects (all traits) and 29 genomic regions associated with maternal genetic effects on BW and WW traits. Furthermore, biological processes and pathways associated with survival to adult age, calf behavior, fatty acid metabolism, muscle development, fertility, and immune system were identified. The findings of this study greatly contribute to a better understanding of the genetic architecture of growth traits in the Montana Tropical® Composite population. Furthermore, the genomic regions identified can be given more importance (weight) when implementing genomic selection for these traits, by using weighted ssGBLUP or Bayesian approaches.

Reproductive performance of cows and genetic correlation with weight gains and principal components of traits used in selection of Nelore cattle

The objectives of this study were to estimate heritability and genetic correlations for female traits (HR: heifer rebreeding; NC53: number of calves at 53 months of age; HP: heifer pregnancy at 18 months of age; AFC: age at first calving) and weight gains (BWG: from birth to weaning; WYG: from weaning to yearling) in Nelore cattle. Additionally, the relationship of these female traits with four principal components (PC) of predicted breeding values for traits used as selection criteria in this population was evaluated (i.e., weaning and postweaning weight gain, visual scores of conformation, finishing precocity and muscling, and scrotal circumference). The PC were obtained in previous analyses using phenotypic data from 600,132 animals. Low to moderate heritability were estimated for the females traits (HR: 0.12 ± 0.01; NC53: 0.13 ± 0.01; HP: 0.33 ± 0.02; AFC: 0.20 ± 0.01) and weight gains (BWG: 0.24 ± 0.01 and 0.14 ± 0.04 for direct and maternal effects; WYG: 0.21 ± 0.01). The genetic correlations between female traits were favorable, with positive and high estimates between HR, NC53 and HP (0.83 ± 0.03–0.94 ± 0.01) and negative between HR, NC53 and HP with AFC (-0.66 ± 0.02–−0.98 ± 0.01). Heifer rebreeding showed a moderate and negative genetic association with BWG and a positive association with WYG. The genetic association of NC53 with weight gains was positive and favorable (0.31 ± 0.03 with BWG and 0.42 ± 0.04 with WYG). Low genetic correlations were obtained between weight gains with HP and AFC. The first PC, with positive coefficients for all traits, showed a low and favorable genetic association with HP and AFC, but zero with HR and NC53. The second PC, which contrasted weaning and yearling traits, was genetically associated with HR (−0.17 ± 0.03). The third PC, related to early maturity, showed low and negative (favorable) genetic correlations with HR, NC53 and HP (−0.09 ± 0.01–−0.14 ± 0.02) and a positive genetic association with AFC (0.13 ± 0.01). The combination PC showed positive and low genetic correlations with HR and HP (0.12 ± 0.03 and 0.19 ± 0.02, respectively), and negative with NC53 and AFC (−0.08 ± 0.01 and −0.18 ± 0.02, respectively). In general, no relevant genetic antagonism was observed between female traits and weight gains; thus, simultaneous genetic improvements in these traits are possible. The selection based on principal components to achieve a particular breeding objective can provide low or no genetic gains in female traits. Our results thus reinforce the need to use reproductive traits measured directly in females as selection criteria to obtain improvements in sexual precocity and longevity of beef cows.

Genetic evaluation models for post-weaning weight gain in a multibreed Angus-Nelore population

Abstract: The objective of this work was to identify the most suitable model for the genetic evaluation of post-weaning weight gain in a multibreed Angus-Nelore population. Three models were tested using the Bayesian inference method: traditional animal model (M1), multibreed animal model without (M2) and with segregation (M3). The choice of the best model followed the criteria: number of parameters (Np), deviance information criterion (DIC), conditional predictive ordinate (CPO), and deviance based on Bayes factors. Spearman’s rank correlations were estimated for the top 10, 20, and 30% sires. M1 presented the highest values for all criteria, except for Np, and the lowest direct heritability estimate of 0.15±0.01. The heritability estimates for M2 and M3 were higher and similar, being 0.29±0.02 and 0.27±0.02, respectively. M3 showed the lowest values for mean deviance, DIC, and CPO, being the best-fitting model among the three tested. Spearman’s correlation between the predicted genetic values for the models ranged from 0.69 to 0.99. The multibreed models are the most suitable for the genetic evaluation of multibreed populations, and M3 shows the best fit for the studied population.

Reduced body weight at weaning followed by increased post-weaning growth rate interacts with part-per-trillion fetal serum concentrations of bisphenol A (BPA) to impair glucose tolerance in male mice.

There is evidence from longitudinal studies that being light at birth and weaning is associated with subsequent rapid weight gain in infants. This is referred to as “centile crossing”, which can lead to increased risk of lifetime obesity, glucose dysregulation and type 2 diabetes. Here, pregnant CD-1 mice were hemi-ovariectomized so that the entire litter was contained in one uterine horn to increase variability in fetal growth rate. Pregnant females were implanted on gestation day (GD) 9 with a Silastic capsule containing 6, 60 or 600 μg bisphenol A (BPA). On GD 18 the mean fetal serum unconjugated BPA concentrations were 17, 177 and 1858 pg/ml, respectively. Capsules were not removed, to avoid maternal stress, and were predicted to release BPA for at least 3 weeks. Body weight at weaning was strongly negatively correlated with post-weaning weight gain in both control and BPA-treated male mice, consistent with human data; female offspring were excluded, avoiding complications associated with postpubertal estrogens. Within each treatment group, male offspring were sorted into tertiles based on relative weight gain during the two weeks after weaning, designated as having Rapid (R), Medium (M) or Slow (S) growth rate. BPA exposure was associated with altered growth rate between weaning and postnatal week 12 (young adulthood), when a low-dose (20 mg/kg, i.p.) glucose tolerance test (GTT) was performed. We found altered glucose regulation in response to all doses of BPA. However, glucose tolerance was only significantly impaired (blood glucose levels were elevated) compared to controls in males in the rapid post-weaning growth group exposed perinatally to BPA. We conclude that male mice that are light at weaning, but then experience rapid catch-up growth immediately after weaning, represent a sensitive sub-population that is vulnerable to the metabolic disrupting effects of very low pg/ml fetal serum concentrations of BPA.

Sire breed effect on carcass and temperament traits

This paper aimed to identify and evaluate the effects of sire breed on temperament and productive traits of different cross-breeds between Nellore (NE), Tabapua (TB), and Brahman (BR) bulls mated with Angus cows (AN), as well as the relationship between temperament and productive traits. The productive traits measured in this study include slaughter weight and post weaning weight gain. Temperament was assessed by flight-speed (FS). Carcass data collected in this study include hot carcass weight, hot carcass percentage, cold dressing percentage, carcass length, initial pH, ultimate pH, subcutaneous fat thickness and carcass longissimus muscle area. The sire breed effect was greater for slaughter weight. Hot carcass weight was not affected by the sire breed. The longissimus muscle area was larger for AN x TB and AN x NE crossbreeds than for AN x BR crossbreeds. Subcutaneous fat thickness and cold dressing percentage were not affected by sire breed. The offspring of NE, TB, and BR sires mated with AN cows had similar carcass measurements, except for the longissimus muscle area, which was smaller for offspring sired by the Brahman breed. The temperament trait was not influenced by sire breed.