Multitissue transcriptomics demonstrates the systemic physiology of methionine deficiency in broiler chickens.

Methionine (Met) supplementation is common practice in broilers to support nutrition, yet there are gaps in the understanding of its role in systemic physiology. Furthermore, several different Met sources are available that may have different physiological effects. This study evaluated the mode of action of Met deficiency (no Met-supplementation) and supplementation (0.25% DL- or L-Met, 0.41% liquid methionine hydroxy analog-free acid (MHA-FA)), and of Met source (DL-, L- or MHA-FA) in broiler chickens, via host transcriptomics. Biological pathway activation modeling was performed to predict the likely phenotypic effects of differentially expressed genes (DEGs) in tissue samples from the jejunum, liver and breast obtained at 10, 21 and 34/35 d of age from three experiments in a combined analysis. Animal performance data showed that Met deficiency reduced BW, daily BW gain, daily feed intake, and breast yield, and increased feed conversion ratio in all experiments (P < 0.05). Effects of Met deficiency on gene expression were least evident in the jejunum and most evident in the liver and breast, as evidenced by the number of DEG and activated pathways. Activated pathways suggested Met deficiency was associated with inhibited protein turnover, gut barrier integrity, and adaptive immunity functions in the jejunum, that predicted reduced breast yield. There was an interaction with age; in Met-deficient birds, there were 333 DEGs in the jejunum of starter vs finisher birds suggesting young birds were more sensitive to Met deficiency than older birds. In the liver, Met deficiency activated pathways associated with lipid turnover, amino acid metabolism, oxidative stress, and the immune system, whereas in breast, it activated pathways involved in metabolic regulation, hemostasis, the neuronal system, and oxidative stress, again predicting a negative impact on breast yield. In the starter phase, supplementation with DL-Met compared to MHA-FA inhibited gamma-aminobutyric acid activity and oxidative stress in breast tissue. When data from all tissues were integrated, increased expression of a liver gene (ENSGALG00000042797) was found to be correlated with the expression of several genes that best explained variation due to the Met deficiency in jejunum and breast muscle. Some of these genes were involved in anti-oxidant systems. Overall, the findings indicate that impaired growth performance due to Met deficiency results from an array of tissue-specific molecular mechanisms in which oxidative stress plays a key systemic role. Young birds are more sensitive to Met-deficiency and DL-Met was a preferential source of Met than L- or MHA-FA during the starter phase.

Acceptability of short message service reminders as the support tool for PrEP adherence among young women in Mukono district, Uganda.

Adolescent girls and young women (AGYW) have a disproportionately high incidence of HIV compared to males of the same age in Uganda. AGYW are a priority sub-group for daily oral Pre-Exposure Prophylaxis (PrEP), but their adherence has consistently remained low. Short Message Service (SMS) reminders could improve adherence to PrEP in AGYW. However, there is paucity of literature about acceptability of SMS reminders among AGYW using PrEP. We assessed the level of acceptability of SMS reminders as a PrEP adherence support tool and the associated factors, among AGYW in Mukono district, Central Uganda. We consecutively enrolled AGYW using PrEP in Mukono district in a cross sectional study. A structured pre-tested questionnaire was administered to participants by three trained research assistants. Data were analyzed in STATA 17.0; continuous variables were summarized using median and interquartile range (IQR) while categorical variables were summarized using frequencies and percentages. Acceptability of SMS was defined as willingness to accept SMS reminders to support PrEP adherence and was assessed using the seven constructs of the theoretical framework of acceptability. The relationship between the outcome and independent variables was assessed using a modified Poisson regression with robust standard errors. During the month of August 2022, 142 AGYW with median age 22 years (IQR; 18, 24) of whom 80.3% owned a personal mobile phone were assessed. SMS reminders were highly acceptable [90.9%, 95% Confidence Interval (CI) [84.9, 95.0]]. Rural residence was negatively associated with acceptability of SMS reminders (aPR: 0.92, 95% CI (0.84, 0.99)) and having belief that SMS cannot breach individual's privacy (aPR: 1.40, 95% CI (1.07, 1.84)) was positively associated with acceptability of SMS reminders. The acceptability of SMS reminders was high in this sub-population. SMS reminder can be leveraged to support AGYW to adhere to PrEP but should be designed in a way that maintains confidentiality, and supports AGYW living in rural settings.

Viral Load Status Before Switching to Dolutegravir-Containing Antiretroviral Therapy and Associations With Human Immunodeficiency Virus Treatment Outcomes in Sub-Saharan Africa.

BACKGROUND: Dolutegravir is being rolled out globally as part of preferred antiretroviral therapy (ART) regimens, including among treatment-experienced patients. The role of viral load (VL) testing before switching patients already on ART to a dolutegravir-containing regimen is less clear in real-world settings. METHODS: We included patients from the International epidemiology Databases to Evaluate AIDS consortium who switched from a nevirapine- or efavirenz-containing regimen to one with dolutegravir. We used multivariable cause-specific hazards regression to estimate the association of the most recent VL test in the 12 months before switching with subsequent outcomes. RESULTS: We included 36 393 patients at 37 sites in 5 countries (Democratic Republic of the Congo, Kenya, Rwanda, Tanzania, Uganda) who switched to dolutegravir from July 2017 through February 2020, with a median follow-up of approximately 11 months. Compared with those who switched with a VL <200 copies/mL, patients without a recent VL test or with a preswitch VL ≥1000 copies/mL had significantly increased hazards of an incident VL ≥1000 copies/mL (adjusted hazard ratio [aHR], 2.89; 95% confidence interval [CI], 1.99-4.19 and aHR, 6.60; 95% CI, 4.36-9.99, respectively) and pulmonary tuberculosis or a World Health Organization clinical stage 4 event (aHR, 4.78; 95% CI, 2.77-8.24 and aHR, 13.97; 95% CI, 6.62-29.50, respectively). CONCLUSIONS: A VL test before switching to dolutegravir may help identify patients who need additional clinical monitoring and/or adherence support. Further surveillance of patients who switched to dolutegravir with an unknown or unsuppressed VL is needed.

An assessment of implementation science research capacity in Uganda.

BACKGROUND: In Uganda and other resource-poor countries, relevant research findings face a tortuous path to translation into policy and routine practice. Implementation science (ImSc) research could facilitate faster translation. Presently it is unclear what ImSc research capacity and possible training needs exist among Ugandan researchers. To assess both components, we interviewed potential trainees in Kampala, Uganda. METHODS: We used a cross-sectional design to survey potential ImSc trainees who had some research training and involvement in generating or utilizing research. Using a questionnaire, we documented eligibility for ImSc training, knowledge and interest in training, existing self-assessed confidence in initiating clinical research (SCICR) and self-assessed confidence in initiating ImSc research (SCIIR), availability for training and preferred modes of training. We developed scores from the Likert scales and used descriptive statistics, logistic regression and ordinal logistic regression to evaluate predictors of SCIIR. RESULTS: Between November 2016 and April 2017, we interviewed 190 participants; 60% were men, with a median age of 37 years. Among participants, 33% comprised faculty, 37% were graduate students and 30% were project staff. The majority of respondents knew about ImSc (73%) and were research-trained (80%). Only 9% reported any ImSc-related training. Previous ImSc training was associated with higher odds of a SCIIR score ≥ 75th percentile. Previous ImSc training compared to not having any training was associated with higher odds of reporting abilities in behaviour change theory integration (OR: 3.3, 95% CI: 1.3-8.5, p = 0.01) and framework use in intervention design and implementation (OR: 2.9, 95% CI: 1.1-7.4, p = 0.03), accounting for age, sex and current employment. In addition, 53% of participants preferred in-person (face-to-face) short ImSc courses compared to a year-long training, while 33% preferred online courses. Participants reported median availability of 6 hours per week (IQR: 4, 10) for training. CONCLUSION: Most participants had some understanding of ImSc research, had research training and were interested in ImSc training. Those with previous ImSc training had better skills and SCIIR, compared to those without previous training. A hybrid approach with modular face-to-face training and online sessions would suit the preferences of most potential trainees.

The Effect of Increased Temperatures on Viability, Morphology, Infectivity, and Development of Eimeria tenella.

Commonly found in backyard and commercial poultry production, coccidiosis, caused by Eimeria species, presents a self-limiting intestinal infection based on the number of ingested oocysts. Heat stress (HS) is one of the major environmental stressors in poultry, predisposing broiler chickens to immunosuppression and rendering them susceptible to diseases. There are suggestions that HS reduces Eimeria oocyst shedding in chickens; however, the relationship between HS and coccidiosis is not well elucidated. The objective of this study was to investigate the effect of temperature on viability, morphology, infectivity, and development of Eimeria tenella in vitro, and merozoite production and oocyst shedding in vivo. In vitro exposure of sporozoites to 55 C for at least 60 min reduced sporozoites viability as shown by morphological changes and rendering them unable to invade Mardin-Darbi bovine kidney (MDBK) cells. Intracellular development of merozoites was significantly reduced by an increase in 2 C in the optimal temperature of incubation in vitro. Most importantly, the induction of HS in the live chickens caused significantly lower lesion scores, reduced merozoite production, and oocyst shedding, resulting in a much less severe disease outcome.

Gene expression differences in the methionine remethylation and transsulphuration pathways under methionine restriction and recovery with D,L-methionine or D,L-HMTBA in meat-type chickens.

This study examined the molecular mechanisms of methionine pathways in meat-type chickens where birds were provided with a diet deficient in methionine from 3 to 5 weeks of age. The birds on the deficient diet were then provided with a diet supplemented with either D,L-methionine or D,L-HMTBA from 5 to 7 weeks. The diet of the control birds was supplemented with L-methionine from hatch till 7 weeks of age. We studied the mRNA expression of methionine adenosyltransferase 1, alpha, methionine adenosyltransferase 1, beta, 5-methyltetrahydrofolate-homocysteine methyltransferase, 5-methyltetrahydrofolate-homocysteine methyltransferase reductase, betaine-homocysteine S-methyltransferase, glycine N-methyltransferase, S-adenosyl-L-homocysteine hydrolase and cystathionine beta synthase genes in the liver, duodenum, Pectoralis (P.) major and the gastrocnemius muscle at 5 and 7 weeks. Feeding a diet deficient in dietary methionine affected body composition. Birds that were fed a methionine-deficient diet expressed genes that indicated that remethylation occurred via the one-carbon pathway in the liver and duodenum; however, in the P. major and the gastrocnemius muscles, gene expression levels suggested that homocysteine received methyl from both folate and betaine for remethylation. Birds who were switched from a methionine deficiency diet to one supplemented with either D,L-methionine or D,L-HMTBA showed a downregulation of all the genes studied in the liver. However, depending on the tissue or methionine form, either folate or betaine was elicited for remethylation. Thus, mRNA expressions show that genes in the remethylation and transsulphuration pathways were regulated according to tissue need, and there were some differences in the methionine form.

Transcriptional analysis of abdominal fat in chickens divergently selected on bodyweight at two ages reveals novel mechanisms controlling adiposity: validating visceral adipose tissue as a dynamic endocrine and metabolic organ.

BACKGROUND: Decades of intensive genetic selection in the domestic chicken (Gallus gallus domesticus) have enabled the remarkable rapid growth of today's broiler (meat-type) chickens. However, this enhanced growth rate was accompanied by several unfavorable traits (i.e., increased visceral fatness, leg weakness, and disorders of metabolism and reproduction). The present descriptive analysis of the abdominal fat transcriptome aimed to identify functional genes and biological pathways that likely contribute to an extreme difference in visceral fatness of divergently selected broiler chickens. METHODS: We used the Del-Mar 14 K Chicken Integrated Systems microarray to take time-course snapshots of global gene transcription in abdominal fat of juvenile [1-11 weeks of age (wk)] chickens divergently selected on bodyweight at two ages (8 and 36 wk). Further, a RNA sequencing analysis was completed on the same abdominal fat samples taken from high-growth (HG) and low-growth (LG) cockerels at 7 wk, the age with the greatest divergence in body weight (3.2-fold) and visceral fatness (19.6-fold). RESULTS: Time-course microarray analysis revealed 312 differentially expressed genes (FDR ≤ 0.05) as the main effect of genotype (HG versus LG), 718 genes in the interaction of age and genotype, and 2918 genes as the main effect of age. The RNA sequencing analysis identified 2410 differentially expressed genes in abdominal fat of HG versus LG chickens at 7 wk. The HG chickens are fatter and over-express numerous genes that support higher rates of visceral adipogenesis and lipogenesis. In abdominal fat of LG chickens, we found higher expression of many genes involved in hemostasis, energy catabolism and endocrine signaling, which likely contribute to their leaner phenotype and slower growth. Many transcription factors and their direct target genes identified in HG and LG chickens could be involved in their divergence in adiposity and growth rate. CONCLUSIONS: The present analyses of the visceral fat transcriptome in chickens divergently selected for a large difference in growth rate and abdominal fatness clearly demonstrate that abdominal fat is a very dynamic metabolic and endocrine organ in the chicken. The HG chickens overexpress many transcription factors and their direct target genes, which should enhance in situ lipogenesis and ultimately adiposity. Our observation of enhanced expression of hemostasis and endocrine-signaling genes in diminished abdominal fat of LG cockerels provides insight into genetic mechanisms involved in divergence of abdominal fatness and somatic growth in avian and perhaps mammalian species, including humans.

Effect of heat stress on amino acid digestibility and transporters in meat-type chickens.

The present study was conducted to investigate the effect of heat stress (HS) on performance, digestibility, and molecular transporters of amino acids in broilers. Cobb 500 chicks were raised from hatch till 13 d in floor pens. At d 14, 48 birds were randomly and equally divided between a control group (25°C) and a HS treatment group (35°C). Birds in both treatment classes were individually caged and fed ad libitum on a diet containing 18.7% CP and 3,560 Kcal ME/Kg. Five birds per treatment at one and 12 d post treatment were euthanized and the Pectoralis major (P. major) and ileum were sampled for gene expression analysis. At d 33, ileal contents were collected and used for digestibility analysis. Broilers under HS had reduced growth and feed intake compared to controls. Although the apparent ileal digestibility (AID) was consistently higher for all amino acids in the HS group, it was not significant except for hydroxylysine. The amino acid consumption and retention were significantly lower in the HS group when compared to the control group. Meanwhile, the retention of amino acids per BWG was higher in the HS group when compared to the control group except for hydroxylysine and ornithine. The dynamics of amino acid transporters in the P. major and ileum was influenced by HS. In P. major and ileum tissues at d one, transporters SNAT1, SNAT2, SNAT7, TAT1, and b0,+AT, were down-regulated in the HS group. Meanwhile, LAT4 and B0AT were down-regulated only in the P. major in the treatment group. The amino acid transporters B0AT and SNAT7 at d 12 post HS were down-regulated in the P. major and ileum, but SNAT2 was down-regulated only in the ileum and TAT1 was down-regulated only in the P. major compared with the control group. These changes in amino acid transporters may explain the reduced growth in meat type chickens under heat stress.

Innovative Demand Creation for Voluntary Medical Male Circumcision Targeting a High Impact Male Population: A Pilot Study Engaging Pregnant Women at Antenatal Clinics in Kampala, Uganda.

BACKGROUND: Circumcision has been shown to be an effective method of HIV prevention; however, only 27% of Ugandan men aged 15-49 years are circumcised. There is a paucity of data on the role of intimate partners in generating demand for voluntary medical male circumcision (VMMC). We conducted a pilot study to assess the feasibility of a partner-focused intervention targeting males >25 years. METHODS: Among pregnant women in their third trimester attending antenatal care we evaluated the impact of a pilot behavior change intervention on VMMC through a quasi-experimental approach. We observed VMMC numbers among spouses of women as per standard practice (comparison phase), and after introducing a behavioral change communication package (intervention phase). Logistic regression was used to compare the odds of VMMC uptake between comparison and intervention phases. We used qualitative methods to evaluate the casual chain using a thematic approach. RESULTS: Of the 601 women studied, 90% articulated the health benefits of VMMC and 99% expressed interest in their spouse getting circumcised. Women's knowledge was not increased by the intervention. Four men were circumcised in the comparison and 7 in the intervention phase. The intervention was not associated with higher odds of circumcision (odds ratio 1.5, 95% CI: 0.3 to 6.0, P = 0.65). We interviewed 117 individuals overall with the main enablers for VMMC being: free VMMC, transport reimbursement, and health benefits. Deterrents included misconceptions, lost wages and fear of pain. Most of the uncircumcised men interviewed reported interest in VMMC. CONCLUSIONS: Our pilot intervention had no significant impact on increasing VMMC demand. The study demonstrated the feasibility of pregnant women engaging their spouses to discuss VMMC.

Transcriptomic differences of genes in the avian target of rapamycin (avTOR) pathway in a divergent line of meat-type chickens selected for feed efficiency.

Avian target of rapamycin (avTOR) is a highly conserved serine-threonine kinase that serves as an intracellular energy and nutrient sensor and regulates cell division, growth, and apoptosis. The role of avTOR in mediating feed intake and growth in poultry is unknown. We studied avTOR signaling activities in duodenum and liver tissues at days 35 and 42 in chickens divergently selected for low (LRFI) or high (HRFI) residual feed intake. The differential expression of genes involved in the avTOR pathway was assayed using real-time polymerase chain reaction. In the duodenum, avTOR was up-regulated in the LRFI chickens at both time points as compared with the HRFI chickens. Other genes found to be differentially expressed at day 35 included v-akt murine thymoma viral oncogene homolog, eukaryotic translation elongation factor 2, eukaryotic translation initiation factor 4E binding protein 1, 3-phosphoinositide dependent protein kinase-1, ribosomal protein S6 kinase, 70 kDa, polypeptide 1 (RPS6KP1), avTOR associated protein, LST8 homolog, ghrelin, phosphoinositide-3-kinase (PI3K), forkhead box O1, and p53 E3 ubiquitin protein ligase homolog (MDM2). At day 42, there was no change in the expression of the avTOR target RPS6KP1 or MDM2. In the liver, changes in the expression of components of the avTOR pathway primarily occurred at day 42, and differential gene expression suggests that avTOR complex 1 (avTORC1) affects feed efficiency at day 42. avTORC1 may be activated in the duodenum of feed-efficient birds to increase nutrient mobilization to other peripheral tissues. Furthermore, activation of avTOR in relation to feed efficiency may be tissue specific and may depend on the tissue's need for growth and nutrient transport. Genetic markers in key genes involved in the avTOR/PI3K pathway could be developed to improve feed efficiency in meat-type chickens.

Multi-generational imputation of single nucleotide polymorphism marker genotypes and accuracy of genomic selection.

Availability of high-density single nucleotide polymorphism (SNP) genotyping platforms provided unprecedented opportunities to enhance breeding programmes in livestock, poultry and plant species, and to better understand the genetic basis of complex traits. Using this genomic information, genomic breeding values (GEBVs), which are more accurate than conventional breeding values. The superiority of genomic selection is possible only when high-density SNP panels are used to track genes and QTLs affecting the trait. Unfortunately, even with the continuous decrease in genotyping costs, only a small fraction of the population has been genotyped with these high-density panels. It is often the case that a larger portion of the population is genotyped with low-density and low-cost SNP panels and then imputed to a higher density. Accuracy of SNP genotype imputation tends to be high when minimum requirements are met. Nevertheless, a certain rate of genotype imputation errors is unavoidable. Thus, it is reasonable to assume that the accuracy of GEBVs will be affected by imputation errors; especially, their cumulative effects over time. To evaluate the impact of multi-generational selection on the accuracy of SNP genotypes imputation and the reliability of resulting GEBVs, a simulation was carried out under varying updating of the reference population, distance between the reference and testing sets, and the approach used for the estimation of GEBVs. Using fixed reference populations, imputation accuracy decayed by about 0.5% per generation. In fact, after 25 generations, the accuracy was only 7% lower than the first generation. When the reference population was updated by either 1% or 5% of the top animals in the previous generations, decay of imputation accuracy was substantially reduced. These results indicate that low-density panels are useful, especially when the generational interval between reference and testing population is small. As the generational interval increases, the imputation accuracies decay, although not at an alarming rate. In absence of updating of the reference population, accuracy of GEBVs decays substantially in one or two generations at the rate of 20% to 25% per generation. When the reference population is updated by 1% or 5% every generation, the decay in accuracy was 8% to 11% after seven generations using true and imputed genotypes. These results indicate that imputed genotypes provide a viable alternative, even after several generations, as long the reference and training populations are appropriately updated to reflect the genetic change in the population.

History of the Athens Canadian Random Bred and the Athens Random Bred control populations.

The University of Georgia maintains two meat-type chicken control strains: the Athens Random Bred (ARB) and the Athens Canadian Random Bred (ACRB). The Athens Random Bred was developed from colored plumage commercial meat chicken strains in 1956. The ACRB is a replicate population of the Ottawa Meat Control strain which was developed in 1955 from white plumage commercial meat-type chickens. These genetic lines have been extremely valuable research resources and have been used extensively to provide comparative context to modern meat-type strains. The ACRB may be the oldest pedigreed control commercial meat-type chicken still in existence today. This paper reviews the history of the breed backgrounds for both control populations and reviews research utilizing the ACRB.

MHC variability in heritage breeds of chickens.

The chicken Major Histocompatibility Complex (MHC) is very strongly associated with disease resistance and thus is a very important region of the chicken genome. Historically, MHC (B locus) has been identified by the use of serology with haplotype specific alloantisera. These antisera can be difficult to produce and frequently cross-react with multiple haplotypes and hence their application is generally limited to inbred and MHC-defined lines. As a consequence, very little information about MHC variability in heritage chicken breeds is available. DNA-based methods are now available for examining MHC variability in these previously uncharacterized populations. A high density SNP panel consisting of 101 SNP that span a 230,000 bp region of the chicken MHC was used to examine MHC variability in 17 heritage populations of chickens from five universities from Canada and the United States. The breeds included 6 heritage broiler lines, 3 Barred Plymouth Rock, 2 New Hampshire and one each of Rhode Island Red, Light Sussex, White Leghorn, Dark Brown Leghorn, and 2 synthetic lines. These heritage breeds contained from one to 11 haplotypes per line. A total of 52 unique MHC haplotypes were found with only 10 of them identical to serologically defined haplotypes. Furthermore, nine MHC recombinants with their respective parental haplotypes were identified. This survey confirms the value of these non-commercially utilized lines in maintaining genetic diversity. The identification of multiple MHC haplotypes and novel MHC recombinants indicates that diversity is being generated and maintained within these heritage populations.

Genetic relationship between leg problems and bone quality traits in a random mating broiler population.

We herein report the genetic association between leg problems and bone quality traits in a random mating broiler control population. The leg problem traits were valgus (VL), varus (VR), and tibial dyschondroplasia (TD), and that of bone quality were shank weight (SW), shank length (SL), shank diameter (SDIAM), tibia weight (TW), tibia length (TL), tibia diameter (TDIAM), tibia density (TDEN), tibia breaking strength (TBS), tibia mineral density (TMD), tibia mineral content (TMC), and tibia ash content (TAC). A threshold-linear mixed model, implemented via a Bayesian approach, was employed for the joint analysis of the traits. Genetic correlations of leg problems with bone quality traits ranged from -0.06 to 0.11 suggesting that genetic relationship between leg problems and quality is weak, and management strategies could better alleviate leg problems than genetic improvement.

Genetic properties of residual feed intakes for maintenance and growth and the implications of error measurement.

A procedure for estimating residual feed intake (RFI) based on information used in feeding studies is presented. Koch's classical model consists of using fixed regressions of feed intake on metabolic BW and growth, and RFI is obtained as the deviation between the observed feed intake and the expected intake for an individual with a given weight and growth rate. Estimated RFI following such a procedure intrinsically suffers from the inability to separate true RFI from the sampling error. As the latter is never equal to 0, estimated RFI is always biased, and the magnitude of such bias depends on the ratio between the true RFI variance and the residual variance. Additionally, the classical approach suffers from its inability to dissect RFI into its biological components, being the metabolic efficiency (maintaining BW) and growth efficiency. To remedy these problems we proposed a procedure that directly models the individual animal variation in feed efficiency used for body maintenance and growth. The proposed model is an extension of Koch's procedure by assuming animal-specific regression coefficients rather than population-level parameters. To evaluate the performance of both models, a data simulation was performed using the structure of an existing chicken data set consisting of 2,289 records. Data was simulated using 4 ratios between the true RFI and sampling error variances (1:1, 2:1, 4:1, and 10:1) and 5 correlation values between the 2 animal-specific random regression coefficients (-0.95, -0.5, 0, 0.5, and 0.95). The results clearly showed the superiority of the proposed model compared to Koch's procedure under all 20 simulation scenarios. In fact, when the ratio was 1:1 and the true genetic correlation was equal to -0.95, the correlation between the true and estimated RFI for animals in the top 20% was 0.60 and 0.51 for the proposed and Koch's models, respectively. This is an 18% superiority for the proposed model. For the bottom 20% of animals in the ranking, the superiority was 17%. Even when the ratio of variances was 10:1, the superiority of the proposed model was around 6%.

Genetic analysis of bone quality traits and growth in a random mating broiler population.

We report the genetic relationship between growth and bone quality traits in a random mating broiler control population. Traits studied were growth rates from week 0 to 4 [body weight gain (BWG) 0 to 4], from week 0 to 6 (BWG 0 to 6), and residual feed intake (RFI) from week 5 to 6 (RFI 5 to 6). Bone quality traits were obtained at 6 weeks of age. These traits were shank weight (SW), shank length (SL), shank diameter (SDIAM), tibia weight (TW), tibia length (TL), and tibia diameter (TDIAM). Likewise, tibia was used to obtain the tibia density (TDEN), tibia breaking strength (TBS), tibia mineral density (TMD), tibia mineral content (TMC), and tibia ash content (TAC). At the phenotypic level, growth traits were positively correlated with most of the bone quality traits except with TDEN and TAC which tended to show unfavorable associations (-0.04 to -0.31). Heritability of bone quality traits ranged from 0.08 to 0.54. The additive genetic associations of growth traits with weight, length, and diameter of shank and tibia were positive (0.37 to 0.80). A similar pattern was observed with TMD and TMC (0.06 to 0.65). In contrast, growth traits showed unfavorable genetic associations with TDEN, TBS, and TAC (-0.03 to -0.18). It was concluded that bone quality traits have an additive genetic background and they can be improved by means of genetic tools. It appears that selection for growth is negatively correlated with some traits involved in the integrity, health, and maturity of leg bones.

Genetic analysis of leg problems and growth in a random mating broiler population.

Improvement in growth has been widely reported as the cause of increased incidence of leg problems in broiler chickens. We report herein the genetic relationship between growth and leg problems in a random mating broiler control population. The traits studied were valgus (VL), varus (VR), and tibial dyschondroplasia (TD), which were expressed on a binary scale of 0 (normal) and 1 (abnormal); growth rates from 0 to 4 wk (BWG 0-4) and from 0 to 6 wk of age (BWG 0-6); and residual feed intake from 5 to 6 wk of age (RFI 5-6). A threshold-linear mixed model was employed for the joint analysis of the categorical and linear traits. Incidences of VL, VR, and TD were 26, 4, and 2%, respectively. Heritability of leg problems ranged from 0.11 to 0.13. Phenotypic correlations alluded to an unfavorable relationship between growth and leg problems; however, the genetic relationship between growth and leg problems was extremely weak, ranging from 0.01 to 0.08. There is, therefore, a basis for genetic improvement in leg problems. However, improved management practices would also be important to reduce incidence of leg problems in broiler chickens.

Mortality and immunological recovery among older adults on antiretroviral therapy at a large urban HIV clinic in Kampala, Uganda.

BACKGROUND: We describe older (>50 years) HIV-infected adults after antiretroviral therapy (ART) initiation, evaluating immunological recovery by age category, considering individual trajectories based on the pretreatment CD4. We also describe mortality on ART and its risk factors by age category including the contribution of poor immunological recovery at a large urban clinic in Kampala, Uganda. METHODS: We performed a cohort analysis of adult (>18 years) HIV-infected patients who initiated ART between January 1, 2004 and January 3, 2012. Immunological response was evaluated using mixed-effects linear regression. We described mortality using Kaplan-Meier survival methods analyzing for risk factors of mortality using multivariate Weibull survival regression stratified by age category. RESULTS: Among 9806 individuals who initiated ART, mean age was 37 years (SD: 8.8), average follow-up 5.7 years (SD: 1.7), and median baseline CD4 was 115 cells per cubic millimeter (interquartile range: 42-184). Adults younger than 50 years had on average a higher CD4 increase of 45 cells per cubic millimeter (95% confidence interval: 17 to 72; P = 0.001) compared with counterparts aged 60 years and older. Mortality was highest among older adults compared with younger counterparts. Only CD4 count <100 cells per cubic millimeter after 1 year on ART and a CD4 count less than baseline were associated with a statistically significant higher rate of death among older adults. CONCLUSIONS: Older adults had a slower immunological response, which was associated with mortality, but this mortality was not typically associated with opportunistic infections. Future steps would require more evaluation of possible causes of death among these older individuals if survival on ART is to be further improved.

Quality attributes in breast muscle from broilers of an Arkansas randombred line varying in growth rate.

The physico-chemical quality attributes of meat from broilers with significant differences in growth rate were investigated in this study. Two chicken populations from a random mating broiler control population were established as a slow-growing subpopulation (SG) with an average growth rate of 229 g/wk and a fast-growing subpopulation (FG) with an average growth rate of 319 g/wk. The initial pH at 15 min and final pH after 24 h were higher (P < 0.05) in breast muscle from FG than muscle from the SG population. Muscle from the SG had higher (P < 0.05) L* and b* of 57.0 and 11.2, compared with L* and b* of 55.8 and 10.5 from the FG. Although no difference in a* was observed, hue angle was different (P < 0.05) at 52.7 and 50.4 in FG and SG populations, respectively. Water-holding capacity was 25 to 27% and not different between the populations, but 5-d drip loss at 8.48% was higher (P < 0.05) in the muscle from the SG compared with the FG at 6.44%. Cook yield was higher (P < 0.05) in the FG muscle at 86.92% compared with the SG muscle at 85.96%. There was a positive correlation of +0.20 between pH difference and drip loss only in the FG. Significantly higher (P < 0.05) cook yields were observed in muscle from FG than SG chickens. The lower weight, higher L* value, and lower initial and final pH values in the SG population, coupled with higher drip loss and lower cook yield, likely result from differences in growth rate.