Understanding the genetic architecture of beef cattle growth cannot be limited simply to the genome-wide association study (GWAS) for body weight at any specific ages, but should be extended to a more general purpose by considering the whole growth trajectory over time using a growth curve approach. For such an approach, the parameters that are used to describe growth curves were treated as phenotypes under a GWAS model. Data from 1,255 Brahman cattle that were weighed at birth, 6, 12, 15, 18, and 24 months of age were analyzed. Parameter estimates, such as mature weight (A) and maturity rate (K) from nonlinear models are utilized as substitutes for the original body weights for the GWAS analysis. We chose the best nonlinear model to describe the weight-age data, and the estimated parameters were used as phenotypes in a multi-trait GWAS. Our aims were to identify and characterize associated SNP markers to indicate SNP-derived candidate genes and annotate their function as related to growth processes in beef cattle. The Brody model presented the best goodness of fit, and the heritability values for the parameter estimates for mature weight (A) and maturity rate (K) were 0.23 and 0.32, respectively, proving that these traits can be a feasible alternative when the objective is to change the shape of growth curves within genetic improvement programs. The genetic correlation between A and K was -0.84, indicating that animals with lower mature body weights reached that weight at younger ages. One hundred and sixty seven (167) and two hundred and sixty two (262) significant SNPs were associated with A and K, respectively. The annotated genes closest to the most significant SNPs for A had direct biological functions related to muscle development (RAB28), myogenic induction (BTG1), fetal growth (IL2), and body weights (APEX2); K genes were functionally associated with body weight, body height, average daily gain (TMEM18), and skeletal muscle development (SMN1). Candidate genes emerging from this GWAS may inform the search for causative mutations that could underpin genomic breeding for improved growth rates.

We performed a genome-wide mapping for the age at first calving (AFC) with the goal of annotating candidate genes that regulate fertility in Nellore cattle. Phenotypic data from 762 cows and 777k SNP genotypes from 2,992 bulls and cows were used. Single nucleotide polymorphism (SNP) effects based on the single-step GBLUP methodology were blocked into adjacent windows of 1 Megabase (Mb) to explain the genetic variance. SNP windows explaining more than 0.40% of the AFC genetic variance were identified on chromosomes 2, 8, 9, 14, 16 and 17. From these windows, we identified 123 coding protein genes that were used to build gene networks. From the association study and derived gene networks, putative candidate genes (e.g., PAPPA, PREP, FER1L6, TPR, NMNAT1, ACAD10, PCMTD1, CRH, OPKR1, NPBWR1 and NCOA2) and transcription factors (TF) (STAT1, STAT3, RELA, E2F1 and EGR1) were strongly associated with female fertility (e.g., negative regulation of luteinizing hormone secretion, folliculogenesis and establishment of uterine receptivity). Evidence suggests that AFC inheritance is complex and controlled by multiple loci across the genome. As several windows explaining higher proportion of the genetic variance were identified on chromosome 14, further studies investigating the interaction across haplotypes to better understand the molecular architecture behind AFC in Nellore cattle should be undertaken.

Uso de redes neurais artificais na predição de valores genéticos para peso aos 205 dias em bovinos da raça Tabapuã

Efeito da interação idade da matriz x peso do ovo sobre o desempenho de codornas de corte (class 1: 11.0-12.9; class 2: 13.0-14.9, and class 3: 15.0-16.9g

 RESUMOEstudou-se a exigência de metionina + cistina para codornas de corte em crescimento. O delineamento experimental foi inteiramente ao acaso, com cinco repetições de 13 codornas por unidade experimental. Os tratamentos consistiram de seis níveis de metionina + cistina -0,73; 0,79; 0,85; 0,91; 0,97 e 1,03%. Foram registrados peso corporal (g), ganho de peso (g), consumo de ração (g) e conversão alimentar (g/g) em cada fase de crescimento (7 o ao 21 o dia) e total (7 o ao 42 o dia de idade). No 42 o dia, quatro codornas de cada unidade experimental (dois machos e duas fêmeas), após jejum de sólidos de oito horas, foram amostradas, pesadas e abatidas para avaliação dos pesos e rendimentos de carcaças em relação ao peso vivo e rendimentos dos cortes (peito e coxas) e das vísceras comestíveis (fígado, moela e coração) e gordura abdominal em relação ao peso da carcaça eviscerada (sem pés e sem cabeça). Os níveis de metionina + cistina da dieta influíram de forma quadrática no peso ao 21o dia e no ganho de peso do 7 o ao 21 o dia de idade das codornas, com máximo desempenho em 0,95% de metionina + cistina. A conversão alimentar apresentou comportamento linear decrescente significativo. Houve efeito linear dos níveis dos aminoácidos metionina + cistina sobre o peso ao 42 o dia, ganho de peso e consumo de alimento do 7 o ao 42 o dia de idade. Não houve efeito dos níveis de metionina + cistina da dieta sobre o peso vivo, peso e rendimento de carcaça, peito, coxa, gordura abdominal, fígado, moela e coração. Maiores peso corporal, carcaça eviscerada, coxa, peito, gordura abdominal, moela, peso e rendimento de fígado foram observados nas fêmeas, enquanto os machos apresentaram maior rendimento de carcaça eviscerada. Maior ganho de peso foi observado em codornas de corte EV2 em crescimento alimentadas com dietas que continham 0,95% de metionina + cistina na fase inicial (7 o ao 21 o dia) e 1,03% na fase total (7 o ao 42 o dia de idade), o que corresponde às relações de metionina + cistina: lisina de 0,73 e 0,79%, e ao consumo de metionina + cistina diário de 0,134g e 0,234g/codorna, respectivamente.Palavras chave: codorna, exigência nutricional, aminoácido, desempenho, metionina + cistina, característica de carcaça ABSTRACT Methionine + cystine requirements for meat type quails during the growing phase were evaluated in a completely randomized experimental design with five levels of methionione + cystine (.73, .79, .85, .91, .97