The assessment of the presence of genotype by environment interaction (GxE) in beef cattle is very important in tropical countries with diverse climatic conditions and production systems. The present study aimed to assess the presence of GxE by using different reaction norm models for eleven traits related to growth, reproduction, and visual score in Nellore cattle. We studied five reaction norm models (RNM), fitting a linear model considering homoscedastic residual variance (RNM_homo), and four models considering heteroskedasticity, being linear (RNM_hete), quadratic (RNM_quad), linear spline (RNM_l-l), and quadratic spline (RNM_q-q). There was the presence of GxE for age at first calving (AFC), scrotal circumference (SC), weaning to yearling weight gain (WYG), and yearling weight (YW). The best models were RNM_l-l for YW and RNM_q-q for AFC, SC, and WYG. The heritability estimates for RNM_l-l ranged from 0.07 to 0.20, 0.42 to 0.61, 0.24 to 0.42, and 0.47 to 0.63 for AFC, SC, WYG, and YW, respectively. The heteroskedasticity in reaction norm models improves the assessment of the presence of GxE for YW, WYG, AFC, and SC. Additionally, the trajectories of reaction norms for these traits seem to be affected by a non-linear component, and selecting robust animals for these traits is an alternative to increase production and reduce environmental sensitivity.

Beef cattle affected by feet and legs malformations (FLM) cannot perform their productive and reproductive functions satisfactorily, resulting in significant economic losses. Accelerated weight gain in young animals due to increased fat deposition can lead to ligaments, tendon and joint strain and promote gene expression patterns that lead to changes in the normal architecture of the feet and legs. The possible correlated response in the FLM due to yearling weight (YW) selection suggest that this second trait could be used as an indirect selection criterion. Therefore, FLM breeding values and the genetic correlation between FLM and yearling weight (YW) were estimated for 295,031 Nellore animals by fitting a linear-threshold model in a Bayesian approach. A genome-wide association study was performed to identify genomic windows and positional candidate genes associated with FLM. The effects of single nucleotide polymorphisms (SNPs) on FLM phenotypes (affected or unaffected) were estimated using the weighted single-step genomic BLUP method, based on genotypes of 12,537 animals for 461,057 SNPs. Twelve non-overlapping windows of 20 adjacent SNPs explaining more than 1% of the additive genetic variance were selected for candidate gene annotation. Functional and gene prioritization analysis of candidate genes identified six genes (ATG7, EXT1, ITGA1, PPARD, SCUBE3, and SHOX) that may play a role in FLM expression due to their known role in skeletal muscle development, aberrant bone growth, lipid metabolism, intramuscular fat deposition and skeletogenesis. Identifying genes linked to foot and leg malformations enables selective breeding for healthier herds by reducing the occurrence of these conditions. Genetic markers can be used to develop tests that identify carriers of these mutations, assisting breeders in making informed breeding decisions to minimize the incidence of malformations in future generations, resulting in greater productivity and animal welfare.

O objetivo deste trabalho foi demonstrar a utilização da estatística como ferramenta para minimizar o risco em operações de hedge de boi gordo, tendo como base a série histórica de preços na cidade de Itapetinga no estado da Bahia. Os preços no mercado futuro foram obtidos junto ao Centro de Estudos Avançados em Economia Aplicada [CEPEA] Esalq/USP. Os preços do mercado físico foram levantados junto a Secretária da Agricultura, Pecuária, Irrigação, Pesca e Aquicultura [SEAGRI-BA]. Foi calculada a correlação entre os preços nos mercados físico e futuro com o objetivo de saber o quanto a variação de um acompanha a variação do outro. Foram calculadas as bases para todos os dias do período de tempo em análise, em seguida foram encontrados a média e o desvio padrão da base. Encontrado o risco de base das operações de hedge, tendo como referência a tabela da distribuição normal-padrão, foram simulados contratos de compra e venda diariamente no período de um ano, utilizando o conceito de custo de base para determinar o preço objetivo, aumentando a segurança nas operações. Sugeriu-se na prática encerrar algumas posições e assumir outras à medida que o mercado se movimenta a favor ou contra a posição do hedge. Desta forma, estratégias hedge em mercados futuros se mostram como excelentes opções para se precaver contra a variação de preços de boi gordo.

Genetic evaluation studies in Tabapuã cattle breed using random regression models-Review