Heritability estimates and genome-wide association study of methane emission traits in Nellore cattle.

The objectives of the present study were to estimate the heritability for daily methane emission (CH4) and residual daily methane emission (CH4res) in Nellore cattle, as well as to perform genome-wide association studies (GWAS) to identify genomic regions and candidate genes influencing the genetic variation of CH4 and CH4res. Methane emission phenotypes of 743 Nellore animals belonging to three breeding programs were evaluated. CH4 was measured using the sulfur hexafluoride (SF6) tracer technique (which involves an SF6 permeation tube introduced into the rumen, and an appropriate apparatus on each animal), and CH4res was obtained as the difference between observed CH4 and CH4 adjusted for dry matter intake. A total of 6,252 genotyped individuals were used for genomic analyses. Data were analyzed with a univariate animal model by the single-step GBLUP method using the average information restricted maximum likelihood (AIREML) algorithm. The effects of single nucleotide polymorphisms (SNPs) were obtained using a single-step GWAS approach. Candidate genes were identified based on genomic windows associated with quantitative trait loci (QTLs) related to the two traits. Annotation of QTLs and identification of candidate genes were based on the initial and final coordinates of each genomic window considering the bovine genome ARS-UCD1.2 assembly. Heritability estimates were of moderate to high magnitude, being 0.42 ± 0.09 for CH4 and 0.21 ± 0.09 for CH4res, indicating that these traits will respond rapidly to genetic selection. GWAS revealed 11 and 15 SNPs that were significantly associated (P < 10-6) with genetic variation of CH4 and CH4res, respectively. QTLs associated with feed efficiency, residual feed intake, body weight and height overlapped with significant markers for the traits evaluated. Ten candidate genes were present in the regions of significant SNPs; three were associated with CH4 and seven with CH4res. The identified genes are related to different functions such as modulation of the rumen microbiota, fatty acid production, and lipid metabolism. CH4 and CH4res presented sufficient genetic variation and may respond rapidly to selection. Therefore, these traits can be included in animal breeding programs aimed at reducing enteric methane emissions across generations.

Estimation of economic losses due to leptospirosis in dairy cattle.

There are few studies that effectively quantify the economic losses resulting from problems caused by leptospirosis in naturally infected dairy cattle. Given this gap, the objective of this study was to propose and apply a method to quantify the economic losses resulting from productive and reproductive problems in a commercial dairy herd naturally infected by Leptospira spp. For this study, the zootechnical and economic indicators at a property with Jersey cattle were analyzed during the period from 2014 to 2017. The leptospirosis outbreak occurred in 2014, and the therapeutic approach was carried out between 2015 and 2017, with the latter considered the year of control of the outbreak. The adopted integrated control strategy consisted of dividing the herd according to the serological results obtained through the microscopic agglutination test, the treatment of reagents with streptomycin, and vaccination against leptospirosis of non-reagent heifers and cows. The method used to evaluate the economic indicators of the property was the calculation of the gross margin by taking into account the implicit and explicit cost parameters associated with the manifestation of leptospirosis. The prevalence rate of leptospirosis decreased from 49.4 % in 2015 to 21.6 % in 2017. There was a reduction in the abortion rate (from 40.00 % in 2014 to 9.00 % in 2017), in the stillborn rate (from 2.63 % in 2014 to 1.69 % in 2017) and an increase in the calving rate (from 65.00 % in 2014 to 86.00 % in 2017). In addition, there were increases in the number of lactating cows (from 38 in 2014-57 in 2017) and the mean times of lactation duration, which increased from 275 days in 2014-295 days in 2017. As a result, the average annual production of milk increased from 164,655 liters in 2014-248,521 liters in 2017. In 2014, when treatment hadn't yet started, the gross margin per liter of milk sold, considering implicit and explicit costs, was US$0.00. In 2015 and 2016, US$0.27 and US$0.30 were obtained, respectively, for this variable. In 2017, with the disease under control on the property, the gross margin per liter of milk reached US$0.36. The gross margin per liter of milk sold was higher in the period when the disease was controlled, showing losses of up to 84 % of the gross margin during the outbreak. Immediate treatment of positive cows and preventive measures had a significant impact on improving the productive and economic efficiency of the property.

Effects of inbreeding on production traits and genetic evaluations in Guzerá beef cattle raised under tropical conditions.

The objectives of this study were to evaluate the influence of inbreeding on growth traits and body measurements, as well as on the estimation of genetic parameters and genetic trends in Guzerá cattle. Phenotypic records of 4,212 animals selected for postweaning weight from Guzerá Breeding Program of Advanced Beef Cattle Research Center were utilized. The pedigree file contained records from 7,213 animals born from 1928 to 2019. The traits analyzed were: birth weight (BW), weights adjusted to 210, 378 and 550 days of age (W210, W378 and W550, respectively), chest girth at 378 and 550 days of age (CG378 and CG550), scrotal circumference (SC), and hip height at 378 and 550 days of age (HH378 and H550). Linear regression was used to evaluate the effects of inbreeding on traits. Genetic parameters were obtained using models including or not the effect of inbreeding as a covariate. Inbreeding had negative effects (P ≤ 0.01) on BW (-0.09 kg), W378 (-2.86 kg), W550 (-2.95 kg), HH378 (-0.10 cm), and H550 (-0.29 cm). The lowest and highest heritability estimates were obtained for W210 (0.21 ± 0.07) and HH550 (0.57 ± 0.06), respectively. The genetic correlations were strong and positive between all traits, ranging from 0.44 ± 0.08 (SC x HH) to 0.99 ± 0.01 (W378 x W550). Spearman correlations between EBVs obtained with or without inbreeding effect ranged from 0.968 to 0.995 (P < 0.01). The results indicate loss of productive performance in inbred animals. However, the inclusion of inbreeding coefficient in genetic evaluation models did not alter the magnitude of genetic parameters or genetic trends for the traits studied.

Understanding nitrogen dynamics in the Brazilian beef industry: A comprehensive decadal analysis.

Brazil stands as a prominent beef producer and exporter, witnessing major transformations and expansions in its production chain over the past 20 years. These changes have prompted concerns regarding waste generation and environmental pressure. This study employs material flow analysis (MFA) to quantify nitrogen flows throughout the cattle slaughter process and subsequent beef consumption in Brazil, spanning from 2011 to 2021. The analysis encompasses co-production streams like leather, tallow, viscera, and blood. Nitrogen use efficiency (NUE) and the nitrogen cascade indicator (NCI) were used to evaluate efficiency and nitrogen accumulation in the production chain. Nitrogen inputs in the system increased by 8.47 %, while beef production rose by 7.29 %. In contrast, per capita beef consumption decreased by 1.29 kg, despite an overall consumption increase of 2.84 %, attributed to population growth in Brazil. Beef exports witnessed a notable surge of 86.03 %. Conversely, human excreta and food waste losses experienced increments of 10.88 % and 2.84 %, respectively. Examining NUE reveals the highest values during the slaughter phase (90 %), followed by processing, transportation, and storage stages (79-88 %). The consumption phase exhibited the lowest NUE values (29-34 %). Regarding the cumulative nitrogen effect, the NCI varied between 77 % and 82 % throughout the study period. This highlights opportunities for enhancing nitrogen use efficiency, particularly by addressing food waste at the consumer level. Notably, the study observes nitrogen accumulation across the Brazilian beef production chain, potentially contributing to the nitrogen cascade effect and heightening environmental pressure. Recognizing these dynamics provides avenues for targeted improvements, emphasizing the need to address nitrogen-related challenges and enhance sustainability in the beef production and consumption landscape.

Relationship between FAMACHA© scores and zootechnical indicators of a sheep production system / Relação entre os graus FAMACHA© e indicadores zootécnicos de um sistema de produção de ovinos

In Brazil, lamb producers face challenges raising their animals because of high anthelmintic resistance and loss of productivity due to parasites. It is well known that parasitic infections can reduce the performance of sheep. However, until the publication of this work, no research was found that quantified the effects that anemia reflected by FAMACHA© scores can exert on other zootechnical indicators in a lamb production system. The objective of this study was to use the FAMACHA© scores to quantify the impacts of anemia in ewes at breeding and lambing on the productive and reproductive performance of a meat sheep flock. The variables evaluated were i) FAMACHA© score of ewes at breeding and lambing, ii) body condition score of ewes at breeding and at lambing, iii) average daily gain of lambs until weaning, iv) ewe's age, v) birth weights per individual lamb and litter, vi) weaning weight, vii) ewe's weight, viii) litter size and ix) pre-weaning survival. The treatments evaluated corresponded to the FAMACHA© score of the ewes during breeding and lambing. Quantitative responses were submitted to analyses of variance and compared by Duncan's test. In contrast, qualitative or discrete responses were evaluated by the Kruskal & Wallis test and compared to Dunn's test. The Wilcoxon test was performed to compare the FAMACHA©scores of ewes at breeding and lambing. All statistical analyzes were performed using the R-Studio software version 4.2.0 at a 5% significance level. The FAMACHA© score of breeding ewes was related to the body condition score at breeding, ewe weight, pre-weaning survival, ewe age, litter size, and birth weight. Furthermore, the FAMACHA© score of ewes at lambing was related to the body condition score at lambing, ewe weight, pre-weaning survival, birth weight per lamb and litter, pre-weaning average daily gain, weaning weight, and age of the ewe. There was no significant difference between the test times of the FAMACHA© scores of the ewes, indicating that an ewe will present a similar score at both stages. It was concluded that ewes with FAMACHA© scores of 4 and 5 and their offspring showed the worst productive and reproductive performances. Conversely, the ewes with FAMACHA© 1 obtained the opposite result, demonstrating better technical performance.(AU)

No Brasil, produtores de cordeiros enfrentam desafios na criação de seus animais devido à alta resistência anti-helmíntica e perda de produtividade devido a parasitoses. Sabe-se que as infecções parasitárias podem reduzir o desempenho de matrizes ovinas, contudo, até a elaboração desse trabalho não foram encontradas pesquisas que mensuraram os efeitos que a anemia refletida pelos graus FAMACHA© podem exercer sobre outros indicadores zootécnicos em um sistema de produção de cordeiros. Sendo assim, o objetivo desse estudo foi quantificar os impactos das verminoses em matrizes ovinas, representadas pelo grau FAMACHA©, durante a estação de monta e a parição, no desempenho produtivo e reprodutivo de um rebanho ovino de corte. As variáveis avaliadas foram: i) grau FAMACHA© das matrizes à monta e ao parto, ii) escore de condição corporal das matrizes à monta e ao parto, iii) ganho médio diário até o desmame, iv) idade da matriz, v) pesos dos cordeiros ao nascer individual e por parto, vi) peso ao desmame, vii) peso da matriz, viii) prolificidade e ix) sobrevivência pré-desmame. Os tratamentos avaliados corresponderam ao grau FAMACHA© das matrizes durante a monta e parto. As respostas quantitativas foram submetidas à análise de variância e comparadas pelo teste de Duncan, já as respostas qualitativas ou discretas foram avaliadas pelo teste de Kruskal & Wallis e comparadas pelo teste de Dunn. Realizou-se o teste de Wilcoxon para comparar os graus FAMACHA© das matrizes nos momentos de monta e parto. Todas as análises estatísticas foram realizadas no software R-Studio versão 4.2.0 ao nível de 5% de significância. O grau FAMACHA© das matrizes à monta foi relativo ao escore de condição corporal à monta, peso da matriz, sobrevivência pré-desmame, idade da matriz, prolificidade e peso ao nascer coletivo por parto. Já o grau FAMACHA© das matrizes ao parto foi relativo ao escore de condição corporal ao parto, peso da matriz, sobrevivência pré-desmame, pesos ao nascer individual e coletivo por parto, ganho médio diário pré-desmame, peso ao desmame e idade da matriz. Não houve diferença significativa entre os momentos dos graus FAMACHA© das matrizes, indicando que uma ovelha manterá um grau FAMACHA© similar em ambas as fases. Conclui-se que ovelhas com graus FAMACHA© 4 e 5, assim como suas crias, apresentaram os piores desempenhos produtivos e reprodutivos. Em contrapartida, as matrizes com FAMACHA©1 obtiveram o resultado oposto, mostrando indicadores zootécnicos com valores mais eficientes ao sistema de produção.(AU)