Agrarian Academic Journal
doi: 10.32406/v8n3/2025/93-98/agrariacad
Comparative study between birth month and weaning weight of purebred Nelore cattle from embryo transfer and artificial insemination in the municipality of Vilhena – RO, Brazil. Estudo comparativo entre mês de nascimento e peso a desmama de bovinos nelore puro de origem provenientes de transferência de embrião e inseminação artificial no município de Vilhena – RO, Brasil.
Lucas Martins Roveda
1, Lucas Winter de Almeida Soares2, Sallomão Dhankel da Silva Lima2, Giancarlo Rieger3
1- Veterinary Medicine student at Faculdade Marechal Rondon (FARON), Vilhena – RO, Brazil. E-mail: lucasrodevah@gmail.com
2- Veterinary Medicine student at Instituto Federal de Rondônia (IFRO), campus Jaru – RO, Brazil.
3- Professor of Veterinary Medicine at Faculdade Marechal Rondon (FARON), Vilhena – RO, Brazil.
Abstract
Productive and reproductive characteristics positively or negatively determine the efficiency of livestock farming. Therefore, it is important to take into account environmental effects that directly affect characteristics of economic interest in animal farming. A classic example is the calf birth period, which has a strong relationship with weaning weight. In view of this, the present project aimed to evaluate the influence of the month of birth on the weaning weight of animals of the Pure Origin (PO) Nelore breed from two farms in the municipality of Jaru, Rondônia. The data were evaluated to find the average of the batch of animals evaluated, spreadsheets containing information on the day of birth and weight of the animals at weaning. The spreadsheets are part of the database of the evaluation programs, National Association of Breeders and Researchers (ANCP) and Zebu Genetic Improvement Program (PMGZ), which were correlated to find factors that influence the performance of the animals. Data from 1,253 animals of the Nelore breed were used. The weight at 210 days of age was evaluated taking into account the months of birth of the animals. The individuals that obtained the best performance at weaning were those born in the months of July, August and September, corresponding to the months of the breeding season of the previous year. From the evaluation it was possible to determine the best month for reproduction of the matrices, and consequently the birth of the calves aiming at better performance of the progenies.
Keywords: Body weight. Reproduction. Zebu.
Resumo
Características produtivas e reprodutivas determinam positiva ou negativamente a eficiência da criação. Desse modo, é importante levar em consideração efeitos ambientais que atuam diretamente em características de interesse econômico na criação animal. Um exemplo clássico é o período de nascimento do bezerro, que tem alta relação com o peso a desmama. Diante disso, o presente projeto teve como objetivo avaliar a influência do mês de nascimento sobre o peso a desmama de animais da raça Nelore Puro de Origem (PO) de duas fazendas no município de Jaru-Rondônia. Os dados passaram por uma avaliação para encontrar a média do lote dos animais avaliados, planilhas contendo informações com o dia de nascimento e peso dos animais a desmama. As planilhas fazem parte do banco de dados dos programas de avaliação, Associação Nacional de Criadores e Pesquisadores (ANCP) e Programa de melhoramento genético de zebuínos (PMGZ), os quais foram correlacionados para encontrar fatores que influenciam o o desempenho dos animais. Foram utilizados dados de 1.253 animais da raça Nelore. A característica peso aos 210 dias de idade foi avaliada levando em consideração os meses de nascimento dos animais. Os individuos que obtiveram maior desempenho a desmama foram os nascidos nos meses de julho, agosto e setembro, correspondendo aos meses da estação de monta do ano anterior. A partir da avaliação foi possível determinar o melhor mês para reprodução das matrizes, e consequentemente o nascimento dos bezerros objetivando melhor desempenho das progênies.
Palavras-chave: Peso corporal. Reprodução. Zebuínos.
Introduction
The beef cattle industry is primarily characterized by production systems that consist of three main phases: breeding, growing, and finishing. The breeding phase encompasses all production processes involved, from the selection and care of the parents to the weaning of the offspring (PEREIRA et al., 2013). Additionally, environmental effects directly impact economically significant traits in animals. A classic example is the calving period, which has a strong correlation with weaning weight. This relationship arises mainly due to climatic effects on forage quality and the influence of parasitic and infectious agents (PAZ et al., 1999).
With the constant increase in the cattle herd, it is necessary to develop and acquire new technologies that contribute to greater efficiency and productivity of the animals. Among the available innovations, reproductive biotechnologies stand out as essential tools for the modernization of the sector, with the most widely used being fixed-time artificial insemination (FTAI), a method that stands out for allowing the birth of calves at a planned period and genetic improvement of the herd through the use of semen from breeding animals (BARUSELLI et al., 2019).
To mitigate these environmental effects, cattle ranchers often utilize a breeding season, concentrating calvings during a specific time of year. Typically, calving occurs during the dry seasons, as this period provides better physiological conditions for the development of neonates (PEREIRA et al., 2002). Evaluating the influence of environmental factors on pre-weaning weights of Nelore cattle is crucial. It is essential to quantify and identify these environmental factors to select genetically superior breeders and dams effectively. Understanding these effects allows ranchers to adapt their management practices and accurately identify the genetic potential of their animals (QUEIROZ et al., 2019).
It is important to note that Brazil has two well-defined climatic periods: the wet and dry seasons. The transitions between wet and dry periods dictate these changes, unlike temperate countries that experience four distinct seasons. However, Brazil’s vast territorial expanse results in considerable environmental differences across regions, leading to significant variability in pastures, fluctuating climates throughout the year, and some areas with consistently warm temperatures. These factors directly influence the management and production of Nelore cattle and, consequently, their weaning weights. Therefore, producers implement breeding seasons on their farms to optimize productivity according to the most favorable times of the year (BOCCHI et al., 2004).
Depending on the season in which the dam becomes pregnant, the availability of forage and its nutritional value may or may not be favorable for the development of the fetus. In addition, there may also be variation in the availability of nutrients during the lactation period, factors that may directly interfere with the performance of the offspring until weaning (NOVAES, 2025). Therefore, the present study aimed to evaluate the relationship between the month of birth and the weaning weight of purebred Nelore calves of origin on two farms in the State of Rondônia.
Material and methods
The data used in this study were obtained from the database of the genetic improvement program of ANCP (National Association of Breeders and Researchers) and PMGZ (Genetic Improvement Program of Zebu cattle) from two farms located in Jaru, Rondônia. Data from 1,253 Nelore animals, born between 2022 and early 2023, were evaluated. These animals were conceived through artificial insemination and embryo transfer. The evaluation considered factors such as climate, time, and pasture quality. The trait assessed was weaning weight, measured at 210 days of age (the standard age for weaning).
Assessing individual performance based on weaning weight is important for selecting animals, as it accurately reflects genetic differences even among different herds, and allows for earlier identification of genetically superior animals for this trait. The animals evaluated were on pasture during the assessment period, with free access to water and minerals according to their nutritional needs. Weights were obtained using an electronic scale combined with a restraint chute, ensuring more precise measurements. The data were analyzed statistically using the t-test and ANOVA method with the SAS software (2000 version) to test for differences between means, considering a significance level of 5%. Figure 1 represents the city where the experiment was conducted.
Figure 1 – Location of the city of Jaru – RO, Brazil. Source: Google Maps.
Results and discussion
In the description, the weight of the animals at 210 days of age and its final relationship between the month of birth and the weaning weight of males and females is presented (Table 1).
Table 1 – Average weights in kg of calves separated by sex and month of birth
Month |
Animals |
|
Male |
Female |
|
January |
228 |
201 |
February |
225 |
197 |
March |
226 |
200 |
April |
227 |
203 |
May |
237 |
204 |
June |
245 |
210 |
July |
264 |
216 |
August |
259 |
240 |
September |
256 |
232 |
October |
249 |
227 |
November |
240 |
221 |
December |
234 |
218 |
Cattle born in February had an average weaning weight of 225 kg, with males and females weighing 197 kg each, corroborating the results obtained by (OLIVEIRA et al., 2024), where animals born in February had lower weights compared to those born in other months of the year. This result aligns with Silva (2022), who indicated that the abundance of forage promotes the emergence of environmental pathogens that impair calf development.
Analysis of growth characteristics, such as body weight at different ages, should consider fixed effects associated with sex, genetic group, season of birth, birth order, and nutritional strategies. Ignoring these factors can compromise the accuracy of genetic estimates and reduce the effectiveness of breeding programs (PEREIRA et al., 2002). The use of mixed models allows for effective separation of genetic and environmental components, enabling a more precise evaluation of the animals’ genetic merit in relation to their environment.
Births occurring between July and October, considered early-season animals, had the advantage of passing their first months during a period of higher pasture availability of quality. Thus, lactating cows and calves have access to better nutrition, favoring their initial growth (NOVAES, 2025). Similar to our study’s results, calves born in August showed better performance, with 264 kg for males and 240 kg for females, a finding also reported by Morais (2023) in a study with Nelore and Angus breeds. This variation can be understood by analyzing the extremes of weaning weights in relation to the birth season. The environment during August, characterized by less rainfall, reduced humidity, and consequently lower incidence of ecto- and endoparasites, supports early calf development (COSTA, 2008). Nutritional and sanitary management practices significantly influence the environment in which calves are raised, impacting their zootechnical performance until weaning (NASCIMENTO, 2025). Factors such as feed quality and availability, supplementation, parasite control, and vaccination are crucial for healthy development during this critical phase, reflecting how environment and season affect animal performance. Additionally, the interaction between genetic and environmental factors, such as pasture quality and climate, can explain part of the observed variation. Studies show that selecting animals with greater adaptability to the environment, considering both genetic components and environmental factors, can improve calf performance.
In a study by Carneiro et al. (2012), cows that calved at the beginning of the birth season weaned heavier calves because they had access to abundant, high-quality forage for a longer period. Bocchi et al. (2004), evaluating the productive performance of Nelore calves across four regions of Brazil, observed that animals born between July and December had higher weaning weights than those born between January and March. The results indicating higher average daily gain (ADG) in early born animals align with the findings of Gelsinger et al. (2016) and Zanton; Heinrichs (2005). This superior performance is directly related to higher milk production by the dams, which peaks during periods of greater forage availability (SANTOS et al., 2009). Based on this, it is recommended that, under Brazilian conditions, the breeding season be planned to concentrate births in the early second semester, ensuring better development conditions for the calves.
Conclusion
It is concluded that establishing the breeding season during the appropriate period is crucial, as it can reduce the negative effects of the environment on the animal’s productive efficiency. A well-timed breeding season decreases mortality rates and increases weaning weights, directly impacting the profitability of the properties.
Conflicts of interest
There were no conflicts of interest among the authors.
Authors’ contributions
Lucas Martins Roveda – data collection, result interpretation and writing; Lucas Winter de Almeida Soares – data collection and result interpretation; Sallomão Dhankel da Silva Lima – data collection; Giancarlo Rieger – text revision, supervision and corrections.
Funding
Marechal Rondon Veterinary School (FARON).
Acknowledgments
We thank the Marechal Rondon Veterinary School (FARON) and the companies that provided the supplies.
References
BARUSELLI, P. S.; CATUSSI, B. L. C.; ABREU, L. Â.; ELLIFF, F. M.; SILVA, L. G.; BATISTA, E. S.; CREPALDI, G. A. Evolução e perspectivas da inseminação artificial em bovinos. Revista Brasileira de Reprodução Animal, v. 43, n. 2, p. 308-314, 2019. https://www.cbra.org.br/portal/downloads/publicacoes/rbra/v43/n2/p308-314/2019
BOCCHI, A. L.; TEIXEIRA, R. A.; ALBUQUERQUE, L. G. Idade da vaca e mês de nascimento sobre o peso ao desmame de bezerros nelore nas diferentes regiões brasileiras. Acta Scientiarum. Animal Sciences, v. 26, n. 4, p. 475-482, 2004. https://doi.org/10.4025/actascianimsci.v26i4.1724
CARNEIRO, L. C.; SILVA, J. C. C.; MENDES, G. P.; FERREIRA, I. C.; SANTOS, R. M. Efeito do mês de parição na taxa de gestação subsequente e no peso ao desmame dos bezerros de vacas Nelore. Acta Scientiae Veterinariae, v. 40, n. 2, p.1-5, 2012. https://www.ufrgs.br/actavet/40-2/PUB1030
COSTA, G. Z.; QUEIROZ, S. A.; OLIVEIRA, J. A.; FRIES, L. A. Estimativas de parâmetros genéticos e fenotípicos de escores visuais e de ganho médio de peso do nascimento a desmama de bovinos formadores da raça Brangus. Ars Veterinaria, v. 24, n. 3, p. 172-176, 2008. https://doi.org/10.15361/2175-0106.2008v24n3p172-176
GELSINGER, S. L.; HEINRICHS, A. J.; JONE, C. M. A meta-analysis of the effects of preweaned calf nutrition and growth on first-lactation performance. Journal of Dairy Science, v. 99, n. 8, p. 6206-6214, 2016. https://doi.org/10.3168/jds.2015-10744
MORAIS, A. S. Uso da suplementação no desmame de bezerros. 42f. Trabalho de Conclusão de Curso (Graduação em Zootecnia) – Universidade Estadual de Goiás, São Luís de Montes Belos, 2023. https://repositorio.ueg.br/jspui/handle/riueg/2724
NASCIMENTO, M. L. S. Relação entre altura de garupa de vacas da raça Nelore com peso a desmama da progênie. 19f. Trabalho de Conclusão de Curso (Graduação em Zootecnia) – Universidade Federal de Uberlândia, Uberlândia, 2025. https://repositorio.ufu.br/handle/123456789/45635
NOVAES, T. O. Efeito da época de nascimento sobre o desempenho de bezerros Nelore na desmama. 26f. Trabalho de Conclusão de Curso (Graduação em Zootecnia) – Universidade Estadual Paulista, Ilha Solteira, 2025. https://hdl.handle.net/11449/261721
OLIVEIRA, K. M. Desempenho de bezerros em período e aleitamento: estudo de caso da Fazenda Escola Lagoa do Sino. 26f. Trabalho de Conclusão de Curso (Graduação em Engenharia Agronômica) – Universidade Federal de São Carlos, Lagoa do Sino, 2024. https://repositorio.ufscar.br/handle/20.500.14289/19258
PAZ, C. C. P.; ALBUQUERQUE, L. G.; FRIES, L. A. Efeitos ambientais sobre ganho de peso no período do nascimento ao desmame em bovinos da raça Nelore. Revista Brasileira de Zootecnia, v. 28, n. 1, p. 55-64, 1999. https://doi.org/10.1590/S1516-35981999000100008
PEREIRA, A. M. V. S.; MUNIZ, C. A. S. D. Efeitos ambientais sobre características pré-desmama em bovinos da Raça Nelore Mocha. Semina: Ciências Agrárias, v. 34, n. 1, p. 359-366, 2013. https://doi.org/10.5433/1679-0359.2013v34n1p359
PEREIRA, E.; ELER, J. P.; FERRAZ, J. B. S. Análise genética de características reprodutivas na raça Nelore. Pesquisa Agropecuária Brasileira, v. 37, n. 5, p. 703-708, 2002. https://doi.org/10.1590/S1678-3921.pab2002.v37.6392
QUEIROZ, G. R.; GOULART, G. R.; BALDI, F.; CASTRO, L. M.; LÔBO, R. B.; VENTURINI, G. C. Relaçao entre mês de nascimento e peso à desmama em bovinos da raça nelore uberaba. In: Congresso Brasileiro de Zootecnia, 29., 2019, Uberaba. Anais eletrônicos… Galoá, 2019. https://proceedings.science/zootec-2019/trabalhos/a-relacao-entre-mes-de-nascimento-e-peso-a-desmama-em-bovinos-da-raca-nelore?lang=pt-br
SANTOS, M. E. R.; FONSECA, D. M.; EUCLIDES, V. P. B.; RIBEIRO JÚNIOR, J. I.; NASCIMENTO JÚNIOR, D.; MOREIRA, L. M. Produção de bovinos em pastagens de capim-braquiária diferidas. Revista Brasileira de Zootecnia, v. 38, n. 4, p. 635-642, 2009. https://doi.org/10.1590/S1516-35982009000400007
SILVA, J. C. Manejo de ofertas de forragem em pastagem natural: estudo dos tipos funcionais e estabilidade de produção. 108f. Tese (Doutorado) – Programa de Pós-Graduação em Zootecnia, Faculdade de Agronomia, Universidade Federal do Rio Grande do Sul, Porto Alegre, 2022. https://lume.ufrgs.br/handle/10183/252844
ZANTON, G. I.; HEINRICHS, A. J. Meta-analysis to assess effect of prepubertal average daily gain of Holstein heifers on first-lactation production. Journal of Dairy Science, v. 88, n. 11, p. 3860-3867, 2005. https://doi.org/10.3168/jds.S0022-0302(05)73071-X
Recebido em 12 de outubro de 2024
Retornado para ajustes em 27 de maio de 2025
Recebido com ajustes em 29 de maio de 2025
Aceito em 17 de junho de 2025