Intervalo de partos de fêmeas bovinas Nelore, Guzerá x Nelore, Red Angus x Nelore, Marchigiana x Nelore e Simental x Nelore

Perotto, Daniel; Abrahão, José Jorge dos Santos; Kroetz, Inácio Afonso

doi:10.1590/s1516-35982006000300014

Cited by 15 publications

(8 citation statements)

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“…The evaluation of reproductive index comprising age at first calving and calving interval provides an accurate diagnosis of reproductive efficiency in cows [2]. However, these indicators are greatly influenced by non-genetic factors such as nutrition and management [3, 4].…”

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confidence: 99%

Vulvar width and rima length as predictors of the ovarian follicular reserve in bovine females

Mesquita

Maculan

Maciel

et al. 2016

Journal of Reproduction and Development

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The aim of this study was to investigate possible relationships between morphometric characteristics of the bovine reproductive tract and measures of fertility, such as antral follicle counts (AFCs) and the number and quality of recovered cumulus oophorus complexes (COCs). First, the genital tracts of 360 abattoir Zebu/Holstein crossbred cows were studied. Rima vulvae length (RL), vulvar width (VW), ovarian size, pelvic fat, number of aspirated COCs, and AFCs were recorded. An index of COC quality (CQI) was established, which weighed overall gamete quality based on the IETS classification. Second, the same external measurements and AFCs (by ultrasound) were analyzed in live Tabapuã (Zebu) cows (n = 48). Relative RL and vulvar width were defined as the original measurements divided by the body weight of each cow for statistical analyses. In abattoir tracts, the AFC was smaller (P < 0.05) in animals with large VW (34.88 ± 3.50) than in animals with small (45.71 ± 2.57) and intermediate (42.25 ± 2.45) VW. The CQI was higher (P < 0.05) when the pelvic fat score was intermediate (3.22 ± 0.06) than that in lean (2.99 ± 0.08) and obese (2.90 ± 0.12) animals. The CQI was higher (P < 0.05) in the intermediate ovary group (3.19 ± 0.08) than in the small (2.96 ± 0.08) and large (2.95 ± 0.09) ovary groups. In live cows, the AFC was higher (P = 0.035) in females with large relative rima length than in those with small relative rima length (18.96 ± 1.97 and 14.76 ± 1.51, respectively). Similarly, AFC was greater (P = 0.0001) in females with large relative VW than in those with small relative VW (20.08 ± 1.36 and 11.16 ± 1.60, respectively). In conclusion, larger external genitalia relative to body size were good predictors of the ovarian follicular reserve in live animals.

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confidence: 99%

Vulvar width and rima length as predictors of the ovarian follicular reserve in bovine females

Mesquita

Maculan

Maciel

et al. 2016

Journal of Reproduction and Development

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“…Once again the crossbreds were heavier than the pure breeds. Perotto et al (2006b) did not observe any influence of calf sex on milk production traits. Weaning weight was influenced by genetic group, month and year of calving, body condition score at calving, daily average milk yield and lactation length.…”

Section: Resultsmentioning

confidence: 63%

“…Year of calving had a significant effect (P<0.05) on all the traits studied except calving interval and cow weight at calving, improving along the years as cows that did not adapt to the system were eliminated. According to Perotto et al (2006a), calvinginterval for beef cattle in the range of 12 to 13 months are important as it means that the herds in question can attain greater efficiency with one calf per cow per year. Calving interval here was 13.6 months (409.83 days), similar to that found by Facó et al (2005) with Gyr × Holstein cows and less than found by McManus et al (2002) and Perotto et al (2006b), who found 471 days 477 days respectively.…”

Section: Resultsmentioning

confidence: 99%

“…According to Perotto et al (2006a), calvinginterval for beef cattle in the range of 12 to 13 months are important as it means that the herds in question can attain greater efficiency with one calf per cow per year. Calving interval here was 13.6 months (409.83 days), similar to that found by Facó et al (2005) with Gyr × Holstein cows and less than found by McManus et al (2002) and Perotto et al (2006b), who found 471 days 477 days respectively. This may have been influenced by a higher body condition score than found by McManus et al (2002).…”

Section: Resultsmentioning

confidence: 99%

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Production indices for dual purpose cattle in central Brazil

McManus

Louvandini

Carneiro³

et al. 2011

R. Bras. Zootec.

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-This study examined the effects of crossbreeding low genetic potential cows of Bos indicus origin characterized by Gyr crossed with Holstein-Friesian and Simmental bulls to produce animals in a low input dual purpose system. The farm is situated near Brasilia, in the savannah region of Brazil. The climate of the region is classified as Aw by Köppen.Data was available on 1580 calvings and completed lactations of cows with three genetic types: Gyr, Holstein-Friesian × Gyr and Simmental × Gyr. The bulls ran with the cows all year round and the diet comprised of pasture (mainly Brachiaria and Andropogon) during the summer (rainy season) and milled sugar cane with added urea during the winter (dry season). A mineral salt mixture was available ad libitum. Data was analysed using Statistical Analysis System. The results show that, under low input management conditions, the crossbred cows produce approximately twice the volume of milk per lactation, calve at a younger age and have a shorter open period, but there are no significant differences between crosses for growth rates of the calves or body condition of the cows. In this system, crossbred cows had production higher indices than zebu cattle. The best indices were found for cows calving in the rainy season (September to December) and thinner cows (with body condition 3-5 on a scale of 9).

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“…Diferenças nos números de registros em cada ordem de parto também podem contribuir para a existência de diferenças nas variâncias residuais. A superioridade da variância residual para a produção de leite na segunda lactação também pode ser parcialmente justificada pela superioridade do primeiro intervalo de partos, em relação aos demais (Perotto et al, 2006). Durante o primeiro intervalo de partos, a vaca primípara ainda está em crescimento e apresenta exigências nutricionais maiores e, portanto, mais difíceis de serem atendidas (Perotto et al, 2006).…”

Section: Resultsunclassified

Modelos para avaliação genética da produção de leite em múltiplas lactações

Filho

Verneque

Torres

et al. 2015

Pesq. agropec. bras.

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Resumo -O objetivo deste trabalho foi avaliar componentes de covariância e valores genéticos para produção de leite acumulada em até 305 dias, a partir dos dados das três primeiras lactações de vacas Gir. Foram analisados dados de 14.659 lactações, de 9.079 vacas, por meio dos modelos de repetibilidade, multicaracterístico (Mult) e de regressão aleatória com variância residual homogênea (MRAHo) ou heterogênea (MRAHe). A produção de leite foi considerada como característica distinta em cada lactação, no modelo Mult. Polinômios lineares foram utilizados nos modelos de regressão aleatória para ajuste das trajetórias médias e dos efeitos genético aditivo e de ambiente permanente individuais, de acordo com a ordem de parto. As médias a posteriori da herdabilidade foram semelhantes entre os diferentes modelos e lactações, e variaram entre 0,24 e 0,29. Os modelos Mult e MRAHe ajustaram-se melhor aos dados, uma vez que observou-se heterogeneidade de variâncias genéticas e residuais entre lactações. As correlações genéticas da produção acumulada de leite em até 305 dias nas três primeiras lactações foram próximas de 1,0; portanto, a seleção de reprodutores já pode ser feita a partir dos resultados da primeira lactação. Modelos de regressão aleatória com variâncias genéticas e residuais heterogêneas permitem modelar adequadamente as covariâncias das produções de leite acumuladas em múltiplas lactações e obter valores genéticos para seleção de reprodutores com base nos dados já da primeira lactação.Termos para indexação: Bos indicus, Gir leiteiro, modelo multicaracterístico, regressão aleatória, repetibilidade, seleção precoce. Models for genetic evaluation of milk yield in multiple lactationsAbstract -The objective of this work was to evaluate covariance components and breeding values for 305-day cumulative milk yield with data from the first three lactations of Gyr cows. A total of 14,659 lactations of 9,079 cows were evaluated, using the models of repeatability, multiple-trait (MT), and random regression with residual homoscedasticity (RRMHo) or heteroscedasticity (RRMHe). Milk yield was considered as a different trait in each lactation, in the MT model. Linear polynomials were used in random regression models to fit the mean trajectories and the additive genetic and permanent environment individual effects, according to calving order. Posteriori means for heritability were similar among different models and lactations, and varied from 0.24 to 0.29. The MT and RRMHe models had a better fit to the data, since heterogeneity was observed for genetic and residual variances between lactations. The genetic correlations of cumulative milk yield up to 305 days in the first three lactations were close to 1.0; therefore, the selection of reproducers can be made with data already from the first lactation. Random regression models with heterogenous genetic and residual variances allow for proper modeling of the covariances in cumulative milk yields in multiple lactations and for obtaining the genetic values to be used in the select...

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Intervalo de partos de fêmeas bovinas Nelore, Guzerá x Nelore, Red Angus x Nelore, Marchigiana x Nelore e Simental x Nelore

Cited by 15 publications

References 4 publications

Vulvar width and rima length as predictors of the ovarian follicular reserve in bovine females

Vulvar width and rima length as predictors of the ovarian follicular reserve in bovine females

Production indices for dual purpose cattle in central Brazil

Modelos para avaliação genética da produção de leite em múltiplas lactações

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