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São José do Rio Preto, Brazil

Siqueira J.B.,Federal University of Vales do Jequitinhonha and Mucuri | Oba E.,Sao Paulo State University | Pinho R.O.,Federal University of Vicosa | Guimaraes S.,Federal University of Vicosa | And 2 more authors.
Reproduction in Domestic Animals | Year: 2014

The objective of this work was to verify that mothers classified as super precocious (M1) and precocious (M2) produce more precocious bulls than females classified as normal (M3). This study included 21 186 animals with an average age of 21.29 ± 1.77 months that underwent a breeding soundness evaluation from 1999 to 2008. Of these animals, 2019, 6059 and 13 108 were offspring of M1, M2 and M3 females, respectively. In the breeding soundness examination, the animals were classified as sound for reproduction, sound under a natural mating regime, unsound for reproduction and discarded. To compare the averages obtained for each category of mother within the individual breeding soundness classes, a chi-square test with a 5% error probability was used, considering the effects of year and month of birth and farm. For the three classes of mothers (M1, M2 and M3), 67.26, 67.22 and 64.16% of bull calves were considered sound for reproduction and 19.71, 19.46 and 21.90% were considered unsound for reproduction, respectively. There was no difference in the frequency of animals that were sound for reproduction under the natural breeding regime between the three classes of mothers (8.87, 9.31 and 9.19%, respectively). There was a difference between the numbers of precocious and normal females that were discarded, with frequencies of 4.01 and 4.75%, respectively (p < 0.05). There were differences in year and month of birth and farm between super precocious and precocious cows in relation to the breeding soundness classification of the animals. It was concluded that the bull offspring of super precocious and precocious cows presented a higher percentage of approval in the breeding soundness examination than the bull offspring of normal cows, demonstrating that the selection for precocity of females has contributed to an increase in the sexual precocity of the herd in relation to the sexual maturity of bulls. © 2014 Blackwell Verlag GmbH. Source

Siqueira J.B.,Federal University of Espirito Santo | Oba E.,Sao Paulo State University | Pinho R.O.,Federal University of Vicosa | Quintino H.P.,Municipal Foundation of Higher Education of Braganca Paulista FESB | And 4 more authors.
Reproduction in Domestic Animals | Year: 2012

Contents: The present work aimed to estimate heritability and genetic correlations of reproductive features of Nellore bulls, offspring of mothers classified as superprecocious (M1), precocious (M2) and normal (M3). Twenty one thousand hundred and eighty-six animals with average age of 21.29months were used, evaluated through the breeding soundness evaluation from 1999 to 2008. The breeding soundness features included physical semen evaluation (progressive sperm motility and sperm vigour), semen morphology (major, minor and total sperm defects), scrotal circumference (SC), testicular volume (TV) and SC at 18months of age (SC18). The components of variance, heritability and genetic correlations for and between the features were estimated simultaneously by restricted maximum likelihood, with the use of the vce software system vs 6. The heritability estimates were high for SC18, SC and TV (0.43, 0.63 and 0.54; 0.45, 0.45 and 0.44; 0.42, 0.45 and 0.41, respectively for the categories of mothers M1, M2 and M3) and low for physical and morphological semen aspects. The genetic correlations between SC18 and SC were high, as well as between these variables with TV. High and positive genetic correlations were recorded among SC18, SC and TV with the physical aspects of the semen, although no favourable association was verified with the morphological aspects, for the three categories of mothers. It can be concluded that the mother's sexual precocity did not affect the heritability of their offspring reproduction features. © 2011 Blackwell Verlag GmbH. Source

Pinho R.O.,Federal University of Vicosa | Costa D.S.,Federal University of Mato Grosso do Sul | Siqueira J.B.,Federal University of Espirito Santo | Chaya A.Y.,Federal University of Vicosa | And 4 more authors.
Revista Brasileira de Zootecnia | Year: 2012

The objective of this study was to investigate the relationship between testicular echotexture and seminal quality, in addition to evaluate the testicular parenchyma echogenicity pattern in young Montana bulls classified as sound and unsound for breeding. Fifty-two young Montana Tropical Compound bulls from 22 to 33 months of age were used. The animals were previously evaluated by breeding soundness evaluation and thereafter divided into two groups of breeding soundness classes: 1 = 16 animals sound for breeding; 2 = 36 animals unsound for breeding by means of physical and morphological analysis of semen. All animals underwent an ultrasound examination of the testes, and the images were analyzed with the software "Image J". ANOVA was used for statistical analysis, to determine the effect of groups in relation to testicular measurements, physical and morphological semen features and ultrasound pixel analysis. There was a difference between scrotal circumference between classes, with 39.7±2.1 cm and 37.3±3.1 cm for sound and unsound animals, respectively. Regarding testicular echotexture, mean values for the pixel intensity were 95.7 and 94.0 for sound and unsound animals for breeding, respectively, with no difference between the classes. None of the studied parameters were correlated with each other, indicating that the quantification of the pixel intensity in testicular echotexture was not effective in determining the degree of sexual maturity in Montana Tropical Compound bulls. © 2012 Sociedade Brasileira de Zootecnia. Source

Pinho R.O.,Federal University of Vicosa | Costa D.S.,Federal University of Mato Grosso do Sul | Siqueira J.B.,Federal University of Espirito Santo | Martins L.F.,Anhanguera | And 3 more authors.
Livestock Science | Year: 2013

The objective of this study was to describe the pattern of testicular echogenicity and the degree of commitment caused by fibrotic lesions in semen quality in adult Nelore bulls. A total of 402 extensively raised adult Nelore bulls were evaluated for breeding soundness and submitted to ultrasound examinations of their testes. Additionally, a testicular fibrosis score ranging from 0 to 5 was assigned to each bull to quantify the patterns, sizes and frequencies of the fibrotic lesions. No correlation was detected among the studied semen features and the pixel intensity values of the studied images. The testicular fibrosis score was only slightly correlated with scrotal circumference, testicular volume, and animal age. The other examined features did not correlate with the studied ultrasound parameters (p>0.05). No correlation was detected between the fibrosis score and testicular sperm quality (p>0.05). Thus, the appearance of the testicular parenchyma of the adult bulls did not correlate with breeding ability. Moreover, the varying degrees of testicular fibrosis did not appear to affect sperm quality. As a result, ultrasonic evaluation of the testes is not a useful tool for evaluating breeding soundness in old Nelore bulls. © 2013 Elsevier B.V. Source

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