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      Puberdade e maturidade sexual em touros jovens da raça Simental, criados sob regime extensivo em clima tropical Translated title: Puberty and sexual maturity in young Simmental bulls, raised under pasture conditions in a tropical climate

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          Abstract

          Objetivou-se determinar a idade à puberdade e maturidade sexual e sua relação com peso corporal e mensurações testiculares em tourinhos da raça Simental criados sob regime extensivo em clima tropical. Utilizaram-se 44 tourinhos com 1 a 30 meses de idade. As mensurações corporais e testiculares foram feitas mensalmente e os ejaculados coletados quinzenalmente, a partir dos seis meses de idade, utilizando-se o método de eletroejaculação. Observou-se idade à puberdade aos 13,42 ± 3,02 meses e maturidade sexual aos 21,43 ± 6,6 meses de idade, com peso corporal e perímetro escrotal, respectivamente, de 324,2 ± 23,7 kg e 26,90 ± 1,41 cm para a puberdade e 360 ± 69,04 kg e 34,88 ± 3,9 cm para maturidade sexual. Este estudo revelou idade tardia para a cronologia dos eventos reprodutivos, com relação direta do tipo de manejo adotado.

          Translated abstract

          The objective of this study was to determine the age at puberty and sexual maturity and its relationship with body weight and testicular measurements in Simmental young bulls raised under pasture conditions in a tropical climate. Forty-four young bulls at 1 to 30 months of age were used. Body and testicular measurements were made monthly and ejaculates collected fortnightly, from six months of age by using the method of electroejaculation. Age at puberty was 13.42 ± 3.02 months and sexual maturity was observed at 21.43 ± 6.6 months of age, with body weight and scrotal circumference of 324.2 ± 23.7 kg and 26.90 ± 1.41 cm for puberty and 360 ± 69.04 kg and 34.88 ± 3.9 cm to sexual maturity, respectively. This study found late age to the timing of reproductive events, with direct relation to the type of management adopted.

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          SISTEMA de análises estatísticas e genéticas - SAEG

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            The morphology of boar spermatozoa.

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              Puberty in beef bulls: acrosome morphology and semen quality in bulls of different breeds.

              Semen characteristics were evaluated every 2 wk from 7 through 13 mo of age in 31 beef bulls representing six breed groups (Hereford, Angus, Hereford x Angus crossbreeds, Angus x Hereford crossbreds, Red Poll and Brown Swiss). Breeds differed in age at puberty, defined as the age at which an ejaculate was first obtained that contained a minimum of 50 x 10(6) total spermatozoa with at least 10% progressive motility (Hereford, 326 +/- 9 d; Angus, 295 +/- 4 d; Hereford x Angus, 300 +/- 8 d; Angus x Hereford, 296 +/- 9 d; Red Poll, 283 +/- 9 d and Brown Swiss, 264 +/- 9 d). Significant breed differences also were observed in concentration of spermatozoa, progressive motility, seminal protein concentration, abnormal spermatozoa and acrosomal morphology. Considerable variation was observed for the majority of pubertal traits among the 31 bulls, indicating that differences in stage of pubertal development existed among and within breeds of beef bulls between 7 and 13 mo of age. However, adjustment of data to age at puberty negated breed differences (P greater than .10), indicating that the pubertal patterns of change occurring in each semen characteristic were similar for the breeds evaluated. Concentration of spermatozoa, progressive motility, seminal protein concentration, percentage spermatozoa with normal head and tail morphology and percentage spermatozoa with normal acrosomal morphology increased (P less than .01) from puberty through 16 wk after puberty in all bulls and all breds. During the first 6 wk after puberty, rapid increases (P less than .01) were observed in percentage spermatozoa exhibiting normal head morphology (excluding acrosomes) and progressive motility, and a rapid decrease (P less than .01) was observed in percentage spermatozoa with proximal cytoplasmic droplets, with values at +6 wk approaching those reported for mature bulls. Percentage spermatozoa with normal acrosomal morphology and concentration of spermatozoa improved more slowly and had not reached mature levels by 16 wk after puberty. Because age at puberty varied by 62 d among breeds and 88 d among bulls and important characteristics of semen quality improved slowly after puberty, careful evaluation of the stage of pubertal development in individual bulls is recommended before selecting young bulls for natural breeding or artificial insemination. Additional investigations are needed to define the patterns of pubertal development through sexual maturity in beef bulls and to establish relationships to fertility.
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                Author and article information

                Contributors
                Role: ND
                Role: ND
                Role: ND
                Role: ND
                Role: ND
                Role: ND
                Journal
                rbz
                Revista Brasileira de Zootecnia
                R. Bras. Zootec.
                Sociedade Brasileira de Zootecnia (Viçosa )
                1806-9290
                September 2011
                : 40
                : 9
                : 1917-1925
                Affiliations
                [1 ] Universidade Federal de Viçosa Brazil
                Article
                S1516-35982011000900011
                10.1590/S1516-35982011000900011
                175fbb08-8d08-4ae9-9af7-5b8e5ee67554

                http://creativecommons.org/licenses/by/4.0/

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                SciELO Brazil

                Self URI (journal page): http://www.scielo.br/scielo.php?script=sci_serial&pid=1516-3598&lng=en
                Categories
                AGRICULTURE, DAIRY & ANIMAL SCIENCE
                VETERINARY SCIENCES

                Animal agriculture,General veterinary medicine
                extensive farming,puberty,sexual maturity,Simmental,tropical climate,clima tropical,maturidade sexual,puberdade,regime extensivo,Simental

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