Abstract
The purpose of this study was to evaluate the functional morphology of the spermatogenesis of Gir bulls, with emphasis on the testicular biometry and testicular parenchyma histomorphometry. Testicular fragments from eight Gir bulls were used. The fragments were fixed by tissue perfusion with Karnovsck’s solution, and inclusion was subsequently performed using glycol methacrylate. Histological sections of 4 μm were made and stained with a 1% toluidine blue-sodium borate solution. The mean age of the bulls was 8.0 ± 1.3 years and the mean body weight was 467.5 ± 26.7 kg. Testicular weight was 289.2 ± 30.5 g on average, and the average gonadosomatic index was 0.12% ± 0.02%. The seminiferous tubules, Leydig cells, stroma, and intertubular tissue composed 80.9% ± 1.7%, 5.4% ± 1.3%, 13.7% ± 1.1%, and 19.1% ± 1.7% of the total testicular weight, respectively. The mean length of the seminiferous tubule per gram of testicle was 17 ± 0.8 m. Losses during spermatogonia mitosis averaged 75.5% ± 3.22%, while losses were 30.6% ± 8.17% during the meiotic phase, which resulted in an average total loss of 81.49% ± 2.58% of cells during the entire process of spermatogenesis. The average daily sperm production per gram of parenchyma was 28.0 × 106 cells. It was concluded that the histometric measurements of testicular parameters in the Gir breed are within the averages reported for other zebu cattle breeds.
Highlights
The Brazilian cattle herd was formed by animals with no defined breed in the 19th century
The purpose of this study was to evaluate the functional morphology of the spermatogenesis of Gir bulls, with emphasis on the testicular biometry and testicular parenchyma histomorphometry
This study aimed to evaluate the functional morphology of the spermatogenesis of Gir bulls, with emphasis on the testicular biometry and histomorphometry of the testicular parenchyma
Summary
The Brazilian cattle herd was formed by animals with no defined breed in the 19th century These animals, originating from European countries (Iberian Peninsula), came with the first colonizers of Brazil. The dominant taurine genetics were challenged by huge problems with endo- and ecto-parasites, causing great concern to rural producers. With this scenario came the need to import cattle of Indian origin, which is rustic and better adapted to the tropical environment [1] [2]. The beginning of the mid-20th century saw the largest numbers of zebu cattle imported from India to Brazil. Gir cattle are the zebuine breed with the highest milk productivity in tropical climates due to efficient thermoregulation characteristics that have allowed increased levels of milk production
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