Características reprodutivas de garanhões da raça Mangalarga Marchador em diferentes faixas etárias

• Autor(a) principal: Oliveira, Renan Reis de
• Data de Publicação: 2014
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/1889
• topic: Mangalarga (cavalo); Cavalo - Reprodução; Andrologia; Sêmen - Criopreservação; Mangalarga (horse); Horse - Reproduction; Andrology; Semen - Cryopreservation; CNPQ::CIENCIAS AGRARIAS::ZOOTECNIA

The Breeders Association of Mangalarga Machador race is the largest in Latin America; however, the reproductive characteristics are not complete known for stallions of different ages. The aim was to evaluate the main reproductive characteristics of Mangalarga Marchador stallions as follows: pre-breeding behavior, testicular biometry, characteristics of accessory glands, seminal quality and semen resistance to cooling and freezing. Experiment 1: 110 stallions were evaluated to measure the reproductive behavior (time to react, latency time, breeding time, duration of semen collection and number of Flehmen reflex) during two consecutive semen collections (C1 and C2) with one hour-interval. The stallions were grouped according to four age intervals: G1: 2-3 years old, G2: 4-6 years, G3: 7-14 years, and G4: older than 15 years. The averaged time for semen collection was 162 sec for C1 and 171.9 sec for C2. No difference was detected for reproductive behavior characteristics among the four age categories. Experiment 2: testicular biometry was evaluated in 101 stallions. The averaged scrotal diameter was reduced in G1 stallions (88.7 mm) compared to G2 (94.5 mm), and was also reduced in G2 stallions compared to G3 (104.1 mm) and G4 (108.6 mm; P<0.05). An age effect was also observed for some accessory glands. During testicular evaluation was detected hydrocele and testicular rotation in 10 and 12 % of stallions, respectively. Experiment 3: two consecutives semen collections were done in 107 stallions to evaluate the semen characteristics (volume with and without gel, total motility, progressive motility, vigor, sperm concentration, total number of sperm, morphologic alterations, and total number of motile and normal sperm (TMNS). The TMNS was affected by the age categories in C1; TMNS was lower in the G1 (2.8 billions) and G2 stallions (3.6 billions) than in the G3 (5.4 billions). Experiment 4: semen collections of 94 stallions were used for evaluation of semen resistance to cooling in two different temperatures (15oC/12 hours, R12 ; and 5oC/24 hours, R24) and to freezing. Cooled semen was evaluated by a subjective analysis to measure the total (TM) and progressive motility (MP) and vigor of sperm. The plasma membrane integrity (PMI) was also evaluated by the supravital test. Frozen-thawed semen was submitted to a computerized analysis to evaluated motility parameters. No difference was detected among the stallions age categories (P>0.05). The averaged TM, PM, vigor and PMI were respectively: 64.4%, 56.1%, 3.2 and 70.4% for R12 (n=71), and 59.3%, 52.5%, 2.8 and 67.2% for R24 (n=77). The PM was superior to 35% in 89% after cooling to 15oC/12 hours (R12). For the frozen-thawed semen, the averaged values of TM, PM and VAP were respectively: 60.9%, 43.8% and 77.6 um/sec in C1 (n=89), and 61.4%, 44.5% and 79.1 um/sec in C2 (n=78). The PM was superior to 35% in 73% frozen-thawed semen. In conclusion, the reproductive characteristics of stallions of Mangalarga Marchador breed are compatible in the normal breeding behavior and semen quality aspects reported for horses. Stallion s age may affect some characteristics. The high percentage of stallions with high resistance of semen to cooling and freezing procedures indicates that these techniques may be useful in large scale in the routine and among breeders of Mangalarga Marchador breed.