ABSTRACT
Heat stress reduces the reproductive capacity of bulls raised in tropical climate. However, the reestablishment of scrotal thermoregulation and the dynamics of sperm defects emergence after stress are not completely known in buffaloes. Thus, the study aimed to evaluate the effect of short-term heat stress over scrotal thermoregulation and sperm attributes, relating them to spermatogenesis stages. Five buffalo bulls went through scrotal insulation during 48 h (from day 0 to day 2). Semen samples were collected every 7 days (from day -7 to day 49) and analyzed about the progressive motility, viability, and sperm morphology. Heat stress significantly destabilized scrotal thermoregulation (P < 0.001). Scrotal temperature was from 4.2 to 6.3 °C lower than the core body temperature, except on insulation days (P < 0.001), and returned to the basal condition five days after the removal of the stressing stimulus. More significant deleterious effects were observed in sperm morphology than in cell concentration, motility, and viability. The chronology of morphologic defects expression demonstrated tail defects (days 7-14), cytoplasmic droplets (days 14-28), and head defects (day 28), returning to pre-insulation condition 35 days after the thermal challenge. Thus, hyperthermia harmed more intensely spermatozoa in epididymal transit, elongated spermatids, and secondary spermatocytes. It is concluded that water buffalo bulls present a peculiar manifestation of sperm morphology after short-term stress, indicating an important difference related to the bovine species. Therefore, during the andrological evaluation of buffalo bulls, it is necessary to avoid the allometric extrapolation between these species.
Subject(s)
Buffaloes/physiology , Heat-Shock Response , Scrotum/physiology , Spermatozoa/abnormalities , Spermatozoa/physiology , Animals , Body Temperature Regulation , Heat Stress Disorders/physiopathology , Heat Stress Disorders/veterinary , Humidity , Male , Sperm Count , Sperm Motility , TemperatureABSTRACT
O trabalho apresenta uma metodologia de avaliação de sistemas de produção através da mensuração da competitividade interna na bovinocultura de corte. Durante o primeiro trimestre de 2010, foram aplicados 65 questionários com pecuaristas, sendo 36 entrevistas na Região Sul (Estado do Rio Grande do Sul) e 29 na Região Norte (Estados do Pará e Rondônia). Foram definidos os principais direcionadores que afetam a competitividade interna - tecnologia, gestão, relações de mercado e ambiente institucional, sendo atribuído um peso específico para cada direcionador, a fim de obter o índice de competitividade. Os resultados foram analisados estatisticamente pela teoria de resposta ao item e pela análise de correspondência (ANACOR) com o software SPSS®. A Região Sul apresentou uma maior competitividade que a Região Norte. Independente da região, os fatores críticos de competitividade foram: integração lavoura-pecuária, planejamento estratégico, cálculo de indicadores financeiros, formação de preços, acesso a inovações tecnológicas e organização dos produtores.
This paper presents a methodology for evaluating production systems by measuring the intern competitiveness of in beef cattle. During the first quarter of 2010, questionnaires were administered to 65 farmers, 36 interviews in the Southern Region (State of Rio Grande do Sul) and 29 in the Northern Region (States of Pará and Rondônia). Defined the key drivers that affect the international competitiveness - technology, management, market relations and institutional environment, an specific weight was assigned to each in order to get the index of competitiveness. The results were statistically analyzed by the item response theory and the correspondence analysis (ANACOR) with the SPSS® software. The South was more competitive than the North. Regardless of region, the critical factors of competitiveness were: crop-livestock integration, strategic planning, calculation of financial indicators, beef pricing, access to technological innovations and organization of farmers.
