Mecanismo neuro-hormonal de ejeção de leite
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Data
2021-12-14
Autores
Ribeiro, Luiz Eduardo Rodrigues
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Este trabalho teve por objetivo avaliar os resultados publicados na literatura científica acerca do mecanismo neuro hormonal de ejeção do leite de vaca leiteira. Usando informações de diversas fontes, dentre elas instituições de pesquisas, sites especializados, revistas de divulgação nacionais e internacionais, boletins técnicos, circulares técnicas, anais de congressos e simpósios, artigos publicados em periódicos nacionais e internacionais e livros. O reflexo neuro-hormonal da ejeção do leite estabelece que da palpação do teto, a amamentação do bezerro, e outros estímulos que associam os ruminantes a ordenha como a presença do operário, o barulho da máquina de ordenha, etc., resulta em um estímulo nervoso que ao alcançar o sistema nervoso central determina a liberação de ocitocina pela hipófise à corrente sanguínea. Da estimulação pelo tato (táctil) até o aumento da pressão intramamária transcorrem 30 a 60 segundos. Esta ação hormonal tem uma curta duração, de 5 a 7 minutos, daí a importância de colocar as teteiras o mais rápido possível após ter ocorrido o estímulo, caso contrário o efeito hormonal desaparece, deixando leite residual no úbere da vaca, comprometendo a produção de leite.
This study aimed to evaluate the results published in the scientific literature about the neurohormonal mechanism of ejection of dairy cow's milk. Using information from various sources, including research institutions, specialized websites, national and international dissemination magazines, technical bulletins, technical circulars, conference and symposium proceedings, articles published in national and international journals and books. The neurohormonal reflex of milk ejection establishes that from palpation of the roof, breastfeeding of the calf, and other stimuli that associate ruminants with milking such as the presence of the worker, the noise of the milking machine, etc., results in a nervous stimulus that upon reaching the central nervous system determines the release of oxytocin by the pituitary into the bloodstream. From stimulation by touch (tactile) to increased intramammary pressure, 30 to 60 seconds elapse. This hormonal action has a short duration, from 5 to 7 minutes, hence the importance of placing the liners as soon as possible after the stimulus has occurred, otherwise the hormonal effect disappears, leaving residual milk in the cow's udder, compromising the production of milk.
This study aimed to evaluate the results published in the scientific literature about the neurohormonal mechanism of ejection of dairy cow's milk. Using information from various sources, including research institutions, specialized websites, national and international dissemination magazines, technical bulletins, technical circulars, conference and symposium proceedings, articles published in national and international journals and books. The neurohormonal reflex of milk ejection establishes that from palpation of the roof, breastfeeding of the calf, and other stimuli that associate ruminants with milking such as the presence of the worker, the noise of the milking machine, etc., results in a nervous stimulus that upon reaching the central nervous system determines the release of oxytocin by the pituitary into the bloodstream. From stimulation by touch (tactile) to increased intramammary pressure, 30 to 60 seconds elapse. This hormonal action has a short duration, from 5 to 7 minutes, hence the importance of placing the liners as soon as possible after the stimulus has occurred, otherwise the hormonal effect disappears, leaving residual milk in the cow's udder, compromising the production of milk.
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Palavras-chave
Ordenha, Leite, Anatomia, Fisiologia, Relação homem-animal, Ocitocina, Bovino, Células mioepiteliais, Hipófise posterior, Leite residual, Produção de leite, Glândulas mamárias