RESUMEN
This study addresses the hypothesis that different acute stressors can cumulatively decrease milk yield. In fact, in a time of global warming, the impact of environmental stress and farm management practices on milk production remains unclear. In this context, our objective was to investigate the effect of acute and cumulative stress on gene expression in mammary tissue and their interactions with physiological responses and milk yield in Saanen goats. Thirty lactating goats were subjected to two treatments: (1) control (CT), in which goats were maintained following a habitual routine under comfort conditions; (2) stress (ST), in which the goats were subjected to different types of environmental stress: heat stress, adrenocorticotropic hormone administration, hoof care management, and exposure to rain. These stressors were performed sequentially, with one stress per day on four consecutive lactation days, to evaluate their effect on milk quality and milk yield. Our results showed that compared to CT goats, cumulative stress increased the gene expression of glucocorticoid receptor (GR), interferon-gamma (IFN-γ), superoxide dismutase (SOD), and catalase (CAT) in mammary tissue, which are indicators of cortisol action, inflammatory response, and antioxidant enzymes. Furthermore, the acute challenges imposed on ST goats changed their rectal temperature and respiratory frequency and increased cortisol, glucose, cholesterol, triglycerides, and high-density lipoprotein release in plasma when compared to CT goats. Although these physiological and metabolic responses restore homeostasis, ST goats showed lower milk yield and higher somatic cell count in milk than CT goats. In conclusion, the results confirmed our initial hypothesis that different acute stressors cumulatively decrease the milk yield in Saanen goats.
RESUMEN
This study addresses the hypothesis that acute stress can cumulatively cause a decrease in milk yield in Saanen goats. In fact, dairy animals are subject to several environmental and management challenges that may cause acute stress during the same lactation. However, the cumulative effect of acute stress on milk yield remains unclear. Thus, the objective of this study was to evaluate the effects of different acute stressors on milk yield and milk quality in goats. Thirty Saanen goats were either maintained on their usual routine and comfort conditions (control group) or subjected to different environmental stressors (heat stress, adrenocorticotropic hormone [ACTH] administration, hoof care, and rain). These stressful challenges were performed sequentially, one challenge per day, on four consecutive days to evaluate the influence of the challenge on milk yield and milk quality. The acute stress imposed on goats caused significant changes in respiratory rate, rectal temperature, cortisol, insulin, triiodothyronine, insulin-like growth factor 1, and glucose concentrations when compared to the control group. Although these acute-stress-triggered physiological responses are fundamental to restoring homeostasis, the cumulative effects of different imposed challenges caused a change in hormone release, an increase in somatic cell count (SCC), and a decrease in milk yield. In this context, the results of this study indicate that farmers should avoid concurrently subjecting goats to management and environmental challenges that can induce acute stress because these stressors have a negative and cumulative impact on SCC and milk yield.(AU)
Este estudo aborda a hipótese de que o estresse agudo pode causar cumulativamente uma diminuição na produção de leite de cabras Saanen. De fato, os animais leiteiros estão sujeitos a vários desafios ambientais e de manejo que podem causar estresse agudo durante a mesma lactação. No entanto, o efeito cumulativo do estresse agudo na produção de leite ainda não está claro. Assim, o objetivo deste estudo foi avaliar os efeitos de diferentes estressores agudos na produção e qualidade de leite de cabras Saanen. Trinta cabras Saanen foram mantidas em sua rotina habitual e condições de conforto (grupo controle) ou submetidas a diferentes estressores ambientais (estresse por calor, administração de hormônio adrenocorticotrófico [ACTH], cuidados com os cascos e chuva). Esses desafios estressantes foram realizados sequencialmente, um desafio por dia, em quatro dias consecutivos para avaliar a influência do desafio na produção e qualidade do leite. O estresse agudo imposto as cabras causou alterações significativas na frequência respiratória, temperatura retal, cortisol, insulina, triiodotironina, fator de crescimento semelhante à insulina 1 e concentrações de glicose quando comparado ao grupo controle. Embora essas respostas fisiológicas desencadeadas pelo estresse agudo sejam fundamentais para restaurar a homeostase, os efeitos cumulativos de diferentes desafios impostos causaram uma mudança na liberação de hormônios, um aumento na contagem de células somáticas (CCS) e uma diminuição na produção de leite. Neste contexto, os resultados deste estudo indicam que os produtores devem evitar submeter as cabras concomitantemente a desafios de manejo e ambientais que possam induzir estresse agudo, pois esses estressores têm impacto negativo e cumulativo na CCS e na produção de leite.(AU)
Asunto(s)
Animales , Femenino , Estrés Fisiológico/fisiología , Cabras/fisiología , Lactancia/fisiología , Glándulas Mamarias Animales/fisiologíaRESUMEN
The present study investigated the male effect on the estrus behaviors, estradiol and progesterone release in prepubertal Saanen goats. Twenty-nine female Saanen goats at 135 ± 10 days old with body weight of 22.8 ± 3.3 Kg were randomly assigned to three treatments: exposure to sexually active male (male treatment), exposure to androgenized females (androgenized female treatment), and prepubertal goats isolated from active male and androgenized females (control treatment). Sexual behaviors associated with estrus were recorded daily, and blood samples were taken weekly to determine estradiol and progesterone concentrations over 24 weeks. The experimental goats subjected to male or androgenized female had significantly higher frequency of estrus (mount acceptance) (P ≤ 0,02), progesterone (P ≤ 0,01), and estradiol (P ≤ 0,01) release than the control goats. Furthermore, goats exposed to a male showed estrus behavior two weeks earlier and maintained this estrus behavior for three weeks more than goats of both female and control treatments. Estrus was observed in 70 % of goats in male and female treatments during the breeding season versus 44 % of the control goats. Finally, significantly more goats subjected to male treatment (60 % of goats) showed progesterone concentrations higher than 1 ng mL-1 (which indicates the presence of a functional corpus luteum) compared to the female and control treatment (40 and 22 % of goats, respectively). These results shows that male treatment significantly increased the number of females showing estrus behavior, estradiol and progesterone release, and the number of animals with a functional corpus luteum, anticipating puberty for experimental goats, suggesting that the male effect could be used to anticipate the onset of puberty in goats.(AU)
O presente estudo investigou o efeito do macho sobre o comportamento do estro, liberação de estradiol e progesterona em cabritas Sannen pré-púberes. Vinte e nove cabritas com 135 ± 10 dias de idade e peso corporal de 22,8 ± 3,3 kg foram submetidas à três tratamentos: macho; fêmeas androgenizadas; controle (mantidas isoladas do efeito macho ou de fêmeas androgenizadas) . Os comportamentos sexuais foram registrados diariamente e as amostras de sangue foram colhidas semanalmente ao longo de 24 semanas. Os tratamentos macho e fêmea androgenizada aumentaram significativamente a ocorrência comportamental do estro (P ≤ 0,02), a concentração de progesterona (P ≤ 0,01) e estradiol (P ≤ 0,01) em comparação ao tratamento controle. As cabritas expostas ao efeito macho anteciparam o comportamento de estro em duas semanas, e o mantiveram por mais três semanas quando comparado às cabritas dos tratamentos fêmea androgenizada e controle. Apenas 44% das cabritas controle foram observadas em estro, sendo que 70% das cabritas submetidas aos tratamentos macho e fêmea androgenizada foram observadas em estro. Além disso, 60% das cabritas expostas ao efeito macho, 40 % das cabritas expostas ao efeito fêmea androgenizada e 22% das cabritas controle apresentaram concentrações de progesterona superiores a 1 ng mL-1, o que indica a presença de corpo lúteo funcional. De fato, o efeito macho aumentou significativamente o número de fêmeas em estro, a concentração de estradiol e progesterona, o número de fêmeas com corpo lúteo funcional, sugerindo que o efeito macho pode ser usado para antecipar o início da puberdade em cabritas Saanen.(AU)
Asunto(s)
Animales , Masculino , Femenino , Conducta Sexual Animal/fisiología , Maduración Sexual/fisiología , Estro/fisiología , Cabras/fisiología , Progesterona/biosíntesis , Cuerpo Lúteo/citología , Estrógenos/biosíntesisRESUMEN
Estudou-se no estuário de Cananéia, litoral do estado de São Paulo, Brasil, a presença de Ascocotyle (Phagicola) longa Ransom, 1920 (Digenea: Heterophylidae), trematódeo, em tainha (Mugil platanus, Günther, 1880). Foram realizadas amostragens a fresco e cortes histológicos em tecidos provenientes de 61 exemplares. A presença de metacercárias foi comprovada em 100 por cento dos peixes examinados, com a seguinte distribuição: coração (21,6 por cento), fígado (19,7 por cento) e rins (58,6 por cento). As alterações histológicas no tecido cardíaco foram caracterizadas pela presença de um granuloma parasitário formado por uma cápsula de tecido conjuntivo ao redor do parasita, levando a um edema generalizado. Para determinar a infecção em alevinos de tainha da espécie M. platanus, foram capturados 100 exemplares nas entradas de córregos da região estuarino-lagunar. Esses peixes foram eviscerados para a pesquisa de metacercárias pelo exame a fresco, verificando-se que 100 por cento dos alevinos não estavam infectados.
The present research was carried out the coast of the state of São Paulo, Brazil, when it was studied the presence of Ascocotyle (Phagicola) longa Ransom, 1920 (Digenea: Heterophylidae), trematode, in mullet (Mugil platanus, Günther, 1880). Fresh samples and histological tissues sections from 61 animals were obtained. The results showed presence of metacercariae of A. (P.) longa in 100 percent of the fish examined, with the following distribution: heart (21.6 percent), liver (19.7 percent) and kidneys (58.6 percent). Histological alterations in cardiac tissues were characterized by the presence of a parasitic granuloma formed by a connective tissue capsule around the parasite, leading to generalized edema. To determine the infection in juvenile grey mullets of the M. platanus species, 100 of them were captured in the stream entrances of the estuary region, each fish was individually sacrificed and fresh mounts were prepared to determine the presence of metacercariae, demonstrating that 100 percent of the juveniles were not infected.