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Our aims were to evaluate changes in body characteristics, milk yield and milk constituents as well as to determine the relationship between the thermal environment and production characteristics during the first lactation of dairy Gyr cows managed on pasture. Between 2013 and 2015, forty-five primiparous dairy Gyr cows were evaluated from prepartum to 10 months of lactation in Southeast of Brazil. Body weight, body condition score (BCS), subcutaneous fat thickness (SFT), milk yield (305 d), and milk constituents were collected monthly and progesterone was collected weekly. Additionally, we determined the temperature humidity index (THI) based on microclimate data. Overall, the cows lost body weight until six months of lactation and there was a progressive decrease in BCS, SFT, milk yield and milk lactose as the months in lactation progressed. In contrast, there was an increase in milk fat, milk protein and milk solids. The thermal environment did not pose a consistent heat challenge, nevertheless, we found a positive correlation between the average THI two days before milk collection with milk yield, fat and lactose contents, but in contrast a negative correlation was found with total solids and protein. In conclusion, the THI and months of lactation affected the yield and constituents of milk. However, more studies are necessary to understand the impacts of body characteristics and thermal environment on yield and milk constituents throughout the productive life of Gyr dairy cows.

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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.

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Reactive dairy cows are more susceptible to stress, and this may result in negative effects on milk yield and quality. The aims of this study were to investigate the relationships between temperament traits and concentration of milk cortisol and oxytocin, milk yield, milkability, and milk quality in Holstein-Gyr cows. Temperament traits were assessed in 76 Holstein-Gyr cows in the milking parlor (by scoring milking reactivity and recording the numbers of steps and kicks during pre-milking udder preparation and when fitting the milking cluster) and during handling in the corral (by measuring the time to enter in the squeeze chute, ET and flight speed, FS). Milk samples were collected for milk quality (% fat, % protein, % lactose, and somatic cell count, SCC), and milk cortisol and oxytocin. Milk yield, milking time, and average flow were also measured. The calmer cows during milking management (class 'low') produced milk with higher protein (p = 0.028) content and tendencies for lower fat (p = 0.056) and higher lactose (p = 0.055) contents. Regarding the hormones, the most reactive cows (class 'high') in the milking and handling corral produced milk with higher concentrations of cortisol (p<0.001) and oxytocin (p = 0.023). In addition, the temperament of the animals affected some of the productive measures evaluated. Cows with reactive temperament had lower milk flow and longer milking time than the intermediate ones and had higher fat and a tendency for lower protein percentage in milk compared to cows with intermediate temperaments. Calm and intermediate cows in the handling corral produced more milk and presented better milkability parameters, such as a shorter milking time and greater average milk flow. Our results suggest that the cows' behavioral reactivity can be related to the intensity of their response to stress during handling.

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In dairy systems with Zebu breeds, calves are not immediately separated from their dams after calving; consequently, maternal care and protective behavior are important, influencing both productive performance and stockpeople's safety. Our objectives were to: (1) investigate the effects of a training protocol involving pre-calving positive stimulation, delivered prior to calving, on the maternal care of primiparous Gyr cows; and (2) evaluate the effects of this training protocol on maternal protective behavior towards handlers during the first calf handling. Primiparous dairy Gyr cows (n = 37) were allocated into two groups: training (n = 16) and control (n = 21). Animal behaviors were recorded in three periods: post-calving, first calf handling, and post-handling. Maternal protective behavior during calf handling was assessed from measures of aggressiveness, attention, displacement, and agitation. Calf latency to stand up (p < 0.01) and sex (p < 0.01) differed between the training and control groups. The training group had less touching (p = 0.03), more time not interacting with the calf (p = 0.03), tended to be less protective (p = 0.056), and moved less (p < 0.01) during the first handling of their calves. In conclusion, the primiparous dairy Gyr cows subjected to pre-calving training protocol displayed less maternal care and displacement during the first handling of their calves and tended to be less protective.

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Aiming to evaluate the effects of increased body energy reserve (BER) in Nellore cows' reproductive efficiency, cows were fed with different nutritional plans to obtain animals with high BER (HBER; Ad libitum diet) and moderate BER (MBER: cows fed 70% of HBER group ingestion). To evaluate the BER, cows were weekly weighted and evaluated for subcutaneous fat thickness and insulin serum concentration along the experimental period. At the end of the experimental period, animals were submitted to estrous synchronization and artificial insemination. Animals were slaughtered approximately 120 h after ovulation induction and the reproductive tracts were collected for embryo recovery and samples collection. Cumulus-oocyte-complexes (COC) and follicular fluid were collected from 3-6 mm in diameter ovarian follicles to perform miRNA analysis of cumulus cells (CC) and extracellular vesicles from follicular fluid (EV FF). As expected, differences were observed among MBER and HBER groups for body weight, fat thickness, and insulin serum concentration. HBER animals showed lower ovulation and embryo recovery rates compared to MBER animals. Different miRNAs were found among CC and EV FF within groups, suggesting that the BER may influence follicular communication. This suggests that small follicles (3-6 mm diameter) are already under BER effects, which may be greater on later stages of follicular development.

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This research paper addresses the hypothesis that stress, induced by ACTH administration and cortisol release increases somatic cell count (SCC) in mammary secretion, and improves the effectiveness of dry off in goats. We report indicators of milk synthesis and mammary gland involution during dry off. Thirty Saanen goats were subjected to abrupt dry off and treatments: (1) ACTH administration (ACTH) or (2) placebo (Control) on days 1, 3, 6, 9, 12, 15, 30, and 60 of dry off. The expression of target genes in mammary tissue that are related to milk synthesis and cell survival such as insulin-like growth factor 1 receptor (IGF1R), phosphatidylinositol-3-kinase (PIK3CA), protein kinase B (AKT1) and mechanistic target of rapamycin (MTOR), casein (CSN2), lactalbumin (LALBA) and lactoferrin (LF) were evaluated, and plasma cortisol concentration, SCC, leucocyte count, and microbiological analyses in milk and mammary secretions were assessed. ACTH significantly downregulated the expression of IGF1R and upregulated the expression of PIK3CA in mammary tissue, increased lactoferrin concentration and SCC, and changed immune cell levels in mammary secretions compared to Control. Furthermore, ACTH administration increased the percentage of dry goats compared to the Control (73 vs. 46%, respectively). We conclude that the effect of stress via ACTH administration and cortisol release accelerated mammary involution during the early dry-off period.

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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)

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Technological devices are increasingly present in livestock activities, such as identifying the reproductive status of cows. For this, predictive models must be accurate and usable in the productive context. The aims of this study were to evaluate estrus-associated changes in reticulo-rumen temperature (RRT) and activity (ACT) in Dairy Gyr heifers provided by reticulo-rumen boluses and to test the ability of different models for estrus prediction. The RRT and ACT of 45 heifers submitted to estrus synchronization were recorded using reticulo-rumen boluses. The means of RRT and ACT at different time intervals were compared between the day before and the day of estrus manifestation. An analysis of variance of RRT and ACT was performed using mixed models. A second approach employed logistic regression, random forest, and linear discriminant analysis models using RRT, ACT, time of day, and the temperature-humidity index (THI) as predictors. There was an increase in RRT and ACT at estrus (p < 0.05) compared to the same period on the day before and on the day after estrus. The random forest model provided the best performance values with a sensitivity of 51.69% and specificity of 93.1%. The present results suggest that RRT and ACT contribute to the identification of estrus in Dairy Gyr heifers.

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The long exposure to heat negatively changes performance and productivity of animals, particularly when heat stress is associated with gestation. Indeed, little is known about the negative effects of long-term heat stress on the final gestation of dairy goats. In this context, the physiological and cellular responses of Saanen goats submitted to heat stress (37°C from 10:00 to 16:00 h) were investigated from day 60th pre-partum to day 60th post-partum. At final gestation, 46 pregnant Saanen goats were randomly assigned to the treatments: control (CT; thermal neutral conditions) and heat stress (HS; climatic chamber). After partum, all experimental goats were maintained in thermal neutral conditions. The rectal, dorsal, mammary temperatures and respiratory frequency, cortisol release, milk yield, milk quality, and the genes HSP60, HSP70, HSP90, Glucocorticoid receptor and ACTHR. Goats subjected to HS showed significantly (P < 0.05) higher rectal, dorsal, and mammary temperatures and significantly mobilized the increase of respiratory frequency to lose heat as compared to CT goats. The HS challenge significantly increased cortisol release from day 15th pre-partum to day 15th post-partum. CT goats produced more milk than HS from weeks 4 to 10 of lactation (P <0.001), with no difference in milk quality. However, on day 15th post-partum, there was a significant effect of HS treatment on the expression of HSP70 and ACTHR genes as compared to CT treatment, confirming the long-term effect of HS on Saanen goats. In conclusion, the physiological parameters studied increased pre-partum in the hottest hour, and cortisol peaked on day 15 pre-partum for heat-stressed goats. Although on the 15th day post-partum, all goats were in thermal comfort, and the physiological parameters were within the normal range, the concentration of cortisol continued to be significantly higher for goats submitted to thermal stress. Indeed, milk yield was greater for goats subjected to pre-partum thermal comfort. Furthermore, the expression of HSP70 and ACTHR genes on peripheral blood mononuclear cells are interesting biomarkers for studying the long-term effect of heat stress on Saanen goats.

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OBJECTIVE: This work was carried out to evaluate the effects of zilpaterol hydrochloride (ZH) and ractopamine hydrochloride (RH) combined with immunocastration on the welfare traits of feedlot Nellore cattle. METHODS: Ninety-six Nellore males (average body weight [BW] = 409±50 kg; average 20 mo of age) were divided into two groups according to BW; half of the animals in each group received two doses of an immunocastration (ImC) vaccine in a 30 day interval, and the other half did not receive the vaccine (NoC). Afterward, the animals were housed and fed a common diet for 70 days. Then, they were split into three groups and fed one of the following diets for 30 additional days: control (CO) diet, with no ß-AA; ZH diet, containing 80 mg/d ZH; and RH diet, containing 300 mg/d RH. Welfare traits were assessed by monitoring body surface temperature using infrared thermography (IRT) and plasma cortisol and temperament measurements. RESULTS: There was no interaction between sexual condition and diet for any trait. The ImC and NoC groups did not differ in rectal and ocular temperatures. The ImC animals had higher flight speeds (p = 0.022) and tended to have higher cortisol levels (p = 0.059) than the NoC animals. Animals fed ZH and RH did not differ in cortisol levels, respiratory rate, rectal temperature, temperature measured by IRT, or temperament behaviour. CONCLUSION: The ImC animals showed a less stable temperament during handling practices than NoC, whereas ZH and RH supplementation had no adverse effects on animal welfare.

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This study evaluated 53 primiparous cows (36.8±1.23 months old and 484±40.9 kg of body weight) performance tested (GrowSafe® System) from 22±5 to 190±13 days of lactation in order to obtain daily dry matter intake (DMI). The animals received a high-forage diet (forage-to-concentrate ratio of 90:10). Milk production of the cows was evaluated three times by mechanical milking and the energy-corrected milk yield (ECMY) was calculated. Energy status (through the indicators glucose, cholesterol, triglycerides, and ß-hydroxybutyrate), protein status (indicators albumin, urea, and creatinine), mineral status (indicators calcium, phosphorus, and magnesium), and hormonal status (indicators insulin and cortisol) were estimated four times throughout lactation. The residual feed intake (RFI) of cows was calculated considering DMI, average daily gain (ADG) and mid-test metabolic weight (BW0.75) obtained in early lactation (from 22±5 to 102±7 days), and the animals were classified as negative (most efficient) or positive RFI (least efficient). The RFI model explained 53% of the variation in DMI. The mean DMI, ADG, ECMY, and calf weight as a percentage of cow weight were 12.47±2.70 kg DM/day, 0.632±0.323 kg/day, 10.47±3.23 kg/day, and 36.6±5.39%, respectively. Negative RFI cows consumed 11.5% less DM than positive RFI cows, with performance and metabolic profile being similar to those of positive RFI cows, except for a lower milk protein content and higher blood cholesterol concentration. In conclusion, negative (most efficient) and positive RFI (least efficient) Nellore cows, fed an ad libitum high-forage diet, produced similar amounts of milk, fat and lactose and had similar subcutaneous fat thickness, weight, calf weight as a percentage of cow weight, and blood metabolite concentrations (except for cholesterol). Therefore, there are economic benefits to utilizing RFI in a cow herd since cattle had decreased DMI with similar overall performance, making them more profitable due to lower input costs.

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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)

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The objective of this study was to measure the effect of supplementation with molasses blocks compared with conventional mineral supplementation (with specific formulations for the rainy and dry season) in 92 7-month-old Nellore heifers (Experiment 1) and 40 primiparous 31-month-old Nellore cows (Experiment 2) in Marandu grazing areas. The following measurements were obtained: weight, supplement intake, blood urea and glucose in heifers (Experiment 1), supplement intake, cow weight, body score, calf weight and ruminal temperature and drinking events in primiparous females (Experiment 2). The average molasses block intake was 242 g day-1 per heifer, with an average weight gain of 0.290 kg day-1; the heifers who consumed the molasses blocks were heavier during the rainy season (P < 0.05; Experiment 1). In Experiment 2, molasses block intake varied from 77 to 821 g day-1 per primiparous female, and the average intake in the control group was between 100 and 370 g day-1. The primiparous females given molasses blocks displayed lower weight loss due to calving (P < 0.05) and retained higher body scores at 150 days postpartum (P < 0.05). Ruminal temperature (P < 0.05) and drinking events (P < 0.05) were higher in primiparous Nellore females given molasses blocks. Overall, molasses blocks effectively increased Nellore female performance during the rainy season in Marandu grass pastures.(AU)

Objetivou-se medir o efeito da suplementação utilizando blocos de melaço, em comparação à suplementação mineral convencional, em 92 novilhas Nelore de 7 meses de idade (Experimento 1) e 40 primíparas Nelore de 31 meses de idade (Experimento 2), com formulações específicas para épocas chuvosas ou secas em pastagens de capim Marandu. Também foram realizadas as seguintes medições: peso, consumo do suplemento, ureia e glicose em novilhas (Experimento 1) e consumo de suplemento, peso de vacas primíparas, condição corporal, peso de bezerros, temperatura ruminal e frequência da ingestão hídrica nas primíparas (Experimento 2). O consumo médio dos blocos de melaço, por novilha, foi de 242 g dia-1, com ganho de peso de 0,290 kg dia-1. As novilhas que consumiram os blocos contendo melaço tiveram maiores pesos durante a estação chuvosa (P < 0,05) (Experimento 1). No experimento 2, a ingestão de blocos de melaço variou de 77 a 821 g dia-1 por primípara, e a ingestão média no tratamento controle foi entre 100 e 370 g dia-1. As fêmeas primíparas tratadas com blocos de melaço apresentaram menor perda de peso devido ao parto (P < 0,05), e mantiveram escores corporais mais elevados aos 150 dias pós-parto (P < 0,05). A temperatura ruminal (P < 0,05) e a frequência do consumo de água (P < 0,05) foram maiores nas primíparas Nelore do tratamento com blocos de melaço. O uso de blocos de melaço incrementam o desempenho de fêmeas Nelore durante a estação chuvosa em pastagens de capim Marandu.(AU)

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The objective of this study was to measure the effect of supplementation with molasses blocks compared with conventional mineral supplementation (with specific formulations for the rainy and dry season) in 92 7-month-old Nellore heifers (Experiment 1) and 40 primiparous 31-month-old Nellore cows (Experiment 2) in Marandu grazing areas. The following measurements were obtained: weight, supplement intake, blood urea and glucose in heifers (Experiment 1), supplement intake, cow weight, body score, calf weight and ruminal temperature and drinking events in primiparous females (Experiment 2). The average molasses block intake was 242 g day-1 per heifer, with an average weight gain of 0.290 kg day-1; the heifers who consumed the molasses blocks were heavier during the rainy season (P < 0.05; Experiment 1). In Experiment 2, molasses block intake varied from 77 to 821 g day-1 per primiparous female, and the average intake in the control group was between 100 and 370 g day-1. The primiparous females given molasses blocks displayed lower weight loss due to calving (P < 0.05) and retained higher body scores at 150 days postpartum (P < 0.05). Ruminal temperature (P < 0.05) and drinking events (P < 0.05) were higher in primiparous Nellore females given molasses blocks. Overall, molasses blocks effectively increased Nellore female performance during the rainy season in Marandu grass pastures.

Objetivou-se medir o efeito da suplementação utilizando blocos de melaço, em comparação à suplementação mineral convencional, em 92 novilhas Nelore de 7 meses de idade (Experimento 1) e 40 primíparas Nelore de 31 meses de idade (Experimento 2), com formulações específicas para épocas chuvosas ou secas em pastagens de capim Marandu. Também foram realizadas as seguintes medições: peso, consumo do suplemento, ureia e glicose em novilhas (Experimento 1) e consumo de suplemento, peso de vacas primíparas, condição corporal, peso de bezerros, temperatura ruminal e frequência da ingestão hídrica nas primíparas (Experimento 2). O consumo médio dos blocos de melaço, por novilha, foi de 242 g dia-1, com ganho de peso de 0,290 kg dia-1. As novilhas que consumiram os blocos contendo melaço tiveram maiores pesos durante a estação chuvosa (P < 0,05) (Experimento 1). No experimento 2, a ingestão de blocos de melaço variou de 77 a 821 g dia-1 por primípara, e a ingestão média no tratamento controle foi entre 100 e 370 g dia-1. As fêmeas primíparas tratadas com blocos de melaço apresentaram menor perda de peso devido ao parto (P < 0,05), e mantiveram escores corporais mais elevados aos 150 dias pós-parto (P < 0,05). A temperatura ruminal (P < 0,05) e a frequência do consumo de água (P < 0,05) foram maiores nas primíparas Nelore do tratamento com blocos de melaço. O uso de blocos de melaço incrementam o desempenho de fêmeas Nelore durante a estação chuvosa em pastagens de capim Marandu.

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Twenty-seven Nellore cow-calf pairs were submitted for feed efficiency testing. The animals were weighed every 21 ± 5 days to obtain metabolic body weight (BW0.75) and average daily gain (ADG). Subcutaneous fat thickness (SFT; at 20, 83, 146, and 176 days post-calving); milk yield and components (63, 85, and 151 days); levels of glucose, cholesterol, triglycerides, ß-hydroxybutyrate, albumin, urea, creatinine, calcium, phosphorus, magnesium, insulin, and cortisol (15, 41, 62, and 124 days); and ingestive behavior were evaluated. Residual feed intake was calculated for the first stage (RFI1; 21 to 100 days post-calving) and the second stage of lactation (RFI2; 100 to 188 days post-calving), and the cows were classified based on RFI1 as most efficient (RFI1 < 0) and least efficient (RFI1 > 0). Negative RFI1 cows consumed 1.3 kg/day of dry matter, or 9.77%, less than positive RFI1 cows. Most- and least-efficient cows did not differ in terms of subcutaneous fat thickness traits and milk yield or energy-corrected milk (ECM). Glucose (P = 0.0785), triglycerides (P = 0.0795), and phosphorus (P = 0.0597) concentrations were higher in the first stage of lactation in most-efficient cows. Maternal characteristics such as calf weight at birth and at 205 days and ADG were similar in most- and least-efficient cows. The most-efficient cows are more economic as they consume less feed for the same level of production.

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This study aimed to investigate the use of maximum eye surface temperature (ESTmax), recorded by infrared thermography, as an indicator of physical fitness in ranch horses. Data collection was carried out with 16 horses by recording six physical fitness biomarkers (ESTmax, respiratory rate, creatine kinase activity [CK], and concentrations of total serum protein, plasmatic cortisol, and lactate) before and after a regular working day. We also recorded heart rate during the exercise, exercise duration, average velocity, distance traveled, and air temperature and humidity. The variation between the sampling times was compared by using repeated measures ANOVA or Wilcoxon paired test. The t-test was used to compare ESTmax means of dehydrated and nondehydrated horses. The differences (DIF-) between each variable's sampling times were calculated, and the Spearman's correlation coefficients between DIF-ESTmax and DIF- of other variables were estimated. A hierarchical cluster analysis was used to classify the horses according to their physical fitness. All biomarkers increased after the workday, and the ESTmax means of dehydrated and nondehydrated horses did not differ (P < .05). DIF-CK and DIF-ESTmax were positively correlated (rs = 0.56, P < .05). The cluster analysis defined two groups of horses (LOW and HIGH), with DIF-ESTmax and DIF-CK differing statistically between them. HIGH horses showed CK higher than 350 U/L, indicating some degree of muscle damage. These results suggest that ESTmax has potential to predict changes in CK and, thus could be a useful indicator of physical fitness in ranch horses; although, its effectiveness has to be confirmed in future studies.

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The relationships between rectal temperatures and physiological and cellular responses to heat stress can improve the productivity of Saanen goats in tropical environments. In this context, this study evaluated the physiological responses and gene expression of heat shock proteins (HSP60, 70, and 90) and genes related to apoptosis (Bax, Bcl-2, and p53) of Saanen goats subjected to acute heat stress. Ten health Saanen goats were exposed to solar radiation during 3 consecutive days. The expression of HSP60, HSP70, HSP90, Bax, Bcl-2, and p53 genes in blood leukocytes, rectal and superficial temperatures, respiratory frequency, cortisol, triiodothyronine, and thyroxine was measured at 06:00, 13:00, and 18:00 h. In vitro, blood leukocytes were subjected to 38 °C and 40 °C for 3 h to measure the expression of the same target genes. The temperature humidity index, measured from 12:00 to 15:00, was greater than 80 and black globe temperatures were greater at 40 °C, indicating the intensity of the solar radiation. Although the solar radiation caused acute heat stress, increased cortisol release, and the expression of HSP60 and 70 in dry Saanen goats, the increased respiratory frequency and decreased T4 and T3 restored the homeothermy of the experimental goats. In vitro, the 40 °C increased the expression of p53 (pro-apoptotic protein), Bcl-2 (anti-apoptotic protein), HSP60, HSP70, and HSP90, suggesting that these genes have protective functions. However, further studies are necessary to understand the physiological and cellular responses to heat stress.

Assuntos

RESUMO

In this study, we evaluated the effects of supplementation with peanut and sunflower oils on intake and digestibility, milk yield and composition, energy balance (EB), changes in weight and body condition score (BW and BCS), and blood metabolites of Jersey cows on pasture in early lactation. Twenty-four cows were distributed in a randomized block design where they received the following treatments: concentrate without oil (CON), concentrate plus 59.6 g/kg DM peanut oil (PEA), concentrate plus 59.6 g/kg DM sunflower oil (SUN), and concentrate plus 59.6 g/kg DM of a 1:1 mixture of peanut oil and sunflower oil (MIX). The data were analyzed at 30 and 60 days in milk (DIM). Oil supplementation did not affect total dry matter intake or forage intake. The treatment SUN reduced daily milk yield, 4% fat-corrected milk yield, and milk fat, while the other treatments generated similar results. The treatment SUN reduced the milk net energy and the use efficiency of the NEL for milk production and BW and BCS changes, and improved EB up to 60 DIM. On tropical pastures, supplementation with unsaturated oils for cows in early lactation does not result in better milk performance. The supplementation with sunflower oil improves the energy balance in early lactation.

Assuntos

RESUMO

Inadequate corral facilities and improper handling are major causes of stress in beef cattle. The purpose of this study was to evaluate the effects of minor changes in the corral and adoption of good handling practices on the behavior, cortisol release, and time spent taking blood samples in Nellore cows. Minor corral changes included obstructing the cow's vision when the handler walked deep into the animal's flight zone and the elimination of bright objects, color contrasts, puddles, shadows, and darkness in the corral. Handling was improved by eliminating dogs, electric goads (prods), and yelling, as well as adopting a calm behavior. A total of 141 Nellore cows from two typical extensive livestock farms were studied. The cows were evaluated individually before and after the corral changes. Blood samples were collected in the restraint device for cortisol measurement. The minor corral changes and the adoption of good handling practices result in better results for all variables studied. The results showed differences in the interactions between treatment and ranch for chute score (P = 0.0091) and exit score (P < 0.0001). The cortisol release was lower (P < 0.001) and better for the improved methods, resulting in calmer cows compared to cortisol released before the minor changes (41.03 ± 2.9 vs 60.40 ± 3.8 ng/mL). Minor changes made in the corrals and the adoption of good handling practices were effective in improving cow behavior in the chute and in reducing exit velocity, cortisol released, and the time spent taking blood samples.

Assuntos

RESUMO

We hypothesised that different endocrine profiles associated with pre-ovulatory follicle (POF) size would impact on uterine prostanoid pathways and thereby modulate the histotroph composition. Beef cows (n=15 per group) were hormonally manipulated to have small (SF-SCL group) or large (LF-LCL group) pre-ovulatory follicles (POF) and corpora lutea (CL). Seven days after induction of ovulation, animals were slaughtered and uterine tissues and flushings were collected for quantification of prostanoids. The POF and CL size and the circulating progesterone concentrations at Day 7 were greater (P<0.05) in the LF-LCL cows than in the SF-SCL group, as expected. The abundance of 5 out of 19 genes involved in prostanoid regulation was different between groups. Transcript abundance of prostaglandin F2α, E2 and I2 synthases was upregulated (P<0.05) and phospholipase A2 was downregulated (P<0.05) in endometrium of the LF-LCL group. No difference (P>0.1) in prostanoid concentrations in the endometrium or in uterine flushings was detected between groups. However, prostaglandin F2α and E2 concentrations in the uterine flushings were positively correlated with the abundance of transcripts for prostaglandin endoperoxide synthase 2 (0.779 and 0.865, respectively; P<0.002). We conclude that endometrial gene expression related to prostanoid synthesis is modulated by the peri-ovulatory endocrine profile associated with POF size, but at early dioestrus differences in transcript abundance were not reflected in changes in prostanoid concentrations in the uterine tissue and fluid.

Assuntos