RESUMO: A região Norte de Minas possui a produção de leite limitada, principalmente em função da seca, no entanto, esta é a base econômica da agricultura familiar que sustenta a região. Assim, realizou-se um estudo com o objetivo de avaliar o efeito do ambiente térmico sobre as respostas fisiológicas de vacas ¾ Holandês-Zebu, na região do semiárido mineiro a fim de se verificar a adaptabilidade destes animais. O experimento foi conduzido no verão e inverno, na fazenda Bela Vista localizada no município de Verdelândia (MG), onde foram avaliadas 10 vacas ¾ Holandês x Zebu (HxZ), em cada época. O ambiente térmico foi caracterizado por meio de medições diárias da temperatura do ar, umidade relativa do ar, índice de temperatura de globo e umidade e carga térmica radiante. Os parâmetros fisiológicos: frequência respiratória e cardíaca, temperatura de superfície corporal e temperatura retal, espessura, cor e densidade do pelame, e comprimento dos pelos foram mensurados antes da ordenha matutina, em função das estações do ano, diariamente, durante 15 dias. As variáveis e índices climáticos foram superiores no verão e no período da tarde. A frequência respiratória e a espessura do pelame não diferiram estatisticamente, no entanto as demais variáveis foram superiores no verão. As variáveis climáticas induziram diferenças nos parâmetros fisiológicos, mas foram assimiladas pelos animais, o que permite concluir que as vacas ¾ HxZ adaptam-se ao clima do semiárido mineiro sem manifestarem situação de estresse térmico.Palavras-chave: agricultura familiar, ambiência, bovinos leiteiros, cruzamento genético. PHYSIOLOGICAL RESPONSES AND ADAPTABILITY OF ¾ HOLSTEIN X ZEBU COWS TO SEMIARID CLIMATEABSTRACT: The northern region of Minas Gerais has limited milk production, mainly due to drought, however, this is the economic base of family agriculture that sustains the region. Thus, a study was carried out to evaluate the effect of the thermal environment on the physiological responses of Holstein-Zebu cows in the semi-arid region of Minas Gerais in order to verify the adaptability of these animals. The experiment was conducted in the summer and winter at the Bela Vista farm located in the Verdelândia city (MG), where 10 cows ¾ Holstein x Zebu (HxZ) were evaluated in each season. The thermal environment was characterized by means of daily measurements of air temperature, relative humidity, air temperature index and humidity and radiant thermal load. The physiological parameters: respiratory and heart rate, body surface temperature and rectal temperature, thickness, hair color and density, and hair length were measured before morning milking, as a function of the seasons of the year for 15 days. Climatic variables and indexes were higher in the summer and in the afternoon. The respiratory rate and the pelt thickness did not differ statistically, however the other variables were higher in the summer.

This study aimed to evaluate the effects of different nutritional plans on the productive, physiological and metabolic parameters of F1 ½ Holstein x ½ Zebu cows in different stages of lactation. Sixty lactating cows were allotted to a completely randomized 5 x 3 factorial design with five feed allowances and three lactation periods. The dry matter intake, milk yield and heart rate were reduced by 5.69kg, 2.41kg and 10.36 beats/min (morning) and 10.25 beats/min (afternoon) for each 1% feed restriction, respectively. There was no difference in the concentration of glucose, total protein, albumin, cholesterol and non-esterified fatty acids for cows subjected to different feed allowances, with means of 95.25, 7.98, 2.95, 121.68 and 0.45mg/dL, respectively. Feed restriction of up to 2.50% BW is a cost reduction strategy that does not alter milk yield, regardless of the stage of lactation.

The objective this study was to assess ergonomic factors, posture and biomechanics of workers of a broiler egg hatchery. The analysis of ergonomic factors was based on physical work load, thermal environment, and exposure to light and noise. The posture of workers was analyzed using photographic records which were evaluated by the software program OWAS (Ovako Working Posture Analysing System). A biomechanics analysis was also performed based on the photographs taken of the employee at various angles, which were used as inputs to the Michigan two-dimensional biomechanical model software program. The results show that certain activities can be considered unhealthy due to the exposure of employees to physical and thermal overload. The continuous noise levels and lighting were outside the range considered adequate by the regulations of the Brazilian Ministry of Labor. The manner in which certain activities are carried out when associated with weight and poor posture can result in body lesions in broiler hatchery employees. It is therefore necessary to apply specific ergonomic programs, including scheduled breaks, training, and other measures in order to reduce or to eliminate the risks involved in these activities.

RESUMO INTRODUÇÃONos países de clima tropical, o aumento na produção leiteira é limitado pelos baixos níveis produtivos das raças nativas e pelas dificuldades adaptativas das raças de origem europeia (Vasconcellos et al., 2003).A eficácia produtiva e reprodutiva dos animais está relacionada à adaptação dos seus genótipos ao conjunto de fatores ambientais que caracterizam o sistema de produção da região, podendo esses ser favoráveis a alguns genótipos e desfavoráveis a outros (Mcmanus et al., 2008). Portanto, para aperfeiçoar a produção leiteira, é importante identificar os genótipos mais convenientes a cada região.Como uma alternativa viável para o aumento da eficiência produtiva, utiliza-se o cruzamento http://dx

The objective of this study was to evaluate the different lactation stages of F1 Holstein x Zebu cows on intake and digestibility of nutrients, nitrogen use efficiency, feeding behavior and performance. Thirty-six F1 Holstein × Zebu cows with initial body weight (BW) of 482±43kg were used. The early, mid and late lactation stages were characterized after 50±13, 111.5±11.75 and 183.0±17.5 days in milk, respectively. A completely randomized design with three lactation stages and 12 cows in each treatment group was used. Dry matter intake (P=0.01) was higher in late lactation. Milk yield (P<0.01) was 24.17% higher in early lactation than in other stages. Body weight was lowest in mid-lactation cows (465.63kg; P<0.01). The feed efficiency was 23.36% higher in early lactation than in other stages (0.82kg of milk/kg of DM). F1 Holstein x Zebu cows have increased dry matter intake in late lactation. Milk yield and feed efficiency in early lactation were benefited by changes in feeding behavior, such as increased rumination time.