Physiological responses and adaptability of ¾ Hostein X Zebu cows to semiarid climate / Respostas fisiológicas e adaptabilidade de vacas ¾ Holandês x Zebu ao clima do semiárido

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.Climatic variables induced differences in the physiological parameters, but were assimilated by the animals, which leads to the conclusion that ¾ HxZ cows adapt to the climate of the semi-arid region of Minas Gerais without showing a situation of thermal stress.

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.

Physiological responses and adaptability of ¾ Hostein X Zebu cows to semiarid climate / Respostas fisiológicas e adaptabilidade de vacas ¾ Holandês x Zebu ao clima do semiárido

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.Climatic variables induced differences in the physiological parameters, but were assimilated by the animals, which leads to the conclusion that ¾ HxZ cows adapt to the climate of the semi-arid region of Minas Gerais without showing a situation of thermal stress.(AU)

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.(AU)

Effect of litter substrates on the performance, carcass traits, and environmental comfort of red-winged tinamou (Rhynchotus rufescens)

The study aimed at evaluating the effect of litter substrates on the performance, carcass traits, and environmental comfort of red-winged tinamou (Rhynchotus rufescens). In this experiment, 160 birds, with 100 and 300 days of age, were housed into 20 pens, and distributed according to a completely randomized experimental design into five treatments with four replicates of eight birds each. Treatments consisted of five litter substrates: wood shavings, rice husks, peanut hulls, grass hay, or sand. Feed intake; weight gain; breast, hock, and footpad lesions; back feathering; total meat production; carcass and parts yield; and leukocyte counts were evaluated. Litter substrates were analyzed for dry matter content, standard microbial count, ammonia volatilization potential, water content, water holding capacity, temperature, and radiant heat load. The results showed that litter substrate did not influence the evaluated bird parameters, despite the higher microbial counts and released ammonia values determined in peanut hulls and sand, respectively. Sand also tended to have higher average temperature than the other litter substrates. It was concluded that litter substrate should be chosen at farmer discretion, taking into consideration its cost and utilization after use.

Effect of litter substrates on the performance, carcass traits, and environmental comfort of red-winged tinamou (Rhynchotus rufescens)

The study aimed at evaluating the effect of litter substrates on the performance, carcass traits, and environmental comfort of red-winged tinamou (Rhynchotus rufescens). In this experiment, 160 birds, with 100 and 300 days of age, were housed into 20 pens, and distributed according to a completely randomized experimental design into five treatments with four replicates of eight birds each. Treatments consisted of five litter substrates: wood shavings, rice husks, peanut hulls, grass hay, or sand. Feed intake; weight gain; breast, hock, and footpad lesions; back feathering; total meat production; carcass and parts yield; and leukocyte counts were evaluated. Litter substrates were analyzed for dry matter content, standard microbial count, ammonia volatilization potential, water content, water holding capacity, temperature, and radiant heat load. The results showed that litter substrate did not influence the evaluated bird parameters, despite the higher microbial counts and released ammonia values determined in peanut hulls and sand, respectively. Sand also tended to have higher average temperature than the other litter substrates. It was concluded that litter substrate should be chosen at farmer discretion, taking into consideration its cost and utilization after use.(AU)