Soraia Vanessa Matarazzo

Variabilidade espacial do microclima de um galpão utilizado para confinamento de bovinos de leite

O conhecimento da variabilidade espacial de atributos climaticos e a construcao de mapas de krigagem podem auxiliar no manejo adequado de animais confinados em galpoes. Portanto, o trabalho teve como objetivos caracterizar a variabilidade espacial do microclima de um galpao do tipo free-stall utilizado para confinamento de bovinos leiteiros empregando a tecnica de geoestatistica e verificar se as variaveis climaticas encontram-se dentro dos limites de conforto dos animais. Os atributos microclimaticos - temperatura, umidade relativa, velocidade do vento, luminosidade e indice de temperatura e umidade (ITU) - foram amostrados em 152 pontos, em intervalos regulares de 2m, na forma de malha. Por meio dos resultados obtidos, foi possivel verificar que o uso da geoestatistica possibilitou definir areas com diferentes variabilidades espaciais para os atributos microclimaticos, definindo areas especificas no galpao onde a umidade relativa, a temperatura, a velocidade do vento e a luminosidade estao acima do recomendado para o conforto termico animal. O sistema de climatizacao utilizado nao garantiu a homogeneizacao do ambiente. Os valores de ITU permaneceram fora da condicao de conforto termico, portanto, a condicao de ambiencia do galpao possivelmente nao propicia conforto aos animais.

Efeito da utilização de sistemas de climatização nos parâmetros fisiológicos do gado leiteiro

This research evaluated the thermal efficiency of two evaporative cooling systems, sprinkler and misting, associated with forced ventilation, on the dairy cows thermal stress relief. The study was carried out in a commercial dairy cattle farm located in Sao Pedro city, state of Sao Paulo, Brazil. The duration of the experiment was twenty-eight consecutive days of November 2003, and 10 Holstein cows lodged in a freestall barn were studied. The relative humidity, the dry bulb temperature and black globe temperature were registered every 15 minutes, during all experimental period. Among these cows, five were selected for collecting physiological data (respiratory frequency, rectal temperature and temperature in white and black surfaces) at 9:00 a.m., 11:00 a.m., 1:00 p.m., 3:00 p.m. and 5:00 p.m., during nine non-consecutive days. According to the results, it was concluded that both of the cooling systems studied did not cause any significant differences on the rectal temperature, respiratory frequency and temperature in black surface. However, the temperature in white surface was significantly lower in the sprinkling system, at the time of 11 a.m. and 1 p.m. The misting system reduced significantly the wet bulb temperature, black globe temperature and humidity index, when compared to the sprinkling system. Both cooling systems reduced the maximum wet bulb temperature of the barn compared to the external environment.

Teores plasmáticos de hormônios, produção e composição do leite em sala de espera climatizada

The objective of this study was to evaluate the effects of acclimatization of the milking ambient (ventilation and ventilation + water spraying) on milk production, milk composition (fat, protein, lactose) and plasma concentration of cortisol, T3 and T4. The experiment was conducted from August to October during 90 days. Twenty-one lactating dairy cows with milk yield around 21 kg d-1 were allocated three random treatments. The tested treatments were: 1) waiting room without climatization (CONTR); 2) waiting room with ventilation (V) and 3) waiting room with ventilation + water spraying (VA). Milk production data were collected daily and for milk composition, samples were collected once a week. Blood samples for hormone determination were collected weekly, from the coccigea vein. Data were analyzed by computer program SAS PROC ANOVA. Results showed no significant differences among treatments for milk production; the treatment ventilation had higher fat content; and the control group had higher concentrations of cortisol, T3 and T4 followed by treatments 2 and 3. The treatment VA although increased animal comfort it was insufficient to improve milk production, probably because of short time exposure (30 min).

Respostas fisiológicas de vacas em lactação à ventilação e aspersão na sala de espera

The aim of this study was to evaluate the effects of climatization (ventilation or ventilation plus sprinkler) inside a holding pen in a milking parlor on environmental and physiological parameters. The experiment was conducted from August to October during 90 consecutive days. Twenty-one lactating dairy cows with an average milk yield of 21kg.d-1 were randomly allocated in three treatments. The treatments were: holding pen without cooling (control); holding pen with ventilation (V) and holding pen with ventilation plus sprinkler (VS). The physiological parameters measured were respiratory rate (RR), body temperature (BT) and skin temperature (head, flank and mammary gland). These measurements were taken before and after each treatment. The data on the environmental parameters dry bulb temperature (DBT), black globe temperature (BGT) and relative humidity (RH) were collected both from each treatment session and from a meteorological station at a nearby site three times a day. Results showed that VS reduced DBT (6.4°C) and BGT (6.5°C); and increased the RH. Both V and VS reduced significantly respiratory rate. The skin temperature, with VS showed a decrease of 4.2°C for the head and 2.8°C for the flank. Hence, VS improved the environmental condition and physiological responses and increased heat losses of the dairy cows.

Perfil tecnológico de sistemas de produção de leite resfriado

This study aimed to characterize the dairy producers in Territory of Itapetinga region using a semi-structured questionnaire. Seventeen dairy producers were interviewed and stratified into: small (up to 50kg milk/day), medium (51 to 200kg of milk/day) and large (more than 200kg of milk/day). The data analysis was performed using one-dimensional analysis and nonparametric analysis. Small producers have not been identified. Of all dairy producers interviewed, 17.6% were characterized as medium and 82.4% as large dairy producers. The average time in dairy activity was 22 years to medium dairy producers and 20 years to large dairy producers. The herd genetic composition was crossbreed Zebu x Taurus. The average milk production was 1260kg/milk/lactation to medium dairy producers and 1594kg/milk/lactation to large dairy producers. The lactation period was 274 days to both strata. The age at first calving ranged from 25 to 28 months, respectively, to large or medium dairy producers. The calving interval was 406 days to medium dairy producers and 480 days to large producers. All interviewed dairy producers vaccine their herds against foot and mouth disease. Only one dairy producer realizes the tuberculin´s test. The production systems evaluated showed low use of technologies and require a strategic management to improve animal production.

Effects of environmental modification on mastitis occurrence and hormonal changes in Holstein cows

The purpose of this research was to evaluate the effects of evaporative cooling in freestall on mastitis occurrence, milk production, and composition, as well as cortisol, T3 (triiodothyronine), and T4 (thyroxin) levels in lactating dairy cows. Twenty-eight multiparous cows averaging 70 ± 10 day postpartum were used in four treatments from January to March 2003. The treatments were: Day (cooling from 7:00 a.m. to 7:00 p.m.); Night (cooling from 7:00 p.m. to 7:00 a.m.); 24-hour (cooling 24-hour); and Control (no cooling). Wired cup test was used for clinical mastitis diagnosis, and the California Mastitis Test (CMT) was used to identify subclinical mastitis. Blood and milk samples were taken weekly for microbiological and hormonal analyses. The cortisol levels were higher than normal values in all treatment groups, suggesting stress conditions, but T3 and T4 levels remained normal in all groups. The occurrence of subclinical mastitis was lower in Day and Night groups than in Control and 24-hour groups. Regarding the microbiological analyses, in all groups the isolation of Corynebacterium sp. from milk samples increased while negative coagulase staphylococci (CNS) declined as etiological agents of subclinical mastitis. However, in Day and 24-hour groups, coagulase positive staphylococci (CPS) increased mainly Staphylococcus aureus (49.8% and 47.7% respectively). The Night group showed a decrease in subclinical mastitis occurrences. Our data indicate that all animals subjected to treatments presented high levels of cortisol, indicating a stress condition. The Night treatment presented a reduction in microbial isolation, suggesting a reduced susceptibility to mastitis.