Irineu Arcaro Júnior

Influência de ventilação e aspersão em sistemas de sombreamento artificial para vacas em lactação em condições de calor

The present research was carried out at Animal Science Institute, in Sao Paulo and had the objective of evaluating three different types of cooling systems (physical) to reduce thermal stress for milking cows. The tested treatments used artificial shade using a propylene screen 80% direct solar radiation reduction; the same shade using a 0.5 HP fan; and the same shade structure using a 0.5 HP fan with fogging system. Eighteen milking cows were used in the treatments - 12 Holstein cows and 6 brown swiss - equally distributed in the treatments according to their age and milk production level. The parameters analyzed were: milk production and fat content, body temperature, respiratory frequency, and cardiac frequency. Environmental parameters measured were: dry bulb, black globe temperature and relative humidity, collected in each treatment and at a meteorological station at a nearby site. The results showed that the best treatment was the shade using forced ventilation associated with a fogging system.

Aspectos relacionados à ocorrência e mecanismo de ação de fumonisinas

Fumonisins are micotoxins produced by a fungus of the genera Fusarium, one of the main fitopathogens that occur in maize. Isolated in 1988, from moudly corn samples in a high incidence area of esophageal cancer in Africa, fumonisins are related with several diseases including equine leucoencephalomalacia and porcine pulmonary edema and hydrothorax. The present review approaches the natural occurrence of fumonisins in maize, its physical and quimical molecular characteristics and toxicological effects in horses, porcine, poultry and cattle. This review also discusses the micotoxins pathophisiology.

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.

Selenium sources in the diet of dairy cows and their effects on milk production and quality, on udder health and on physiological indicators of heat stress

Twenty-four dairy cows, with daily average milk production of 18.1 kg, were fed diets containing different selenium (Se) sources. The purpose of this paper is to evaluate the effects of such diets on milk production and quality, on the occurrence of mastitis, and on physiological variables. During the experimental period (124 days), all the cows received the same diet: a total mixed feed with 0.278 mg.kg-1 DM of selenium. In the inorganic Se treatment, the selenium source was sodium selenite and in the organic Se treatment the source was selenium yeast (Saccharomyces cerevisiae CNCM I-3060). There were no significant differences in milk yield or in Se concentration in the milk. No significant differences between the treatments were observed in protein, lactose, solids-not-fat andpercentage of total solids. The animals subjected to the organic Se treatment presented higher (P=0.013) percentage of milk fat and lower (P=0.014) somatic cell count (SCC) than those subjected to the inorganic Se treatment. There was no significant difference in subclinical mastitisas determined by the California Mastitis Test (CMT) between the treatments. However, both Se sources reduced the incidence of mastitis (subclinical positive mastitis and strongly positive mastitis) between the pre-experimental and experimental phases. There was no significant difference in rectal temperature (RT) between the treatments. Respiratory frequency (RF) was lower (P=0.027) in the inorganic treatment than in the organic one, whereas haircoat temperature (HT) was lower (P=0.007) in the organic treatment than in the inorganic one.

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.

Effects of housing systems on physiological responses of newborn Holstein calves

The objective of this work was to evaluate the effects of housing system on the physiological responses of newborn Holstein calves. The experiment was carried out during the summer of 2006. Twenty female Holstein calves, 1-month old and 46.2±7.0 kg of body weight were randomly assigned to the treatment groups. Treatments were: individual shelter covered with recycled tiles maintained on pasture or individual cage maintained inside the barn. The calves were fed milk (4L/day) during all experimental period. Also, were offered Tifton hay and a started concentrate ad libitum. Physiological data, as respiratory frequency (RF), rectal temperature (RT) and skin temperature (ST), were taken each 2-hour from 08:00 a.m. to 04:00 p.m. Dry bulb temperature (DBT), air relative humidity (RH) and black globe temperature (BGT) inside and outside of facilities were measured every 15 minutes through a period of 24 hours. Rectal temperature did not differ (P>0.05) among animals from different treatments. The respiratory frequency and skin temperature were higher during the afternoon in calves kept in individual cage.

Physiological evaluation of heat stress in gestating sows under different housing systems in bedding and concrete floor

The purpose of this paper was to observe the use of bedding (wood shavings) in physiological variables that indicate thermal stress in gestating sows. The experiment was conducted in order to evaluate the effect of two types of floor (concrete and wood shavings). Worse microclimatic conditions were observed in bedding systems (P 0.05) but the skin surface temperature was higher in the bedding systems. The same occurred with the respiratory rates. The physical characteristics of the floor material influenced the rate of heat loss by conductance. Estimated values were 35.04 and 7.99 W m-2 for the conductive heat loss between the animal and floor for treatments with or without bedding, respectively. The use of bedding in sow rearing has a negative impact on microclimatic conditions, what implies in thermoregulatory damages.