Juliana Rodrigues Pozzi Arcaro

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).

Molecular Typing of Mastitis-Causing Staphylococcus aureus Isolated from Heifers and Cows

Staphylococcus aureus is among the main etiologic agents of bovine mastitis. A total of 83 isolates of S. aureus from mammary glands of primiparous heifers were collected in the prepartum, calving and during lactation. For lactating cows, a total of 27 isolates of S. aureus from mammary glands were collected during lactation. The samples were taken in two dairy farms located in Sao Paulo State, Brazil. The highest frequency of S. aureus isolation in heifers was at the end of lactation. Strains were typified through Pulsed-field gel electrophoresis (PFGE) and grouped according to patterns of restriction enzyme SmaI. PFGE generated seven clonal profiles that were grouped into three different lineages, with the LA lineage being predominant and identified in heifers, as well as in the cows from the two regions studied. It was concluded that the cows showed a significant source of dispersion of S. aureus. At the first lactation the heifers were infected by the same clonal profiles of S. aureus which were isolated from multiparous lactating cows. The heifers were infected during milking over the months of lactation.

Silagem de cana-de-açúcar em substituição a silagem de sorgo granífero para vacas leiteiras

Twelve Holstein and Schwyz lactating cows were used in a switch-back trial to evaluate the following silages corrected to a same nitrogen level by addiction of cottonseed meal, to supply the required nutrients for maintenance and production of the eight first kg of milk per cow by day, concentrate meals being used to supplement the milk produced above this level: Treatment A) grain sorghum silage; Treatment B) 50% grain sorghum silage and 50% sugar cane silage; Treatment C) sugar cane silage. Milk production per cow per day was respectively 12.9 kg, 12.3 kg and 11.8 kg and treatment A was superior to C (p<0.05). Total dry matter consumption by 100 kg of body live-weight (3.0kg, 3.0kg and 2.8kg), as the TDN consumptions (9.2kg, 8.8kg and 8.0kg) for treatments A,B and C respectively, presented no statistical differences. Twelve Ideal breed lambs were used to run an apparent digestibility trial with the same treatments applied to the lactating cows: the dry matter digestibility values were 54.4%, 56.8% and 52.0% respectively for A,B and C treatments, with no statistical differences among them.

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.

Investigation of biofilm production and icaA and icaD genes in Staphylococcus aureus isolated from heifers and cows with mastitis.

Biofilm formation and antimicrobial resistance of Staphylococcus aureus are important virulence factors in cases of mastitis in dairy cows. However, few studies have investigated mastitis strains isolated from heifers. Within this context, the objective of the present study was to investigate biofilm formation on Congo red agar, the presence of the icaA and icaD genes by polymerase chain reaction (PCR), and the percentage of in vitro antimicrobial resistance of 110 S. aureus isolates from mammary gland secretions of heifers and cows with mastitis. PCR detected the icaA and icaD genes in 98% and 100% of isolates, respectively. However, only 55.5% of all isolates produced a biofilm on Congo red agar. Antimicrobial susceptibility testing revealed that 47.0% of isolates from heifers and 70.4% of isolates from cows were resistant to at least one of the antimicrobial agents tested. Resistance to penicillin and/or ampicillin was the most frequent (44.5%). These results indicate the need to implement prophylactic and control measures of mastitis for heifers. Heifers and cows can carry resistant strains with the capacity of biofilm production, a fact representing a threat to public health and animal well-being and generating losses to dairy farmers.

Desempenho de bezerros recebendo silagens de sorgo ou de cana-de-açúcar como únicos alimentos volumosos

Silagens de sorgo granifero (tratamento SS) e de cana-de-acucar (tratamento SC), suplementadas com farelo de algodao para ajustar o nivel proteico das dietas a 16%, foram fornecidas a bezerros da raca Holandesa variedade malhada de preto, para avaliacao de seus desempenhos em termos de consumo de alimentos, ganhos de peso e conversoes alimentares. Os animais apresentaram media de peso de 97,7 ± 1,0 kg ao inicio do periodo de adaptacao, de 14 dias, ao qual seguiu-se periodo experimental de 70 dias. Os resultados mostraram que o tratamento com silagem de sorgo granifero foi superior ao com cana-de-acucar (p 0,05).

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.

Eficácia do tratamento Ovsynch associado à inseminação artificial prefixada em rebanhos Bos taurus e Bos indicus

The present study aimed to evaluate the efficiency of Ovsynch treatment associated with prefixed-time artificial insemination on Bos taurus and Bos indicus cows. Herds of Holstein, Caracu, Nelore and Mantiqueira breeds were used. A herd of Gir cows with poor reproductive performance was also included. Each breed was divided in tree groups. Group 1 received Ovsynch treatment and was inseminated at prefixed time. Group 2 was induced to estrus with cloprostenol and inseminated thereafter. Group 3 was inseminated at natural heat. Conception and pregnancy rates were determined by ultra-sound. No significant interactions were detected among breeds, age, parity, postpartum period and lactating cows with or without their calves. Conception rates did not differ (P>0.05) among groups while pregnancy rate was higher (P<0.05) for group 1 and 2 comparing to group 3. In the Gir herd Ovsynch treatment did not enhance conception nor pregnancy rates. Independently of breed, conception rate is similar after Ovsynch, cloprostenol and control treatments, and pregnancy rate can be improved with Ovsynch and cloprostenol treatments. In cows with unspecific reproductive ovarian disorders, Ovsynch treatment do not enhance conception or pregnancy rates.