Staphylococcus aureus: Resistance patterns to antimicrobials and Penicillinase among strains isolated from apparently healthy lactating cows

Ninety-two strains of Staphylococcus aureus isolated from the nasal fossa and udder skin of apparently healthy lactating cows were analyzed for resistance to antibiotics and production of penicillinase.The results showed a greater frequency of resistance patterns to penicillin and ampicillin.All strains were sensitive to oxacyllin and gentamicin.The most frequent Barber and Burston model was SSSS (60.90%), followed by RSSS (18.50%).With respect to the production of penicillinase although the Lucas method indicated a larger number of positive samples, we suggest the use of the Haight and Finland method due to a greater consistency of data obtained with it.

Voluntary intake of Tanzania grass (Panicum maximum) under rotational grazing by lactating cows

The study was conducted at Nucleo de Pesquisas Zootecnicas Nordeste of the Instituto de Zootecnia, Ribeirao Preto, SP, in a rotational grazing area of Tanzania grass (Panicum maximum), to estimate the dry matter intake by lactanting cows. The estimation of dry matter intake was calculated from the feces production estimated using extrusa Chromium-mordent and the in vitro digestibility of diet. The three treatments were crossbreed cows fed 3 kg.day(-1) of concentrate, crossbred cows without concentrate suplementation and pure Gir cows also without concentrate supplementation. The milk production was 11.98, 6.53 and 5.46 kg per cow per day, the grass intake was 8.26 +/- 5.66, 11.01 +/- 5.37 and 9.55 +/- 2.31 kg of dry matter per day or 2.15%, 2.37% and 2.34% of live weight for the three experimental groups respectively. The milk production was higher (P<0.01) for cows fed with concentrate. No difference was found for dry matter intake.

Subclinical mastitis caused by staphylococcus aureus: Analysis cost benefit of antibiotic therapy in lactating cows

The cost benefit analysis of treatment of bovine subclinical mastitis caused by S. aureus was evaluated. Two hundred and seventy udder quarters with subclinical mastitis and healthy were selected in four groups, in conformity to lactational stage and with the treatment or not. Group 1 included treated animals 10 to 60 days in milk; group 2 included treated animals 61 days in milk until two months before the end of lactation; group 3 included animals not treated 10 to 60 days in milk; group 4 included animals not treated from 61 days in milk until two months before the end of lactation. Treatment with gentamicin (150 mg) was accomplished by intramammary doses, once a day, after sensitivity tests. The mammary quarters were evaluated after 30 days again. The costs with the treatment were calculated considering a S. aureus prevalence of 5%, expenses with antibiotic, loss in milk, tests of sensitivity and workload. There was loss of income of 2% and 14% in the groups 1 and 2, respectively, when compared with the incomes before treatment. In such case, the treatment of bovine subclinical mastitis by S. aureus in the lactation was economically not practicable.

Effects of propiogenic ingredients on serum concentration of insulin and progesterone in non-lactating cows

Three experiments evaluated serum insulin and progesterone (P4) concentrations in grazing Gir×Holstein cows supplemented with monensin (MON) or propylene glycol (PPG; 2.5mL/kg of live weight0.75 per drench). Cows were non-lactating, ovariectomized, and received an intravaginal drug-releasing device containing 1.9g of P4 to estimate treatment effects on hepatic P4 degradation. In Exp. 1, 15 cows received, in a crossover design containing 2 periods of 21d, 0.1kg/d of corn in addition to 2g/d of kaolin (CON) or 0.2g/d of MON. Blood samples were collected on d 13 and 20 of each period. Cows receiving CON had greater (P<0.05) serum insulin concentrations compared with MON prior to and 6h after feeding. However, MON cows had greater (P=0.01) serum P4 concentrations compared with CON 18h after feeding. In experiment 2, 15 cows received, in a replicated crossover design containing 2 periods of 24h, a single drench of PPG or water (WT). Cows receiving PPG had greater (P<0.01) serum insulin concentrations compared with WT from 0.5 to 3h after drench. However, PPG cows had reduced (P<0.05) serum P4 concentrations compared with WT at 1 and 2h after drench. In experiment 3, 13 cows received, in a replicated 3×3 Latin square design containing 3 periods of 24h, 3 PPG drenches administered 1h apart (PPG3x), 3 WT drenches administered 1h apart, or 1 PPG drench+2 WT drenches administered 1h apart (PPG1x). Serum insulin concentrations increased proportionally to PPG dosage (treatment×hour; P<0.01). However, mean serum P4 concentration was greater (P<0.01) in WT cows compared with PPG1x and PPG3x, but similar (P=0.25) between PPG1x and PPG3x cows. In conclusion, feeding propiogenic ingredients to grazing cows failed to substantially increase serum P4 concentrations. © 2013 Elsevier B.V.

Voluntary intake of dry matter and performance of Nellore cows and their Nellore and crossbred Simental x Nellore calves

This study aimed to investigate the influence of calf genetic group on the performance of Nellore lactating cows. The variables studied included milk ingestion, pasture intake, calf weight gain and cow body weight. A total of 13 Nellore calves and 8 crossbred Simental x Nellore calves were used, all born from Nellore mothers. During the experimental period of 210 days, calves were weighted at birth and at 30-day intervals, whereas cows were weighed every 14 days. Milk intake was estimated using the weigh-suckle-weigh method. Pasture intake was determined 6, 12, and 24 weeks after birth by using chromic oxide as an external marker and indigestible acid detergent fiber as an internal marker. Average weight of crossbred calves was 10.1 kg and their milk intake was 0.42 kg higher than in purebred calves. There was no difference, however, in pasture intake between genetic groups. In Nellore cows, body weight and pasture consumption (9.2 kg of DM/cow/day) were not influenced by calf heterosis.

Voluntary intake of dry matter and performance of Nellore cows and their Nellore and crossbred Simental × Nellore calves

This study aimed to investigate the influence of calf genetic group on the performance of Nellore lactating cows. The variables studied included milk ingestion, pasture intake, calf weight gain and cow body weight. A total of 13 Nellore calves and 8 crossbred Simental × Nellore calves were used, all born from Nellore mothers. During the experimental period of 210 days, calves were weighted at birth and at 30-day intervals, whereas cows were weighed every 14 days. Milk intake was estimated using the weigh-suckle-weigh method. Pasture intake was determined 6, 12, and 24 weeks after birth by using chromic oxide as an external marker and indigestible acid detergent fiber as an internal marker. Average weight of crossbred calves was 10.1 kg and their milk intake was 0.42 kg higher than in purebred calves. There was no difference, however, in pasture intake between genetic groups. In Nellore cows, body weight and pasture consumption (9.2 kg of DM/cow/day) were not influenced by calf heterosis.

Endocrine profiles and ovulation rate of cows superovulated with FSH following passive immunization against steroid free-bovine follicular fluid

Dez vacas multíparas, secas, foram distribuídas aleatoriamente em dois grupos de cinco animais cada. Nos dias 8 a 12 do diestro, o primeiro grupo recebeu 100 ml de anti-soro contra líquido folicular livre de esteróides (anti-LFb) produzido em ovelhas ovariectomizadas. O segundo grupo (controle) recebeu 100 ml de soro de ovelhas não-imunizadas. Seis horas após a aplicação, os dois grupos foram superovulados com FSH (18 NIH-FSH-S1 unidades) e LH (0,29 NIH-LH-S1 unidades) administrados em quantidades decrescentes durante quatro dias. Na manhã do terceiro dia, foi administrada uma dose luteolítica de cloprostenol. Duas inseminações foram realizadas 48 e 60 horas após. Os embriões foram recuperados pelo método cervical 7 dias após a primeira inseminação. Amostras de sangue foram coletadas durante todo o período experimental para determinar, por radioimunoensaio, as concentrações plasmáticas de FSH, LH e progesterona. Todas as vacas do grupo imunizado e 3 do grupo controle apresentaram mais de 2 CL. Não existiu diferença significativa (P>0,05) na taxa de ovulação entre os grupos imunizado e controle (14,4 e 9,9, respectivamente). O número de embriões recuperado não foi significativamente diferente (P>0,05) entre os grupos, embora o grupo imunizado tenha apresentado maior número de embriões transferíveis (3,4 ± 1,0 versus 0,8 ± 0,4, P<0,05). As concentrações de gonadotrofinas plasmáticas não foram correlacionadas com a taxa de ovulação ou com o número de embriões recuperados. As concentrações de progesterona plasmática foram positivamente correlacionadas (r = 0,88, P<0,01) com a taxa de ovulação. Os resultados sugerem que o anti-LFb, aplicado antes da superovulação, não reduz a variabilidade da resposta ovariana.

Prediction of dry matter intake based on ruminal degradation from milking cows grazing coast-cross grass

Dry matter intake (DMI) of coast-cross grazing by crossbred Holstein-Zebu and Zebu lactating cows was calculated using in vitro dry matter digestibility from extrusa (four esophageal fistulated cows) and fecal output estimate with mordent chromium. Pasture was rotationally grazed with three days grazing period and 27 days testing period, adopting a stocking rate of 1.6 and 3.2 cows/ha, during the dry and rainy season respectively. Voluntary DMI was estimated from degradation characteristics using different equations. Predicted coast-cross DMI varied with models. The prediction of tropical forages dry matter intake from equations based in ruminal degradation parameters needs farther investigation before being employed in practice.

Acute reduction in serum progesterone concentrations after feed intake in dairy cows

This study tested the hypothesis that high feed consumption will acutely decrease circulating progesterone concentrations. In the first experiment, a Latin Square design was used to test whether feeding pattern would alter circulating progesterone in pregnant lactating Holstein cows (n = 12). Feed was removed for 12 h before the experiment and cows were then either fed 100% of the total mixed ration (TMR), 50% of TMR every 12 h, 25% of TMR every 6 h, or left unfed for an additional 12 h. Blood samples were taken every hour for 24 h. Provision of 100 or 50% of TMR decreased circulating progesterone by 1 h after feeding and progesterone remained depressed until 8-9 h after feeding. Feeding 25% of TMR did not reduce circulating progesterone concentrations. Experiment 2 used a crossover design to measure the effect of acute feeding on circulating progesterone and LH concentrations during delivery of a constant amount of exogenous progesterone (Eazi-Breed CIDRs) in lactating Holstein cows (n = 8) and nonpregnant dry Holstein cows (n = 6). Blood samples were taken every 15 min for 8 h. There was no change in serum progesterone during the 8 h treatment period in unfed cows; however, feeding decreased (P < 0.05) circulating progesterone between 2 and 6 h after feeding. In lactating cows, feeding increased mean LH (P < 0.05). There were more LH pulses (P = 0.01) in lactating than nonlactating cows. Thus, acute feeding reduced circulating progesterone in pregnant lactating cows apparently due to an increase in progesterone metabolism. Interestingly, feeding multiple smaller meals eliminated the acute effect of feeding on circulating progesterone. © 2003 Published by Elsevier B.V.

Incidence of subclinical endometritis and its effects on reproductive performance of crossbred dairy cows

In dairy cattle, uterine infections are not life threatening and often unavoidable; however, they reduce fertility and increase the production costs of properties. The aim of this study was to evaluate the incidence of subclinical endometritis from 32 to 70 days in milk (DIM) and its effects on the reproductive performance of crossbred dairy cows. Lactating cows (Holstein/Gir; n = 172), with no history of retained placenta, without clinical signs of uterine infection were used. The body condition score (BCS) was evaluated on a scale from 1 to 5. Ultrasound examination was performed to evaluate uterine lining and ovarian activity, while vaginal mucus was analyzed by gloved hand. The diagnosis of subclinical endometritis was performed by endometrial cytobrush technique. The samples were collected, stained, and examined microscopically; positive cases for subclinical endometritis were considered with the presence of a parts per thousand yen5 % of neutrophils. Later, the cows were submitted to conventional artificial insemination or timed artificial insemination. The incidence of subclinical endometritis in the herd was 26 %, and this was not affected by the season of calving, presence of corpus luteum, DIM, and parity. Cows with a BCS a parts per thousand currency sign2.50 had a higher incidence of subclinical endometritis. The conception rate to first insemination and pregnancy rate at 150 days postpartum were not influenced by the presence of subclinical endometritis in crossbred dairy cows.

Fluorescent amplified fragment length polymorphism genotyping of human and animal Staphylococcus aureus isolates from dairy farms with manual milking

Fluorescence amplified fragment length polymorphism (fAFLP) was used to assess the genetic relatedness of 40 Staphylococcus aureus strains isolated from human and animal skin samples in seven dairy farms with manual milking. S. aureus was isolated from 11 out of 30 (36%) human skin samples and from 29 out of 100 (29%) teat skin samples from apparently healthy cows. Genomic DNA from each isolate was double-digested with EcoRI and MseI and complementary oligonucleotide adaptors were ligated to the restriction fragments. Pre-selective and selective, amplification reactions were performed, the amplified fragments were separated by electrophoresis in an ABI377 sequencer and analysed using GeneScan 3.1 and Genotyper 2.5. Three single isolates (a-c), a predominant cluster with 35 isolates (d) and another cluster with two isolates (e) were identified. Both clusters d and e included human and animal isolates genetically related, because the profiles had 90-100% homology. Since no cluster was comprised uniquely of human or animal isolates and given the close genetic relatedness among human and animal samples in the farms, the present findings support the. hypothesis that dairy workers can spread S. aureus through manual milking. (C) 2005 Elsevier B.V. All rights reserved.

Influence of the season of year, stage of lactation and milking time on the chloride content in bovine milk

From January to October 1995, chloride content determinations were accomplished in 2,218 samples of milk collected from 67 quarters of 17 lactating cows, in initial, middle and final stages of lactation, in the morning and afternoon milking. The highest means of chloride contents were observed among the milk samples collected in the final stage of lactation (0,203 gC1/100ml), in the summer (0,212 gC1/100ml) and in the morning milking (0,189 g C1/100ml). The differences observed between the chloride contents in the samples obtained in the different stages of lactation and the seasons of the year were statistically significant (P<0.0001). The gratest occornce of chloride at rates superior to 0.22 gC1100ml was observed in the final stge of lactation (31.4%), summer (44.2%) and after the morning milking (27.8%). These results evidentiate the influence of physiological and external factors (stage of lactation and season of the year) on the concentration of chloride of milk.

Estudo da papila mamária em fêmeas bovinas (Bos taurus - Linnaeus, 1758), mediante as características ultra-sonográficas em modo-B (tempo real)

Nesta pesquisa foram utilizadas vinte fêmeas bovinas, sem patologias aparentes nas glândulas mamárias, em lactação, objetivando avaliar estruturas anatômicas das papilas mamárias. Quatro técnicas ultra-sonográficas foram avaliadas. Utilizou-se transdutor linear de 7,5 MHz para uso endoretal, na obtenção das imagens, padronizando-se o lado direito do animal para visualização das papilas craniais e caudais, em dois planos anatômicos (sagital e transversal). Os animais foram divididos em quatro grupos (G1, G2, G3, G4) que representaram as diferentes técnicas empregadas em momentos distintos (antes e após ordenha). Os resultados indicaram que entre as técnicas estudadas, as de exame direto e com uso de almofadada de silicone, foram as que apresentaram maior aplicabilidade, quando considerada a sua facilidade de uso na rotina com complementação do exame clinico. Entretanto, pólipos e cálculos lácteos tem sua extensão e localização convenientemente visibilizados mediante uso da técnica de pressão de liquido. Já a técnica de imersão em água, mostrou-se mais eficiente quanto à qualidade das imagens obtidas e na caracterização das estruturas anatômicas. O experimento realizado, traz subsídios anatomo-topográfico que irão contribuir com a qualidade do diagnóstico em pacientes que possam ter indicação cirúrgica (telotomia) e levanta questões que poderão ser respondidas conforme a casuística e a experiência consolidada do cirurgião.