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O Osterås

Publications and source records attributed to O Osterås.

At least 19 recordsLinked to original sources

Milk culture results in a large Norwegian survey--effects of season, parity, days in milk, resistance, and clustering.

A nationwide random computerized assignment survey that included 3,538 sets of 4 quarter milk samples from 2,834 dairy cows was conducted during 2000. Every fifth cow from every 50th herd was randomly selected for sampling and culture during each quarter of the year. Milk culture results of pathogens known to be related to mastitis were recorded regardless of whether mastitis had been indicated by any inflammatory measure or not. Farmers were blinded to all test results to minimize any potential interventions that might be prompted by the results. The most prevalent isolate was Staphylococcus aureus, which was identified in 8.2% of the quarter milk samples. More than 15 colony-forming units/0.01 mL of Staph. aureus were found in 4.3% of the quarter milk samples, whereas 3.5% had only 1 to 3 colony-forming units/0.01 mL. Streptococcus dysgalactiae, coagulase-negative staphylococci (CNS), and Streptococcus uberis were isolated from 1.2, 3.3, and 0.4% of quarter milk samples, respectively. No isolates were found in 76.6% of the quarter milk samples tested. Among individual cows, 22.2% had an isolate of Staph. aureus in > or = 1 quarter. Only Strep. dysgalactiae exhibited a higher prevalence with increased parity. Prevalence of Staph. aureus decreased throughout days in milk, but prevalence of Strep. dysgalactiae increased. There was a strong seasonal effect; the highest prevalence of Strep. dysgalactiae and CNS was observed during April and May (late indoor season), and the highest prevalence of Staph. aureus and Strep. uberis was observed during June and July (the outdoor season). A substantial within-cow clustering effect was found for Strep. dysgalactiae, Staph. aureus, and CNS. Additionally, a within-herd effect was found for Strep. uberis, penicillin-resistant Staph. aureus, total Staph. aureus, and CNS. No within-county cluster effect was found. Lastly, both Staph. aureus and CNS exhibited a surprisingly high seasonal effect regarding the prevalence of resistance to penicillin G. Penicillin resistance of Staph. aureus was likely due to higher prevalence of Staph. aureus as a whole, but for CNS, there was also an additional increase caused by a higher proportional rate of penicillin resistance during the late indoor season.

Animals↗

Relationships between milk culture results and treatment for clinical mastitis or culling in Norwegian dairy cattle.

In quarter milk samples from 2,492 randomly sampled cows that were selected without regard to their current or previous udder health status, the relationships between the following outcome variables were studied: treatment of clinical mastitis; the joint event of either treatment or culling for mastitis; culling for all reasons; culling specifically for mastitis; and the covariates of positive milk culture for Staphylococcus aureus, Streptococcus spp., and coagulase-negative Staphylococcus spp., or other pathogens, or of negative culture for mastitis pathogens. Microbiological diagnoses were assigned at the cow level, and altogether 3,075 diagnoses were related to the outcome variables. The relation between the absence of pathogens and rich (>1,500 cfu/mL of milk) or sparse (<or=1,500 cfu/mL of milk) growth of Staph. aureus were also assessed separately for each outcome variable. The hazard of treatment of clinical mastitis was greater for cows diagnosed with Staph. aureus compared with cows with no pathogens in all analyses. Cows with sparse growth of Staph. aureus upon microbiological analysis were more likely to be treated for clinical mastitis, and cows with rich growth of the bacteria experienced a higher overall risk of culling when the models adjusted for cow composite milk somatic cell count. No difference between rich and sparse growth of Staph. aureus was found when mastitis was defined as the joint event of either culling for mastitis or treatment of clinical mastitis, and when the relationship with culling specifically for mastitis was assessed. The combined outcome of treatment and culling for mastitis was related to a positive diagnosis of Strep. spp. after cow composite milk somatic cell count was omitted from the model. Presence of Streptococcus spp. was also related to culling specifically for mastitis, whereas culling for all reasons and treatment of clinical mastitis was not related to a positive culture of Strep. spp. Presence of coagulase-negative Staph. spp. or other pathogens was not associated with either of the outcome variables.

Animals↗

Plasma vitamin E and blood selenium concentrations in Norwegian dairy cows: regional differences and relations to feeding and health.

Plasma alpha-tocopherol (vit E) and blood selenium (Se) concentrations in February were determined in samples from 314 dairy cows in Norway, selected to provide a representative subset of the Norwegian dairy cow population. Each sample was followed by a questionnaire with information about feeding of the cow at the time of sampling. The results were correlated to herd data and to calving and health data for each cow from the Norwegian Dairy Herd Recording System and the Norwegian Cattle Health Recording System. The mean concentrations were 6.9 microg vit E per ml plasma and 0.16 microg Se per g blood. Both levels were highest in mid lactation. Plasma vit E varied with the amount of silage fed to the cow, while blood Se varied with the amount of concentrates and mineral supplements, and with geographical region. No differences in vit E or Se levels were found between cows with recorded treatments for mastitis, parturient paresis or reproductive disorders in the lactation during or immediately prior to sampling, and those without such treatments. For ketosis, a small difference in blood Se was found between the groups with or without recorded treatments. It is concluded that winter-fed lactating cows in Norway had an adequate plasma level of vit E and a marginal-to-adequate level of Se.

Animal Feed↗

Lameness and claw lesions of the Norwegian red dairy cattle housed in free stalls in relation to environment, parity and stage of lactation.

Approximately 88% of Norwegian dairy cattle are housed in tie stalls. Free stall housing for all dairy cattle will be implemented within 20 years. This means that the majority of existing stalls will be rebuilt in the near future. Fifty-seven free stall herds of the Norwegian Red breed were randomly selected and 1547 cows and 403 heifers were trimmed by 13 claw trimmers during the late winter and spring of 2002. The claw trimmers had been taught diagnosing and recording of claw lesions. Environment, management- and feeding routines were also recorded. Fifty-three herds had concrete slatted alleys while 4 had solid concrete. Thirty-five herds had concrete as a stall base, while 17 had rubber mats, 2 had wood and 3 had deep litter straw beds. The prevalence of lameness was 1.6% in hind claws. Models for lameness and claw lesions were designed to estimate the influence of different risk factors and to account for the cluster effects within herd and claw trimmer. Detected risk factors for lameness were: parity three and above and narrow cubicles; for heel horn erosions: lactation stage around 5-7 months after calving and solid concrete alleys; for haemorrhages of the white line: lactation stage around 3-5 months after calving and solid concrete alleys; for haemorrhages of the sole: parity one, lactation stage around 5-7 months after calving and short cubicles, for white line fissures: slatted concrete alleys; for asymmetrical claws: parities two and above and for corkscrewed claws: solid concrete alleys. The prevalence of lameness in heifers was low, however 29% had one or more claw lesions. Heifers that were housed in pens or free stalls had more heel-horn erosions, haemorrhages of the sole and white-line fissures than heifers in tie stalls. As new free stalls are being built, it is important to optimise the conditions for claw health.

Animals↗

Blood selenium associated with health and fertility in Norwegian dairy herds.

A survey of blood selenium (Se) concentrations in Norwegian Red heifers and dry period cows was conducted to reveal possible association to management, feeding, health and fertility. Selenium contents were determined in 254 herd blood samples consisting of pooled samples from individual non-lactating animals from herds in 5 counties. The Se concentrations showed a normal distribution with mean 0.09 microg Se/g blood, with a standard deviation (SD) of 0.05, and ranged from 0.02 to 0.23 microg/g, with 50 % of the samples being between 0.06 and 0.11 microg/g. The herds with Se concentrations below 0.06 microg/g were smaller (21.4 +/- 8.7 cow-years) than those with Se levels above 0.11 microg/g (27.5 +/- 14.1 cow-years) (P<0.01), but there were no differences in milk yield, incidence of replacement, proportion of animal culling, amount of concentrate or grass silage as percentage of energy consumption between the groups. Treatment registration records showed a tendency that more animals in the low Se herds were treated for all the diseases included in this investigation (64.8 animals per 100 cow-years) than those in the high Se herds (57.5 per 100 cow-years), while no such differences were revealed for individual disorders. There was, however, a significant difference in bulk milk somatic cell counts (BMSCC) between low and high Se herds, their values being 137 000 and 155 000 cells/ml, respectively. This difference was significantly influenced by herd size. Furthermore, a total of 4916 lactations were analyzed from individual health and fertility recordings, including 2 934 first lactations and 1 982 later lactations. The present study revealed a reduced incidence of disease treatment with increased Se concentrations from 0.02 to 0.23 microg Se/g blood. In this regard, there seemed to be an optimum of 0.10 to 0.15 microg Se/g for all types of mastitis treatments summarized, and for treatment of retained placenta. Thus, herd Se concentrations below and above these values was connected with increased probability for sum mastitis and retained placenta, reflecting the effect of the quadratic term of Se. The cow (composite) milk somatic cell count (SCC) was lower in lactations from low Se herds than in high Se herds with a marked SCC increase in the Se concentration interval from 0.11-0.13 microg/g blood. In conclusion, heifers and dry period cows in Norway are low in blood Se content and there seems to be a positive association between increased blood Se concentration pre partum and decreased incidence of mastitis, ovarian cysts and anoestrus/silent oestrus post partum.

Animal Feed↗

Cumulative risk of bovine mastitis treatments in Denmark, Finland, Norway and Sweden.

Data from the national dairy cow recording systems during 1997 were used to calculate lactation-specific cumulative risk of mastitis treatments and cumulative risk of removal from the herds in Denmark, Finland Norway and Sweden. Sweden had the lowest risk of recorded mastitis treatments during 305 days of lactation and Norway had the highest risk. The incidence risk of recorded mastitis treatments during 305 days of lactation in Denmark, Finland, Norway and Sweden was 0.177, 0.139, 0.215 and 0.127 for first parity cows and 0.228, 0.215, 0.358 and 0.204 for parities higher than three, respectively. The risk of a first parity cow being treated for mastitis was almost 3 times higher at calving in Norway than in Sweden. The period with the highest risk for mastitis treatments was from 2 days before calving until 14 days after calving and the highest risk for removal was from calving to 10 days after calving in all countries. The study clearly demonstrated differences in bovine mastitis treatment patterns among the Nordic countries. The most important findings were the differences in treatment risks during different lactations within each country, as well as differences in strategies with respect to the time during lactation mastitis was treated.

Animals↗

Factors prior to dry period associated with high and low levels of cow milk somatic cell counts in next lactation.

Data from a randomized controlled field study of selective dry cow therapy were used in which 686 cows had been allocated to 2 control groups (sampling only or placebo) or 2 therapy groups. Possible factors from previous lactation were assessed in determining their association with the probability of 'failure', designated as a cow milk somatic cell count (CMSCC) of greater than 399,000 per ml in geometric mean of several measurements during subsequent lactation. Success cows were those with a CMSCC of less than 200,000 per ml. For our analyses, this targeted 187 success cows and 186 failure cows. Therapy was given as a total dose of 400,000 IU penicillin and 100 mg neomycin per infected quarter as dry cow preparation once, or as a lactation formula with a total dose of 1.2 million IU penicillin and 1,200 mg dihydrostreptomycin per infected quarter during a 1-week period. Significant factors in the predictive model for success included therapy, low level of CMSCC (geometric mean of the 3 last tests) in previous lactation, low level of CMSCC (weighted by daily milk yield mean) in the herd, young cows, and not having had a case of treatment for chronic clinical mastitis. Additional information on the probability of failure in treated and untreated cows can be predicted by number of quarters infected with Staphylococcus aureus approximately 1.5 months before drying off. The models derived are considered for use as tools in selective treatment and culling decisions.

Animals↗

Possible risk factors associated with penicillin-resistant strains of Staphylococcus aureus from bovine subclinical mastitis in early lactation.

A randomized controlled field study of selective dry cow therapy with 686 cows allocated to two control groups (sampling only or placebo) or two therapy groups was used to screen for possible factors associated with penicillin-resistant strains of Staphylococcus aureus after the dry period. Therapy was given either as a total dose of 400,000 IU of penicillin and 100 mg of neomycin per infected quarter as dry cow preparation or as a total dose of 1.2 million IU of penicillin and 1200 mg of dihydrostreptomycin per infected quarter as a lactation formula. Success cows had all quarters identified as being free of penicillin-resistant strains of Staphylococcus aureus both at calving and at 30 +/- 17 d after calving. Failure cows were those having penicillin-resistant strains of Staph. aureus in any quarter at both or one of these two samples after the dry period. Using logistic regression, four variables were found to be associated with penicillin-resistant strains of Staph. aureus after the dry period. These included the identification of penicillin-resistant strains of Staph. aureus either at 45 +/- 32 d before drying off and at drying off, treatment for acute clinical mastitis at least once during the previous lactation, the weighted SCC of all cows' milk by daily milk yield within the herd, and therapy in the lactation formula compared with the two control groups. Our finding that the use of lactation formula increases the risk of resistance development is contradictory to present arguments underlying Norwegian dry cow therapy strategy.

Animals↗

Determinants of success or failure in the elimination of major mastitis pathogens in selective dry cow therapy.

Discriminant factors for the elimination of major pathogens (mainly Staphylococcus aureus and Streptococcus dysgalactiae) were identified from a randomized, double-blind, field study on dry cow therapy. From an original study of 686 cows, 269 fulfilled the criteria for this analysis: 93 from the control group, 83 from group C (treated with Benestermycin vet. "LEO") and 93 from group D (treated with Leocillin with Dihydrostreptomycin vet. "LEO"). A "success" cow was defined as a cow that had all quarters healthy in two tests after dry period. Isolation of a major pathogen (mainly Staph. aureus or Strep. dysgalactiae) in any quarter in both samples after the dry period was defined as "failure." Better elimination was associated with short-acting preparations (therapy D) rather than with long-acting therapy C (odds ratio = 0.32), as was a smaller mean value of the last three composite milk somatic cell counts (CMSCC) before dry cow therapy. Cows with a major pathogen in the right hind quarter at drying off or at least one case of acute clinical mastitis during the previous lactation were more likely to have a major pathogen in the next lactation (odds ratio = 4.1 and 3.6, respectively). Young cows without major pathogens at drying off should not be recommended for dry cow therapy, and cows with high CMSCC should be considered for culling if their profiles also show previous acute clinical mastitis in combination with generally high CMSCC and low cure rates in the herd.

Animals↗

Comparison of ketosis, clinical mastitis, somatic cell count, and reproductive performance between free stall and tie stall barns in Norwegian dairy herds with automatic feeding.

Differences in ketosis and clinical mastitis rates, mean somatic cell counts (SCC) and reproductive performance scores (fertility status index = FS-index) between herds housed in free stall (n = 533) and tie stall (n = 59) barns were measured in relation to management and environmental factors in a retrospective cohort study of Norwegian dairy farms with automatic grain feeding systems. Herds with tie stalls were found to have a higher clinical mastitis rate, (61.6 cases per 100 cow-years versus 46.4 cases per 100 cow-years (p < 0.01)); a significantly higher proportion of herds with ketosis, (relative risk = 1.59, (p < 0.01)); and a lower mean fertility status index, (67.3 versus 82.8 (p < 0.01)). No significant difference in mean SCC was found between the 2 groups of dairies (p = 0.32). Large herds had higher Loge geometric mean SCC than small herds (p < 0.01) and herds with high SCC had lower milk production than herds with low SCC (p < 0.01). Herds that scored "very good" on cow cleanliness had significantly lower adjusted mean SCC than herds with scores of "average" or "good" (p < 0.05). Herds in barns with a concrete floor had an adjusted mean number of cases of clinical mastitis of 51.4 per 100 cow-years, 14 per cent higher than herds in barns with rubber mats, litter bed or wood (45.2 cases per 100 cow-years) (p < 0.05). Herds with high milk production level had higher FS-index than herds with low milk production (p < 0.01). Lower disease rates and the higher fertility status measured in the present study favor free stall herds over tie stall herds.

Animal Husbandry↗

Evaluation of additional acetone and urea analyses, and of the fat-lactose-quotient in cow milk samples in the herd recording system in Norway.

The purpose of this study was to evaluate the use of additional acetone and urea analyses to the established herd recording system (protein, fat, lactose, and somatic cell count) in cow milk samples every second month. Samples were obtained from 43/82 herds (800/1368 cows) in a lowland/highland area. Acetone concentration (mmol/l) were classified into acetone classes 1 (<0.7); 2 (0.7-1.4); and 3 (>1.4). There was an association between increasing acetone class and increasing ketosis incidence in herd (Kendall's Tau-b = 0.13). The highest percentage frequencies of acetone classes 2 and 3 were in weeks 4-6 postpartum. Milk yield, urea, and lactose were significantly lower; milk protein not different, and milk fat was significantly higher in herds with high ketosis incidence and in cows in acetone classes 2 and 3. General linear models, obtained by backward elimination of non-significant variables, showed that milk protein was negatively associated to milk yield and positively associated to milk fat. Milk yield decreased, and milk fat concentration increased with increasing acetone level. Milk fat and milk lactose were negatively associated, and a fat-lactose-quotient might be promising in a model to rule out subclinical ketosis cows.

Acetone↗

Evaluation of bulk milk analyses of acetone, urea, and the fat-lactose-quotient as diagnostic aids in preventive veterinary medicine.

The purpose of this study was to evaluate the use of additional acetone and urea analyses to the established milk quality system (protein, fat, lactose, and somatic cell count) in bulk milk samples twice a month. Samples were obtained from 44/93 herds in a lowland/highland area. When ranging herds with most acetone values over 0.24mmol/1 (90th percentile), only two out of 10 herds would be on a corresponding list when ranged for highest ketosis treatment incidence. Most high acetone values occur after periods with concentrated calvings, but also in periods without calvings, presumably because of feeding with inferior silage high in butyric acid. Milk fat concentration, milk lactose concentration and the interaction term between these, the fat-lactose-quotient, show the largest absolute values in all three models with ketosis treatment incidence, milk protein concentration, and milk yield as dependent variables in general linear analyses on standardized variables. Acetone and urea concentrations in bulk milk show only small absolute values or are omitted from the models. The practical conclusion from these analyses on bulk milk samples to be used by advisory personnel is small, but it seems that high bulk milk fat concentrations and low lactose concentrations are unfavourable when it comes to ketosis treatment incidence, but favourable when it comes to milk protein concentration. Bulk milk acetone concentrations as a measure of the energy supply in herds must only be interpreted after calving intensity and silage quality are assessed.

Acetone↗

Effects of selective dry-cow therapy on culling rate, clinical mastitis, milk yield and cow somatic cell count. A randomized clinical field study in cows.

The effect of dry-cow therapy was evaluated on the basis of the culling rate, occurrence of clinical mastitis, mean of cow milk somatic cell counts (CMSCC), and milk yield, in a trial including 608 cows. The cows were randomly divided into four groups: control group A (92 cows), group B treated with placebo (base ointment of Benestermycin (Leo) without antibiotics) (105 cows), one intramammary dose per infected quarter, group C treated with Benestermycin (Leo), one intramammary dose being infused in each infected quarter (196 cows); and group D treated with Leocillin with dihydrostreptomycin (Leo); one intramammary dose being used every second day, on four occasions per infected quarter (215 cows). The study included infected cows. If less than three of the quarters of the udder were diagnosed as having mastitis at first sampling, only infected quarters were treated. Otherwise, all quarters were treated. Multivariable analysis showed no significant effect of therapy on culling rate. The control groups (A + B) had a greater increase of cows having at least one case of clinical mastitis compared to the therapy groups (C + D), (from 0.26 to 0.57 in controls comparing to 0.38 to 0.43 in therapy groups). The difference between control and therapy groups during lactation was close to significant both before and after in the lactation after therapy (P < 0.10). The multivariable analysis showed a significant benefit of dry-cow therapy of 0.409 In unit in geometric mean CMSCC (corresponding to 125,000/ml), 200,000/ml in weighted CMSCC and 189 kg milk yield per lactation. According to these results selective dry-cow therapy for cows included in this study is recommended.

Animals↗

Field studies show associations between pulsator characteristics and udder health.

Four different field studies including 64, 140, 850 and 180 herds were used to investigate the association between pulsator characteristics and udder health. The results indicate that the best udder health is found in herds with a d phase > 330 ms and a pulsation rate > 55 min-1. A d phase of < 250 ms was associated with significant elevation in bulk milk somatic cell count, a higher incidence of acute clinical mastitis and a higher frequency of cows having mastitis associated with major pathogens (mainly Staphylococcus aureus) as compared with a d phase of > 331 ms. There was also a significant positive association between a shorter d phase and a high incidence of teat lesions needing veterinary treatment. Herds having no such teat lesions had pulsators with significantly longer d phase than herds with teat lesions (300 ms v. 288 ms). These results strongly suggest that in high-line milking machines the d phase should not be as short as 250 ms and should preferably be approximately 300 ms, and the pulsation rate should be at least > 55 cycles min-1. There was a strong relationship between the effect of d phase and the rate of pulsation.

Animals↗

Effect of dry-cow therapy on subclinical mastitis--an evaluation of long-acting and short-acting intramammaria.

This field study was conducted to evaluate the effect of selective dry-cow therapy with long-acting and short-acting antibiotics, respectively, and also in comparison to control groups without antibiotic treatment. A total of 684 cows from 288 different herds in three Norwegian regions fulfilled the criteria of the study design. There were 104 cows in control group A (sampling only), 115 cows in control group B (placebo), 221 cows treated with long-acting intramammaria Benestermycin vet. 'Leo' for 1 day at drying off in group C, and 244 cows treated with four short-acting intramammaria Leocillin with Dihydrostreptomycin vet. 'Leo' every second day before drying off in group D. The overall effect, measured as the cow being healthy after therapy, was 14.2% in control groups and 33.7% in therapy groups 30 +/- 17 days into the next lactation. Of quarters infected with S. aureus both in late lactation (45 +/- 32 days before drying off) and at drying off, 38.4% in the control group were bacteriologically negative 30 +/- 17 days into the next lactation, compared with 49.5% in the long-acting group and 68.6% in the short-acting group. Of quarters infected with Str. dysgalactiae both in late lactation (45 +/- 32 days before drying off) and at drying off, 10 out of 27 were still infected with Str. dysgalactiae in the control group 30 +/- 17 days into next lactation, compared with 0 out of 31 in the therapy groups. Dry-cow therapy in coagulase-negative Staphylococcus spp. (CNS)-infected quarters led to a 5.2 odds ratio of being healthy quarters 30 +/- 17 days into the next lactation, compared with control groups. Despite this, the overall frequency of CNS in the material was unchanged after therapy compared with controls. Short-acting compared to long-acting preparations had a significantly better effect in preventing new infection with S. aureus or Str. dysgalactiae in untreated healthy quarters in cows with fewer than three infected quarters. This difference in preventive effect was greater in cows with one infected quarter during previous lactation (the new infection rates being 0.078 for short-acting and 0.149 for long-acting) than in those with two infected quarters (the new infection rates being 0.042 and 0.063, respectively).

Animals↗

Assessment of strategy in selective dry cow therapy for mastitis control.

Seven hundred and three cows were treated at drying off, using three main types of therapy: control, long-acting intramammaria and short-acting intramammaria. Selective dry cow therapy in infected quarters was used. Of the cows with one or two infected quarters one to six weeks before drying off, 57.7 per cent had one or more new infected quarters at drying off. Thus selective dry cow therapy on quarter basis determined from the results of samples taken one to six weeks before drying off would give "inadequate" therapy (i.e. new infection in non-treated quarters at drying off) for more than 50 per cent of the cows. For those cows given "adequate" therapy (no new infection at drying off) long-acting therapy, short-acting and control yielded 53.6%, 49.3% and 30.7% healthy cows respectively two to five weeks post partum. In cows with "inadequate" therapy the treatment groups yielded 42.9%, 52.9% and 29.7% healthy cows respectively. Our conclusion is that if long-acting intramammaria are to be used, all the quarters of infected cows should be treated, whereas if short-acting preparations are to be used, treatment can be restricted to infected quarters only.

Animals↗

Teat lesions with reference to housing and milking management.

Potential associations between teat lesions and housing, hoof care, milking machine and milking management, were investigated. Overmilking, pulsation ratios of 71%, height of manger edge in the short type of stalls, and insufficient hoof care were associated with an increased incidence of teat lesions. The associations of pulsation ratio and overmilking suggest that factors disposing for teat end oedema and/or irritation during milking might cause teat lesions. Accordingly, milking machine control and milking technique evaluation might help in decreasing the incidence of teat lesions, together with correct constructed stalls and good hoof care. These factors should receive attention in dairy herd health programmes.

Animal Husbandry↗