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1.
An observational study was conducted in Wisconsin to compare production and management on organic and conventional dairy farms. Thirty organic dairy herds, where antimicrobials are rarely used for calves and never used for cows, were compared with 30 neighboring conventional dairy farms on which antimicrobials were routinely used for animals of all ages. A seven-page questionnaire regarding milk production, milking practices, housing, incidence of the major dairy diseases and medical treatments was used to assess management and production during 2000-2001. Body condition scores (BCS) of lactating cows and environmental and animal sanitation scores (EASS) were also collected on each of two occasions. The organic herds had significantly fewer cattle than did the conventional herds (P=0.017). The average daily milk production per cow in organic dairy herds (20.2 kg/day) was lower than that of conventional herds (23.7 kg/day). The incidence of clinical mastitis (CM) on organic farms (28 cases per 100 cow-years at risk) was not statistically different from that of on conventional farms (32 cases per 100 cow-years at risk). No significant difference in bulk tank somatic cell count (BTSCC) was observed between organic farms (262,000 cells/ml) and conventional farms (285,000 cells/ml). The average annual cull rate was 18.0 cases per 100 cow-years for the conventional farms and 17.2 for the organic farms (P=0.426). Our paired t-test results indicated significantly higher parasite burden on organic dairy farms; however, no significant difference between the two farm types when controlling for season (March and September), grazing intensity (no grazing, little grazing, grazing with access to housing and grazing only) and herd average milk production per cow. There was little evidence of other fundamental differences between the two farm types in other management and production parameters.  相似文献   

2.
The objective was to determine the incidence and transmission of mycoplasma mastitis in the hospital pen in a dairy herd of 650 lactating cows after a hospital pen was established following an outbreak of this disease. Mycoplasma mastitis status was monitored for 3 months through repeated collection of milk samples from cows with clinical mastitis (CM) and from bulk tank milk. During the outbreak 13 cows were diagnosed with Mycoplasma bovis CM, 1 cow with Mycoplasma sp. mastitis and 8 cows showed signs of arthritis, 3 of which were confirmed as having M. bovis arthritis. M. bovis isolates from cows with CM, arthritis and bulk tank milk had indistinguishable chromosomal digest pattern fingerprints. Incidence rates of M. bovis CM cases in the milking and hospital pens were 0.01 and 1.7 cases per 100 cow-days at risk. Approximately 70% of cows with M. bovis CM became infected within 12 days of entering the hospital pen. Transmission of M. bovis in the hospital pen occurred as 3 episodes. Each episode corresponded to the introduction of a cow with M. bovis CM from a milking pen. Evidence indicates that cows with M. bovis CM from milking pens were the source of transmission of the disease in the hospital pen and thus their presence in the hospital pen appeared to be a risk factor for transmission of M. bovis mastitis in this single case study herd.  相似文献   

3.
Because of the high variability of cattle infestation, selective breeding has been proposed to control three-host ticks in Africa in the same way as it has been implemented to control the one-host tick Boophilus microplus in Australia. Interbreeding (divergent selection experiment) between Gudali zebu cattle was performed at the Wakwa Research Centre, Adamawa, Cameroon to assess the feasibility and impact of such a selective breeding programme. Fifty cows (chosen out of 129) and 2 bulls (chosen out of 10) were selected according to their greater or lesser attractiveness for the tick Amblyomma variegatum, assessed by their infestation degree (ID, ratio between individual animal infestation and mean herd infestation). Half of the animals displayed a high ID (H) and the remainder a low ID (L). The presence of a suckling calf had a significant effect on the infestation of its dam, the udder of lactating cows being significantly less infested (P<0.001) because of a tick removal effect by the calves. Observed infestation data were therefore corrected to allow comparison between lactating and non-lactating cows. The ID of the cows was assessed on five occasions from 1992 to 1994: the consistency of the infestation hierarchy was good overall (P<0.001) despite high variability seen in some animals which would complicate the selection of cattle with low infestation. Four breeding groups were set up (LxL, LxH, HxL, HxH) and 40 calves were born in 1993 and 1994. There was a correlation (P<0.02-0.001) between liveweight (or age) and ID when the younger calves of the groups were 6 months old, but the correlation disappeared by the time the calves were all older than 1 year. There was no difference between the average ID of the calves from the four breeding groups, and no correlation was observed between dam ID and calf ID. The average ID of the 10 calves born of the dams with the lowest ID was however significantly lower than that of the 10 calves born of the dams with the highest ID (0.82 versus 1.15, P=0.03), but the difference was much less than that observed between the dams (0.35 versus 2.30, P=7x10(-9)). A positive correlation between dam ID and calf ID was found when only these 20 cows were taken into consideration (r=0.57, P<0.01). These results indicate that selective breeding of Gudali zebu cattle to produce animals with low infestation by the tick A. variegatum would be uncertain but that a more drastic selection of the breeders than that implemented in the present study may perhaps have some positive impact.  相似文献   

4.
The effect of residual calf suckling on sub-clinical (SM) and clinical mastitis (CM) in dual-purpose cows was assessed. Prevalence, incidence rate, and relative risk were determined from 30 cows allocated to two treatments: (i) residual calf suckling once after milking (RCS) and, (ii) no residual calf suckling (NRCS). The overall prevalence of SM and CM, at cow and at quarter levels was higher in NRCS cows (P < 0.05). The incidence rate of CM for NCRS and RCS cows was 53 cases per 10,000 animal-days at risk, and eight cases per 10,000 animal-days at risk, respectively. Cows that did not suckle their calves after milking were 6.59 (3.15–13.93) times more likely to develop CM than cows which did suckle after milking. In both experimental groups, coagulase-negative staphylococci were the most frequently isolated pathogens, followed by Staphylococcus aureus and Pseudomonas aeruginosa. Eliminating the practice of residual calf suckling presents a high risk for development of mastitis in dual-purpose cows.  相似文献   

5.
The association between quarter somatic-cell counts (QSCCs) of milk and the risk of clinical mastitis (CM) was investigated in a 1-year study on three dairy herds in Somerset, UK. The three herds had 95-130 milking cows and an annual mean bulk milk somatic-cell count (BMSCC) of <150 x 10(3)cells/ml. The farms were visited every 4-6 weeks at morning milking when quarter-milk samples were collected. The farmers recorded all cases of CM and were trained to collect sterile milk samples from affected quarters, before treatment for bacteriology.The three herds had CM incidence rates of 25.4, 55.2, and 67.6 quarter-cases per 100 cow-years. Escherichia coli and Streptococcus uberis were cultured from approximately 50% of cases. QSCC was categorised and the risk of CM occurring in the month after the QSCC was examined using multilevel models to account for the correlated nature of the dependent data. Three models were developed: one for all cases of CM, one for those caused by coliforms and one for those caused by S. uberis. When all cases of CM were considered, quarters with somatic-cell count (SCC) 21-100 x 10(3)cells/ml had reduced odds (OR=0.60, P=0.06) and quarters with SCC >200 x 10(3)cells/ml has over three time the odds (OR=3.7, P<0.01) of CM compared with QSCC 1-20 x 10(3)cells/ml. When only coliform CM were investigated, quarters with SCC 6-200 x 10(3)cells/ml had reduced odds of coliform CM (OR=0.47, P=0.04) compared with QSCC 1-5 x 10(3)cells/ml, and SCC >200 x 10(3)cells/ml were not significantly different from the baseline. Finally, when S. uberis CM were investigated, quarters with SCC >200 x 10(3)cells/ml had more than three times the odds of S. uberis CM compared with QSCC 1-20 x 10(3)cells/ml (OR=3.73, P<0.01). QSCC <21 x 10(3) and >200 x 10(3)cells/ml are associated with increased odds of CM in the following 4-6 weeks; this association may be pathogen specific.  相似文献   

6.
A questionnaire, in which 7 cases of udder disease were described, was distributed to 890 veterinarians in Norway. They were requested to classify the cases according to the diagnostic alternatives listed in the Norwegian Health Card System for Cattle (NHCSC). The NHCSC recordings are used for progeny testing of bulls, for disease monitoring, and for research purposes. The aim of this study was to evaluate the quality of the recordings for udder diseases. The questionnaire was answered by 633 veterinary surgeons. Four cases of clinical mastitis (CM) with abnormal secretion as well as other clinical signs of inflammation were correctly classified as CM by almost 100% of the veterinary surgeons. A cow in the final stage of lactation, showing no clinical signs except for clots in the milk, was considered not to be a clinical case by more than 25% of the veterinary surgeons. A typical case of subclinical mastitis (SM) was reported as SM by 83% of the veterinary surgeons, and as CM by 16%. A subclinical case with a recent history of clots in the secretion was classified as SM by 66% of the veterinary surgeons, but almost 40% either reported CM as their sole diagnosis or considered the case to be CM in combination with SM. Of the clinical cases, those exhibiting marked local signs of inflammation and a systemic reaction were correctly classified as acute clinical mastitis (ACM) by 96%-98% of the veterinary surgeons. In the NHCSC, the diagnostic alternatives for cases of CM are ACM and chronic clinical mastitis (CCM). One case, for which the diagnosis subacute clinical mastitis was appropriate according to standard definitions, was classified as CCM by 66%, and as ACM by 6%. Based on the information given in the questionnaire, the diagnosis for 2 of the clinical cases could have been either ACM or CCM, and for both cases each of these 2 alternatives was reported by more than 43% of the veterinary surgeons. A teat lesion, which was present together with ACM in one cow, was reported by 91% of the veterinary surgeons.  相似文献   

7.
The main objective of this study was to describe the incidence of mammary tumors (MTs) and the survival after MTs, in female dogs between 3 and 10 years of age (insured for veterinary care and with life insurance in a Swedish animal-insurance company) from 1995 to 2002. Measures of incidence are presented crudely, by breed and across age categories and birth cohorts (1991-1998). The survivals until MT diagnosis and after a MT diagnosis were computed. The overall incidence for any MT claim was 111 dogs per 10,000 dog-years at risk (DYAR). The overall MT rate in the 1992 and 1993 birth cohorts was 154 dogs per 10,000 DYAR. The incidence for any MT claim increased with age and varied by breed, from 319 dogs per 10,000 DYAR in the English springer spaniel to 5 dogs per 10,000 DYAR in the rough-haired collie. At the ages 6, 8 and 10 years, 1%, 6% and 13% respectively, of all females had at least one MT claim. The MT mortality was 6 deaths per 10,000 DYAR and increased with age. The overall-case fatality was 6%.  相似文献   

8.
The objective of this study was to estimate the effects of clinical mastitis (CM) (both with and without specific pathogen identification) occurring in different stages of lactation on length of herd life in two New York State dairy farms. The 2,697 cows in the study were followed for one lactation (the first-occurring one on or after 1 October 1999), until it ended because of a new lactation, culling, or end of study (31 March 2001 in one farm; 31 July 2001 in the other). A Cox proportional hazards model with time-dependent covariates, in SAS((R)), was used to measure, within a lactation, the effect of the first occurrence of CM (without specific pathogen identification) occurring 1--7, 8--66, 67--100, 101--225, or >or=226 days in milk (DIM), on how long cows remained in the herd. For the first occurrence of CM due to Streptococcus spp., Staphylococcus aureus, Staphylococcus spp., Escherichia coli, Klebsiella spp., and 'no pathogen isolated', the intervals were before and after the median DIM of first occurrence of each pathogen. There were too few cases due to Arcanobacterium pyogenes, and 'other pathogens grouped together' to split into intervals, so they were modeled as binary variables, i.e. as they occurred. CM was modeled using time-dependent covariates, to account for its differing effects throughout lactation on culling. Other variables controlled for were herd, parity, calving season, and other significant diseases. In the dataset, the lactational incidence risk of the first occurrence of CM was 18.2%; 20.0% of the cows did not survive the lactation that was studied. The overall annual culling percentage for both herds during the study period (including all cows, whether eligible for the study or not) was 35.6%. For cows with CM without pathogen identification, their highest hazard ratio (HR) of culling occurred from 67 to 100 DIM. All of the pathogens modeled markedly reduced herd life. On average over the entire lactation, cows with Staphylococcus spp. CM had the highest HRs for culling, although there were no significant differences among pathogens (at p=0.0018 (reflecting 28 pairwise comparisons)). For early-occurring (before median DIM of first occurrence) S. aureus CM, the daily rate of change of the HR of culling increased over time. The HRs for culling were particularly high for late-occurring (after median DIM of first occurrence) E. coli and Klebsiella spp. CM early in the interval, but the daily rate of change of the hazard of culling for these two pathogens decreased sharply over time. Treating CM as time-dependent therefore allowed us to measure in greater detail, its varying effects (of when it occurred) on herd life.  相似文献   

9.
A 2-yr grazing performance study was conducted in Eastern Colorado to evaluate the effects of feeding raw cull beans (Phaseolus vulgaris) or canola meal, compared to sunflower meal, to beef cows grazing dormant, native winter range on body weight and body condition score (BCS) change, reproductive performance, and calf performance. Ninety-five pregnant, spring-calving crossbred cows (541 +/- 51 kg) in 1995 to 1996 and 65 cows (602 +/- 60 kg) in 1996 to 1997 were randomly assigned to one of five treatments (19 and 13 cows per treatment in 1995 to 1996 and 1996 to 1997, respectively): 1) unprocessed Great Northern beans to supply 182 g/d of CP (GNB); 2) canola meal to supply 182 g/d of CP (CM); 3) a mixture of Great Northern beans and sunflower meal, each to supply 91 g/d of CP, for a total of 182 g/d of CP (MIX); 4) sunflower meal to supply 182 g/d of CP (SFM+); and 5) sunflower meal to supply 91 g/d of CP (SFM-). Cow weight and body condition performance were broken into a gestation and a lactation phase in 1995 to 1996; calves were weighed at birth, at the end of the lactation phase in April, and at weaning the following September. Only gestation performance was monitored in 1996 to 1997, and subsequent calf birth and weaning weight were recorded. The SFM- group lost more weight during the gestation phase than other treatments (P < .05), yet no differences were detected for gestation phase daily BCS change, calf birth weight, lactation phase daily weight change, lactation phase daily BCS change, first-service conception rate to AI, or overall pregnancy rate. Off-test calf weight was higher in April for calves from dams of the SFM+ and CM treatments than for calves from dams on the GNB or SFM- treatments (P < .05), and calves from cows on the CM treatment were heavier in April than calves from cows on the MIX treatment (P < .05). No differences in calf weight were present at weaning. Consumption of beans by cows on the GNB treatment was low because of palatability problems. Mixing the beans with sunflower meal in the MIX treatment eliminated this problem. Canola meal, Great Northern beans, or a combination of sunflower meal and Great Northern beans were comparable to sunflower meal as protein supplements for beef cows grazing native winter range, despite obvious palatability problems with the beans.  相似文献   

10.
The objectives were to describe the pattern of losses through culling, sales of breeding stock, mortality, and disappearance, and to characterize the causes of mortality of cows and replacement heifers of breeding age from Western Canadian beef herds. Cows and replacement heifers from 203 herds were observed for a 1-year period starting June 1, 2001. Veterinarians examined dead animals on-farm using a standard postmortem protocol. The incidence of culling in cows and replacements heifers was 14.3 per 100 cow-years at risk, and the frequencies of sales for breeding stock, mortality, and cows reported missing per cow-years at risk were 4.0, 1.1, and 0.4, respectively. During the study, 355 animals died or were euthanized, 209 were examined postmortem, and the requested tissues were submitted for histopathologic examination from 184. A cause of death was determined for 70% (128/184) of the cows with complete gross postmortem and histopathologic examinations. Hardware disease (traumatic reticuloperitonitis), malignant neoplasia (cancer), calving-associated injury, rumen tympany (bloat), myopathy, and pneumonia accounted for 56% (72/128) of the animals where a cause of death was determined. Twenty-three other causes of death accounted for the remaining 44% (56/128). Factors relating to cow nutrition accounted for 25% of the deaths, emphasizing the importance of feeding management as a determinant of cow health in western Canada.  相似文献   

11.
AIMS: To determine the impact of treatment with internal teat sealant (ITS) compared to no treatment at drying-off on the incidence of clinical mastitis (CM) during the dry period and 84 days after calving, and the prevalence of cows with somatic cell counts (SCC) ≥200,000?cells/mL at the first lactation herd test, for cows wintered on forage crops.

METHODS: In four dairy herds in the South Island of New Zealand, cows with no history of CM or individual SCC >100,000?cells/mL during the 2015–16 season were randomly assigned to treatment with ITS in each quarter (ITS group) at drying-off or no treatment (Control group). Cows were otherwise treated similarly, wintered on forage crops and transferred to pasture for calving and lactation. Cows were monitored over the dry period and for 84 days after calving, and any case of CM recorded. Individual SCC were recorded at the first herd test after calving.

RESULTS: Between drying-off and 84 days after calving 36/470 (7.7%) cows in the ITS groups and 73/442 (16.5%) cows in the Control group were diagnosed with CM (RR=0.46; 95% CI=0.26–0.73). The final multivariable logistic regression model included an interaction between treatment group and length of dry period. For a Friesian/Jersey cow, aged 4–8 years, with a dry period of 30–80 days, dried off without ITS, the probability of CM in the study period was 0.12 (95% CI=0.09–0.16), and for such a cow treated with ITS the probability was 0.07 (95% CI=0.05–0.10). For an equivalent cow, with a dry period of 81–140 days, which was untreated, the probability was 0.21 (95% CI=0.14–0.29), and for such a cow treated with ITS it was 0.05 (95% CI=0.02–0.11). At the first herd test after calving 77/383 (20.1%) cows in the Control group and 57/425 (13.4%) cows in the ITS group had SCC ≥200,000?cells/mL (RR=1.51; 95% CI=1.10–2.06).

CONCLUSIONS AND CLINICAL RELEVANCE: For these farms, treatment of cows with no history of elevated SCC or CM with ITS at drying-off halved the incidence of CM between drying-off and 84 days after calving, and reduced by 33% the proportion of cows with SCC≥200,000 at the first herd test after calving, compared with untreated cows. Treatment with ITS reduced the risk of CM proportionally more for cows with a dry period of 81–140 days than for cows with a shorter dry period.  相似文献   

12.
Factors affecting bacteriological cure rates (BCR) and new intramammary infections (IMI) during the dry period as well as clinical mastitis (CM) during early lactation were investigated in 414 German Holstein dairy cows receiving dry cow therapy. Cows were treated with either benethamine benzylpenicillin (300,000 IU), penethamate hydriodide (100,000 IU), and framycetin sulphate (100 mg, n = 136), or cefquinome (150 mg, n = 135), or benzathine cloxacillin (1,280 mg, n = 143). Overall BCR, IMI, and CM at parturition were 86.4%, 20.7%, and 4.3%, respectively. The three antibiotic treatments differed only in BCR, with cloxacillin yielding better results than the others. Udder quarters from cows with > 4 lactations had a higher risk of IMI and CM at calving. Chronic changes in udder tissues were linked to a lower BCR and were associated with a higher risk of CM during early lactation. The risk of CM at calving was higher in udder quarters with unspecific or subclinical mastitis before drying off. In conclusion, with antibiotic dry cow therapy, age and health status of the udder appear to be major determinants of IMI and CM during the dry period and early lactation, while BCR was associated with the antibiotic type and udder tissue status.  相似文献   

13.
High composite somatic cell counts (CSCC) in dairy cows may develop into clinical mastitis (CM), suggesting that prevention or intervention of high CSCC may prevent CM later in lactation. The objective of this study was to quantify the relationship between high CSCC in dairy cows and the first subsequent case of CM in the same lactation. Farmer-diagnosed cases of CM and test day CSCC measurements during 1 year of 13,917 cows in 196 randomly selected Dutch dairy herds were available for analysis. Cows were followed in 1 lactation from the first test day postpartum until CM, drying off, culling or end of study. Cox proportional hazards models with time-varying CSCC levels were used to estimate the effect of high CSCC (≥200,000cells/ml) on the time until the first case of CM. A shared frailty effect was included to adjust for clustering of cows within herds. The proportion of cows developing CM after a CSCC measurement was 11%. Primiparae with a high CSCC had a 4-fold higher hazard for subsequent CM than primiparae with a low CSCC; multiparae with a high CSCC had a 2-fold higher hazard than multiparae with a low CSCC. Additionally, multiparae with a low CSCC had a 2-fold higher hazard for CM occurrence than primiparae with a low CSCC. Increasing the threshold for high CSCC showed that the risk for CM increased. If the last CSCC before CM was low, CSCC information of 2 preceding test days was more predictive than CSCC information from only the last test day. When the last CSCC was high, CSCC information of 2 preceding test days did not have added predictive value. This study identified that approximately 25% of first subsequent CM cases after a CSCC measurement can potentially be prevented when cows are prevented to get high CSCC or when high CSCC cows are removed from the population. This corresponded with a decrease in the proportion of lactating cows with CM after a CSCC measurement from 11% to 7%.  相似文献   

14.
OBJECTIVE: To describe the distribution and prevalence of cattle herds with detectable antibody to bovine pestivirus in Queensland in 1994/95. MATERIALS AND METHODS: The study used 7,838 serum samples collected from 250 herds in Queensland, as part of a structured animal health surveillance program conducted in 1994 and 1995. Samples were collected from female cattle bred on the property. In each herd, 10 to 20 heifers less than two years of age and 10 to 15 older cows were sampled giving a 95% probability of detecting one or more seropositive animals if the seroprevalence was approximately 10% or greater. Sera were analysed for antibodies to bovine pestivirus using a virus neutralisation test. RESULTS: Total cattle numbers in sampled herds varied from 62 to 24,600 head, while total area of properties sampled varied from 50 to 395,400 hectares. Eleven percent of herds contained no seropositive animals among those sampled, and in 38% of herds, all sampled cattle aged one to two years of age were seronegative. There was a trend for larger herds to have one or more animals seropositive for bovine pestivirus (chi-squared for Linear trend = 3.656, p = 0.056). Herds with more than 500 head of cattle were significantly more likely than herds with less than 500 head to contain one or more seropositive animals in any age group (prevalence ratio = 1.12; 95% confidence interval 1.01 - 1.23; p = 0.026). Age specific seroprevalence increased from around 10% in heifers, to between 75% and 85% in cows aged 10 years. The average annual incidence risk for bovine pestivirus infection varied from 0.12 to 0.24 seroconversions per cattle year at risk, and did not vary with age. The overall crude seroprevalence adjusted for herd size was 45%. There was a wide range of seroprevalence recorded for each level of stocking intensity. CONCLUSIONS: This survey provides valuable baseline data on bovine pestivirus infection in Queensland cattle herds.  相似文献   

15.
The aim of this study was to estimate genetic parameters for conformation measures and scores in the Finnhorse and the Standardbred foals presented in foal shows. Studied traits included height at withers and at croup, six subjectively evaluated conformation traits and overall grade. Data were from 10‐year period (1995–2004) and consisted of 5821 Finnhorse foals (1–3 years old) with 7644 records and 2570 Standardbred foals (1–2 years old) with 2864 records. Variance components were estimated with REML – animal model using VCE4 program. The model included age class, year of judging, sex and region as fixed effects, and additive genetic, permanent environmental and residual as random effects. Estimates of heritability for measured traits were very high in both breeds (0.88–0.90). Estimates of heritability for conformation traits varied from 0.13 to 0.32 in the Finnhorse and from 0.06 to 0.47 in the Standardbred. In both breeds, estimates of heritability were lowest for hooves and movements at walk, and highest for type and body conformation among scored traits. Estimate of heritability for overall grade was in the Finnhorse 0.32 and in the Standardbred 0.34. Genetic correlations between overall grade and different conformation traits were 0.35–0.84 in the Finnhorse and 0.31–0.88 in the Standardbred. Thus, selection based on the overall grade would improve all studied characteristics.  相似文献   

16.
Among other factors the nutrient utilization of a cow is influenced by its individual physiological and genetic predisposition. There are large differences within cows in the manner of partition of the nutrients that may affect the size and activity of the individual organs and the whole body composition. High genetic merit dairy cows have a higher potential rate of protein excretion than medium genetic merit dairy cows even when energy and protein intake are equal. Medium genetic merit dairy cows show higher potential rates of protein and fat deposition of the body. This phenomenon was partly explained by the regulatory functions of the hormone insulin (see Brockman and Laarveld 1986; Broucek et al. 1991; Wylie et al. 1998). Additionally, it is widely considered that the somatotropic axis [growth hormone, growth hormone releasing factor and insulin-like growth factor I (IGF-I)], could be involved, as one of the key control and balance mechanisms which regulate the partition of nutrients (Breier and Sauerwein 1995; Schams 1995; Knight 1997). Several studies have provided insights into the physiological action of these and further hormones, transport proteins and enzymes, e.g. the erythrocyte-type glucose transporter, the insulin-responsive glucose transporter or the glycerol-3-phosphate dehydrogenase, and indicate that these molecules may affect nutrient repartitioning and utilization as well as milk yield, growth and fat accumulation (Mathews et al. 1988; Bauman and Vernon 1993; Burton et al. 1994; Girard et al. 1994; Binelli et al. 1995; Zhao et al. 1996; Abe et al. 1997). However, the mechanisms of regulation of most of these processes are insufficiently known. This paper presents a comparison of mRNA patterns of tissues potentially associated with protein and energy turnover in lactating cows of different metabolic types. The technique of differential display of messenger RNA species originally described by Liang and Pardee (1992), has already been applied as a powerful tool for cloning genes that are differentially expressed in various tissues or under altered conditions in the same tissue (e.g. Liang et al. 1993; Aiello et al. 1994; Li et al. 1994; Nishio et al. 1994). This method was applied to characterize the expression patterns in 12 tissues of three cows with divergent metabolic types (milk type, meat/milk type, and meat type) by the display of differentially and identically expressed cDNA bands. The aims of this exploratory study were first to indicate which of the 12 tissues analysed are mainly involved in trait differentiation according to their differentially displayed mRNA patterns. Secondly, the results of this study represent the prerequisite for the identification of tissue-specific expressed sequence tags in general, and individual or type-dependent differentially expressed sequence tags in particular.  相似文献   

17.
The purpose of this study was to determine clinical disease incidence in eight non-seasonally calving, pasture-fed dairy herds in the southern highlands district of New South Wales. This was a longitudinal population study. The study included all cows that calved between January 1994 and December 1995 and consisted of 2111 lactation records from 1430 cows. The incidence of the more common diseases were: calving-associated disorders, 18.0 cases per 100 calvings (95% CI 16.4-19.8 cases per 100 calvings); metabolic disorders, 5.5 cases per 100 cow-yr at risk (95% CI 4.5-6.6 cases per 100 cow-yr at risk); reproductive-tract disorders, 22.3 cases per 100 cow-yr at risk (95% CI 19.2-25.8 cases per 100 cow-yr at risk); udder disorders, 17.6 cases per 100 cow-yr at risk (95% CI 15.9-19.5 cow-yr at risk) and lameness, 3.7 cases per 100 cow-yr at risk (95% CI 2.9-4.7 cow-yr at risk). In agreement with dairy-cow disease-incidence studies conducted elsewhere, disorders of the reproductive-tract and udder were the most frequent clinical conditions encountered. These findings confirm that dairy herd-health programs should emphasise the control of these two groups of disorders.  相似文献   

18.
Smallholder dairy herds around the Dar es Salaam region of Tanzania supply 86% of raw milk consumed by the city dwellers. Previous studies have indicated that clinical mastitis is an important disease affecting smallholder dairy cows and an 18-month questionnaire-based longitudinal field-study was conducted between July 2003 and March 2005 to elucidate risk factors associated with the incidence. A total of 6057 quarter-level observations from 317 lactating cows on 87 randomly selected smallholder dairy herds were analysed at the quarter and cow level using logistic and Poisson regression models, respectively. At the quarter level, the average incidence rate of clinical mastitis was 38.4 cases per 100 quarter-years at risk whereas at the cow level the incidence rate was 43.3 cases per 100 cow-years at risk. The incidence was significantly (P< or =0.001) associated with cow factors (body condition score, parity, stage of lactation, and udder consistency), housing (floor type) conditions and milking (cow and udder preparation) practices. It was concluded that the extrapolation of the classic ten-point mastitis control plan into smallholder dairy herds should be undertaken cautiously. An integrated approach to dairy extension should focus more on the creation of mastitis awareness among smallholder producers and on the improvement of animal nutrition and reproduction indices-factors that may also have a direct impact on milk yield.  相似文献   

19.
The objective of this prospective longitudinal field study was to describe changes in prevalence of seroconversion and fecal shedding and changes in incidence rate of seroconversion, fecal shedding and culling of milk cows for clinical signs of Johne's disease (JD) in six Minnesota (USA) herds participating to the JD Demonstration Herd Project (JDDHP) from 2000 to December 2005. Changes in prevalence and incidence rate were evaluated in light of the owner's compliance to the JDDHP using a risk assessment (RA) score. Adult cows were tested regularly using serum ELISA and bacterial fecal culture to evaluate progress made throughout the control program. Logistic regression was used to evaluate the association between the risk for a cow to test positive and the year on the program. After 5 years of follow-up, the proportion of cows that tested positive to serum ELISA and fecal culture (all positive cultures as well as moderate to heavy shedders only) decreased significantly from the first to the last year (8-3.1%, 10.4-5.6% and 3.1-1.5%, respectively). Cox proportional hazards regression was used to evaluate change of incidence rate across birth cohorts. Birth cohorts were defined by birth date of the animals with the reference cohort or oldest cohort being already 12-24 months of age at the onset of the long-term management program. All cohorts were censored at 45 months of age. Compared to cows from the reference cohort, cows from cohorts that could have benefitted from the JDDHP in their young age (less than 12 months of age at the start of the program or born later) were significantly less at risk of seroconversion and fecal shedding (hazard ratios for seroconversion, any fecal shedding and heavy shedding less than 0.63, 0.67 and 0.62, respectively). For the three herds achieving good management changes with a risk assessment score under 30 at their last year of the study, the cohorts that were born after the program was instituted did better than those born before the start of the program, implying that the program could have helped around birth as well for those herds. This study suggests that reduction of environmental contamination of heifers up to a year of age may have had some impact on the success of the program. The JDDHP appears more beneficial for herds achieving a better reduction of their RA score with a decrease risk for infection in very young calves.  相似文献   

20.
A clinical field trial was performed on a herd of Hereford beef cows in central Saskatchewan. The herd had a history of being severely affected with vertical fissures. The objective of the study was to determine the effects of supplemental dietary biotin on the prevalence of vertical fissures in beef cows. In June 1994 and June 1995, 1- and 2-year-old heifers were randomly allocated into 2 treatment groups, each composed of 79 animals. One group received a 10 mg/head/day biotin-supplemented free-choice mineral supplement, while the other groups received an identical free-choice mineral without the biotin supplementation. The claws from these animals were evaluated in June 1994, October 1994, June 1995, October 1995, and June 1996 for the presence of vertical fissures. Supplemental dietary biotin significantly increased serum levels of biotin and significantly increased claw hardness in supplemented cows. Both groups of heifers started the trial without vertical fissures. After 18 months, 15% of the cows fed supplemental dietary biotin had vertical fissures compared with 33% in the nonsupplemented group. The difference was statistically significant (P = 0.01).  相似文献   

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