The association between high milk somatic cell counts in the first lactation and somatic cell counts in the second lactation

With the advent of web-based recording and analysis systems, individual cow composite somatic cell count (SCC) data are being increasingly used for decision support in mastitis control at both the individual cow and herd level. SCC data from first and second lactation dairy cows (n=1912) from 12 farms were analysed using multinomial logistic regression to investigate possible associations between high SCC patterns in the first lactation and the subsequent lactation. Animals with three non-consecutive counts >200,000 cells/mL in their first lactation were significantly more likely to have three non-consecutive counts >200,000 cells/mL (OR 3.11; 95% CI 1.72-5.62) or three consecutive counts >200,000 cells/mL (OR 2.00; 95% CI 1.09-3.68) in their second lactation. Similarly animals with three consecutive counts >200,000 cells/mL in their first lactation were significantly more likely to have three non-consecutive counts >200,000 cells/mL (OR 1.90; 95% CI 1.13-3.19) or three consecutive counts >200,000 cells/mL (OR 4.14; 95% CI 2.81-6.08) in their second lactation. These findings suggest that patterns established in the first lactation may have an impact on udder health in the subsequent lactation. However, simulation modelling of positive predictive values for the first lactation cell count patterns as predictors of second lactation patterns demonstrated that, at prevalences likely to be encountered on UK dairy farms, the associations were not a sufficient basis for major management decisions such as culling.     

Monitoring udder health and milk quality using somatic cell counts

In this article the use of somatic cell counts for monitoring udder health and milk quality is discussed. Somatic cell count dynamics at quarter, cow, herd and population level are discussed and illustrated with examples. Quarter and cow somatic cell counts directly represent the inflammatory status of the mammary gland. Herd and population somatic cell count are related to the inflammatory process in individual cows but much more reflect the udder health status of the herd and the quality of the raw milk in the herd and the population. Application of monitoring tools in herd health management are illustrated using a case study. Understanding infection dynamics requires precise longitudinal data. Monitoring tools are required to find the areas of risk in the herd. It is inevitable that more complete udder health programs and monitoring systems are to be developed and implemented. These programs are necessarily dynamic and complex. Implementation of complete udder health programs should be accompanied by research efforts to further fine-tune these complete udder health control and monitoring programs.     

Dynamics and regulation of bulk milk somatic cell counts.

Somatic cell count (SCC) in milk is inversely related to dairy cow productivity and milk quality. In an effort to improve product quality, and indirectly farm productivity, regulatory limits on somatic cell counts have been established by many of the major dairy producing countries. The purpose of this paper was to assess the impact of regulations on bulk milk somatic cell counts in Ontario and to assist producers in meeting regulatory limits through development of prediction models. Through the use of a transfer function model, provincial SCC was found to have dropped by approximately 60,000 as a result of the reduction program. Limits of the regulatory program, seasonality and herd characteristics were found through time series cross-sectional models to have an impact on prediction of SCC at the farm level, but the major influence was historical SCC levels.     

奶牛乳汁体细胞数的快速检测及其临床意义

本文用新型便携式体细胞计数仪C-Reader对奶牛乳汁体细胞数(SCC)进行快速、精确地检测,同时对乳样中的病原菌进行分离鉴定,旨在指导奶牛乳房炎的诊断、预防及治疗。选用北京及河北地区10个奶牛场的111头奶牛共428份奶样,进行SCC计数。SCC20万/mL的奶样占63.6%,SCC介于20万/mL～50万/mL的奶样占13.1%,SCC50万/mL占23.3%。检测的111头奶牛中,60头奶牛患有隐性乳房炎,头发病率54.1%,乳区发病率23.3%。隐性乳房炎SCC变化范围50.6万/mL～984.3万/mL。对隐性乳房炎乳样进行致病菌分离培养,其阳性率高达82.0%。共鉴定出100株致病菌,其中金黄色葡萄球菌64株,表皮葡萄球菌11株,大肠杆菌8株,链球菌10株,其他菌7株。结果表明,C-Reader计数仪能够快速准确地检测北京及河北地区的奶牛隐性乳房炎,其病原菌以金黄色葡萄球菌为主。     

Variation in somatic cell counts of milk samples from individual cows

Somatic cell counts of 2570 milk samples from 765 cows collected bimonthly from November 1975 to May 1976 were transformed to logarithmic values and analysed statistically. Components of variance were estimated as follows: Herds 0.033 (13 %), age groups 0.021 (8%), cows (within herds and age groups) 0.080 (31%), months 0.014 (6%), residual 0.107 (42%). Correction of actual cell counts for the influence of milk yield on the day of sampling led to only small changes in the magnitude of the various components. The coefficient of correlation between samples from the same cow was computed as 0.60 when the samples were from the same lactation, and 0.37 for samples from consecutive lactations.The proportionately small variation among herds as compared to the variation among cows of the same herd throws doubt on the efficiency of cell counting in samples of herd milk as a way of identifying cows with high cell counts.     

Coagulase-positive staphylococcal mastitis in a herd with low somatic cell counts

An increase in clinical mastitis infections was observed in a high-producing 77-cow Holstein herd. Low bulk tank somatic cell counts and individual cow Dairy Herd Improvement Association somatic cell counts observed before, during, and after the epizootic were suggestive of herd environmental mastitis. However, bacteriologic culture survey of the total herd indicated that, in addition to infections possibly attributable to environmental pathogens, 22% (17/77) of the cows were infected with coagulase-positive Staphylococcus spp. Conceivably, investigative efforts and management changes, without bacteriologic culturing, might have resulted in reduction of the clinical infection rate in this herd. However, the continued high prevalence of a contagious pathogen with potential future implications would have gone unnoticed. Somatic cell count in milk from individual cows generally is a useful tool for monitoring the probability of intramammary infection, but must be complemented with bacteriologic culture of milk to determine whether contagious or environmental pathogens are responsible.     

Influence of genetic merit and environment on somatic cell counts of Holstein-Friesian cows

Financially, mastitis is one of the most important diseases affecting dairy cattle in the United Kingdom. Seven commercial farms were monitored over a 2.5 year period and data from 1040 cows were included in a study that examined both straw yard and cubicle housing systems. The influence of genetic merit for milk production (PIN(95) and PTA(f+p)) on somatic cell counts (SCC) as an indicator of mastitis under commercial farm conditions was assessed. The mean genetic potential ( poundPIN(95)) was 39.0 (+/-0.80) and the mean 305-day milk yield (kg) was 7980 (+/-54.2). In all, 5618 monthly records of SCC and 1040 records of 305-day SCC were included in the analysis. A multiple regression model was used to assess the influence of genetic merit and the level of concentrate intake on SCC (the log(10) transformation was used) under the two housing systems. Significant interactions between genetic merit and housing system, and concentrate intake and housing system were found. Log(10) SCC increased with genetic merit when cows were housed in straw yard accommodation, but decreased when cows were housed in cubicle accommodation. The increase in SCC with concentrate feeding was higher for straw yards. For parity 2 animals, there was a significant positive correlation between PIN(95) and SCC (r(p)=0.184, P=0.003) but the correlations between 305-day milk production and SCC were negative for animals greater than parity 2.     

Total and differential bulk cow milk somatic cell counts and their relation with lipolysis

Endocrine system plays a major role in the control of reproductive functions which are regulated by the hypothalamus–pituitary–gonad axis and its interactions. FSH and LH receptor genes are expressed at the gonads and GnRH receptor gene is expressed at the anterior pituitary gland. Misense mutations of the FSH, LH or GnRH receptors, activating or inactivating their functions in mammals, are potentially useful to allow the understanding of the role of this group of gonadotropins in reproductive phenotypes as early puberty and birth interval length. In the present study, polymorphisms in bovine exon 11 and 3′UTR of LHR, exon 10 and 3′UTR of FSHR and GnRHR genes were characterized with some of them resulting in changes in the aminoacidic chain. These polymorphic sites were found in a Bos taurus indicus (Nellore) female population by means of PCR–SSCP and DNA sequencing. Association between nucleotidic/aminoacidic changes and early puberty were determined by Chi-square analysis. It was found association between FSHR 3′UTR polymorphisms at position 2181, 2248 and 2249 bp and early puberty phenotype (p < 0.05). The presence of these new molecular markers might be considered in further studies to validate its correlation with early puberty or other reproduction associated phenotypes in cattle breeds.     

The association of milking management practices with bulk tank somatic cell counts

An instrument for assessing milking management practices was used to identify factors associated with udder health. The instrument included 48 individual management variables in 12 categories. Bulk tank somatic cell count (BTSCC) was recorded on 56 randomly selected Dairy Herd Improvement Association (DHIA) dairies, and the dairy's management practices were evaluated on four occasions during November 1988 to July 1989. The log-transformed BTSCC, question score 5 and category scores were subjected to a series of analyses, including principal-component analysis, correlation analysis, multivariate analysis of variance (MANOVA) and stepwise, all-possible-subsets multiple regression. Principal-component analysis was applied to the time-period-specific category scores and major data reduction was not seen for any time period. The correlation analyses between category scores revealed 26 pairs with highly significant correlations. These results indicate that although the categories in the instrument were correlated to the degree that some of the correlations were statistically significant, the strengths of the correlations were not sufficient for the catergories to cluster together in a relatively small number of independent components. The MANOVA results indicated that there was a significant time-period effect. The regression analysis identified sanitation, milking equipment, cow condition, pre-milking procedures and the mastitis control catergories as significantly reducing BTSCC.     

Mastitis control services and utilization of milk somatic cell count data by veterinarians in Ohio

A telephone survey was conducted of 50 randomly selected Ohio-licensed veterinarians engaged in dairy practice. The survey's purpose was to determine the extent of mastitis control services offered by practitioners and to assess their utilization of milk somatic cell count (SCC) data on individual cows available from the Dairy Herd Improvement Association (DHIA). During the preceding year, 96% (48/50) of practitioners surveyed had performed bacteriologic culture of milk samples. Practitioners were twice as likely to have performed culture on milk from mastitic cows that failed to respond to treatment as they were to have performed culture for purposes of identifying pathogen trends within a herd. Veterinarians in predominantly dairy practices were more likely to have completed bacteriologic examination of milk in their own laboratories than were veterinarians who were engaged in less than 50% dairy practice (P = 0.016). Most veterinarians (83%) reported that coagulase test results were available or that Staphylococcus aureus was differentiated from other staphylococcal species. Streptococcus agalactiae was not differentiated from other streptococcal species by 35% of practitioners surveyed. For veterinarians with clients enrolled in the DHIA, 91% (43/47) reported looking at, discussing, or otherwise using the DHIA records. Eighty-one percent (35/43) of veterinarians who had clients using services from the DHIA reported that clients also received individual cow milk SCC results. Veterinarians engaged in predominantly, dairy practice expressed a greater familiarity with the linear score method of SCC reporting than did veterinarians whose practices were less than 50% dairy (P = 0.085); however, both groups reported a preference for raw SCC data.(ABSTRACT TRUNCATED AT 250 WORDS)     

Bacteriology and somatic cell counts in milk samples from ewes on a Scottish farm

Milk samples from 50 sheep on a single Scottish research farm were collected weekly for 10 wk postpartum. Samples were analyzed for somatic cell counts (SCC) each week and bacteriologic culture was done for 7 of the 10 wk. A total of 492 udder half samples were cultured, of which 467 had corresponding cell count data. Statistical analysis on complete SCC and culture data showed no association between SCC and bacterial isolation, even when more than 10 colonies of a single bacterial species were present. Only 3.6% of the samples were simultaneously positive for high count (> 10 colonies from 0.01 mL of milk) of any one bacterial species and high SCC (> 1 x 10(6)/mL). The bacteria recovered were: Staphylococcus equorum (19 times), S. xylosus (7 times), S. simulans (6 times), Streptococcus uberis (3 times) and other streptococci (4 times), Mannheimia (Pasteurella) haemolytica (2 times), Staphylococcus aureus (1 time), S. capitis (1 time), and Enterococcus faecium (1 time). There was an association between the test day and SCC, with higher SCC values in the first 2 wk. In addition, significantly higher SCC values were found in the oldest animals compared to the other age groups.