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Our objective was to derive predictions of intramammary infection (IMI) prevalence based on somatic cell score (SCS), cow, and herd factors. IMI cultures on composite samples were performed by New York Quality Milk Production Services during 1992 to 2004. Cow records containing DHI SCS in IMI sampling month with 0, 1, or 2 pathogens were retained. Herds were required to test at least 60% of cows and ≥ 30 cows tested. Final data set consisted of 79,308 cows from 1124 herds. Pathogens were classified as contagious or environmental. Models were derived using the glimmix macro in SAS with a logistic link function and employing backward elimination with P < .01. Three models were investigated with binary dependent variables: presence/absence of contagious IMI (CONT), environmental IMI (ENV), and all IMI (ALL). Independent variables included SCS, quadratic SCS (SCS2), parity, days in milk (DIM), milk/day, J5 vaccine use, survey type, production system, season, year, herd (fitted as a random effect), and significant interactions of SCS with other terms. For all models SCS, SCS2, parity, DIM, and production system were significant. In each model additional terms were: CONT: survey type; ENV and ALL: year, parity*SCS, and parity*SCS2; ENV: milk/day and survey type; ALL: production system*SCS. Prevalence of IMI varied by herd and cow factors and increased at a decreasing rate as SCS increased. The rate of increase with SCS was uniform for CONT, but differed among production systems (ALL) and parities (ENV and ALL). [ABSTRACT FROM AUTHOR]

The objective of this study was to estimate genetic variability of Mycobacterium avium ssp. paratuberculosis infection in US Holsteins. Blood and fecal samples were collected primarily from daughters of 12 bulls in their second or third lactation. Routine disease testing of the sires documented that they were not infected. Herds without a "suspect" or positive ELISA (sample/ positive ratio ≥ 0.10) or positive fecal culture test were deleted from the data set. The remaining 4,603 cows from 238 herds and 46 sires were used to estimate heritability of M. paratuberculosis infection. Heritability was estimated with 3 Johne's disease diagnostic tests: 1) fecal culture alone, 2) serum antibody ELISA alone, and 3) both tests (combined) with a positive animal defined as all animals with either a positive fecal culture or ELISA test. Four statistical models were used to estimate heritability: 1) linear (ELISA), 2) threshold (fecal culture and combined), 3) ordered threshold (ELISA), and 4) bivariate linear-threshold (ELISA-fecal culture). A sire model and Bayesian approach using Markov chain Monte Carlo methods were used in each case. Heritability of infection based on the fecal culture test was 0.153 [posterior standard deviation (PSD) = 0.115]. Heritability with the ELISA was 0.159 (PSD = 0.090) with a linear model and 0.091 (PSD = 0.053) with an ordered threshold model. Heritability of the combined tests was 0.102 (PSD = 0.066). Heritability estimates of fecal culture and ELISA with the bivariate model varied slightly from estimates obtained with the univariate models (0.125 and 0.183, respectively), with a corresponding increase in precision (PSD = 0.096 and 0.082, respectively). This study demonstrates that exploitable genetic variation exists in dairy cattle for M. paratuberculosis infection susceptibility. [ABSTRACT FROM AUTHOR]

Survival analysis in a Weibull proportional hazards model was used to evaluate the impact of somatic cell count (SCC) on the involuntary culling rate of US Holstein and Jersey cows with first calvings from 1990 to 2000. The full data set, consisting of records from 978,043 Holstein and 250,835 Jersey cows, was divided into subsets (5 for Holsteins and 3 for Jerseys) based on herd average lactation SCC values. Functional longevity (also known as herd life or length of productive life) was defined as days from first calving until culling or censoring, after correcting for milk production. Our model included the time-dependent effects of herd-year-season, parity by stage of lactation interaction, within-herd-year quintile ranking for mature equivalent production, and lactation average SCC (rounded to the nearest 50,000 cells/mL), as well as the time-independent effect of age at first calving. Parameters of the Weibull distribution, as well as variance components for herd-year-season effects, were estimated within each group of herds. Mean failure and censoring times decreased as herd average SCC increased, and a nonlinear relationship was observed between SCC and longevity in all groups. The risk of culling for Holstein cows with lactation average SCC >700,000 cells/mL was 3.4, 2.7, or 2.3 times greater, respectively, than that of Holstein cows with SCC of 200,000 to 250,000 cells/mL in herds with low, medium, or high average SCC. Likewise, the risk of culling for Jersey cows with lactation average SCC >700,000 cells/mL was 4.0, 2.9, or 2.2 times greater, respectively, than that of Jersey cows with SCC of 200,000 to 250,000 cells/mL in low, medium, or high SCC herds. These trends may reflect more stringent culling of high SCC cows in herds with few mastitis problems. In addition, cows with lactation average SCC <100,000 cells/mL had a slightly higher risk of culling than cows with SCC of 100,000 to 200,000 cells/mL in both breeds, particularly in herds wi... [ABSTRACT FROM AUTHOR]

A functional candidate gene approach was used to search for genes affecting milk production traits in Holstein dairy cattle. Signal transducer and activator of transcription 1 (STAT1) was chosen because of its involvement in the development of the mammary gland. Using the pooled genomic DNA sequencing approach, we identified a single nucleotide polymorphism. Genomic DNA was extracted from 1,292 sons obtained from the Cooperative Dairy DNA Repository and from 715 blood samples of daughters of 12 bulls obtained from the University of Wisconsin resource population. Daughter yield deviation data for the sons and yield deviation for the daughters were obtained for milk production traits from the USDA Animal Improvement Programs Laboratory. For the Repository population, allele C was associated with significant increases in milk fat and protein percentages. For the University of Wisconsin population, genotypes CC and CT were associated with significant increases in milk, fat, and protein yields. Results from this study are consistent with previous studies on the role of STAT1 in regulating the transcription of genes involved in milk protein synthesis and fat metabolism. [ABSTRACT FROM AUTHOR]

Floods are common in Thailand. A flood in the southern part of the country in 1988 was of unprecedented magnitude. Several villages and vast tracts of agricultural land were covered with mud slides washed away from deforested hills. Rehabilitation of the affected areas, a task which required complex planning, was a challenge for the District Development Committee (DDC), which is the local level planning body. The Committee encountered several problems, including inability to use the existing data base and lack of accurate information, human resources, adequate funds and coordination among agencies. Unable to cope with the new challenges, the DDC resorted to conventional planning which failed to address the problems caused by the flood. Guidelines should be formulated to strengthen district level planning for rehabilitation after a disaster.