Association of conception rate with pattern and level of somatic cell count elevation relative to time of insemination in dairy cows

The aim was to evaluate the effects of mastitis, determined by the pattern and level of somatic cell count (SCC) around first artificial insemination (AI), on conception rate (CR). Data from 287,192 first AI and milk records covering a 7-yr period were obtained from the Israeli Herd Book. Analyses examined the association of probability of conception with SCC elevation relative to timing of AI, using generalized linear mixed models. A SCC threshold of 150,000 cells/mL of milk was set to distinguish between uninfected cows and cows with mastitis. Accordingly, cows with high SCC before and low SCC after AI were designated cured, those with low SCC before and high SCC after AI were designated newly infected, and cows with high SCC before and after AI were designated chronic (likely subclinical) mastitic cows. Compared with uninfected cows, the cured, newly infected, and chronic subgroups showed reduced CR (39.4 ± 0.1, 36.6 ± 0.2, 32.9 ± 0.3, and 31.5 ± 0.2, respectively). In the chronic, subclinical group, probability of conception was lowered by 14.5% in the mild and moderately elevated SCC subgroups and by 20.5% in cows with high SCC elevation compared with the uninfected group (CR of 29.7 vs. 39.4%, respectively). A single high elevation of SCC (>10⁶ cells/mL on only 1 milk test day) lowered the probability of conception by 23.6% when it occurred during the 10 d immediately before AI, but not when it occurred earlier. For 30 d after AI, probability of conception was lowered by about 23%, as reflected in a CR of about 27% compared with the uninfected group. Probability of conception was lowered in cows with uterine and foot health problems (33.9%), in multiparous cows (34.1%), and in cows in the summer (29.1%), but no interactions with mastitis were detected. Results indicate that SCC elevation around AI, typical for subclinical mastitis, was associated with a significant reduction in probability of conception, and that even mild SCC elevation reduced CR. Severe elevation of SCC before AI, typical for clinical intramammary infection, reduced the probability of conception.     

Short communication: Effect of subclinical mastitis on proteolysis in ovine milk

The aim of this work was to evaluate the effect of intramammary infection (IMI) on the endogenous proteolysis of milk. Four control checks were carried out in the half-udder milk of 10 ewes that acquired unilateral subclinical mastitis. Two of these checks were conducted before the infection was established and 2 after. Ten healthy ewes were tested as a control group. The presence of a subclinical IMI involved an increase of the products of casein hydrolysis, the proteose-peptone (p-p) fraction and minor (m) caseins, and a decrease of β-casein. As a result, a significant increase in the proteolysis index (PI), calculated as the ratio of m-casein to the sum of caseins (α + β + κ), took place. α-Casein and κ-casein were not significantly affected by IMI. Correlations confirmed the scenario: log₁₀ of somatic cell count (SCC) was positively correlated with p-p content and negatively with β-casein, whereas log₁₀ SCC was not correlated with α-casein or κ-casein. On the other hand, p-p content was positively correlated with m-casein and PI and negatively with β-casein, but no correlation was detected between p-p content and α- or κ-casein. Furthermore, between casein fractions, m-casein was only significantly correlated with β-casein. These results suggest that use of indices of proteolysis of caseins such as p-p, m-casein, and PI, could be applied together with SCC to evaluate the cheese-making quality of milk.     

A genome scan for quantitative trait loci affecting milk somatic cell score in Israeli and Italian Holstein cows by means of selective DNA pooling with single- and multiple-marker mapping

Mastitis is an important and common dairy cattle disease affecting milk yield, quality, and consumer safety as well as cheese yields and quality. Animal welfare and residues of the antibiotics used to treat mastitis cause public concern. Considerable genetic variation may allow selection for increased resistance to mastitis. Because of high genetic correlation to milk somatic cell score (SCS), SCS can serve as a surrogate trait for mastitis resistance. The present study intended to identify quantitative trait loci (QTL) affecting SCS in Israeli and Italian Holstein dairy cattle (IsH and ItH, respectively), using selective DNA pooling with single and multiple marker mapping. Milk samples of 4,788 daughters of 6 IsH and 7 ItH sires were used to construct sire-family high- and low-tail pools, which were genotyped at 123 (IsH) and 133 (ItH) microsatellite markers. Shadow correction was used to obtain pool allele frequency estimates. Frequency difference between the tails and empirical standard error of D, SE(D), were used to obtain P-values. All markers significant by single marker mapping were also significant by multiple marker mapping, but not vice versa. Combining both populations, 22 QTL on 21 chromosomes were identified; all corresponded to previous reports in the literature. Confidence intervals were set by chi-squared drop method. Heterozygosity of QTL was estimated at 44.2%. Allele substitution effects ranged from 1,782 to 4,930 cells/mL in estimated breeding value somatic cell count units. Most (80%) of the observed variation in estimated breeding value somatic cell score could be explained by the QTL identified under the stringent criteria. The results found here can be used as a basis for further genome-wide association studies for the same trait.     

基于体细胞数的奶牛乳腺炎检测方法研究进展

介绍了检测奶牛乳腺炎的常用方法,然后就基于体细胞数的检测方法和技术进行了综述,并分析了这些方法存在的问题和不足,最后展望了基于体细胞数的检测方法和技术的发展趋势及应用前景。     

Relationships between somatic cell count and intramammary infection in buffaloes

The objectives of this study were to evaluate the presence of intramammary infections (IMI) in dairy buffaloes and to examine the relationships among IMI, somatic cell counts (SCC), and milk production traits. Two farms in northern Italy were visited monthly for a complete milking season. Quarter-based milk samples were collected at each visit from 46 buffaloes. A total of 1,912 samples were assessed in this experiment. Samples were cultured for bacterial presence and were tested for SCC and percentages of milk protein and fat. In addition, daily milk yield was recorded from each buffalo. Prevalence of IMI was large; 63% of quarters were infected. No buffalo remained free from IMI throughout the course of the study. Coagulase-negative staphylococci were the most common pathogen (66% of positive samples). The SCC was distinctly greater in infected quarters; 100% of quarters with SCC >200,000 cell/mL had IMI, whereas 98% of quarters with SCC below this threshold were uninfected. The somatic cell scores (SCS) in these buffaloes were much lower than those commonly observed in dairy cattle. The mean SCS from quarters with IMI was only 2.93. The highest SCS was observed in quarters infected by streptococci. No drastic decrease in milk yield was observed among infected buffaloes relative to healthy contemporaries. The relatively low SCS and lack of a strong effect on milk yield provide evidence to discourage antibiotic treatment of buffaloes for subclinical IMI during lactation.     

Effects of housing, management, and health of dairy heifers on first-lactation udder health in southwest Sweden

Data on health, management, and housing from birth to first calving were collected for 2,126 heifers on semi-monthly visits made by project veterinarians to 107 dairy herds from southwest Sweden. Additional data were obtained from the official milk- and health-recording program. Factors associated with incidence of veterinarian-treated clinical mastitis (VTCM) in the period 7 d before (d −7) to 30 d after first calving and of elevated cow composite somatic cell count (SCC, ≥200,000 cells/mL) at first test milking after first calving, respectively, were investigated using a 2-level (animal and herd) logistic regression analysis after initial screening by univariate analyses. The incidence risk of VTCM during the complete first lactation (305 d) was 10.8%. Ten percent of the diseased animals had more than 1 case of VTCM and 51% of total cases occurred from −7 to 30 d postcalving. The incidence rate of VTCM during the complete first 305-d lactation was 1.13 cases per 100 cow-mo. In total, 18.1% of the animals had elevated SCC at first test milking (mean 21 d) after calving. Veterinarian-treated clinical mastitis at −7 to 30 d postcalving was associated with higher overall incidence of mastitis in the herd and with reproductive disorders (i.e., retained placenta, endometritis, pyometra, dystocia, or twin birth). The risk of elevated SCC increased with increasing percentage of cows in the herd that, some time during the year, had had an increased udder disease score (chronically increased SCC). Other factors associated with increased risk of elevated SCC were increasing amounts of concentrates fed to 11- to 16-mo-old heifers, moving to confined housing the day of calving instead of earlier, and use of restraint measures at milking. In addition, growth rate from birth to weaning, and several feed-related variables (e.g., amount of concentrates and type of roughage given) were associated with VTCM at −7 to 30 d post-calving or elevated SCC at first test milking in the univariate analyses.     

Genetic associations between clinical mastitis and somatic cell score in early first-lactation cows

The objectives of this study were to examine genetic associations between clinical mastitis and somatic cell score (SCS) in early first-lactation cows, to estimate genetic correlations between SCS of cows with and without clinical mastitis, and to compare genetic evaluations of sires based on SCS or clinical mastitis. Clinical mastitis records from 15 d before to 30 d after calving and first test-day SCS records (from 6 to 30 d after calving) from 499,878 first-lactation daughters of 2,043 sires were analyzed. Results from a bivariate linear sire model analysis of SCS in cows with and without clinical mastitis suggest that SCS is a heterogeneous trait. Heritability of SCS was 0.03 for mastitic cows and 0.08 for healthy cows, and the genetic correlation between the 2 traits was 0.78. The difference in rank between sire evaluations based on SCS of cows with and without clinical mastitis varied from −994 to 1,125, with mean 0. A bivariate analysis with a threshold-liability model for clinical mastitis and a linear Gaussian model for SCS indicated that heritability of liability to clinical mastitis is at least as large as that of SCS in early lactation. The mean (standard deviation) of the posterior distribution of heritability was 0.085 (0.006) for liability to clinical mastitis and 0.070 (0.003) for SCS. The posterior mean (standard deviation) of the genetic correlation between liability to clinical mastitis and SCS was 0.62 (0.03). A comparison of sire evaluations showed that genetic evaluation based on SCS was not able to identify the best sires for liability to clinical mastitis. The association between sire posterior means for liability to clinical mastitis and sire predicted transmitting ability for SCS was far from perfect.     

Multiple-trait multiple-country genetic evaluations for udder health traits

International genetic bull evaluations of somatic cell counts (SCC) from 8 different Holstein populations and clinical mastitis from 3 of these populations were inferred simultaneously using a multiple-trait-multiple-country evaluation (MT-MACE) model. This model considered effective independent weighting factors and multivariately deregressed national genetic evaluations for countries with multiple-trait national models. Predictions of genetic merit from MT-MACE and their reliabilities were compared with the corresponding results from 2 separate single-trait-multiple-country evaluations (ST-MACE) for different groups of bulls. The assumed heritabilities for clinical mastitis (h² = 0.02 to 0.05) were substantially lower than the heritabilities for SCC (h² = 0.08 to 0.27). The predictive ability of MT-MACE was essentially equal to or better than the predictive ability of ST-MACE for all country-trait combinations, but both methods yielded effectively unbiased and consistent consecutive predictions (correlation > 0.93). Both sets of predictions also agreed well with future national genetic evaluations for bulls receiving additional daughter information (correlation > 0.96), except for evaluations for which within-country correlations were utilized internationally, but not nationally (correlation = 0.86 to 0.97). The reliabilities for MT-MACE were essentially equal to or higher than reliabilities for ST-MACE, depending on the trait and group of bulls in question. Reliabilities increased most for young bulls, and for clinical mastitis in countries that did not use the within-country correlations with SCC in the national evaluation (up to a 23% increase in average reliability).     

The impact of parent behavior-management training on child depressive symptoms.

The present study tested the impact of a parent behavior-management intervention on child depressive and internalizing symptoms. One hundred eighty-one children were randomly assigned to receive a videotape modeling parenting intervention, the Incredible Years, or to a wait-list control group. Children who received the intervention were more likely to have lower mother-rated mood and internalizing symptoms at post-treatment, compared with children in a wait-list control group. The effect sizes observed in the present intervention fell in the small-to-medium range for the sample as a whole, and some evidence supported the authors' hypothesis that effects would be strongest for children with baseline internalizing symptoms in the clinical range. Subsequent analyses also revealed that perceived changes in parenting effectiveness mediated the effect of treatment on children's post-treatment internalizing symptoms. The finding was consistent with study hypotheses and social learning explanations of child internalizing symptoms that guided selection of putative mechanisms. Implications for counseling psychologists and for designing interventions and prevention strategies for children with internalizing symptoms are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Do Behavioral Disturbances in Persons With Alzheimer's Disease Predict Caregiver Depression Over Time?

Random effects models were used to examine the association between behavioral disturbances in persons with Alzheimer's disease (N = 90) and caregiver depressive symptoms at 2-month intervals over an 18-month period. There was substantial variability in trajectories of change in caregiver depressive symptoms over time but no systematic increase in distress despite increased severity of dementia symptoms. Total behavioral disturbances were associated with higher levels of caregiver depressive symptoms: this effect was primarily attributable to aggressive behaviors. No consistent departure from linearity was evident in the relationship between behavior and depression over time. (PsycINFO Database Record (c) 2010 APA, all rights reserved)