Development of an objective and uniform scoring method to evaluate the quality of rearing in Dutch dairy herds

Young stock rearing is an essential part of dairy management, and it is important that the quality of rearing can be monitored and altered if necessary. In this study, a young stock rearing quality system (KalfOK) was developed with the aim to provide an objective and standardized means to evaluate and monitor the quality of young stock rearing in Dutch dairy herds. In the project, 201 dairy farmers participated. Twelve key indicators were defined that were related to calving and successful rearing, antimicrobial use, and herd health. For each of the key indicators, the value was calculated per herd and quarter of the year between January 2014 and April 2017. Benchmark values were determined to compare herd-specific results and for selection of threshold values. Each of the key indicators was graded when the value scored above the threshold. Combining the grades resulted in the herd-specific KalfOK score, which could vary between 0 and 100. Subsequently, 100 of the participating dairy herds were visited and the quality of young stock rearing was scored by a trained veterinarian. Using principal component analysis, the results of the herd health checks were combined into a factor score that represented the observed quality of young stock rearing during the visit. The amount of variance in observed quality of rearing during the herd health check that was explained by the key indicators in KalfOK was evaluated. Additionally, the validity of KalfOK to distinguish herds with an excellent or insufficient quality of young stock rearing was assessed by comparing the top and bottom 10% herds in the herd health check with the proportion of herds with a KalfOK score above or below a prespecified cutoff value. The results of the linear regression model showed that the key indicators included in KalfOK accounted for 56% of the variation in the score of the herd visits by a veterinarian. The moving average of the annual KalfOK score, which was the sum of the grades of all key indicators, was 77 points (25th percentile = 71, 75th percentile = 85 points). The combination of the sensitivity (88%, 95% confidence interval = 47–100%) and specificity (67%, 95% confidence interval = 54–78%) of KalfOK to correctly classify herds with an excellent quality of young stock rearing was highest when a cutoff value of 80 points was applied. Detection of dairy herds with an insufficient quality of young stock rearing was best at a cutoff value of 70 points (sensitivity 86%, 95% confidence interval = 42–100%; specificity 77%, 95% confidence interval = 66–86%). The KalfOK score that was based on routinely collected herd data provided an indication of the quality of young stock rearing in individual Dutch dairy farms. The KalfOK score illustrates how such data can be transferred into herd-specific information in support of animal health and welfare. Given the increasing availability of automatically assembled data, the development of similar monitoring tools seems a feasible option to enhance herd-specific management.     

Motivation of dairy farmers to improve mastitis management

The aims of this study were 1) to explore different motivating factors and to quantify their importance in decisions of farmers on improving mastitis management, 2) to evaluate different quality payment schemes as extra incentive mechanisms for farmers, and 3) to link the motivating factors to farmer characteristics. Data on characteristics of farmers were obtained through a traditional paper-based questionnaire (n = 100). Data on the factors motivating farmers to improve mastitis management were collected in a computer-interactive mode. Adaptive conjoint analysis was used to investigate perceptions of farmers of the importance of factors. Factors that are internal to the farm performance and the individual farmer provided more motivation than external factors implying esteem and awareness of the whole dairy sector performance. Internal nonmonetary factors relating to internal esteem and taking pleasure in healthy animals on the farm were equally motivating as monetary factors affecting farm economic performance. The identified difference in perceptions of farmers of importance of extra financial incentive based on bulk milk somatic cell count (BMSCC) depending on whether farmers think in terms of quality premium or penalty for a lower and a higher BMSCC, respectively, suggested that farmers are expected to be more motivated by a price decrease for milk with a greater BMSCC than by a price increase for milk with a lower BMSCC. In this respect, quality penalties were found to be more effective in motivating farmers than quality premiums. Two-stage cluster analysis of individual perceptions resulted in 3 distinct clusters according to motivation of farmers: premium- or penalty-oriented motivation, motivation to have an efficient (well-organized) farm that easily complies with regulatory requirements, and basic economic motivation. The obtained results highlight possible areas of improvement in incentive and educational programs aimed at improving mastitis management.     

Ranking experts' preferences regarding measures and methods of assessment of welfare in dairy herds using Adaptive Conjoint Analysis

Welfare in dairy herds can be addressed using different concepts. The difficulty is to extract which measures are the most important to practically address welfare at the herd level and the methods to assess traits considered most important. Therefore, the preferences of 24 acknowledged European welfare experts were ranked regarding 70 measures suitable to assess dairy cattle welfare at herd level using the Adaptive Conjoint Analysis (ACA; Sawtooth Software, Inc., Sequim, WA) technique. The experts were selected on the basis of 3 criteria: at least 5 yr experience in animal welfare research; recent scientific publications in the field of animal welfare; and, at the most, 3 animal species including dairy cattle as their field of expertise. The 70 traits were ranked by using the median ACA questionnaire utility scores and the range between the answers of the 24 experts. A high utility score with a low range between the answers of the experts was considered as suitable to assess welfare at farm level. Measures meeting these criteria were prevalence of lameness cases (107.3 ± 11.7), competition for feed and water (96.4 ± 13.9), and number of freestalls per 10 cows (84.8 ± 13.3). Based on the utility score alone, these former measures were replaced by stereotypic behavior (111.7 ± 17.1), prevalence of lameness cases (107.3 ± 11.7), body condition score (108.0 ± 18.9), and hock lesions (104.7 ± 16.1). Subsequently, to demonstrate that the ACA technique can be used to rank either well-known or inconclusive methods of assessment, the methods for the traits lameness cases and the hygiene of the calving pen were ranked using another 2 ACA questionnaires. The results are based on the opinions of selected, internationally acknowledged dairy cattle welfare experts within the European Union. In the future, other parties like dairy farmers and farmers’ organization should be included to achieve consensus about the most suitable traits applicable in practice. The currently investigated traits do not always apply to all dairy husbandry systems across the world, but are based on a system that includes indoor housing during winter. It is concluded that ACA is a useful technique to rank the different scientific opinions of experts regarding suitable traits and methods of assessment of dairy cattle at the herd level.     

Lifetime risk and cost of clinical mastitis in dairy cows in relation to heifer rearing conditions in southwest Sweden

Relationships between heifer rearing conditions and the risk of veterinary-reported clinical mastitis (VRCM) during productive life were studied by generalized linear mixed modeling at the lactation level. Data consisted of 5,693 lactations in 2,126 Swedish Reds, Swedish Holsteins, or dairy cows of other or mixed breeds, representing all female animals born in 110 herds in southwest Sweden in 1998. During a lactation, a cow was defined as affected by VRCM if one or more cases were reported by a veterinarian, starting from 7 d precalving. The applied model of VRCM included effects of breed, parity, diarrhea between 3 and 7 mo of age, increase in body weight from weaning to first breeding, increase in daily concentrate ration before first calving, herd-level median age at first calving, cow housing, and random effects of cow and herd. The VRCM incidence was 14% in a given lactation, or 0.11 cases/cow annually; 31% of the cows had VRCM at least once during their productive life. Ninety percent of the variation in mastitis risk was due to factors at the lactation level such as parity, milk yield, cow diseases, and other disturbances, instead of cow or herd factors. Severe diarrhea between 3 and 7 mo of age was associated with 2.8-fold higher odds of VRCM compared with mild diarrhea during the same period, whereas the VRCM odds of calves with mild diarrhea were half that without diarrhea. The odds of VRCM had a predicted maximum at an estimated prepubertal growth rate of 859 g/d and increased with 10% for every 1-kg increase in concentrate ration during the last 2 mo before first calving. Costs of VRCM were estimated based on assumptions regarding veterinary service, extra labor, culling and herd replacement, discarded milk, and production loss depending on parity and lactation stage when VRCM was diagnosed. The total mean costs of VRCM were estimated to be $735 per lactation with a diagnosis of CM, $103 per lactation across all cows, or $95 per cow annually during lifetime.     

Costs and efficacy of management measures to improve udder health on Dutch dairy farms

Many different management measures are available to control mastitis, a very costly disease in the dairy sector. The objective of this paper was to evaluate the costs and efficacies of 18 of these management measures, for contagious and environmental pathogens, and their effect on bulk tank somatic cell count (BTSCC) and incidence of clinical mastitis (CM). To determine the efficacies for these management measures, literature data and expertise were combined using Monte Carlo expert evaluation analysis. The effect of management measures varied with the incidence of CM and BTSCC, as well as for environmental and contagious problems. On average, postmilking teat disinfection was found to be the most effective measure in all situations. All management measures had large uncertainty around the most likely value. Results of a data envelopment analysis showed that 4 of the management measures included formed the best-practice frontier (the most cost-efficient measures): keeping cows standing after milking, rinsing clusters after milking a clinical case, using a separate cloth for all cows, and wearing milkers’ gloves. Of the top 25 management measures (the 18 base management measures including levels of compliance), 8 were measures with 100% compliance; the others were sublevels of these measures with compliance varying between 25 and 100%. A lower hourly rate of the farmer did not influence management measures from the best-practice frontier, but had some effect on the efficiency scores of the other management measures.     

Use of multivariate analysis to extract latent variables related to level of production and lactation persistency in dairy cattle

Multivariate factor analysis and principal component analysis were used to decompose the correlation matrix of test-day milk yields of 48,374 lactations of 21,721 Italian Simmental cows. Two common latent factors related to level of production in early lactation and lactation persistency, and 2 principal components associated with the whole lactation yield and persistency were obtained. Factor and principal component scores were treated as new quantitative phenotypes related to prominent features of lactation curve shape. Genetic parameters were estimated by univariate and bivariate animal models. Estimates of heritability were moderately low for both latent factors (0.13 for persistency and yield early in lactation). Heritabilities of the principal component related to total lactation yield and 305-d yield were similar (0.19 and 0.20, respectively). Finally, heritability was quite low for the principal component related to lactation persistency (0.07). Repeatabilities between lactations were about 0.27 for both latent factors, around 0.4 for the first principal component and 305-d yield, and 0.11 for the second principal component. Moderate genetic correlation among common factors (0.26) and their high genetic correlation with total lactation yield (>0.60) suggest that selection can be used to change the shape of lactation curve as well as improve yield. Scores of the second principal component can be used to genetically improve persistency while maintaining constant total lactation yield.     

Genetic and genomic analyses of latent variables related to the milk fatty acid profile,milk composition,and udder health in dairy cattle

The aim of this study was to perform genetic, genome-wide association (GWAS), and gene-set enrichment analyses with latent variables related to milk fatty acid profile (i.e., fatty acids factor scores; FAF), milk composition, and udder health in a cohort of 1,158 Italian Brown Swiss cows. The phenotypes under study were 12 FAF previously identified through factor analysis and classified as follows: de novo FA (F1), branched-chain FA-milk yield (F2), biohydrogenation (F3), long-chain fatty acids (F4), desaturation (F5), short-chain fatty acids (F6), milk protein and fat contents (F7), odd fatty acids (F8), conjugated linoleic acids (F9), linoleic acid (F10), udder health (F11) and vaccelenic acid (F12). (Co)variance components were estimated for factor scores using a Bayesian linear animal model via Gibbs sampling. The animals were genotyped with the Illumina BovineSNP50 BeadChip v.2 (Illumina Inc., San Diego, CA). A single marker regression model was fitted for GWAS analysis. The gene-set enrichment analysis was run on the GWAS results using the Gene Ontology and the Kyoto Encyclopedia of Genes and Genomes pathway databases to identify the ontologies and pathways associated with the FAF. Marginal posterior means of the heritabilities of the aforementioned FAF ranged from 0.048 for F12 to 0.310 for F5. Factors F1 and F6 had the highest number of relevant genetic correlations with the other traits. The genomic analysis detected a total of 39 significant SNP located on 17 Bos taurus autosomes. All latent variables produced signals except for F2 and F10. The traits with the highest number of significant associations were F11 (17) and F12 (7). Gene-set enrichment analyses identified significant pathways (false discovery rate 5%) for F3 and F7. In particular, systemic lupus erythematosus was enriched for F3, whereas the MAPK (mitogen-activated protein kinase) signaling pathway was overrepresented for F7. The results support the existence of important and exploitable genetic and genomic variation in these latent explanatory phenotypes. Information acquired might be exploited in selection programs and when designing further studies on the role of the putative candidate genes identified in the regulation of milk composition and udder health.     

基于HACCP标准建立食品“农田到餐桌”全程危害物质防控技术

HACCP（hazard analysis and critical control）作为一种评估危害和建立控制体系的工具，可有效预防物理性、化学性和生物性风险和危害，是一种质量安全管理体系。目前被广泛应用在食品、药品、医疗等多个行业。本文通过梳理和分析国内现行有效的HACCP体系相关标准适用范围、涉及的潜在风险和危害，总结归纳出食品中常见的物理性、化学性和生物性危害物，以及食品不同环节的关键控制点以及监控方法。结合国内现行有效的HACCP体系相关标准，初步探讨基于HACCP危害物质分析与防控方法，建立从“农田到餐桌”食品全过程危害物质防控技术要求和工作程序，对HACCP方法进行研究，对HACCP技术理论进行深度探讨，开拓了HACCP体系的应用思路。