Mastitis has a cumulative and lasting effect on milk yield and lactose content in dairy cows.

Milk lactose content (LC) physiologically decreases with parity order in dairy cows, but also after udder health inflammation(s) and/or in presence of elevated milk SCC in subclinical cases. Therefore, the progressive decrease in milk LC observed along cows' productive life can be attributed to a combination of factors that altogether impair the epithelial integrity, resulting in weaker tight junctions, e.g., physiological aging of epithelium, mechanical epithelial stress due to milking, and experienced clinical or subclinical mastitis. Mastitis is known to affect the udder synthesis ability too, so our intention through this study was to evaluate if there is a cumulative and lasting effect of mammary gland inflammation(s) on milk yield (MY) and LC. For this purpose, we used diagnoses of clinical mastitis and milk data of Austrian Fleckvieh cows to evaluate the effect of cumulative mastitis events on LC and MY. Only mastitis diagnoses recorded by trained veterinarians were used. Finally, we investigated if cumulative mastitis is a heritable trait and whether it is genetically correlated with either LC or MY. Estimates were obtained using univariate and bivariate linear animal models. A significant reduction in LC and MY was observed in cows that suffered from mastitis compared with those that did not experience udder inflammation. The h2 of cumulative mastitis is promising and much greater (0.09) than the h2 of the binary event itself (≤0.03). The genetic correlations between cumulative mastitis with LC and MY were negative, suggesting that cows with a great genetic merit for MY and LC are expected to be more resistant to repeated inflammations and less recidivist. When we used number of lifetime SCC peaks (≥200,000 or 400,000 cells/mL) to calculate cumulative inflammation events, h2 was even higher (up to 0.38), implying that also subclinical mastitis has a relevant negative impact on both LC and MY. Finally, the present study demonstrated how repeated mastitis events can permanently affect the mammary gland epithelial integrity and synthesis ability, and that the number of cumulative mastitis is a promising phenotype to be used in selection index in combination with other indicator traits toward more resistant and resilient mammary glands.

Benchmarking claw health across three dairy cow breeds in 508 dairy farms using numerical claw health indicators.

Currently, prevalence and incidence of claw lesions are used as parameters for benchmarking claw health. The aims of this study were to create a benchmarking system for claw health utilizing the claw health indicators Farm-Claw-Score (FCS) for the herd and Cow-Claw-Score (CCS) for the individual animal, and to benchmark claw health of the three predominant dairy cattle breeds in Austria. Claw health data from 17,642 cows from 508 Austrian dairy farms were analyzed. The CCS and FCS were calculated based on recorded claw lesions and their three severity levels using geometrically weighted scoring. The FCS of each of the dairy farms was classified into five percentile thresholds (P10, P25, P50, P75, P90), with the FCS calculated using the median value of CCS in each herd. Furthermore, claw health was benchmarked for three breeds (Fleckvieh, Holstein, Brown Swiss cows), using claw lesion prevalences and CCS values. When the median FCS was calculated, dairy farms in P50 and below had an FCS of 20.0, indicating very good claw health. However, P90 farms showed an FCS-MEDIAN of 67.5. Evaluation of the prevalences of the 14 claw lesions considered and the CCS values revealed that Fleckvieh cows (CCS-MEDIAN: 24.0), followed closely by Holstein cows (CCS-MEDIAN: 22.7) had significantly poorer claw health (P < 0.0001) compared to Brown Swiss cows (CCS-MEDIAN: 12.0). The use of CCS and FCS as primary claw health indicators allowed for a quick assessment of the current state of an individual cow and a dairy herd in a benchmarking system. Detailed information on the claw health of each animal and the dairy herd can be easily reviewed by examining diagnosis lists that display prevalences, particularly those related to lameness, in the respective electronic documentation systems.

Strategies for keeping dairy cows and calves together - a cross-sectional survey study.

Although it is still most common to rear dairy calves separately from adult cattle, the interest in prolonged contact between dairy calves and lactating cows during early life is increasing. Previous research has documented positive effects of cow-calf contact (CCC) on for example early calf growth and udder health of suckled cows, but also negative effects such as increased separation distress and reduced weight gains after weaning. The aim of this study was to use information from European farms with prolonged cow-calf contact to identify innovative solutions to common challenges for CCC farms. Commercial dairy farms that kept calves with adult lactating cows for seven days or more after birth were invited to participate, and interviews were performed with 104 farmers from six countries. During interviews, information about farm management, calf rearing, farmers' perception of animal health on their farm, and farmers' drivers and barriers for implementing CCC were collected. We found that CCC was practised in a large variety of housing and management systems, and that calves could be reared together with their dam, with foster cows, or using a combination of the two. The contact period varied considerably (7-305 days) between farms and about 25% of the farms manually milk fed the calves during parts of the milk feeding period. Daily contact time varied between farms, from 30 minutes per day to permanent contact except at milking. Behaviours indicative of separation distress, most commonly vocalisation in cows and calves, were reported by 87% of the farmers. Strategies to alleviate separation distress, for example simultaneous gradual weaning and separation, were used on some farms. Building constraints were most often mentioned as a barrier for implementing CCC. Our findings suggest that CCC is practised in a variety of commonly used husbandry systems. Reported challenges were primarily related to weaning and separation, and to building constraints; these aspects should be areas of future research.

Usability of bacteriological milk analyses for genetic improvement of udder health in Austrian Fleckvieh cows.

In addition to somatic cell count records and clinical mastitis diagnoses, results of bacteriological milk analyses provide valuable information regarding udder health. The pathogen causing an udder infection is currently not considered in Austria as part of the information used for estimation of routine breeding values for mastitis resistance. Therefore the objective of this study was to estimate heritabilities for, and genetic correlations between, udder traits of bacterial infection (bacterial infection, gram-positive and gram-negative bacterial infection) and routinely recorded udder health traits [acute mastitis, chronic mastitis, culling due to udder health problems, and somatic cell score (SCS)] in Austrian Fleckvieh cows. The basis for the genetic analyses was a data set with results from bacteriological milk analyses collected from 237 dairy farms and 6,822 cows over a period of 1 yr. Traits were defined as binary, apart from SCS, for which measures were available continuously. Multivariate analyses using a linear animal model were applied for estimating genetic parameters. The heritabilities for the occurrence of bacterial udder infection traits were 0.01. Heritabilities were 0.04 for acute mastitis, 0.02 for chronic mastitis, 0.02 for culling due to udder health problems, and 0.20 for SCS. Genetic correlations between bacteriological infection and the routinely recorded udder health traits were positive and ranged from 0.62 to 0.96. The genetic correlation between gram-positive and gram-negative bacterial infection was -0.20. The genetic correlation between acute and chronic mastitis was also close to zero. These results show that mastitis caused by different pathogens may be seen as different traits. As analyses were based on a relatively small data set and results were associated with rather high standard errors, further research with a larger data set should be carried out to confirm these results.

[Impact of lameness on fertility traits in Austrian Fleckvieh cows - results from the Efficient-Cow-project]. / Auswirkung von Lahmheit auf Fruchtbarkeits­merkmale bei Fleck­vieh-Kühen in Österreich ­ Ergebnisse aus dem Efficient-Cow-Projekt.

INTRODUCTION: The impact of lameness on fertility in dairy cows has already been investigated, however predominantely in Holstein cows. The aim of this study was to evaluate the impact of lameness during the dry period, between calving and first service and between calving and conception (days open) on selected fertility traits in Austrian Fleckvieh cows. Locomotion scoring of dairy cows was performed during the course of routine performance testing in 2014 and 2015. Using the observed maximum locomotion score (MLSC) during pre- and postcalving periods, the cows were classified into three groups: cows never lame (MLSC 1), cows that showed MLSC 2, and cows with MLSC ≥3 during these defined periods. Data sets of 3,998 lactations of 3,058 Austrian Fleckvieh cows from 97 dairy herds could be evaluated. In several statistical models the fixed effects of MLSC (1, 2, ≥ 3), farm, year and season of calving, parity*age class at calving, and early fertility disorders were considered for analysis of the traits days from calving to first insemination, interval from first to last insemination, days from calving to conception and calving interval (CI), as well as the non-return-rate90 (NRR90). Mean lameness prevalence during the dry period was 19,43 %, and reached 27,70 % in the period between calving and conception. Lameness (MLSC ≥ 3) during the dry period significantly (P = 0,030) prolonged the period between calving and conception, and lameness (MLSC ≥ 3) during the period from calving to first service had a significantly detrimental effect on the periods calving to first insemination, days open and CI (P < 0,001). Further, highly significant associations (P < 0,001) in cows showing MLSC ≥ 2 during the period between calving and conception on all fertility traits were determined. Apart from lameness, farm, year and season of calving, parity*-age class at calving, early fertility disorders and, partly, the interaction of the latter two effects significantly (P.

INTRODUCTION: L'impact de la boiterie sur la fertilité chez les vaches laitières a déjà été étudié, mais principalement chez les vaches Holstein. Le but de cette étude était d'évaluer l'impact de la boiterie pendant la période de tarissement, entre le vêlage et la première saillie et entre le vêlage et la conception (« days open ¼) sur certains indices de fertilité chez les vaches autrichiennes Fleckvieh. La notation de la locomotion des vaches laitières a été effectuée au cours des tests de performance de routine en 2014 et 2015. À l'aide de la note de locomotion maximale observée (MLSC) pendant les périodes de pré-vêlage et de post-vêlage, les vaches ont été classées en trois groupes : vaches jamais boiteuses (MLSC 1), vaches ayant montré un MLSC 2 et les vaches avec MLSC ≥3 pendant ces périodes définies. Des ensembles de données de 3 998 lactations de 3 058 vaches autrichiennes Fleckvieh de 97 troupeaux laitiers ont pu être évalués. Dans plusieurs modèles statistiques, les effets fixes de la MLSC (1, 2, ≥ 3), de l'exploitation, de l'année et de la saison de vêlage, de la classe d'âge au vêlage et des troubles de la fertilité précoce ont été pris en compte pour l'analyse des caractéristiques de fertilité : jours du vêlage à la première insémination, intervalle de la première à la dernière insémination, jours du vêlage à la conception et intervalle de vêlage (IC), ainsi que taux de non-retour90 (NRR90). La prévalence moyenne de boiterie pendant la période sèche était de 19,43 % et atteignait 27,70 % entre le vêlage et la conception. La boiterie (MLSC 3) pendant la période tarie (P = 0,030) prolongeait significativement la période entre le vêlage et la conception et la boiterie (MLSC ≥ 3) pendant la période allant du vêlage à la première insémination avait un effet significativement néfaste sur les périodes vêlage-première insémination, « days open ¼ et IC (P < 0,001). De plus, des associations hautement significatives (P < 0,001) chez les vaches présentant une MLSC 2 pendant la période entre le vêlage et la conception sur tous les traits de fertilité ont été relevées. Hormis la boiterie, l'exploitation, l'année et la saison de vêlage, la classe d'âge au vêlage, les troubles de la fertilité précoce et, en partie, l'interaction de ces deux derniers effets a affecté de manière significative (P < 0,05) à très significative (P < 0,001) les caractères de fertilité étudiés. Des associations négatives significatives sur certains caractères de fertilité uniques et tous ceux étudiés ont été évaluées chez des vaches souffrant de MLSC ≥ 2, et en particulier de MLSC ≥ 3, pendant trois périodes définies avant et après le vêlage. La prévention ou la réduction de la boiterie chez les vaches présentant une MLSC2 pendant la période de tarissement et de « days open ¼ aurait probablement un effet bénéfique significatif sur la fertilité et le bien-être des vaches laitières.

[Impact of lameness on milk yield in dairy cows in Austria - results from the Efficient-Cow-project]. / Auswirkung von Lahmheit auf die Milchleistung bei Milchkühen in Österreich ­ Ergebnisse aus dem Efficient- Cow-Projekt.

INTRODUCTION: Introduction The impact of lameness on milk yield in dairy cows has been investigated already in many countries by several authors, taking into consideration almost exclusively locomotion scores ≥ 3. The aim of this study was to evaluate the impact of lameness and of the various lameness scores (2-5) on milk yield and milk solids in cows of the three most important dairy cattle breeds (Fleckvieh, Braunvieh, Holstein-Friesian) in Austria within one lactation period. Material and methods Locomotion scoring of dairy cows was performed by trained personnel every 30-40 days in 2014 during the course of routine performance testing. From the recorded locomotion scores (1-5) and the number of lameness episodes, the cows were classified into five lactation-locomotion-score-groups (LLS-G1-5). In total, data sets of 4005 cows from 144 dairy farms across Austria could be evaluated. Using two statistical models the fixed effects on LLS group, breed (evaluation across all breeds in model 1), farm, year and season of calving, parity and the «continuous effect¼ number of milking days were included in the analyses of milk, fat and protein yield. Results The mean, cumulative lameness prevalence during the observation period was 51.0%, and 8.1% were cows from the LLS-G5 group showing repeated and severe locomotion scores. During the first 100 days in milk 34.7% of all cows were lame. In model 1, all effects considered had a significant impact (P .

INTRODUCTION: Introduction L'impact des boiteries sur le rendement laitier des vaches a déjà été étudié dans de nombreux pays par plusieurs auteurs, en prenant en compte presque exclusivement des scores de locomotion ≥ 3. Le but de cette étude était d'évaluer l'impact de la boiterie et des différents scores de boiterie (2­5) sur le rendement laitier et la matière sèche du lait chez les vaches des trois races bovines laitières les plus importantes (Fleckvieh, Braunvieh, Holstein-Friesian) en Autriche au cours d'une période de lactation. Matériel et méthode Le scoring de locomotion des vaches laitières a été effectué par du personnel formé tous les 30 à 40 jours en 2014 au cours des tests de performance de routine. À partir des scores de locomotion enregistrés (1­5) et du nombre d'épisodes de boiterie, les vaches ont été classées en cinq groupes de score de lactation-locomotion (LLS-G1­5). Au total les données de 4 005 vaches provenant de 144 exploitations laitières de toute l'Autriche ont pu être évaluées. À l'aide de deux modèles statistiques, les effets fixes sur le groupe LLS, la race (évaluation pour toutes les races dans le modèle 1), l'exploitation, l'année et la saison de vêlage, le nombre de lactations et le nombre de jours de traite par rapport aux analyses des quantités de lait, des matières grasses et des protéines ont été pris en compte. Résultats La prévalence moyenne cumulative de boiteries pendant la période d'observation était de 51,0% et 8,1% étaient des vaches du groupe LLS-G5 présentant des boiteries répétées et sévères. Au cours des 100 premiers jours de lactation, 34,7% de toutes les vaches étaient boiteuses. Dans le modèle 1, tous les effets considérés de manière significative (P .

Estimation of genetic parameters for four Peruvian guinea pig lines.

This study aimed to estimate genetic parameters for four guinea pig lines of a crossbreeding scheme. Two paternal lines are selected for growth rate (P1) and feed conversion rate (P2), whereas two maternal lines are selected for growth rate of litter (M1) and litter size at birth (M2). The heritabilities and genetic correlations were estimated with animal linear models employing multivariate analyses with REML. The heritabilities for birth weight (BW) were 0.21±0.02 and 0.23±0.03 for P1 and P2, respectively, and for weaning weight (WW), the heritability was 0.28±0.03 for P2. The estimates for weight at 60 days of age (W60) were 0.34±0.01 and 0.47±0.04 for P1 and P2, respectively, and for partial feed conversion rate was 0.46±0.03 for P2. Heritabilities for litter weight at birth (LW) were 0.09±0.03 and 0.10±0.03 for P1 and M1, respectively. For litter weight at 10 days of age (LW10), the heritability was 0.15±0.03 for M1. Heritabilities for litter size (LS) were 0.17±0.03, 0.20±0.03 and 0.11±0.03, and for number of pups born alive (BA) were 0.09±0.03, 0.14±0.03 and 0.09±0.03 for P1, M1 and M2, respectively. Similarly, high genetic correlations were found between BW, WW and W60 and between LW, LS, LW10 and BA. The genetic correlation between BW direct and maternal was moderately negative (- 0.24 ± 0.10) for P1. These results show the genetic status for all four guinea pig lines, which is essential for the further improvement of the currently implemented breeding programme and also indicate an opportunity for genetic improvement.

Use of benchmarking to monitor and analyze effects of herd size and herd milk yield on cattle health and welfare in Austrian dairy farms.

The modernization and intensification of the dairy industry has led to larger herd sizes and higher milk production, both globally and in Austria. Benchmarking allows the monitoring of animal health and welfare as well as the identification of potential for improvement by comparing certain parameters with other farms with similar management environments. Using data from the Austrian routine recording system of various traits of milk production, fertility, and health, farmers and their veterinarians (with the consent of the farmer) can compare farm parameters with detailed data available from their district or state and ensure more efficient herd management. The aim of the present study was to provide an overview of dairy milk production in Austria based on the annual herd health reports and to examine the effects of herd size and milk production on fertility and health parameters. Annual herd health reports from all farms participating in the health monitoring system were considered, and analyses were conducted across breeds. A large variation between farms was observed. The results showed that, based on parameters of milk yield and herd size for the range of farms within this study, it cannot be concluded that these circumstances automatically lead to poor animal health. Farms with very small herd sizes differed significantly from those with larger herd sizes. Overall herd size effects were however small in Austria. Higher milk production based on a single farm does not necessarily cause more health and fertility problems; however, we detected a tendency for an increased risk of fertility, udder, and metabolic diagnoses. An active health management program might result in higher incidence rates for fertility or udder diagnoses, as a veterinary treatment might be economically superior if, for example, the calving interval can be shortened or the somatic cell count can be reduced. The results of the present study showed that it is advisable to use different benchmarks in combination for monitoring health, as well as for deciding on strategies to improve overall herd health management. Animal health reports on Austrian dairy cows are continuously being developed and new parameters integrated.

Genetic associations of lactose and its ratios to other milk solids with health traits in Austrian Fleckvieh cows.

The genetic correlations (ra) of milk lactose percentage (LP), lactose yield (LY), and ratios of LP to other milk solids with udder, metabolic, and fertility disorders have not been assessed in dairy cattle so far. To evaluate the potential role of milk lactose as indicator of cow health, 142,285 lactation records of 84,289 Austrian Fleckvieh cows were analyzed with univariate and bivariate animal models. Milk traits were on a 150-d basis and health traits were coded as binary (0/1). Other than LP and LY, 3 new phenotypes were defined and included in the present study, namely the lactose-to-fat, lactose-to-protein, and lactose-to-solids ratios. The most heritable trait was LP (0.566 ± 0.008) and heritability of LY was much lower (0.145 ± 0.005). Heritability estimates close to 0.50 were assessed for the ratios. The frequency of health disorders was higher in multiparous cows yielding milk with low LP (≤4.553%) compared with cows yielding milk with high LP (≥5.045%). Heritabilities of health traits were in the expected ranges, with the highest estimate for ovarian cysts (CYS; 0.037 ± 0.004) and the lowest for retained placenta (0.005 ± 0.001). Mastitis (MAS) genetically correlated with LY (0.518 ± 0.057); considering that the amount of synthesized lactose is the key regulator of milk volume, this result confirmed that high-producing cows are more genetically susceptible to MAS than low-producing animals. Similar to MAS, ketosis (KET) was also positively genetically associated with LY (0.420 ± 0.077) and a weak and unfavorable ra between KET and lactose-to-protein ratio was estimated (0.159 ± 0.077). The ra of LY with milk fever (MFV) and CYS were approximately 0.20. The ra of LP with MAS, KET, and MFV were negative (-0.142 on average), supporting the idea that LP is a potential health indicator. Genetic correlations between health traits ranged from zero (retained placenta with MAS and CYS) to 0.463 ± 0.090 (MAS and MFV). Results of the present study suggest that LP has potentiality to be used as indicator trait to improve udder health in Austrian Fleckvieh population.

Short communication: Use of lameness scoring to genetically improve claw health in Austrian Fleckvieh, Brown Swiss, and Holstein cattle.

The specific objective of this study was to evaluate the use of lameness scoring to genetically improve claw health in Austrian Fleckvieh, Brown Swiss, and Holstein cows based on data from the "Efficient Cow" project. In 2014, a 1-yr data collection was carried out. Data from 6,519 cows kept on 161 farms were recorded. At each time of milk recording, lameness scores were assessed by trained staff of the milk recording organizations. Hoof trimming on these farms was documented and recorded as well. Veterinarian diagnoses and culling due to foot and leg problems from these farms were available from the routine recording system. As repeated lameness records per cow and lactation were available, an overall lactation lameness score was calculated. Estimated heritabilities for lameness were 0.11, 0.05, and 0.09 for Fleckvieh, Brown Swiss, and Holstein, respectively; however, only heritability estimates for Fleckvieh were significantly different from zero. Breeding values for lameness were obtained, reversed in sign, and cows were ranked according to their breeding value. A low breeding value for lameness resistance (the bottom 10% of the cows) was associated with a significantly higher frequency of trimmed cows, which indicates that the cows selected by the farmer to be trimmed are not completely random. Additionally, a high breeding value for lameness resistance (the top 10% of the cows) was associated with lower frequencies of claw diseases recorded at trimming, claw and leg diagnoses, and culling due to foot and leg problems, which highlights the usefulness of lameness scoring for genetic improvement of claw health. Overall, selecting for a better lameness score has the potential to reduce claw diseases, especially the frequency of severe claw diseases that lead to culling.

Mountain pasturing of rearing stock reduces the culling risk as dairy cows.

Alpine transhumance or droving livestock to mountainous areas during summer months is highly relevant for Austrian agriculture but also for other countries in Alpine regions. Access of rearing stock to mountain pastures is often claimed to be beneficial with respect to health and longevity, but the robust evidence is scarce. Therefore, its effect was tested by including it in the routine genetic evaluation data set for longevity. Alpine transhumance records from 2004 to 2013 were used. After several plausibility checks and restriction to animals with sire and dam known, records of 871 287 dual-purpose Fleckvieh cows sired by 9953 bulls were available. Data were analysed by means of survival analysis accounting for the time-dependent fixed effects of region-year-season, relative performance within herd, change of herd size, and Alpine pasturing of cows, the fixed effects age at first calving and Alpine pasturing of rearing stock, the random time-dependent effect of herd-year and the random genetic effects of sire and maternal grandsire. Fleckvieh cows that had access to Alpine pasture during their rearing period at least once for a minimum of 60 days had functional longevity that was nearly 2 months prolonged compared with cows that had always stayed on the farms as calves or heifers. In a more detailed analysis, the lowest relative culling risk among the significant estimates was observed for cows that had been Alpine pastured in years 1 and 3; it was about 15% below that of cows that never had access to mountain grazing. Evidence for the beneficial effect of Alpine pasturing of rearing stock on the animals' later fitness, indicated by longevity, could thus be provided.

Genetic analysis of efficiency traits in Austrian dairy cattle and their relationships with body condition score and lameness.

This study is part of a larger project whose overall objective was to evaluate the possibilities for genetic improvement of efficiency in Austrian dairy cattle. In 2014, a 1-yr data collection was carried out. Data from 6,519 cows kept on 161 farms were recorded. In addition to routinely recorded data (e.g., milk yield, fertility, disease data), data of novel traits [e.g., body weight (BW), body condition score (BCS), lameness score, body measurements] and individual feeding information and feed quality were recorded on each test-day. The specific objective of this study was to estimate genetic parameters for efficiency (related) traits and to investigate their relationships with BCS and lameness in Austrian Fleckvieh, Brown Swiss, and Holstein cows. The following efficiency (related) traits were considered: energy-corrected milk (ECM), BW, dry matter intake (DMI), energy intake (INEL), ratio of milk output to metabolic BW (ECM/BW0.75), ratio of milk output to DMI (ECM/DMI), and ratio of milk energy output to total energy intake (LE/INEL, LE = energy in milk). For Fleckvieh, the heritability estimates of the efficiency (related) traits ranged from 0.11 for LE/INEL to 0.44 for BW. Heritabilities for BCS and lameness were 0.19 and 0.07, respectively. Repeatabilities were high and ranged from 0.30 for LE/INEL to 0.83 for BW. Heritability estimates were generally lower for Brown Swiss and Holstein, but repeatabilities were in the same range as for Fleckvieh. In all 3 breeds, more-efficient cows were found to have a higher milk yield, lower BW, slightly higher DMI, and lower BCS. Higher efficiency was associated with slightly fewer lameness problems, most likely due to the lower BW (especially in Fleckvieh) and higher DMI of the more-efficient cows. Body weight and BCS were positively correlated. Therefore, when selecting for a lower BW, BCS is required as additional information because, otherwise, no distinction between large animals with low BCS and smaller animals with normal BCS would be possible.

Short communication: Genetic relationships between functional longevity and direct health traits in Austrian Fleckvieh cattle.

The aim of this study was to conduct a multitrait 2-step approach applied to yield deviations and deregressed breeding values to get genetic parameters of functional longevity, clinical mastitis, early fertility disorders, cystic ovaries, and milk fever of Austrian Fleckvieh cattle. An approximate multitrait approach allows the combination of information from pseudo-phenotypes derived from different statistical models in routine genetic evaluation, which cannot be estimated easily in a full multitrait model. A total of 66,890 Fleckvieh cows were included in this study. For estimating genetic parameters, a simple linear animal model with year of birth as a fixed effect and animal as a random genetic effect was fitted. The joint analysis of yield deviations and deregressed breeding values was feasible. As expected, heritabilities were low, ranging from 0.03 (early fertility disorders) to 0.15 (functional longevity). Genetic correlations between functional longevity and clinical mastitis, early fertility disorders, cystic ovaries, and milk fever were 0.63, 0.29, 0.20, and 0.20, respectively. Within direct health traits genetic correlations were between 0.14 and 0.45. Results suggest that selecting for more robust disease-resistant cows would imply an improvement of functional longevity.

Effect of inbreeding depression on survival of Austrian Brown Swiss calves and heifers.

The aim of this study was to estimate inbreeding depression for juvenile mortality in Austrian Brown Swiss replacement heifers born in the years 2001 to 2007. After data editing, records of 69,571 animals were investigated. In total, the pedigree consisted of 203,894 animals. Mean and median inbreeding coefficients were 0.0514 and 0.0475, respectively. The following periods were defined for analyses of juvenile mortality: P1=48 h to 30 d, P2=31 to 180 d, P3=181 to the day before first calving or a maximum age of 1,200 d if no calving was reported, P4=48 h to the day before age at first calving or a maximum age of 1,200 d if no calving was reported. Mortality during the first 30 d of life was 3.2%; in the total rearing period, 9.3% of the heifers died (excluding slaughtered and exported animals). For the estimation of the effect of inbreeding and of genetic parameters a linear animal model with the random effects herd-year of birth and animal as well as the fixed effects year of birth-month of birth and dam parity, and the continuous effect of inbreeding coefficient (linear and quadratic) was applied. The model was reduced to the linear effect of inbreeding as the quadratic term was not found to have a significant effect. Inbreeding significantly affected all traits unfavorably. In the full rearing period (P4), heifer calves with an inbreeding coefficient of 0.10 had a 4.9% higher mortality rate than heifer calves with no inbreeding.

Hot topic: Effect of breeding strategies using genomic information on fitness and health.

A complex deterministic approach was used to model the breeding goal and breeding structure for the Austrian Fleckvieh (dual-purpose Simmental) breed. The reference breeding goal corresponded to the current total merit index (TMI-R), where dairy traits have a relative weight of 37.9% and fitness traits of 43.7% (beef traits 16.5%; milkability 2%). The breeding program was characterized by 280,000 cows under performance recording, 3,200 bull dams, 100 test bulls with a test capacity of 25%, and 15 proven bulls and 8 bull sires per year. The annual monetary genetic gain (AMGG) was generated mainly by increases in milk fat and milk protein yield (80.6%) and only to a small extent by fitness traits (6.6%). The inclusion of direct health traits (early reproductive disorders, cystic ovaries, and mastitis) with their economic weights increased the relative AMGG for fitness traits from 6.6 to 11.2%. The presently slightly negative AMGG for fertility index and udder health changed in a positive direction. Increasing the weight on the direct health traits by 50% resulted in a further shift toward fitness and health. The effect of strategies using genomic information in a total merit index (TMI) with varying weights on fitness and health traits was also analyzed. The conventional progeny-testing scheme was defined as the reference breeding program. A breeding program was considered to be genomically enhanced (GS50) when 50% of inseminations of herdbook cows and of bull dams were from young bulls with a genomic TMI, and a second program (GS100) did not rely on progeny-tested bulls at all. For GS50, a clear shift of the relative gain in AMGG toward fitness and health traits was observed for all 3 TMI scenarios, as a result of larger progeny groups and a shorter generation interval. For GS100, where no gene flow from progeny-tested bulls was assumed, the genetic gain per generation was lower for the fertility and udder health index but higher per year. The results based on natural genetic gain per year showed that no positive genetic response for fertility and udder health index were achieved for TMI-R (without the inclusion of direct health traits) in GS50 and GS100. The direction of the genetic trend was determined by the weights given to fertility and udder health indices within the TMI. When appropriate weights generated a clear positive trend, GS50 and GS100 reinforced this trend.

Recording of direct health traits in Austria--experience report with emphasis on aspects of availability for breeding purposes.

A project to establish an Austria-wide health-monitoring system for cattle was launched in 2006. Veterinary diagnostic data subject to documentation by law [Law on the Control of Veterinary Medicinal Products (Tierarzneimittelkontrollgesetz)] are standardized, validated, and recorded in a central database. This Austria-wide project is a collaboration among agricultural and veterinary organizations as well as universities, and is also supported by the Austrian government. In addition to providing information for herd management and preventive measures, further objectives of the project include estimating breeding values for health traits and monitoring the overall health status of Austria's cattle. To ensure a high level of participation from farmers and veterinarians, data security issues are extremely important. Valid data are the prerequisite for the efficient use of health records. The challenge hereby is to distinguish between farms with low frequencies of diseases and incomplete documentation and recording. Measures were undertaken to establish a routine monitoring system for direct health traits. A routine genetic evaluation for direct health traits as part of the joint breeding value estimation program between Germany and Austria was introduced for Fleckvieh in December 2010, based on diagnostic data from 5,428 farms with 147,764 Fleckvieh cows. In 2010 to 2011, the reporting of direct health traits as a compulsory part of performance recording and the breeding program was introduced as well. The overall challenge is the availability of sufficient valid direct health data for reliable breeding values. Practical experience gained in Austria in setting up a health registration system, focusing mainly on the availability of direct health data for breeding purposes with its successes and difficulties, is described.

Inbreeding depression on semen quality in Austrian dual-purpose simmental bulls.

Using pedigree data, the inbreeding coefficients of 715 Austrian dual-purpose Simmental (Fleckvieh) bulls stationed in two artificial insemination (AI) centres in Upper and Lower Austria were calculated and incorporated in statistical models for the analysis of semen quality. Five semen quality parameters (volume, concentration, motility, number of spermatozoa per ejaculate and percentage of viable spermatozoa) of approximately 30,000 ejaculates, used in two separate data sets, were investigated. The mixed model included the fixed effects age class of the bull, bull handler, semen collector, month and year of collection, number of collection per bull and day, time interval since last collection, the linear continuous effect of the inbreeding coefficient of the bull, interactions between age class and month, and age class and interval since last collection, respectively, as well as the random effect of the bull and the random residual effect. Non-linear effects of inbreeding were significant for motility only. Despite the quite low inbreeding coefficients (mean 1.3%), all semen quality traits showed inbreeding depression, in four of the five traits significantly in at least one of the data sets. The magnitude of inbreeding depression was small, which might partly be caused by the low inbreeding levels and a potential pre-selection of the bulls in the AI centres. However, monitoring of inbreeding depression on fertility traits is recommended to avoid unrecognized deterioration of such traits.

Genetic evaluation of ovulatory disorders in Austrian Fleckvieh cows: a comparison between linear models and survival analysis.

The objective of this study was to compare linear models and survival analysis for genetic evaluation of ovulatory disorders, which included veterinary treatments of silent heat/anestrus and cystic ovaries. Data of 23 450 daughters of 274 Austrian Fleckvieh sires were analyzed. For linear model analyses, ovulatory disorders were defined as a binary response (presence or absence) in the time periods from calving to 150 days after calving and from calving to 300 days after calving. For survival analysis, ovulatory disorders were defined either as the number of days from calving to the day of the first treatment for an ovulatory disorder (uncensored record) or from calving to the day of culling, or the last day of the period under investigation (until 150 or 300 days after calving; censored record). Estimates of heritability were very similar (0.016 to 0.020) across methods and periods. Correlations between sire estimated breeding value from linear model and survival analysis were 0.98, whereas correlations between different time periods were somewhat lower (0.95 and 0.96). The results showed that the length of time period had a larger effect on genetic evaluation than methodology.

Genetic analysis of clinical mastitis and somatic cell count traits in Austrian Fleckvieh cows.

The objectives of this study were to investigate genetic associations between clinical mastitis (CM) and different somatic cell count traits, and to examine their relationships, in terms of estimated breeding values, with other traits that are routinely evaluated in Austrian Fleckvieh dual-purpose cows. Records on veterinary treatments of CM were available from the Austrian health-monitoring project. For CM, 3 intervals in early lactation were considered: -10 to 50 d, 51 to 150 d, and -10 to 150 d after calving. Within each interval, absence or presence of CM was scored as 1 or 0 based on whether or not the cow had recorded at least one veterinary treatment of CM. The average somatic cell score of the first 2 test-days after calving was defined as early lactation average somatic cell score, and lactation mean somatic cell score was the average of all test-day somatic cell scores from 8 to 305 d after calving. Subclinical mastitis was expressed as a binary trait based on prolonged elevated somatic cell counts. If somatic cell counts on 3 consecutive test-days in the interval from 8 to 305 d after calving were above 200,000 cells/mL, the binary variable subclinical mastitis was defined as 1 and otherwise 0. Records of Austrian Fleckvieh cows, with calving from January 1, 2007, to February 28, 2009, were analyzed using univariate and bivariate sire models. Threshold liability models were applied for binary traits, and Gaussian models were used for early lactation average somatic cell score and lactation mean somatic cell score. A Bayesian approach using Gibbs sampling was applied for genetic analyses. Posterior means of heritability of liability to CM were 0.06 and 0.02 in the first and second interval, respectively, and 0.05 in the full period (-10 to 150 d). Heritability estimates of somatic cell count traits were higher (0.09 to 0.13). The posterior mean of the genetic correlation between CM in lactation period 1 (-10 to 50 d after calving) and 2 (51 to 150 d after calving) was close to unity. Posterior means of genetic correlations between CM and somatic cell count traits ranged from 0.64 to 0.77. Because CM and somatic cell count describe different aspects of udder health, information on both traits should be considered for selection of bulls. Correlations of sire breeding values revealed that especially the udder conformation trait udder depth may be useful as additional information to reduce both CM and somatic cell count.

Genetic analysis of calf and heifer losses in Danish Holstein.

Mortality in dairy cattle is not only relevant with regard to economic losses but also to animal health and welfare. Thus, the aim of this investigation was to explore the genetic background of postnatal mortality in calves and replacement heifers in different age groups until first calving in Danish Holsteins. Records of Danish Holstein heifer calves born in the years 1998 to 2007 were extracted from the Danish Cattle database (Danish Cattle, Skejby, Denmark). The following periods (P) were defined for analyses: P1=d 1 to 30, P2=d 31 to 180, P3=d 181 to 365, P4=d 366 until the day before first calving or a maximum age of 1,200 d if no calving was reported, and the full period P5=d 1 until the day before first calving or a maximum age of 1,200 d if no calving was reported. Records of animals slaughtered or exported within a defined period were set to missing for this and following periods, whereas their records were kept for preceding periods. After further data editing, more than 840,000 calves and heifers born in the years 1998 to 2007 were investigated. Mortality rates were 3.23, 2.66, 0.97, 1.92, and 9.36% for the defined periods P1 to P5, respectively. For the estimation of genetic parameters, linear and threshold sire models were applied. Effects accounted for were the random effects herd × year × season and sire as well as the fixed effects year × month, number of dam's parity (parities >5 were set to 5), calf size, and calving ease. In total, the pedigree consisted of 4,643 sires and 20,821 animals. Heritabilities for the linear model were low, ranging from 0.006 (P3) to 0.042 (P5). Heritabilities estimated by threshold models showed a wider range, from not significantly different from zero for periods with low frequencies to 0.082 for P1. The mortality rate until first calving was higher than the stillbirth rate. Genetic and phenotypic variation seemed to be sufficiently high to genetically improve the trait calf and heifer mortality. Hence, a routine genetic evaluation would be valuable for monitoring and for selecting fitter animals in the Danish Holstein cattle population.