An approximate multitrait model for genetic evaluation in dairy cattle with a robust estimation of genetic trends (Open Access publication)

In a stochastic simulation study of a dairy cattle population three multitrait models for estimation of genetic parameters and prediction of breeding values were compared. The first model was an approximate multitrait model using a two-step procedure. The first step was a single trait model for all traits. The solutions for fixed effects from these analyses were subtracted from the phenotypes. A multitrait model only containing an overall mean, an additive genetic and a residual term was applied on these preadjusted data. The second model was similar to the first model, but the multitrait model also contained a year effect. The third model was a full multitrait model. Genetic trends for total merit and for the individual traits in the breeding goal were compared for the three scenarios to rank the models. The full multitrait model gave the highest genetic response, but was not significantly better than the approximate multitrait model including a year effect. The inclusion of a year effect into the second step of the approximate multitrait model significantly improved the genetic trend for total merit. In this study, estimation of genetic parameters for breeding value estimation using models corresponding to the ones used for prediction of breeding values increased the accuracy on the breeding values and thereby the genetic progress

An approximate multitrait model for genetic evaluation in dairy cattle with a robust estimation of genetic trends

In a stochastic simulation study of a dairy cattle population three multitrait models for estimation of genetic parameters and prediction of breeding values were compared. The first model was an approximate multitrait model using a two-step procedure. The first step was a single trait model for all traits. The solutions for fixed effects from these analyses were subtracted from the phenotypes. A multitrait model only containing an overall mean, an additive genetic and a residual term was applied on these preadjusted data. The second model was similar to the first model, but the multitrait model also contained a year effect. The third model was a full multitrait model. Genetic trends for total merit and for the individual traits in the breeding goal were compared for the three scenarios to rank the models. The full multitrait model gave the highest genetic response, but was not significantly better than the approximate multitrait model including a year effect. The inclusion of a year effect into the second step of the approximate multitrait model significantly improved the genetic trend for total merit. In this study, estimation of genetic parameters for breeding value estimation using models corresponding to the ones used for prediction of breeding values increased the accuracy on the breeding values and thereby the genetic progress

Improving animal health and welfare in organic cattle milk production through breeding and management

Overall summary of main results, discussion and conclusions WP1 The aim in WP1 was to map the performance of local breeds compared to commercial dairy breeds on organic farms in Austria, Switzerland, Sweden, Poland and Germany with regard to health associated traits, fertility and production traits. In a study covering the whole population of the selected breeds, managed under organic conditions during the period 1.7.2011 to 30.6.2014, we found lower milk yields for local breeds. In general we found better fertility performance (less days open, shorter calving intervals, lower number of inseminations) for at least one of the local breeds involved in each country. We also detected lower proportions of milk records with somatic cell counts above 100.000 cells/ ml milk for in at least one of the local breeds in Austria, Switzerland and Sweden, but not so for Poland where the commercial breed performed best. Moreover, we found a lower proportion of test day records with a fat: protein ratio above 1.5 in the first 100 days in milk for many local breeds (Grey Cattle (AL) and Original Braunvieh (OB) in Switzerland. AL by trend in Austria, Swedish Red (SRB) in Sweden and Polish Red and White (ZR) in Poland) hinting at a lower risk of subclinical ketosis for some of the local breeds compared to the respective commercial breed. We could not find breed differences regarding overall occurrence of veterinary treatments or those due to fertility or leg/ claw problems in Austrian data, but found that AL had less treatments due to udder problems than the commercial Braunvieh (BV). In Sweden, the local breed SRB had less overall treatments, fewer treatments due to fertility or udder disorders and also showed less remarks on claw or leg disorders than the commercial breed. We did not find breed differences regarding treatments due to metabolic disorders in Swedish data. We analyzed Austrian and Swiss data from culled cows on productive life span and detected a superiority of local breeds for this trait, but higher lifetime production (kg ECM) in the commercial breed. The second study on cows managed under very similar conditions in Sweden (period: 1.7.2011 to 30.6.2014) and Germany (period 1.7.2011 to 30.6.2015) revealed no significant breed differences in total ECM yield in German data, while we found higher milk fat and milk protein contents for the local breed Original Red Angler Cattle breed (AAZ). In Sweden, we found the highest ECM yield in the commercial breed Swedish Holstein (SH). The local breed Swedish Polled (SKB) had the highest fat and protein contents, followed by the second local breed Swedish Red (SRB), both differed significantly from the respective commercial breed SH and also among each other. We could not detect significant breed differences in the German data set with regard to fertility traits, although the local AAZ tended to have fewer days open than the commercial breed HO. In Sweden, we did not find breed differences for calving interval, but both local breeds had fewer days open, and SKB needed fewer inseminations compared to SH. No breed differences in any of the two countries regarding the proportion of test day records with a SCC content of over 100.000 cells per ml milk was found. We assessed the risk of subclinical ketosis during the first 100 days in milk by comparing fat protein ratios (FPR), applying differing thresholds in Germany (AAZ >1.7, HO >1.5) per breed, without detecting breed differences. However, in Sweden (with a threshold of >1.5) where the local SRB performed best, SKB showed an intermedium position, while SH had the highest proportion of FPR >1.5. Occurrence of veterinary treatments and those due to fertility problems did not differ between German breeds. Data on treatment due to metabolic disorders and leg or claw problems had low incidences, but models did not converge. In Sweden, we found the lowest incidence of overall veterinary treatments and treatments due to mastitis in the local breed SRB, but the local breed SKB did not differ from the commercial SH in neither of the two traits. We did not find breed differences regarding veterinary treatments due to fertility problems or diagnosis of claw/leg problems during claw trimming in the Swedish data set. Incidences of treatments due to metabolic disorders were low in all Swedish breeds, but models for this trait failed to converge. From our finding’s we conclude that local breeds partly have advantages with regard to many functional traits studied and that their potential should be better exploited in future, especially on farms with a medium production level (most clearly shown in the small study on German and Swedish farms). We also found overall high proportions of test day records with elevated SCC in Germany and even more so in Poland from which we deduct a great potential for further overall management improvement regardless of the involved breeds in these countries

Herd characteristics influence farmers’ preferences for trait improvements in Danish Red and Danish Jersey cows

ABSTRACT The aim of this study was to characterize preferences of farmers for breeding goal traits with Danish Red (DR) or Danish Jersey (DJ) cows. A breed-specific survey was established to characterize farmers’ preferences for improvements in 10 traits, by means of pairwise rankings using the online software 1000Minds. These pairwise rankings were based on equal economic worth of trait improvements. The DR survey was filled in by 87 farmers and the DJ survey by 76 farmers. Both DR and DJ farmers gave the highest preference to improvements in mastitis, and the lowest to calving difficulty. By means of a cluster analysis, three distinct clusters of farmers were identified per breed. Comparisons of herd characteristics between clusters suggest that farmers choose to improve traits that are problematic in their herds. This study shows that heterogeneity exists in farmers’ preferences for trait improvements and that herd characteristics influence these preferences in DR and DJ

Organic dairy farmers put more emphasis on production traits than conventional farmers

The overall aim of this research was to characterize the preferences of Danish dairy farmers for improvements in breeding goal traits. The specific aims were (1) to investigate the presence of heterogeneity in farmers’ preferences by means of cluster analysis, and (2) to associate these clusters with herd characteristics and production systems (organic or conventional). We established a web-based survey to characterize the preferences of farmers for improvements in 10 traits, by means of pairwise rankings. We also collected a considerable number of herd characteristics. Overall, 106 organic farmers and 290 conventional farmers answered the survey, all with Holstein cows. The most preferred trait improvement was cow fertility, and the least preferred was calving difficulty. By means of cluster analysis, we identified 4 distinct clusters of farmers and named them according to the trait improvements that were most preferred: Health and Fertility, Production and Udder Health, Survival, and Fertility and Production. Some herd characteristics differed between clusters; for example, farmers in the Survival cluster had twice the percentage of dead cows in their herds compared with the other clusters, and farmers that gave the highest ranking to cow and heifer fertility had the lowest conception rate in their herds. This finding suggests that farmers prefer to improve traits that are more problematic in their herd. The proportion of organic and conventional farmers also differed between clusters; we found a higher proportion of organic farmers in the production-based clusters. When we analyzed organic and conventional data separately, we found that organic farmers ranked production traits higher than conventional farmers. The herds of organic farmers had lower milk yields and lower disease incidences, which might explain the high ranking of milk production and the low ranking of disease traits. This study shows that heterogeneity exists in farmers’ preferences for improvements in breeding goal traits, that organic and conventional farmers differ in their preferences, and that herd characteristics can be linked to different farmer clusters. The results of this study could be used for the future development of breeding goals in Danish Holstein cows and for the development of customized total merit indices based on farmer preferences

Possibilities for a specific breeding program for organic dairy production

Presentation on breeding programs for organic dairy production at the 70th Annual EAAP Meetin

Detailed milk fatty acid profiling of the Danish dairy cattle population

Abstract Milk fatty acid (FA) composition can be manipulated through feeding, and especially effects of grazing have been shown to promote a healthier milk FA profile due to increasing contents of beneficial FAs, like conjugated linoleic acid (CLA) and α-linolenic acid (C18:3, the main n3 FA in milk). In addition to diet-based manipulations, selective breeding for specific FA could also be a strategy for altering the FA profile as milk FA display low to moderate heritabilites (0.07-0.34 in Danish Holstein). Since 2015, milk samples from all Danish dairy cows under yield control have been analyzed using mid infrared spectroscopy. The FOSS Application Note 64 has subsequently been used to predict content of seven FA groups (short-chain FA (SCFA), medium-chain FA (MCFA), long-chain FA (LCFA), saturated FA (SFA), mono-unsaturated FA (MUFA), poly-unsaturated FA (PUFA), and trans FA (TFA)) together with four individual FA (myristic acid (C14:0), palmitic acid (C16:0), stearic acid (C18:0), oleic acid (C18:1)). This access to millions of FA profiles in milk enables large-scale in depth analyses of factors affecting FA profile of milk and accurate genetic parameter estimation. Initially, more than 3.5 million milk samples from three Danish dairy breeds (Holstein, Jersey, Red) and crossbred cows have been analyzed from May 2015 to October 2016. The results showed significant (P ≤ 0.05) effects of cow breed. As reported earlier, Jersey cows have a higher de novo synthesis, resulting in higher proportions of SFA, MCFA, SCFA and C16:0 compared to the other breeds. For parity (only checked in Holstein), the proportion of SFA and SCFA increased with increasing lactation number, whereas the proportion of MUFA and C16:0 decreased. PUFA had the lowest proportion in 2nd parity and the highest in 1st parity. Also, significant effects of production system (organic vs. conventional) was found, as organic dairy cows due to legislation have to be on pasture during summer. In months, where cows were fed fresh grass, the proportion of unsaturated FA increased, whereas the proportion of saturated FA decreased. This was seen in both organic, and to a lesser extent, in conventional milk. A healthier FA profile can be obtained by increasing MUFA and PUFA in milk. However, health aspects in relation to SFA are more complex, but there seems to be a general agreement that most SFA have neutral or even slightly positive effects, whereas palmitic acid exerts a negative effect on human health due to its role in increased LDL cholesterol. Thus from a consumers perspective, our results suggest that organic summer milk from 1st parity Holstein or Red cows are preferred during the grass season, whereas conventional milk may have a healthier FA profile during winter. To explore specific seasonal effect in relation to pasture-based diets in more details, milk samples from 160 cows from eight herds are collected to investigate whether bulls with extreme SFA% breeding values are reflected in the FA milk profile from their daughters. The collected milk samples will be analyzed by AN64 MIR, as well as by gas chromatography, to provide additional information e.g. in relation to CLA and C18:3 and the n3/n6 ratio. So far, milk samples have been collected prior to summer grazing and will be collected again in June 2017, where most cows in the experiment will be on pasture. In conclusion, this study has shown that the choice of breed, parity, lactation stage, season, production system and genetics affect the FA composition of milk. Different strategies may therefore be applied to alter the FA profile, but generally, which could be exploited for product differentiation for e.g. new healthier innovative dairy products

Preferences for Breeding Goal Traits for Danish Red and Jersey Cattle

The aim of this study was to characterize preferences of farmers with Red Danish Cattle (RDC) or Jersey herds. A breed-specific survey was established to characterize preferences of farmers for improvements in ten traits, by means of pairwise rankings using the online software 1000Minds. These pairwise rankings were based on equal economic worth of trait improvements. The RDC-survey was filled in by 87 farmers and the Jersey-survey by 76 farmers. Both RDC and Jersey herds had the highest preference for improvements in mastitis, followed by milk production. The lowest preference was given to calving difficulty. By means of a cluster analysis distinct clusters of farmers were identified and named according to the trait improvements that were the most preferred per cluster. RDC herds were divided into three different clusters: Robustness, Production & Health, and Production & Fertility. The Jersey herds were divided into the clusters Production & Fertility, Production & Robustness, and Survival. For RDC herds we found that the cluster Production & Fertility had the highest percentage of organic farmers (50%), the lowest percentage of crossbreeding and the lowest yields and herd size. The cluster Robustness had the highest yields and the highest prevalence of udder disorders, and these farmers ranked production traits very low and mastitis very high. For Jersey herds, the percentage of dead cows was highest for the cluster Survival. This cluster also ranked mastitis the highest compared to the other clusters, and contained herds with the highest prevalence of udder disorders. These results suggest that farmers choose to improve traits that are more problematic in their herds. This study shows that heterogeneity exists in farmers’ preferences for trait improvements and that some herd characteristics can be linked to the different farmer clusters. The results from this study give a strong basis for setting up customized indexes or breeding goals for the different farmer clusters, which might increase the uptake of genetic merit

Definition of breeding goals for dairy breeds in organic production systems

In this study, we attempt to assess the Danish organic dairy farmers' acceptance of the economic values derived from a stochastic, bio-economic model. We expect the results to show that farmers give increased priority to some traits above the objectively derived economic vaule

Organic and conventional dairy farmers prefer different improvements in breeding goal traits

In dairy cattle breeding, breeding goals (BG) are developed and subsequently a selection index that farmers want to use. Therefore it is important to take their preferences for BG traits into account. Two production systems that are expected to influence farmer preferences for BG traits are organic and conventional systems. The aim of this study was to characterize preferences of organic and conventional Danish dairy farmers for improvements in BG traits for Holstein cattle. A survey was established to characterize preferences for improvements in ten traits, by means of pairwise rankings using the online software 1000Minds. These pairwise rankings were based on equal economic worth of trait improvements. The survey was filled in by 106 organic and 290 conventional farmers. The most preferred trait improvement for both production systems was in cow fertility, and the least preferred improvement was in calving difficulty. Organic farmers ranked milk production and feed efficiency higher than conventional farmers. The reason for this may be that the average milk yield is lower and the milk price is higher in organic herds compared to conventional herds. Organic farmers also ranked calf mortality higher. Conventional farmers ranked mastitis, leg and claw diseases, other diseases and cow mortality higher compared to organic farmers. By means of a cluster analysis distinct clusters of farmers were identified and named according to the trait improvements that were the most preferred per cluster. The cluster analysis for organic farmers identified two production-based clusters ('Production & Fertility' and 'Production & Mastitis') and one robustness-based cluster, whereas a cluster analysis for conventional farmers found one production-based cluster, one health-based cluster and one survival-based cluster. This study shows that organic and conventional farmers differ in their preferences for improvements in BG traits, and the results can be used to set up specific breeding goals for organic and conventional farming systems