Genetic associations between maternal traits and aggressive behaviour in Large White sows.

The present study examined the possibilities and consequences of selecting pigs for reduced aggression and desirable maternal behaviour. Data were recorded from 798 purebred Large White gilts, with an age of 217±17.7 (mean±SD) days, which were observed at mixing with unfamiliar conspecifics. The reaction of the sows towards separation from their litter was assessed for 2022 litters from 848 Large White sows. Sows' performance during their time in the farrowing unit was scored based on the traits farrowing behaviour (i.e. need of birth assistance), rearing performance (i.e. litter quality at day 10 postpartum (pp)), usability (i.e. additional labour input during lactation period e.g. for treatments) and udder quality of the sow (i.e. udder attachment). For agonistic behaviour, traits heritabilities of h 2=0.11±0.04 to h 2=0.28±0.06 were estimated. For the sow's reaction towards separation from her litter low heritabilities were found (h 2=0.03±0.03 for separation test on day 1 pp and h 2=0.02±0.03 for separation test on day 10 pp). Heritabilities for lactating sow's performance (farrowing behaviour, rearing performance, usability of the sow and udder quality) in the farrowing unit ranged from h 2=0.03±0.02 to h 2=0.19±0.03. Due to these results it can be assumed that selection for these traits, for example, for udder quality or reduced aggression, is possible. Antagonistic associations were found between separation test on day 1 pp and different measures of aggressiveness (r g =-0.22±0.26 aggressive attack and r g =-0.41±0.33 reciprocal fighting). Future studies should determine economic as well as welfare-related values of these traits in order to decide whether selection for these traits will be reasonable.

From phenotyping towards breeding strategies: using in vivo indicator traits and genetic markers to improve meat quality in an endangered pig breed.

In endangered and local pig breeds of small population sizes, production has to focus on alternative niche markets with an emphasis on specific product and meat quality traits to achieve economic competiveness. For designing breeding strategies on meat quality, an adequate performance testing scheme focussing on phenotyped selection candidates is required. For the endangered German pig breed 'Bunte Bentheimer' (BB), no breeding program has been designed until now, and no performance testing scheme has been implemented. For local breeds, mainly reared in small-scale production systems, a performance test based on in vivo indicator traits might be a promising alternative in order to increase genetic gain for meat quality traits. Hence, the main objective of this study was to design and evaluate breeding strategies for the improvement of meat quality within the BB breed using in vivo indicator traits and genetic markers. The in vivo indicator trait was backfat thickness measured by ultrasound (BFiv), and genetic markers were allele variants at the ryanodine receptor 1 (RYR1) locus. In total, 1116 records of production and meat quality traits were collected, including 613 in vivo ultrasound measurements and 713 carcass and meat quality records. Additionally, 700 pigs were genotyped at the RYR1 locus. Data were used (1) to estimate genetic (co)variance components for production and meat quality traits, (2) to estimate allele substitution effects at the RYR1 locus using a selective genotyping approach and (3) to evaluate breeding strategies on meat quality by combining results from quantitative-genetic and molecular-genetic approaches. Heritability for the production trait BFiv was 0.27, and 0.48 for backfat thickness measured on carcass. Estimated heritabilities for meat quality traits ranged from 0.14 for meat brightness to 0.78 for the intramuscular fat content (IMF). Genetic correlations between BFiv and IMF were higher than estimates based on carcass backfat measurements (0.39 v. 0.25). The presence of the unfavorable n allele was associated with increased electric conductivity, paler meat and higher drip loss. The allele substitution effect on IMF was unfavorable, indicating lower IMF when the n allele is present. A breeding strategy including the phenotype (BFiv) combined with genetic marker information at the RYR1 locus from the selection candidate, resulted in a 20% increase in accuracy and selection response when compared with a breeding strategy without genetic marker information.

Short communication: a note on the correction for the effect of freezing on the outcome of pregnancy-associated glycoprotein measurement in blood and serum of cows.

Early pregnancy detection is a measure of considerable economic relevance for dairy cattle breeders, and analysis of pregnancy-associated glycoprotein (PAG) values in blood is one of the methods implemented in practice. Starting from d 30 postconception, cows are considered to be pregnant at PAG levels of 2.0 ng of PAG/mL of blood and higher. However, little is known about preanalytic sources of errors that might affect PAG values. Based on blood samples from 65 dairy cows, the present study showed that freezing of samples, such as may be the case during shipping in wintertime, will lower PAG values considerably. Therefore, a Bland-Altman analysis was used to derive a correction factor. Overall, the mean differences (± standard deviation) between frozen and respective fresh samples was -5.5 ± 7.4 ng of PAG/mL of blood and 0.9 ± 6.1 ng of PAG/mL of serum. However, the Bland-Altman plot revealed a concentration-dependent effect of freezing on PAG values with higher variability and larger declines at higher PAG levels. Therefore, to minimize chances of false-negative results, different correction factors are suggested for different levels of PAG (e.g., based on the upper bound of the 95% confidence interval 0.67 for PAG levels between 2.0 and 3.9 ng of PAG/mL and 0.25 for PAG levels between 4.0 and 7.9 ng of PAG/mL). With these concentration-dependent correction factors, implementation into practice will be possible. The accuracy is adequate because no quantitative information but qualitative results (pregnant vs. nonpregnant) are required. However, due to larger chances of false-negative results, the application of the correction factor should only be a last resort if temperature exposure of a sample is unknown.

Impact of health disorders and culling reasons on functional and biological longevity in Warmblood breeding stallions.

The objective of this study was to compare the impact of health disorders and reasons for culling on the functional and biological longevity of warmblood breeding stallions using semi-parametric survival analysis accounting for competing risks. Complete breeding records were collected from 455 warmblood stallions serving between 1975 and 2010 at Marbach State Stud in Germany. The median length of life (18.0 years) was twice as long as the median length of service (9.0 years). However, both figures increased significantly over the time period examined (e.g., functional longevity increased from 5 years in the 1970s to 8 years in the 1980s to 12 years in the 1990s). Compared to disorders of the musculoskeletal system, hazards for termination of functional life were higher for infectious diseases with a hazard ratio (HR) of 3.5, and for dissatisfaction with performance (HR, 2.0). Hazards were lower for disorders of the respiratory system (HR, 0.78), followed by accidents (HR, 0.58), disorders of the reproductive system (HR, 0.51), sale for non-breeding purposes (HR, 0.40), disorders of the gastrointestinal system (HR, 0.36), unknown reasons (HR, 0.32) and disorders of the cardiovascular system (HR, 0.25). For biological life, the relative importance of these disorders was similar. Factors linked to demand for stallions such as coat colour and several parameters of the stallions' genetic merit (negative influence) and own performance (positive influence) in dressage and particularly in show-jumping influenced (P<0.05) or tended to influence (P<0.1) functional, but not biological longevity. Furthermore, hazards for both functional and biological life declined with rising stud fees (both HR, 0.99; P<0.0001). A more direct consideration of both functional and biological longevity in breeding programmes might help to further enhance both figures, and therefore welfare of the horses.

Integration of genomic information into sport horse breeding programs for optimization of accuracy of selection.

Reliable selection criteria are required for young riding horses to increase genetic gain by increasing accuracy of selection and decreasing generation intervals. In this study, selection strategies incorporating genomic breeding values (GEBVs) were evaluated. Relevant stages of selection in sport horse breeding programs were analyzed by applying selection index theory. Results in terms of accuracies of indices (r(TI) ) and relative selection response indicated that information on single nucleotide polymorphism (SNP) genotypes considerably increases the accuracy of breeding values estimated for young horses without own or progeny performance. In a first scenario, the correlation between the breeding value estimated from the SNP genotype and the true breeding value (= accuracy of GEBV) was fixed to a relatively low value of r(mg) = 0.5. For a low heritability trait (h(2) = 0.15), and an index for a young horse based only on information from both parents, additional genomic information doubles r(TI) from 0.27 to 0.54. Including the conventional information source 'own performance' into the before mentioned index, additional SNP information increases r(TI) by 40%. Thus, particularly with regard to traits of low heritability, genomic information can provide a tool for well-founded selection decisions early in life. In a further approach, different sources of breeding values (e.g. GEBV and estimated breeding values (EBVs) from different countries) were combined into an overall index when altering accuracies of EBVs and correlations between traits. In summary, we showed that genomic selection strategies have the potential to contribute to a substantial reduction in generation intervals in horse breeding programs.

Equine behaviour and heart rate in temperament tests with or without rider or handler.

The aim of the present study was to compare horses' heart rate (HR), heart rate variability (RMSSD, pNN50) and behaviour in the same temperament test when being ridden, led, and released free. Behavioural measurements included scores and linear measurements for reactivity (R), activity (A), time to calm down (T) and emotionality (E), recorded during the approach (1) and/or during confrontation with the stimulus (2). Sixty-five horses were each confronted 3 times (1 ridden, 1 led, 1 free running in balanced order) with 3 novel and/or sudden stimuli. Mixed model analysis indicated that leading resulted in the lowest (P<0.05 throughout) reactions as measured by A1, A2, E1, E2, R2, and pNN50 while riding produced the strongest (A1, T2, HR, RMSSD, pNN50) or medium (E1, E2, R2) reactions. Free running resulted either in the strongest (A2, E1, E2, R2) or in the lowest (A1, T2, HR, RMSSD, pNN50) reactions. The repeatability across tests for HR (0.57), but not for RMSSD (0.23) or pNN50 (0.25) was higher than for any behavioural measurement: the latter ranged from values below 0.10 (A1, A2, T2) to values between 0.30 and 0.45 (E1, E2, R2). Overall, the results show that a rider or handler influences, but not completely masks, the horses' intrinsic behaviour in a temperament test, and this influence appeared to be stronger on behavioural variables and heart rate variability than on the horses' heart rates. Taking both practical considerations and repeatabilities into account, reactivity appears to be the most valuable parameter. Emotionality and heart rate can also yield valid results reflecting additional dimensions of temperament although their practical relevance may be less obvious. If a combination of observed variables is chosen with care, a valid assessment of a horse's temperament may be possible in all types of tests. However, in practice, tests that resemble the practical circumstances most closely, i.e. testing riding horses under a rider, should be chosen.