IntroductionThe ease of calving influences the economics of a cow/calf enterprise through increased calf death loss, increased labour and veterinary costs, reduced subsequent reproductive performance of the cow, potential loss of the cow, and reduced milk production. McGuirk et al. (2007) estimated that a slightly difficult calving cost approximately £110 and a seriously difficult calving cost £350-£400. Many countries around the world undertake genetic evaluations for calving ease (CE). The aim of this project was to develop routine national CE evaluations for UK dairy cattle. Materials and methodsData were taken from UK milk recording organisations, and covers farmer recorded CE as well as data collected as part of the progeny test scheme. Genetic parameters for CE were estimated using ASReml (version 2.00, 2006) considering a direct and indirect effect. Fixed effects in the model include herd-year, month of calving, lactation number, calf sex and interaction between lactation number and calf sex. Age and percentage Holstein were fitted as linear regressions. A random effect of service sire was fitted to estimate direct CE predicted transmitting ability (PTA) and random effect of maternal grandsire fitted for indirect CE PTA, with a covariance between the 2 effects also fitted. A maternal CE PTA was then computed as the indirect CE PTA minus one quarter of the direct CE PTA. The direct CE PTA relates to the ease with which a bull's calves are expected to be born and the maternal calving ease PTA relates to the ease with which the bull's daughters are likely to give birth. Bull PTAs for direct and maternal CE were submitted to a test multiple across country evaluation (MACE) of calving traits performed by the Interbull Centre (Uppsala, Sweden), thus allowing UK evaluation of CE to be compared to evaluations from other countries on the UK scale. A data and pedigree file were extracted in September 2009 and contained almost 400,000 calving records, representing almost 6,000 sires. ResultsThe data approximately spanned 15 years, however, the majority of the data falls after 1999. Overall, 84% of calvings were classed as "easy calving". For first calving cows a total of 74% calvings were classed as "easy" and 85% of later calvings. The genetic analysis showed that the heritability for calving ease was low (0.066 and 0.040 for direct and indirect effects respectively with a genetic correlation of -0.685). Figure 1 shows that the calving ease PTAs were expressed as percent easy calving and centred around zero, with a positive value being favourable (i.e., less difficult calvings). There was no evidence of a genetic trend in either direct or maternal CE PTAs. The across country genetic correlations for the MACE run for direct and maternal CE were in line with other countries and suggest that UK CE PTAs would be suitable for an international MACE evaluation. The genetic correlations between countries for the direct calving trait averaged of 0.80 and ranged from 0.619 (with Hungary) to 0.944 (with Canada). The genetic co...

Abstract

Organising the breeding plan of a seasonally breeding species, such as sheep, presents a challenge to farmers and the industry as a whole, since both economical and biological considerations need to be carefully balanced. Understanding the breeding activity of individual animals becomes a prerequisite for a successful breeding program. This study set out to investigate the sources of variation and the genetic profile of the spontaneous, out-of-season ovulatory activity of ewes of the Chios dairy sheep breed in Greece. The definition of the trait was based on blood progesterone levels, measured before exposing the ewes to rams, which marks the onset of the usual breeding season. Data were 707 records, taken over two consecutive years, of 435 ewes kept at the Agricultural Research Station of Chalkidiki in northern Greece. When all available pedigree was included, the total number of animals involved was 1068. On average, 29% of all ewes exhibited spontaneous, out-of-season ovulatory activity, with no substantial variation between the years. Significant sources of systematic variation were the ewe age and live weight, and the month of previous lambing. Older, heavier ewes, that had lambed early the previous autumn, exhibited more frequent activity. Heritability estimates were 0.216 (± 0.084) with a linear and 0.291 with a threshold model. The latter better accounts for the categorical nature of the trait. The linear model repeatability was 0.230 (± 0.095). The results obtained in this study support the notion that spontaneous out-of-season ovulatory activity can be considered in the development of a breeding plan for the Chios sheep breed.

Background This study aimed to determine the association between the lameness advantage genetic index and four outcomes: sole haemorrhage (SH), sole ulcers (SU), white line lesions (WL), and lameness during mobility scoring. Methods We enrolled 2352 Holstein cows from four predominantly housed dairy herds in the UK. Cows were mobility scored and foot lesions recorded at four time points from before calving to late lactation. Cows were genotyped and genetic indexes were assigned to each cow following national genetic evaluations. Lameness records and genetic indexes were matched for 2107 cows. Four separate multivariable logistic regression models, which included farm and parity as covariables, were used to quantify the association between the lameness advantage index and whether animals were affected by SH, SU, WL, or lameness. Results The odds ratios (95% confidence intervals) for one‐point increases in the lameness advantage index were 0.79 (0.72–0.86), 0.68 (0.59–0.78), 0.94 (0.84–1.04), and 0.82 (0.74–0.91) for SH, SU, WL, and lameness, respectively. The same trends were present when the sire's lameness advantage index was evaluated in place of the animal's own, although the strength of this association was generally weaker. Conclusion The lameness advantage index is associated with SH, SU, and lameness, therefore selection on the lameness advantage index could be considered in herds aiming to reduce lameness. Where genomic testing of heifers is not conducted, sire lameness advantage index may still be effective to reduce SH and SU incidence.

National and international Holstein bull evaluations from Canada, France, Germany, Italy, The Netherlands, and the US were examined to determine whether inclusion of data from other countries increased the accuracy of prediction of national evaluations for milk, fat, and protein yields. The six national and six international evaluations from February 1995 were compared with national evaluations in January and February 1999. The later national evaluations were assumed to be improved estimates of true genetic merit because of added data. Correlations with later national evaluations generally were larger for earlier national evaluations than for international evaluations, probably because of the larger part-whole relationship between earlier and later national evaluations. However, standard deviations of difference of 1995 evaluations from later national evaluation were lower for international evaluations than for earlier national evaluations, which suggested improved prediction from inclusion of multinational data. For bulls with substantial increases in daughters, nationally and internationally, correlations were higher, and standard deviations of differences were lower for international evaluations compared with earlier national evaluations. Inclusion of multinational data improved the prediction of future national evaluations, especially for countries that import genetics of dairy cattle.

Background Bovine Digital Dermatitis (BDD) is a prevalent infectious disease, causing painful foot skin lesions and lameness in cattle. We describe herein the bovine foot skin microbiota and its associations with BDD using 16S rRNA gene amplicon and shotgun metagenomic sequencing on samples from 259 dairy cows from three UK dairy farms. Results We show evidence of dysbiosis, and differences in taxonomy and functional profiles in the bovine foot skin microbiome of clinically healthy animals that subsequently develop BDD lesions, compared to those that do not. Our results suggest that taxonomical and functional differences together with alterations in ecological interactions between bacteria in the normal foot skin microbiome may predispose an animal to develop BDD lesions. Using genome-wide association and regional heritability mapping approaches, we provide first evidence for interactions between host genotype and certain members of the foot skin microbiota. We show the existence of significant genetic variation in the relative abundance of Treponema spp. and Peptoclostridium spp. and identify regions in the bovine genome that explain a significant proportion of this variation. Conclusions Collectively this work shows early changes in taxonomic and functional profiles of the bovine foot-skin microbiota in clinically healthy animals which are associated with subsequent development of BDD and could be relevant to prevention of disease. The description of host genetic control of members of the foot skin microbiota, combined with the association of the latter with BDD development offer new insights into a complex relationship that can be exploited in selective breeding programmes.