Performance and carcass traits of progeny of Limousin sires differing in genetic merit

peer-reviewedGenetic indices for growth and carcass classification are published for beef sires used in Ireland for artificial insemination (AI). The objective of this study was to compare growth and carcass traits of progeny of Limousin sires of low and high genetic index for growth. A total of 70 progeny (42 males and 28 females) out of predominantly Holstein-Friesian cows by 7 AI Limousin sires were reared together to slaughter. The 7 sires were classified as low (n=3) or high (n=4) index based on their published genetic index for growth. The male progeny were reared entire and all animals were slaughtered at about 20 months of age. Carcasses were classified for conformation and fatness, and a rib joint (ribs 6 to 10) was separated into fat, muscle and bone. Growth rate did not differ significantly between the index groups but tended to be higher for the high index progeny. This higher growth rate, combined with a significantly higher kill out proportion, resulted in carcass weight andcarcass weight per day of age being significantly higher for the high index progeny. Carcass conformation and fat class were not affected by genetic index, nor was the composition of the rib joint. Compared with males, females had a significantly lower growth rate and kill out proportion and, consequently, had a significantly lower carcass weight. The proportions of fat and bone in the rib joint were significantly higher, and the proportion of muscle was significantly lower for females than for males. It is concluded that carcass weight reflected sire group genetic index for growth but feed intake, carcass classification and rib joint composition were not affected

Evaluation of the Progeny of Beef Sires Differing in Genetic Merit

End of project reportThe Irish Cattle Breeding Federation (ICBF) publishes breeding values (BVs) for beef bulls. Historically, BVs were expressed in index form relative to the base population. Sometime ago this changed to expression in units of measurement of trait. This change occurred in the course of this project and was accompanied by some re-ranking of bulls. BVs are published for growth, carcass grades and calving traits. Growth BV is expressed as carcass weight but there is no indication if this results from higher live weight gain or from a higher kill-out proportion and there is no indication of any consequences for feed intake or efficiency. • The objectives of the project were (i) to compare progeny of bulls of high and low growth genetic index, for growth, feed intake, slaughter traits and carcass traits, (ii) to partition the extra live weight of progeny of high growth index bulls into carcass and non-carcass parts, and (iii) to partition any extra carcass weight of progeny from high growth index bulls into its component fat, muscle and bone fractionsEuropean Unio

Axion Decay in a Constant Electromagnetic Background Field and at Finite Temperature using World-line Methods

We investigate the radiative decay of the axion into two photons in an external electromagnetic field to one loop order. Our approach is based on the world-line formalism, which is very suitable to take into account the external field to all orders. Afterwards we discuss how the calculation could be generalized to finite temperature.Comment: 27 pages, 4 figures, corrected and added some references and added some remarks to appendix

A survey of the liberalisation of public enterprises in the UK since 1979

This paper examines the course of the deregulation and privatisation of public enterprises in the UK since 1979. The UK privatisation programme has been the most significant in the OECD involving the transfer of ownership of over 7% of GDP from the public to the private sectors. We examine the history and genesis of this programme, the development of the regulatory system based around RPI-X price control and the evidence on the effects of the privatisation. We conclude by evaluating the policy in the terms of its original aims. We find that public enterprise privatisation successfully reduced government involvement in industry, led to increased economic efficiency and a reduced fiscal deficit. Less clearly, it contributed to the curbing of Trade Union power and wider share ownership. Most significantly of all, as the most sustained and consistent policy of the 1979-97 Conservative governments, it gained sustained advantage for pro-market political forces in the UK

Ranking of Sire Breeds and Beef Cross Breeding of Dairy and Beef Cows

End of Project ReportSummary There is general agreement across countries on the ranking of beef breeds for production and carcass traits. Differences between dairy and early maturing beef breeds in growth and slaughter traits are small, but the latter have lower feed intake and better carcass conformation. Late maturing beef breeds also have lower feed intake and better carcass conformation and in addition, have a higher growth rate, kill-out proportion and carcass muscle proportion. When factors such as age and fatness are accounted for, differences between breeds in meat quality traits are small. Differences amongst breed types in kill-out proportion can be explained by differences in gut contents (consequent on differences in feed intake), differences in the proportions of gastrointestinal tract and metabolic organs, differences in hide proportion, and differences in offal fats. Growth is an allometric, rather than an isometric, process. Some parts, organs and tissues grow relatively more slowly than the animal overall, and so become decreasing proportions over time, while others grow relatively faster and become increasing proportions. With increasing slaughter weight, the proportions of non carcass parts, hind quarter, bone, total muscle and higher value muscle decrease, while the proportions of non carcass and carcass fats, fore quarter and marbling fat all increase. Because of heterosis or hybrid vigour, the productivity of cross-bred cattle is superior to the mean of the parent breeds. While calving difficulty may be slightly higher (probably due to greater birth weight), calf mortality is much reduced in cross-breds. In addition, general robustness and growth rate are increased. There are additive effects of heterosis in the dam and the progeny. When cross-bred cows are mated to a bull of a third breed, >60 % of total heterosis is attributable to the cross-bred cows. The double muscling phenotype in beef cattle is due to the inactivated myostatin gene, but the inactivating mutation is not the same in all breeds and other genes also contribute to muscling. Compared to normal animals, double muscled animals have lower proportions of digestive tract, internal fats and metabolic organs. This explains their superior kill-out proportion. They also have a smaller hind shin that helps accentuate the muscling in the remainder of the 4 limb. There are similar degrees of muscular hypertrophy in both the hind and fore quarters. Muscle to bone ratio is about one third greater in double muscled than in normal carcasses. Piedmontese cattle with none, one or two mutated myostatin alleles were compared with normal Herefords and Limousins. In the absence of any mutated allele, Piedmontese were similar to Herefords, with one mutated allele they were similar to Limousins and with two mutated alleles they were immensely superior to Limousins. In fact, the response to the second mutated allele was about three times that to the first. If progeny approximated to the mean of the parent breeds, crossing a double muscled sire with a dairy or early maturing beef cow would result in cattle of similar characteristics to pure-bred late maturing beef breeds. This does not happen because double muscling is dependent on a homozygous myostatin genotype. The progeny of a common cow breed and normal late maturing, or double muscled, sire breeds have similar production traits