A Model for the Development of the Rhizobial and Arbuscular Mycorrhizal Symbioses in Legumes and Its Use to Understand the Roles of Ethylene in the Establishment of these two Symbioses

We propose a model depicting the development of nodulation and arbuscular mycorrhizae. Both processes are dissected into many steps, using Pisum sativum L. nodulation mutants as a guideline. For nodulation, we distinguish two main developmental programs, one epidermal and one cortical. Whereas Nod factors alone affect the cortical program, bacteria are required to trigger the epidermal events. We propose that the two programs of the rhizobial symbiosis evolved separately and that, over time, they came to function together. The distinction between these two programs does not exist for arbuscular mycorrhizae development despite events occurring in both root tissues. Mutations that affect both symbioses are restricted to the epidermal program. We propose here sites of action and potential roles for ethylene during the formation of the two symbioses with a specific hypothesis for nodule organogenesis. Assuming the epidermis does not make ethylene, the microsymbionts probably first encounter a regulatory level of ethylene at the epidermis–outermost cortical cell layer interface. Depending on the hormone concentrations there, infection will either progress or be blocked. In the former case, ethylene affects the cortex cytoskeleton, allowing reorganization that facilitates infection; in the latter case, ethylene acts on several enzymes that interfere with infection thread growth, causing it to abort. Throughout this review, the difficulty of generalizing the roles of ethylene is emphasized and numerous examples are given to demonstrate the diversity that exists in plants

Predicting beef carcass meat, fat and bone proportions from carcass conformation and fat scores or hindquarter dissection

peer-reviewedEquations for predicting the meat, fat and bone proportions in beef carcasses using the European Union carcass classification scores for conformation and fatness, and hindquarter composition were developed and their accuracy was tested using data from 662 cattle. The animals included bulls, steers and heifers, and comprised of Holstein–Friesian, early- and late-maturing breeds x Holstein–Friesian, early-maturing X early-maturing, late-maturing X early-maturing and genotypes with 0.75 or greater late-maturing ancestry. Bulls, heifers and steers were slaughtered at 15, 20 and 24 months of age, respectively. The diet offered before slaughter includes grass silage only, grass or maize silage plus supplementary concentrates, or concentrates offered ad libitum plus 1 kg of roughage dry matter per head daily. Following the slaughter, carcasses were classified mechanically for conformation and fatness (scale 1 to 15), and the right side of each carcass was dissected into meat, fat and bone. Carcass conformation score ranged from 4.7 to 14.4, 5.4 to 10.9 and 2.0 to 12.0 for bulls, heifers and steers, respectively; the corresponding ranges for fat score were 2.7 to 11.5, 3.2 to 11.3 and 2.8 to 13.3. Prediction equations for carcass meat, fat and bone proportions were developed using multiple regression, with carcass conformation and fat score both included as continuous independent variables. In a separate series of analyses, the independent variable in the model was the proportion of the trait under investigation (meat, fat or bone) in the hindquarter. In both analyses, interactions between the independent variables and gender were tested. The predictive ability of the developed equations was assed using cross-validation on all 662 animals. Carcass classification scores accounted for 0.73, 0.67 and 0.71 of the total variation in carcass meat, fat and bone proportions, respectively, across all 662 animals. The corresponding values using hindquarter meat, fat and bone in the model were 0.93, 0.87 and 0.89, respectively. The bias of the prediction equations when applied across all animals was not different from zero, but bias did exist among some of the genotypes of animals present. In conclusion, carcass classification scores and hindquarter composition are accurate and efficient predictors of carcass meat, fat and bone proportions

A comparison of Charolais and beef x Friesian suckler cows End of project report

ARMIS no. 3699SIGLEAvailable from British Library Document Supply Centre-DSC:1876.2592(no 9) / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Production of red veal for the EU market End of project report

SIGLEAvailable from British Library Document Supply Centre-DSC:1876.2592(no 4) / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Effect of cattle breed on finishing performance, carcass characteristics and economic benefits under typical beef production system in China

This study compared the finishing performance carcass characteristics and economic benefits of two imported (Limousin and Simmental) and three local (Luxi, Jinnan and Qinchuan) cattle breeds slaughtered at 18.5 months of age under thetypical Chinese beef production system. All cattle (n=71) were reared under the same production system and fed the same finishing diet for 105 days. Eight bulls from each breed were randomly selected for slaughtering. Compared with the three local breeds, the two imported breeds had higher average daily gain, dry matter intake and gain efficiency. Regarding carcass characteristics, the two imported breeds had higher carcass weight, bone weight, net meat weight, and ribeye area (P<0.001). However, the local breeds had higher (P<0.01) marbling scores than the imported breeds. The imported breeds showed higher economic benefits (P<0.001) than the local breeds. In conclusion, the imported cattle breeds had better growth performance, carcass traits and economic benefits compared with the local cattle breeds at 18.5 months old under the typical Chinese feeding conditions whereas, in this study, the local breeds may have some advantage in terms of meat quality