The aim of this study was to assess the effect of castration and slaughter age on the volatile profile of cooked meat from Scottish Blackface (SB) and Texel × Scottish Blackface (T × SB) lambs. M. ...longissimus thoracis et lumborum was sampled at slaughter and subjected to volatile analysis by SPME‐GC‐MS. Rams had higher relative proportions, expressed as relative abundance (RA), in lipid oxidation products while castrates had higher RA in pyrazines and benzenoid compounds. There was no consistent age effect on the RA of volatiles, although rams in November and January had a different volatile profile to castrates. There were higher proportions of free branched‐chain fatty acids in muscle from SB compared to T × SB lambs. Overall, the results showed that production factors affected the volatile profile of cooked lamb meat which may explain differences in lamb flavor.
Practical Application
Lamb meat has a characteristic flavor which, according to the evidence to date, may be influenced by farm production factors like gender or slaughter age. Our results showed variations in the proportions of some flavor compounds in cooked lamb between rams and castrated lambs while an increase in slaughter age did not have a consistent effect on proportions of compounds.
Group living facilitates pathogen transmission among social hosts, yet temporally stable host social organizations can actually limit transmission of some pathogens. When there are few ...between-subpopulation contacts for the duration of a disease event, transmission becomes localized to subpopulations. The number of per capita infectious contacts approaches the subpopulation size as pathogen infectiousness increases. Here, we illustrate that this is the case during epidemics of highly infectious pneumonia in bighorn lambs (Ovis canadensis). We classified individually marked bighorn ewes into disjoint seasonal subpopulations, and decomposed the variance in lamb survival to weaning into components associated with individual ewes, subpopulations, populations and years. During epidemics, lamb survival varied substantially more between ewe-subpopulations than across populations or years, suggesting localized pathogen transmission. This pattern of lamb survival was not observed during years when disease was absent. Additionally, group sizes in ewe-subpopulations were independent of population size, but the number of ewe-subpopulations increased with population size. Consequently, although one might reasonably assume that force of infection for this highly communicable disease scales with population size, in fact, host social behaviour modulates transmission such that disease is frequency-dependent within populations, and some groups remain protected during epidemic events.
The energy expenditure of the sheep always increased during grazing and fell again during the subsequent rest period, but there was no significant change when pre-cut grass was given to the sheep.
Small ruminant lentiviruses include viruses with diverse genotypes that frequently cross the species barrier between sheep and goats and that display a great genetic variability. These ...characteristics stress the need to consider the whole host range and to perform local surveillance of the viruses to opt for optimum diagnostic tests, in order to establish control programes. In the absence of effective vaccines, a comprehensive knowledge of the epidemiology of these infections is of major importance to limit their spread. This article intends to cover these aspects and to summarise information related to characteristics of the viruses, pathogenesis of the infection and description of the various syndromes produced, as well as the diagnostic tools available, the mechanisms involved in transmission of the pathogens and, finally, the control strategies that have been designed until now, with remarks on the drawbacks and the advantages of each one. We conclude that there are many variables influencing the expected cost and benefits of control programs that must be evaluated, in order to put into practice measures that might lead to control of these infections.
Strongylid gastrointestinal nematodes are an important cause of disease and economic loss in small ruminants. These parasites are important in most of the United States, with the bloodsucking ...parasite Haemonchus contortus being the predominant species of concern. Sheep and goats are infected while grazing, and the biology of infective larvae on pastures is important in the design of parasite management programs. Widespread resistance to anthelmintics requires strategies designed to preserve remaining drug activity; these include combination treatments with multiple classes of anthelmintics and targeted treatments.
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•Haemonchus contortus has significantly changed its distribution in Australia over the past 70years.•Inhibition of H. contortus L4s over winter has largely been abolished by more ...effective anthelmintics.•Inhibition of H. contortus L4s over winter has resulted in the advent of yearly rather than seasonal haemonchosis.•Customised on-farm control and monitoring programmes should arise from rapid advances in H. contortus genomics.
Haemonchus contortus (Barber’s pole worm or “BPW”) is the nematode “nemesis” of small ruminant production systems in tropical and subtropical regions of the world. Its reputation derives from a combination of high fecundity and a short generational interval that provides an enviable developmental plasticity for adaptation or resistance to control measures. This review critically examines the historical and current literature on the host–parasite–environment interaction for H. contortus, particularly in sheep, to highlight changes in parasite distribution and ecology on pasture, changes to the seasonal inhibition of fourth stage larvae and the most appropriate models to identify protective responses and assess vaccines. The review also proposes pathways to bring host genetics to fruition and avenues where advances in the parasite genome may complement control measures.
Bacterial mastitis is a significant welfare and financial problem in sheep flocks. This paper reviews the recently published literature, including publications that highlight the significance and ...virulence factors of the causal agents, especially Staphylococcus aureus and Mannheimia haemolytica, the primary causes of the disease. Research has also contributed to the understanding of risk factors, including genetic susceptibility of animals to infections, supporting future strategies for sustainable disease control. Pathogenetic mechanisms, including the role of the local defenses in the teat, have also been described and can assist formulation of strategies that induce local immune responses in the teat of ewes. Further to well-established diagnostic techniques, i.e., bacteriological tests and somatic cell counting, advanced methodologies, e.g., proteomics technologies, will likely contribute to more rapid and accurate diagnostics, in turn enhancing mastitis control efforts.
Control of gastrointestinal nematodes has been based on anthelmintics. However, this strategy is unsustainable owing to anthelmintic resistance. Parasitic nematodes have biologic and genetic features ...that favor the development of drug resistance, making the emergence of resistant nematodes inevitable. The rate of resistance development is affected controllable factors. There is a need to change the paradigm of how gastrointestinal nematodes are controlled to decrease the rate at which resistance develops. This article reviews the biology and prevalence of anthelmintic resistance, and provides recommendations for diagnosing resistance and for strategies that should be implemented to reduce the development of resistance.
•The development of a vaccine for Fasciola spp. in livestock is a challenge.•Harnessing acquired immunity expressed by resistant livestock against fluke infection will inform vaccine ...development.•Antibody-dependent cell-mediated cytotoxicity at the surface of juvenile/immature flukes is a host immune mechanism.•Antigens on the surface tegument of young flukes represent prime candidates for a fluke vaccine.•Type 1 immune response shortly after fluke infection is associated with resistance to infection in resistant sheep.
The development of a vaccine for Fasciola spp. in livestock is a challenge and would be advanced by harnessing our knowledge of acquired immune mechanisms expressed by resistant livestock against fluke infection. Antibody-dependent cell-mediated cytotoxicity directed to the surface tegument of juvenile/immature flukes is a host immune effector mechanism, suggesting that antigens on the surface of young flukes may represent prime candidates for a fluke vaccine. A Type 1 immune response shortly after fluke infection is associated with resistance to infection in resistant sheep, indicating that vaccine formulations should attempt to induce Type 1 responses to enhance vaccine efficacy. In cattle or sheep, an optimal fluke vaccine would need to reduce mean fluke burdens in a herd below the threshold of 30–54 flukes to ensure sustainable production benefits. Fluke infection intensity data suggest that vaccine efficacy of approximately 80% is required to reduce fluke burdens below this threshold in most countries. With the increased global prevalence of triclabendazole-resistant Fasciolahepatica, it may be commercially feasible in the short term to introduce a fluke vaccine of reasonable efficacy that will provide economic benefits for producers in regions where chemical control of new drug-resistant fluke infections is not viable. Commercial partnerships will be needed to fast-track new candidate vaccines using acceptable adjuvants in relevant production animals, obviating the need to evaluate vaccine antigens in rodent models.
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