Massey Documents by Type

Now showing 1 - 3 of 3

Review: Factors affecting sheep carcass and meat quality attributes.
(Elsevier B.V., 2022-02) Prache S; Schreurs N; Guillier L
Sheep meat comes from a wide variety of farming systems utilising outdoor extensive to indoor intensive with animals of various ages at slaughter. In Europe, slaughter may occur from 4 weeks of age in suckling light lambs to adult ages. More than any other animal species used for meat production, there are strong country-specific preferences for sheep meat quality linked to production system characteristics such as dairy or grassland-based systems. This article critically reviews the current state of knowledge on factors affecting sheep carcass and meat quality. Quality has been broken down into six core attributes: commercial, organoleptic, nutritional, technological, safety and image, the latter covering aspects of ethics, culture and environment associated with the way the meat is produced and its origin, which are particularly valued in the many quality labels in Europe. The quality of meat is built but can also deteriorate along the continuum from the conception of the animal to the consumer. Our review pinpoints critical periods, such as the gestation and the preslaughter and slaughter periods, and key factors, such as the animal diet, via its direct effect on the fatty acid profile, the antioxidant and volatile content, and indirect effects mediated via the age of the animal. It also pinpoints methodological difficulties in predicting organoleptic attributes, particularly odour and flavour. Potential antagonisms between different dimensions of quality are highlighted. For example, pasture-feeding has positive effects on the image and nutritional attributes (through its effect on the fatty acid profile of meat lipids), but it increases the risk of off-odours and off-flavours for sensitive consumersand the variability in meat quality linked to variability of animal age at slaughter. The orientation towards more agro-ecological, low-input farming systems may therefore present benefits for the image and nutritional properties of the meat, but also risks for the commercial (insufficient carcass fatness, feed deficiencies at key periods of the production cycle, irregularity in supply), organoleptic (stronger flavour and darker colour of the meat) and variability of sheep carcass and meat quality. Furthermore, the genetic selection for lean meat yield has been effective in producing carcasses that yield more meat, but at a penalty to the intramuscular fat content and eating quality of the meat, and making it more difficult to finish lambs on grass. Various tools to assess and predict quality are in development to better consider the various dimensions of quality in consumer information, payment to farmers and genetic selection.
Influence of dietary fat inclusion on the ileal digestibility of amino acids in broilers : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Animal Science at Massey University, Manawatu, New Zealand
(Massey University, 2018) Whitehouse, Thomas Harrison
The main focus of the present study was to examine nitrogen, dry matter and specific amino acid digestibility, particularly in the jejunum and ileum. Due to the fact that the gizzard and duodenum are primarily sites of digestion, and not absorption and due to limitations of the titanium oxide marker method, results from these segments are less applicable to the overall results. The general trend indicates that the presence of tallow in the diet increases digestibility significantly compared to diets without additional fat. The soybean oil diets generally had intermediary digestibility between the tallow and no-fat diets. Previous studies with similar fat sources indicated the opposite would be true. Differing digestibility of the different fat sources could likely be governing this effect. Future studies could involve birds of differing ages, as well as a more diverse set of fat sources to better determine which factors are affecting these digestibility rates. The speculated mechanism of action for this increased digestibility is an increase in digesta transit time caused by the increased fat content. Future studies could confirm this by using a marker technique to trace the rate of passage in the digestive tract between the different diets. Differences and digestibility between maize and wheat diets were expected, but it was unknown if there would be any major interactions between grain type and fat source in the diet in nitrogen and dry matter digestibility. The present study found no interaction. The decreases in digestibility seen by high NSP ingredients like wheat is likely related to the creation of insoluble gels in the gut. Thus, while fat and these gels may both increase the viscosity of gut contents, the composition of the viscous contents differ substantially, with the fat having less of an inhibitory effect on amino acid digestibility. The present study found no substantial interaction effects in the lower digestive segments between the grain effects (caused by NSP content) and fat effects. This indicates that, while the addition of both can alter digestive viscosity, there is no inhibitory effect exerted by either on the other. No significant effect of fat source was found on amino acid digestibility. This may be due to the fact that these samples were taken from the lower ileum, and the majority of amino acid absorption may have taken place in more proximal segments.
Observations on ruminant fat metabolism with particular relation to lactation : a thesis presented in partial fulfilment of the requirements for the degree of M. Agr. Sc. of the University of New Zealand
(Massey University, 1949) Mayhead, J W
In that animal fat is a major economic "building block" the mechanism of its production has attracted particular study. Although observations regarding digestion of fats may be traced back as far as those of Asellius in 1622 it was in 1843 that specific investigations into body fat production were first instituted by Lawes and Gilbert. From 1900 onwards biochemical research has made its greatest advances but, in spite of the volume of literature published on the subject of fat metabolism the state of knowledge in this field may yet be in its infancy. The three main experiments to be described relate principally to the changes effected in the degree of unsaturation of milk fat from dairy cows when highly unsaturated oils are included in the daily ration. The immediate effects of short-term inanition are also investigated. Two minor experiments are described; the first concerning the tracing of ingested stained fat into the milk and depot fats of simple-stomached animals; the second relation to the keeping qualities of milk fats of varying degrees of unsaturation.

Massey Documents by Type

Browse

Filters

Settings

Sort By

Results per page

Search Results