Roche J.R.,Animal Science |
Kay J.K.,Dairy Cow Nutrition |
Friggens N.C.,systemIC |
Loor J.J.,Urbana University |
Veterinary Clinics of North America - Food Animal Practice | Year: 2013
Body condition score (BCS) is an assessment of a cow's body fat (and muscle) reserves, with low values reflecting emaciation and high values equating to obesity. The intercalving profile of BCS is a mirror image of the milk lactation profile. The BCS at which a cow calves, her nadir BCS, and the amount of BCS lost after calving are associated with milk production, reproduction, and health. Genetics, peripartum nutrition, and management are factors that likely interact with BCS to determine the risk of health disorders. © 2013 Elsevier Inc.
Macbeth G.M.,Animal Science |
Wang Y.-G.,University of Queensland
Aquaculture | Year: 2014
Commercial environments may receive only a fraction of expected genetic gains for growth rate as predicted from the selection environment. This fraction is the result of undesirable genotype-by-environment interactions (G. ×. E) and measured by the genetic correlation (rg) of growth between environments. Rapid estimates of genetic correlation achieved in one generation are notoriously difficult to estimate with precision. A new design is proposed where genetic correlations can be estimated by utilising artificial mating from cryopreserved semen and unfertilised eggs stripped from a single female. We compare a traditional phenotype analysis of growth to a threshold model where only the largest fish are genotyped for sire identification. The threshold model was robust to differences in family mortality differing up to 30%. The design is unique as it negates potential re-ranking of families caused by an interaction between common maternal environmental effects and growing environment. The design is suitable for rapid assessment of G. ×. E over one generation with a true 0.70 genetic correlation yielding standard errors as low as 0.07. Different design scenarios were tested for bias and accuracy with a range of heritability values, number of half-sib families created, number of progeny within each full-sib family, number of fish genotyped, number of fish stocked, differing family survival rates and at various simulated genetic correlation levels. © 2014 Published by Elsevier B.V.
Jonsson N.N.,University of Glasgow |
Bock R.E.,Tick Fever Center |
Jorgensen W.K.,Animal Science |
Morton J.M.,University of Queensland |
Stear M.J.,University of Glasgow
Trends in Parasitology | Year: 2012
Endemic stability is a widely used term in the epidemiology of ticks and tick-borne diseases. It is generally accepted to refer to a state of a host-tick-pathogen interaction in which there is a high level of challenge of calves by infected ticks, absence of clinical disease in calves despite infection, and a high level of immunity in adult cattle with consequent low incidence of clinical disease. Although endemic stability is a valid epidemiological concept, the modelling studies that underpinned subsequent studies on the epidemiology of tick-borne diseases were specific to a single host-tick-pathogen system, and values derived from these models should not be applied in other regions or host-tick-pathogen systems. © 2012 Elsevier Ltd.
Does the sow have a high temperature and is she on her way to getting sick? This is important information - particularly when the sow has just given birth and the lives of the newborn piglets depend on her health. Research at Aarhus University has developed a method that uses an infrared camera to remotely measure the temperature of the sow more accurately than hitherto. In practice, this means that any health problems around the time of farrowing could be nipped in the bud without unnecessary disturbance to the sow. The person responsible for the development of the method is Dennis Dam Sørensen from the Department of Animal Science. The very first thing he did in this PhD study was to map how the technique needed to be improved. "It's very important to know the heat radiation of the skin - or the so-called emissivity - if the infrared measurements are to be converted to a body temperature," explains Dennis Dam Sørensen. "If the emissivity reading has a margin of error of just 0.05°C, this produces an error in the body temperature estimate of around 0.5°C. He took both infrared pictures of sows and measured their body temperature in the traditional way with a thermometer. By relating the infrared pictures to knowledge of the actual body temperature at the time they were taken, he could work out a set of references." When you measure the temperature of a sow remotely, you also have to take into account air particles that can disturb the measurements. The next step for Dennis Dam Sørensen was therefore to measure whether ammonia and dust affected the measurements. It turned out that there was an inverse relationship between the amount of ammonia and dust in the air and the temperature measured. "This indicates that the infrared radiation from the sow was absorbed by the particles in the air," says Dennis Dam Sørensen. "He also examined the influence of the sow's hair and the dampness of the skin on measurements. The presence of hair had no effect, but wet skin gave - perhaps not surprisingly - lower temperature readings." "This shows that it is important to measure the temperature on dry skin if you want an accurate figure," says Dennis Dam Sørensen. "It is also important to measure the temperature in the right place on the sow. His study showed that the best place to measure was at the root of the ear rather than the shoulder or the udder." A cost-benefit analysis showed that the use of infrared heat measurements for measuring fevers in sows can lead to considerable savings for the farmer, particularly if the technique is used in automatic monitoring systems. The PhD study focused on sows around the time of farrowing and on the clinical health complex PPDS (Postpartum Dysgalactia Syndrome in Sows) that encompasses a number of problems in sows, such as mastitis, metritis and agalactia or lack of milk production (MMA). Early detection of the problem using temperature measurements can save the lives of piglets and reduce the use of antibiotics. "A systematic or automatic monitoring of all sows with an infrared camera would be very useful for detecting the sows that may have problems, and then to follow this up with a more accurate measurement with a thermometer," suggests Dennis Dam Sørensen. Explore further: The choice of feed, feed strategies have important effects on gilt and sow performance
The results of new research at the University of Illinois indicate that it is possible for producers to reduce feed costs if yellow dent corn, a staple of swine diets in the United States, is ground to a finer particle size. The smaller particle size allows pigs to derive more energy from the corn, which means producers can reduce the amount of fat added to diets (reducing their costs) without affecting the growth performance or carcass characteristics of pigs. Hans H. Stein, professor of animal sciences at the U of I, and his lab conducted an experiment to determine if growth performance and carcass characteristics differed among pigs fed diets that had the same amount of energy, but contained corn that was ground to different particle sizes. Current industry recommendations call for corn fed to pigs to be ground to a particle size of around 650 microns. "When corn is ground to smaller particle sizes, pigs can derive more energy from it because the increase in surface area means that digestive enzymes have more access to the nutrients in corn, which results in increased digestibility of starch," said Stein. "Therefore, you can reduce the amount of fat added to the diets without a loss of metabolizable energy if you use more finely ground corn. In this study, we tested the hypothesis that added fat can be removed from diets containing finely ground corn without impacting growth performance and carcass characteristics of the pigs." The researchers fed growing-finishing pigs diets containing corn ground to 865, 677, 485, and 339 microns. Diets were formulated to contain the same amount of metabolizable energy by varying the amount of added fat. The diets using the most coarsely ground corn contained 3.60 to 3.87 percent fat, whereas the diets using the most finely ground corn contained 2 percent fat. The carcass characteristics of pigs fed diets containing corn ground to the different particle sizes were very similar. Backfat depth, hot carcass weight, loin eye area, pH of loin eye area, and fat-free lean percentage were not affected by particle size. However, dressing percentage increased, and empty intestinal weight decreased, as particle size decreased. Growth performance was also not affected by corn particle size. The pigs' final body weight, overall average daily feed intake, and overall average daily gain were not different among treatments. For gilts, the gain:feed ratio decreased as particle size decreased, but this was attributable to the reduced intestinal weight. When calculated on the basis of hot carcass weight, gain:feed did not differ among treatments. Stein said that these results indicate that it is possible for producers to reduce feed costs if corn is ground to a finer particle size. "By using corn ground to a smaller particle size, producers can decrease the amount of fat added to growing-finishing diets without affecting growth performance or carcass composition. However, the increased dressing percentage may result in an increase in the amount of saleable meat from the pigs fed diets containing corn ground to a smaller particle size." Although feeding corn ground to smaller particle sizes has been observed to lead to ulcers in some studies, there was no incidence of ulcers in the esophageal region of the stomach in pigs in the current study regardless of particle size. However, an increase in keratinization was observed as particle size decreased, which Stein cautioned might lead to ulcers if pigs are stressed. Explore further: Feeding corn germ to pigs does not affect growth performance More information: The paper, "Effects of particle size of yellow dent corn on physical characteristics of diets and growth performance and carcass characteristics of growing-finishing pigs," was co-authored by Oscar Rojas and Yanhong Liu of the U of I, and is published in a recent edition of the Journal of Animal Science. The full text can be found online at www.animalsciencepublications.org/publications/jas/articles/94/2/619