Analysis of Body Weight and Feed Intake Curves in Selection Lines for Residual Feed Intake in Pigs

A selection experiment for reducing residual feed intake (RFI= feed consumed over and above expected requirements for production and maintenance) in Yorkshire pigs consists of a line selected for lower RFI (LRFI) and a random control line (CTRL). Using 64 LRFI and 87 CTRL boars from generation 5 of the selection experiment, cubic polynomial random regression with heterogeneous residual variance for daily feed intake (DFI) and with homogeneous residual variance for bi-weekly body weight (BW) were identified as the best linear mixed models to describe feed intake and body weight curves. Based on the Gompertz model, significant differences in the decay parameter for DFI and in mature body weight and the inflection point for BW were observed between the lines. In conclusion, selection for lower RFI has resulted in a lower feed intake curve toward maturity, lower mature body weight, and earlier inflection points for growth

Selection Lines for Residual Feed Intake in Yorkshire Swine

A line of Yorkshire pigs was selected for 3 generations for reduced residual feed intake (RFI), a measure of feed efficiency defined as feed consumed over and above average requirements for maintenance and growth. Heritability estimates of RFI, feed intake, growth, and backfat were 0.30, 0.46, 0.33, and 0.67. Comparison of performance of gilts from the selected line (n=49) to those of a randomly selected control line (n=38) from ~40 to ~70 kg showed that selection had significantly decreased feed intake by 123 g/d. There were no significant differences in average daily gain and backfat between the lines, although the selection line tended to have 22 g/d less growth. In conclusion, RFI is a heritable trait and selection for RFI has significantly decreased the amount of feed required for a given rate of growth and backfat

Feeding Behavior of Yorkshire Pigs Selected for Residual Feed Intake

Feeding behavior traits were evaluated in Yorkshire gilts from the fourth generation of the ISU residual feed intake (RFI) selection experiment. Gilts were fed using FIRE feeders. Compared to the randomly selected control line, pigs from the line selected for lower RFI, had lower residual feed intake, ate less per day, spent less time eating per day, and ate faster per visit, regardless of whether analysis was over the whole test period, the first half of test period, or the second half of test period. In conclusion, selection for lower RFI has significantly changed feeding behavior, which could be part of the reason why they are more efficient

Surgical Treatment and Follow-up Results of Pituitary ACTH Microadenoma: 18 Years' Experience

ObjectiveTo review retrospectively our clinical experience with surgical treatment and follow-up of pituitary adrenocorticotropic hormone (ACTH) microadenomas at Rui Jin Hospital of Shanghai Second Medical University.MethodsEighty-seven patients with ACTH microadenomas underwent surgery via the transsphenoidal approach. Preoperative computed tomography and/or magnetic resonance imaging revealed microadenomas in only 46 patients and was negative in the remaining 41 patients, which were classified as microadenoma grade 0. High-dose dexamethasone (Dx) suppression testing was positive in 86% of patients and low-dose Dx suppression testing was negative in all patients.ResultsHistological confirmation of ACTH microadenoma was made in all 87 cases, with a minimum tumour size of only 1 to 2 mm in diameter. The remission rate was 82% for grade I and 92% for grade 0 microadenomas during 2 to 18 years of follow-up.ConclusionsNeuroimaging studies have limited value in diagnosing ACTH grade 0 microadenoma. Clinical manifestation combined with positive Dx suppression testing is decisive in these circumstances. Surgical intervention could achieve a high relief rate for ACTH microadenomas, especially in grade 0 group

IGF-1 Concentration at a Young Age is Associated with Feed Efficiency in Pigs

The concentration of IGF-I in blood of young pigs has previously been found to be genetically associated with feed efficiency and performance in pigs. To test these associations, data from the ISU selection line for residual feed intake (RFI) were used. Compared to controls, in the line selected for increased efficiency through reduced RFI, a correlated response in the expected downwards direction was observed for juvenile IGF-I. Genetic correlations of IGF-I were 0.63 with RFI and 0.78 with feed conversion ratio. These results confirm that juvenile IGF-I is a good physiological indicator of genetic merit for economically important efficiency traits, particularly since it is measured early in an animal’s life

Understanding Feed Efficiency and Growth in Swine through Genetic Marker Studies

Swine feed efficiency has become a concern of producers in recent years as feed prices have risen. Over the last decade, Iowa State University has been developing lines of pigs to research the causes and effects of genetic differences in feed efficiency. Over 700 of these animals were recently genotyped for over 60,000 markers across the genome to determine which regions of the genome play the biggest roles in impacting feed intake, growth, backfat, and efficiency. The goals of the project were to gain a better understanding of the biology behind these traits in order to suggest improved management practices and genetic selection techniques. Several significant genomic regions were identified for each trait

Indian monsoon variability on millennial-orbital timescales

The Indian summer monsoon (ISM) monsoon is critical to billions of people living in the region. Yet, significant debates remain on primary ISM drivers on millennial-orbital timescales. Here, we use speleothem oxygen isotope (δ18O) data from Bittoo cave, Northern India to reconstruct ISM variability over the past 280,000 years. We find strong coherence between North Indian and Chinese speleothem δ18O records from the East Asian monsoon domain, suggesting that both Asian monsoon subsystems exhibit a coupled response to changes in Northern Hemisphere summer insolation (NHSI) without significant temporal lags, supporting the view that the tropical-subtropical monsoon variability is driven directly by precession-induced changes in NHSI. Comparisons of the North Indian record with both Antarctic ice core and sea-surface temperature records from the southern Indian Ocean over the last glacial period do not suggest a dominant role of Southern Hemisphere climate processes in regulating the ISM variability on millennial-orbital timescales

Mechanical properties investigation of monolayer h-BN sheet under in-plane shear displacement using molecular dynamics simulations

The mechanical properties, including wrinkling patterns and fracture behavior, of monolayer h-BN sheets have been investigated using classic molecular dynamics simulations and continuum model. The wrinkling pattern formation and evolution have been first explored. The dependences of the wrinkling shape, amplitude, and wavelength, as well as wrinkling number on shear displacement are extensively elucidated. The influences of geometry and shear load direction, as well as temperature, on the fracture behavior have also been studied to obtain further insights into the properties of the monolayer h-BN sheets