Iron dextran and iron dextran-gentamycin combined, compared as methods of preventing iron-deficiency anemia in neonatal pigs

Giving an iron iron dextran-gentamycin combination to young pigs had no advantages over giving them iron dextran alone, as measured by hemoglobin levels, packed cell volumes, or weight (when 28 days old).; Swine Day, Manhattan, KS, November 10, 197

Evaluation of antibacterial preparations on growth rate and feed efficiency of young pigs

Ninety-six young pigs were used to evaluate various antibacterial preparations on rate and efficiency of gain. Each of the antibacterial preparations increased rate of gain over pigs fed the non-medicated basal diet. There were no significant differences in daily gains of pigs fed ASP-250, CSP-250, Lincomix, Mecadox, or Stafac.; Swine Day, Manhattan, KS, November 11, 197

Lysine and dried whey additions in starter pig diets

A total of 943 newly weaned (18 to 30 days of age) pigs were used in five trials to evaluate the addition of lysine and dried whey in starter diets. The results of these studies show that the lysine requirement is 1.2 to 1.3% during the nursery phase (up to approximately 50 lbs). When lysine levels are greater than 1.3% with added L-Iysine monohydrochloride, a reduction in performance will be evident (P\u3c.05). Rolled dried whey appears to be inferior (P\u3c.10) to spray dried whey in starter pig diets.; Swine Day, Manhattan, KS, November 11, 198

Influence of nonviable lactobacillus fermentation product in artificially reared pigs challenged with e. coli

Two trials were conducted to determine the influence of non viable lactobacillus fermentation product (LFP) in artificially reared pigs removed from sows at 24 to 36 hours postpartum. The pigs were fed a non-medicated milk replacer for 21 days in individual cages in an environmentally controlled room. In Trial I, 5 levels (0, .25, .5, 1.0, and 2.0 ml per pig per day) of LFP were used to determine the dosage rate on growth, feed efficiency, mortality rate, white blood cell count, and hematocrit (8 pigs per treatment). No detectable dosage rate was obvserved in Trial I. In Trial II, a study was conducted to determine the effect of LFP on lactobacill us and coli form (E. coli) counts, histopathology of the small intestine, growth and blood parameters. When pigs were 14 days old they received an inoculum of either a broth containing E. coli (strain K88,91; approximately billion organisms for two days) or broth without E. coli. Pigs were fed three levels of the LFP at 0, .5, and 1.0 ml per day. Pigs were sacrificed five days and seven sections of gastrointestinal tract and feces were excised to enumerate lactobacillus and coliform populations. A dose rate of .5 ml per day increased gain (P\u3c.08) and suppressed E. coli count in the stomach area without affecting lactobacillus populations.- No differences were detected with the pathological evaluation. By challenging the pigs with E. coli, jejunum (section of the small intestine) coliform and white blood cell counts were increased (P\u3c.06). These results suggest that lactobacillus fermentation product suppresses E. coli counts in the stomach and may improve gain in the artificially reared pig.; Swine Day, Manhattan, KS, November 11, 198

Transfer of fatty acids across the swine uterus and placenta

The transfer across the swine uterus and placenta of [1-14C] octanoic acid, [9,10(n)- H] palmitic acid, and [1- 14C] linoleic acid was studied in five gilts and their fetuses during late gestation, following a single bolus injection. Only trace amounts of labeled fatty acids were found in fetal plasma lipid. There were no measureable differences in free fatty acids (FFA) from umbilical artery, and veinous blood. Concentration of FFA in fetal blood was about 40% of the level of uterine values (187, 194, 73, and 82 µEg/1 for uterine artery, uterine vein, umbilical artery, and umbilical vein). In addition, fetal plasma contained larger amounts of 14:0, 16:1, 18:1, and 20:4, whereas maternal plasma contained larger amounts of 18:0 and 18:2. These results indicate that only trace amounts of FFA cross the swine utero-placental unit during late gestation, which are probably not enough to increase energy supply or lipid storage of the fetus.; Swine Day, Manhattan, KS, November 21, 198

Cannibalism as a life boat mechanism

Under certain conditions a cannibalistic population can survive when food for the adults is too scarce to support a non-cannibalistic population. Cannibalism can have this lifeboat effect if (i) the juveniles feed on a resource inaccessible to the adults; and (ii) the adults are cannibalistic and thus incorporate indirectly the inaccessible resource. Using a simple model we conclude that the mechanism works when, at low population densities, the average yield, in terms of new offspring, due to the energy provided by one cannibalized juvenile is larger than one

The shape of ecological networks

We study the statistics of ecosystems with a variable number of co-evolving species. The species interact in two ways: by prey-predator relationships and by direct competition with similar kinds. The interaction coefficients change slowly through successful adaptations and speciations. We treat them as quenched random variables. These interactions determine long-term topological features of the species network, which are found to agree with those of biological systems.Comment: 4 pages, 2 figure

Transition probabilities for general birth-death processes with applications in ecology, genetics, and evolution

A birth-death process is a continuous-time Markov chain that counts the number of particles in a system over time. In the general process with $n$ current particles, a new particle is born with instantaneous rate $\lambda_n$ and a particle dies with instantaneous rate $\mu_n$. Currently no robust and efficient method exists to evaluate the finite-time transition probabilities in a general birth-death process with arbitrary birth and death rates. In this paper, we first revisit the theory of continued fractions to obtain expressions for the Laplace transforms of these transition probabilities and make explicit an important derivation connecting transition probabilities and continued fractions. We then develop an efficient algorithm for computing these probabilities that analyzes the error associated with approximations in the method. We demonstrate that this error-controlled method agrees with known solutions and outperforms previous approaches to computing these probabilities. Finally, we apply our novel method to several important problems in ecology, evolution, and genetics

Confounding conventional wisdom: political not principled differences in the transatlantic regulatory relationship

The transatlantic complaints over hormone-treated beef and genetically modified organisms before the World Trade Organisation (WTO) seem to confirm two separate but related conventional wisdoms about the transatlantic economic relationship: that it is highly conflictual and that many of the conflicts are rooted in profoundly different approaches to regulation. This article argues that neither of the two conventional wisdoms is accurate. Rather, it contends that they are products of two, compounding analytical shortcomings: one methodological, one empirical. The methodological shortcoming takes the form of an implicit selection bias. While WTO complaints are high profile they are rare and extreme examples; it is, therefore, unsound to generalise from them to the regulatory relationship as a whole. The empirical shortcoming has to do with neither the beef hormones nor the GMO dispute demonstrating what it is purported to. The article thus serves as a cautionary tale about the dangers of relying on obvious cases and the need to question whether evidence really does support a prevailing popular narrative

The Formation of Collective Silk Balls in the Spider Mite Tetranychus urticae Koch

Tetranychus urticae is a phytophagous mite that forms colonies of several thousand individuals. These mites construct a common web to protect the colony. When plants become overcrowded and food resources become scarce, individuals gather at the plant apex to form a ball composed of mites and their silk threads. This ball is a structure facilitating group dispersal by wind or animal transport. Until now, no quantitative study had been done on this collective form of migration. This is the first attempt to understand the mechanisms that underlie the emergence and growth of the ball. We studied this collective behaviour under laboratory conditions on standardized infested plants. Our results show that the collective displacement and the formation of balls result from a recruitment process: by depositing silk threads on their way up to the plant apex, mites favour and amplify the recruitment toward the balls. A critical threshold (quorum response) in the cumulative flow of mites must be reached to observe the emergence of a ball. At the beginning of the balls formation, mites form an aggregate. After 24 hours, the aggregated mites are trapped inside the silk balls by the complex network of silk threads and finally die, except for recently arrived individuals. The balls are mainly composed of immature stages. Our study reconstructs the key events that lead to the formation of silk balls. They suggest that the interplay between mites' density, plant morphology and plant density lead to different modes of dispersions (individual or collective) and under what conditions populations might adopt a collective strategy rather than one that is individually oriented. Moreover, our results lead to discuss two aspects of the cooperation and altruism: the importance of Allee effects during colonization of new plants and the importance of the size of a founding group