The effects of dietary energy density and lysine:calorie ratio on the growth performance of the 20 to 55 lb pig

A total of 336 barrows (initially 21.8 lb and 31 ± 2 d of age) was used to evaluate the results of increasing levels of choice white grease and lysine:calorie ratio on pig performance. Increasing levels of both choice white grease and lysine:calorie ratio improved the growth rate and efficiency of pigs fed from 20 to 55 lb.; Swine Day, Manhattan, KS, November 21, 199

Evolution of sex determination and heterogamety changes in section Otites of the genus Silene

Abstract Switches in heterogamety are known to occur in both animals and plants. Although plant sex determination systems probably often evolved more recently than those in several well-studied animals, including mammals, and have had less time for switches to occur, we previously detected a switch in heterogamety in the plant genus Silene: section Otites has both female and male heterogamety, whereas S. latifolia and its close relatives, in a different section of the genus, Melandrium (subgenus Behenantha), all have male heterogamety. Here we analyse the evolution of sex chromosomes in section Otites, which is estimated to have evolved only about 0.55 MYA. Our study confirms female heterogamety in S. otites and newly reveals female heterogamety in S. borysthenica. Sequence analyses and genetic mapping show that the sex-linked regions of these two species are the same, but the region in S. colpophylla, a close relative with male heterogamety, is different. The sex chromosome pairs of S. colpophylla and S. otites each correspond to an autosome of the other species, and both differ from the XY pair in S. latifolia. Silene section Otites species are suitable for detailed studies of the events involved in such changes, and our phylogenetic analysis suggests a possible change from female to male heterogamety within this section. Our analyses suggest a possibility that has so far not been considered, change in heterogamety through hybridization, in which a male-determining chromosome from one species is introgressed into another one, and over-rides its previous sex-determining system

The effect of ingredient processing and diet complexity on growth performance of the segregated early-weaned pig

A 14-day growth trial was conducted to determine the interactive effects of ingredient processing and diet complexity on growth performance of segregated early-weaned pigs. Three processing combinations were used with either a simple or complex diet formulation in 2 x 3 factorial arrangement. Diets were pelleted (control); the corn was moist-extruded, then the complete diet pelleted (extruded); or the complete diet was expanded then pelleted (expanded). An interaction was observed between ingredient processing and diet complexity. Pigs fed the control or extruded diets had improved growth performance as diet complexity increased. However, pigs fed the expanded diets showed little response to increasing diet complexity. Under these experimental conditions, pigs fed moist-extruded corn had the best growth performance. However, further research is warranted to evaluate expander conditioning of complex starter diets

Effects of added choline on performance of weanling pigs

A 28-d growth assay was conducted to determine the effects of added choline on weanling pig performance. Pigs were fed a control diet without added choline or diets containing 150 g/ton of added choline. No differences in pig growth performance were observed. These results suggest that added choline can be removed from weanling pig diets

The effects of dietary energy density and lysine:calorie ratio on the growth performance of the 20 to 55 lb pig

A total of 336 barrows (initially 21.8 lb and 31 ± 2 d of age) was used to evaluate the results of increasing levels of choice white grease and lysine:calorie ratio on pig performance. Increasing levels of both choice white grease and lysine:calorie ratio improved the growth rate and efficiency of pigs fed from 20 to 55 lb

Effects of starch gelatinization on weanling pig performance

Two hundred and ten weanling pigs were fed diets containing nonextruded corn (14.5% gelatinization; control) or corn that was extruded to provide 38.7%, 52.7%, 64.4%, or 89.3% starch gelatinization in the complete diet. With increasing gelatinization, ADG and ADFI decreased and then increased. but apparent digestibility of DM, CP, and energy increased then decreased. These results suggest that the degree of starch gelatinization has an inconsistent effect on weanling pig performance

Influence of dietary tryptophan levels on the growth performance of segregated early-weaned pigs (10 to 20 lb)

A total of 360 pigs (averaging 13 d of age and 9.4 lb) was used to determine the effects of increasing dietary tryptophan:lysine ratio on the growth performance of segregated early-weaned (SEW) pigs. Two apparent digestible lysine levels (1. 15 and 1.50 %) and six apparent digestible tryptophan: lysine ratios (12.5, 15, 17.5, 20, 22.5 and 25%) were fed from d 0 to 16 after weaning. Lysine x tryptophan interactions were observed for ADG and F/G. Increasing the tryptophan: lysine ratio in the low lysine diets improved ADG and F/G in a quadratic manner. Increasing the tryptophan level had no effect in the high lysine diets. Results of this trial indicate that optimal apparent digestible tryptophan: lysine ratio is approximately 15 %

The effect of carbohydrate source and extrusion processing on growth performance on segregated early-weaned pigs

A 21-day growth trial was conducted to determine the effect of various carbohydrate sources with or without moist extrusion processing on growth performance of segregated early-weaned pigs. Treatments included five different carbohydrate sources (corn, corn starch, rice, wheat flour, and grain sorghum) with or without moist extrusion processing in a 2 x 5 factorial arrangement. No interactions were observed among carbohydrate sources and extrusion processing. Growth performance was not improved by extrusion processing. Surprisingly, pigs fed corn had poorer growth performance compared to those fed other carbohydrate sources. These results suggest that corn starch, rice, wheat flour, and grain sorghum are suitable alternatives to corn in diets for segregated early-weaned pigs