Effect of diet composition on postweaning colibacillosis in piglets

The weaning of piglets is often associated with digestive disorders, particularly diarrhea—postweaning colibacillosis (PWC)—which is caused by infection with enterotoxigenic strains of Escherichia coli. It has been shown previously that a diet for newly weaned pigs based on cooked white rice and animal protein decreases the occurrence of PWC, whereas the addition of carboxymethylcellulose (CMC) to this diet enhances PWC. The aims of the current work were to 1) determine whether substitution of animal protein with plant proteins in the cooked-white-rice diet influenced its protective effects on PWC and 2) confirm that an increase in viscosity of the digesta by adding CMC to the diet favors the development of PWC—with (Exp. 1) or without (Exp. 2) experimental infection of piglets with E. coli. The diets were 1) cooked white rice and animal protein sources (RAP), 2) RAP + CMC added at 40 g of CMC/kg (air-dry basis) of diet, 3) cooked white rice and plant protein sources (RPP), and 4) wheat and plant protein sources (WPP). Experiments 1 and 2 were conducted using 32 and 24 piglets (eight and six per treatment), respectively. Piglets were weaned at 21 d (d 1), and fed ad libitum until slaughter on d 9. In Exp. 1, piglets were orally infected with enterotoxigenic E. coli on d 4, 5, 6, and 7. On d 8 of Exp. 1, the E. coli scores in feces of pigs fed RAP + CMC were higher than with RAP (P < 0.01). On d 9 after weaning, feces from pigs fed diet RAP were normal or moist, whereas feces from pigs fed RAP + CMC were wet to diarrheic. On d 7 of Exp. 2, pigs fed diets RAP + CMC and WPP had wetter feces than pigs fed diets RAP or RPP (P < 0.05). On d 8, the E. coli scores in feces were higher (P < 0.01) with pigs fed RAP + CMC than with all other diets. The E. coli scores in the digesta were also higher with pigs fed RAP + CMC, and to a lesser extent with diet WPP, than with pigs fed RAP or RPP (P < 0.01). The large intestine was heavier in pigs fed diets RPP and WPP, and the digesta were more acidic (P < 0.05). This study confirmed that diet RAP was protective against PWC, and that substitution of animal proteins with plant protein in a rice-based diet did not diminish its protective effects. The addition of CMC to cooked white rice increased digesta viscosity and enhanced PWC. Consequently, this diet represents a useful model for studying this condition

Type of rice fed to pigs after weaning influences apparent digestibility of starch at the ileum but not the rectum

Forty-eight male pigs aged 19-24 days and weighing 6.7±0.24 kg were used in a completely randomized block design with four experimental treatments and 12 pigs per treatment. Three rice-based diets with different types of cooked rice incorporated were fed: (i) medium grain (cv. Amaroo, AM); (ii) long grain (cv. Doongara, DOON) and (iii) waxy (WAXY). A fourth diet composed of a weaner diet based on wheat, barley and lupins was also given. The pigs were fed the experimental diets ad libitum for 14 days, at which time they were euthanized for digesta sample collection. Rice types AM and WAXY, having the lowest amylose to amylopectin ratio, showed superior (P=0.004) digestibility of starch at the terminal ileum than the long grain rice DOON and the commercial diet. Differences in the apparent starch digestibility between rice types were not observed in the rectum, although pigs fed diet WBL showed a lower digestibility (P<0.01). Starch digestibility in the ileum between rice types depended on the amylose to amylopectin ratio and the amount of RS but microbial fermentation in the hindgut caused total disappearance of rice starch. Digestibility of starch in pigs fed WBL was incomplete in the rectum, reflecting differences in ingredient composition and physical and chemical properties between diets

Feeding different types of cooked white rice to piglets after weaning influences starch digestion, digesta and fermentation characteristics and the faecal shedding of β-haemolytic Escherichia coli

Forty-eight, 21-d-old pigs were used to examine the effects of different types of cooked white rice on starch digestion, digesta and fermentation characteristics, shedding of b-haemolytic Escherichia coli and performance after weaning. Pigs received one of three rice-based diets: (i) mediumgrain Amaroo (AM), (ii) long-grain Doongara (DOON), and (iii) waxy (WAXY). The remainder of the diet consisted predominantly of animal proteins. A fourth diet contained mainly wheat, barley and lupins (WBL). On days 1, 3, 7 and 9 after weaning, a faecal swab was taken for assessment of b-haemolytic E. coli and faecal consistency. Apparent digestibility of starch measured in the ileum 14 d after weaning was highest (P=0·004) in AM and WAXY and lowest, but the same (P>0·05), in DOON and WBL. Starch digestibility in the rectum was highest in all rice diets (P<0·001). Digesta viscosity was highest in pigs fed WBL in both the ileum (P<0·001) and caecum (P=0·027). Pigs fed rice generally had lighter (P<0·05) gastrointestinal organs than pigs fed WBL. Performance of pigs was similar for all treatments; however, pigs fed rice-based diets had a higher (P<0·001) carcass percentage than pigs fed WBL. Pigs fed WBL produced more acid (P<0·05) but had lower molar proportions of acetate (P<0·05), isobutyrate (P<0·01) and isovalerate (P<0·001) and a higher molar proportion of butyrate (P<0·01) in the large intestine than pigs fed rice. Shedding of E. coli was low; however, pigs fed AM and WBL shed less E. coli than pigs fed other diets

Supported l/y the Western Australian Retinitis Pigmentosa Foundation (Perth), the Australian Retinitis Pigmentosa Association (Spence), and the Lions Save-Sight Foundation

,&quot;\ and IanJ. Constable* Purpose. The aim of this study was to identify whether abnormalities in the synthesis of basic fibroblast growth factor (bFGF) or its receptor (bFGF-R) were responsible for the photoreceptor dystrophy in Royal College of Surgeons (RCS) rats. Methods. The polymerase chain reaction was used to detect the expression of bFGF and bFGF-R messenger RNA in the retinal pigment epithelial (RPE) cells and the neural retina of RCS dystrophic rats and in PVG/C and RCS-rrf)&gt; + control animals. Results. In the RPE, it was found that there was no significant difference in the expression of bFGF and bFGF-R between RCS rats and the controls at the ages of 21 days and 3 mo. In the neural retina, the level of bFGF expression was lower in the 21-day-old RCS rats compared with the control group, but bFGF-R expression was as strong as in the PVG/C and RCS-rd)&gt; + animals. However, in 3-mo-old RCS rat neural retina, the bFGF and bFGF-R expression was found to be significantly lower than in the control animals. Conclusions. Although the mutant gene in RCS rats is expressed in the RPE cells, these results suggest that there is no significant defect in bFGF or bFGF-R expression in the RPE cells of RCS rats, which would be an initiating factor in the development of photoreceptor degeneration in these animals. The lowered bFGF levels in the neural retina at early stages (postnatal day 21) may explain the prolongation of photoreceptor survival when exogenous bFGF is injected. Invest Ophthalmol Vis Sci. 1993; 34:1845-1852 JLJegeneration of photoreceptors leads to permanent blindness because, in common with other central nervous system neuronal cells, they cannot be replaced by cell division in adults. The Royal College of Surgeons (RCS) mutant strain of rats with inherited retinal dys- trophy has been used widely as a model to study photoreceptor degeneration. 1 Although this particular type of defect is not common in humans, the procedures that prolong photoreceptor survival in this condition may be more widely applicable. The cellular nature of the genetic abnormality in RCS rats is known, but the underlying molecular defect has not yet been identified. In the RCS rat, the retinal pigment epithelium (RPE) does not phagocytose shed outer segments, 2 thus resulting in accumulation of membranous debris in the subretinal space and subsequent death of the rod photoreceptors. Transplantation of RPE cells from normal rats results in long-term (5 mo after treatment) rescue of photore

Profile of the genes expressed in the human peripheral retina, macula, and retinal pigment epithelium determined through serial analysis of gene expression (SAGE)

We used the serial analysis of gene expression (SAGE) technique to catalogue and measure the relative levels of expression of the genes expressed in the human peripheral retina, macula, and retinal pigment epithelium (RPE) from one or both of two humans, aged 88 and 44 years. The cone photoreceptor contribution to all transcription in the retina was found to be similar in the macula versus the retinal periphery, whereas the rod contribution was greater in the periphery versus the macula. Genes encoding structural proteins for axons were found to be expressed at higher levels in the macula versus the retinal periphery, probably reflecting the large proportion of ganglion cells in the central retina. In comparison with the younger eye, the peripheral retina of the older eye had a substantially higher proportion of mRNAs from genes encoding proteins involved in iron metabolism or protection against oxidative damage and a substantially lower proportion of mRNAs from genes encoding proteins involved in rod phototransduction. These differences may reflect the difference in age between the two donors or merely interindividual variation. The RPE library had numerous previously unencountered tags, suggesting that this cell type has a large, idiosyncratic repertoire of expressed genes. Comparison of these libraries with 100 reported nonocular SAGE libraries revealed 89 retina-specific or enriched genes expressed at substantial levels, of which 14 are known to cause a retinal disease and 53 are RPE-specific genes. We expect that these libraries will serve as a resource for understanding the relative expression levels of genes in the retina and the RPE and for identifying additional disease genes