Effects of diet on acidic and neutral goblet cell populations in the small intestine of early weaned pigs.

Effects of dietary manipulation on Alcian blue-positive (AB+) and periodic acid-Schiff-positive (PAS+) goblet cell populations were determined for the villi and intestinal crypts in the small intestine of early weaned pigs. Pigs were weaned at 21 days of age and samples from the distal portions of the duodenum and the middle and distal portions of the jejunum were obtained when pigs were 21, 24, 27, 30, 33, and 36 days old. Pigs were assigned to 1 of 3 dietary treatments; all diets contained 20% protein, on the basis of hydrolyzed casein, soybean meal, or corn-soybean meal. By day 24, three days after weaning, the populations of AB+ and PAS+ goblet cells were markedly decreased, regardless of diet. Goblet cell populations in the villi tended to increase from 3 to 15 days after weaning, whereas those in the intestinal crypts remained low throughout the study. Differences between any of the dietary treatments were not apparent for AB+ or PAS+ goblet cell populations in the villi or in the intestinal crypts. It appeared that early weaning per se, and not diet, was the primary cause for decreases in goblet cell populations.     

The impact of resistance on the use of second-generation anticoagulants against rats on farms in Southern England

Resistance amongst rats to second-generation anticoagulants, notably difenacoum, has been recognised since the 1970s. Although initially considered to be of practical significance, doubts were subsequently expressed that the degree of resistance was sufficient to explain ineffective rodenticide treatments. Research published elsewhere demonstrated the overriding importance of poor poisoned bait consumption, caused by the influence of certain ecological factors on rat behaviour, in reducing the effectiveness of second-generation anticoagulant treatments on farms in southern England. In this paper we consider, however, the subtle effects of resistance to anticoagulants on treatment outcome. The prevalence of resistance was increased amongst survivors of treatments and bait consumption by resistant survivors was higher than amongst susceptible survivors. The overall prevalence and degree of resistance to second-generation anticoagulants does not, however, currently represent a practical problem. Nevertheless, selection favouring increased resistance remains a long-term threat to the effectiveness of both difenacoum and bromadiolone.     

Effects of short-chain fructooligosaccharides and galactooligosaccharides, individually and in combination, on nutrient digestibility, fecal fermentative metabolite concentrations, and large bowel microbial ecology of healthy adults cats

Short-chain fructooligosaccharides (scFOS) and galactooligosaccharides (GOS) are nondigestible oligosaccharides that result in a prebiotic effect in some animal species; however, the cat has not been well studied in this regard. This experiment evaluated scFOS and GOS supplementation on nutrient digestibility, fermentative end product production, and fecal microbial ecology of cats. Eight healthy adult cats were fed diets containing no prebiotic, 0.5% scFOS, 0.5% GOS, or 0.5% scFOS + 0.5% GOS (scFOS + GOS) in a replicated 4 × 4 Latin square design. Apparent total tract CP digestibility was decreased (P < 0.05) when cats were fed a diet containing scFOS + GOS compared with the other treatments. Dry matter, OM, acid hydrolyzed fat, and GE digestibilities were not different (P > 0.05) among treatments. Cats fed scFOS-, GOS-, and scFOS + GOS-supplemented diets had greater (P < 0.05) fecal Bifidobacterium spp. populations compared with cats fed the control diet. Fecal pH was less (P < 0.05) for cats fed the scFOS + GOS-supplemented diet compared with the control. Butyrate (P = 0.05) and valerate (P < 0.05) concentrations were greater when cats consumed the scFOS + GOS diet. Acetate tended (P = 0.10) to be greater when cats were fed the scFOS + GOS diet. Total short-chain fatty acid (P = 0.06) and total branched-chain fatty acid (P = 0.06) concentrations also tended to be greater when cats consumed the scFOS + GOS treatment. Fecal protein catabolites, including ammonia, 4-methylphenol, indole, and biogenic amines, blood lymphocytes, neutrophils, total white blood cell counts, or fecal DM concentration and output did not differ (P > 0.05) among treatments. Low level supplementation of scFOS, GOS, and their combination exert positive effects on select indices of gut health in cats.     

A Methodology for Evaluation of Dietary Feeding Stimulants for the Pacific White Shrimp, Litopenaeus vannamei

A simple and practical method for quantification of feeding stimulation of shrimp Litopenaeus vannamei was developed using feed preference as an index of comparison. Feed preference was defined as the percentage of shrimp observed in each feeding tray. Preliminary trials were undertaken with two commercial feeds (45% protein with 5% squid meal and 40% protein without squid meal). Results indicated the following criteria were suitable for use as methodology for evaluating feeding stimulation in 5-m diameter static flow tanks: shrimp density (2.5 shrimp/m2); observational period (1 or 2 h post-addition of feed to trays), feed rate (2%), and between-trial feed rate (2%). A further investigation was undertaken to evaluate the influence of protein level and source on feed preference using a basal diet consisting of wheat flour, casein, carboxymethyl cellulose binder, and limestone, with or without krill meal as a feeding stimulant. A significant difference was shown in feeding preference for the 16% protein/4% krill meal vs. one without krill meal; however, this relationship was not shown in 45% protein feed comparisons. A second trial comparing 0, 16,30, and 45 % protein/casein-based feeds showed similar results. From these findings, it was postulated that casein, itself, also serves as a feeding stimulant at high dietary inclusion levels. A third trial comparing 16% protein/casein or wheat gluten-based feeds Indicated a delay of at least 2 h in maximum feeding preference response in feeds in which 4% krill meal was added as a feeding stimulant. It was postulated that chemical stimulants from krill meal were more slowly released in wheat gluten-based feeds. Our methodology appears suitable for evaluation of potential feeding stimulants when incorporated into low-protein casein-based or wheat-gluten-based feeds.     

Effect of dietary soybean meal on the microscopic anatomy of the small intestine in the early-weaned pig

Two experiments were conducted to determine the effect of soybean meal in postweaning diets on villus height (VH), villus shape and lamina propria depth (LPD) in the small intestine. Intestinal samples were taken at 25, 50 and 75% of the small intestine's length. The first experiment determined the normal effects of age on these structures in nursing pigs from 9 to 36 d of age. Villus height decreased (P less than .01 at the 50 and 75% locations) and LPD increased (P less than .01 at the 25% location) in a quadratic fashion with increasing age. In the second experiment, pigs were weaned at 21 d of age and fed one of three 20% protein diets: 1) protein from hydrolyzed casein (CAS), 2) soybean meal (SBM) or 3) a conventional corn-soybean meal diet (CSBM). Intestinal samples were taken 0, 3, 6, 9, 12 and 15 d post-weaning. Villus height decreased dramatically the first 3 d postweaning, with a continuing decline until 12 d post-weaning. Averaged over the d 3 to 15 interval, VH were generally greater for pigs fed CAS than for pigs fed CSBM or SBM. Pigs fed SBM or CSBM had deformed villi, and pigs fed SBM had greater (P less than .05) LPD at all intestinal locations, suggesting less mature enterocytes on the villi. These data suggest that feeding high concentrations of soybean meal to the pig post-weaning has a detrimental effect on the small intestine, but this effect was minimized when soybean meal was fed as part of a corn-based diet.     

Effect of dietary cholesterol and carbohydrate on small intestinal structure and function in prematurely weaned rats

A study using the prematurely weaned rat as a model for the pig was undertaken to determine the effect of dietary cholesterol and carbohydrate source on small intestinal structure and function. Duodenal and jejunal samples were obtained at 18, 24, and 30 d of age from rats weaned at 15 d of age and from unweaned rats at 15, 18, 24, and 30 d of age. Four 20% CP diets were formulated: two diets used lactose and glucose as the carbohydrate source and two used sucrose and starch as the carbohydrate source; 1% cholesterol was substituted for either glucose or starch in one of each diet type. The unweaned rats consistently gained weight at a faster rate (P less than .01), had greater concentrations of Alcian blue (AB+) and periodic acid-Schiff (PAS+) goblet cells (P less than .03), and had more favorable villus height than did the weaned rats. The animals fed cholesterol tended to gain more weight, had more AB+ and PAS+ goblet cells (P less than .03), and had longer villi than did those not fed cholesterol. Lactase activities tended to be greater in the unweaned rats. Sucrase activities were greater in the weaned rats at 18 d (P less than .02). The data indicate that the addition of cholesterol to weaning diets is beneficial in maintaining small intestinal integrity.     

Stable or changing lakes? a classification of aquatic macrophyte assemblages from a eutrophic shallow lake system in the United Kingdom

1. It is proposed that an appreciation of patterns of change and stability in macrophyte floras is an important tool for lake managers. 2. The presence and abundance of aquatic macrophytes was annually monitored (from 1983 to 1995) along permanent transects in 13 shallow lakes in the Broads wetland in eastern England, United Kingdom. 3. Cluster analysis (TWINSPAN) revealed three Broad Macrophyte Types (BMTs) or assemblages. Two of these were sub-divided into four and then again into six sub-types. BMT1 had a constant presence (i.e. in more than 60% of all samples) of charophytes, Potamogeton pectinatus L.,Myriophyllum spicatum L. and Najas marina L. BMT2 had a constant presence of Nuphar lutea (L.) Smith and filamentous algae. BMT3 consisted of sites without macrophytes. 4. The BMTs provided a useful regional classification for aquatic vegetation in shallow, calcareous, and slightly brackish lakes with relatively organic sediments. The BMTs were compared with national and international classifications. The value of BMTs as conservation targets was assessed. 5. Analysis of changes of macrophyte assemblages with time, using ordination (CANOCO) and time-series plots, revealed lakes with stable, drifting, or erratic and unstable macrophyte assemblages. 6. The method of presentation used facilitates the interpretation of year-to-year macrophyte changes. The implication is that management effort can be more effectively directed towards conservation targets. The effects of management on the aquatic flora, such as dredging and biomanipulation, were shown to be easily evaluated using Cockshoot Broad as an example. © 1998 John Wiley & Sons, Ltd.