A. C. Beynen

Preferences of mice and rats for types of bedding material

The type of bedding material has been reported to affect the environment in both the animal cage and animal room. It has an impact on the health and well-being of the animals and may cause biased experimental results. Requirements for bedding materials, particularly those regarding animal comfort are poorly supported by experimental data. In this study, various types of bedding material were evaluated using preference tests with mice and rats. It was found that beddings consisting of relatively small particles (-1.2 × 1.6 mm2) were generally avoided, whereas beddings consisting of large fibrous particles were preferred. The characteristics of the bedding materials were further investigated by scanning the size and shape of the particles, and by the assessment of ultrasound produced by the moving of the beddings. The results seem to indicate that size and manipulability are among the main determinants of the appreciation of bedding particles by laboratory mice and rats, and larger particles are preferred.

Atherosclerosis in parrots. A review

Summary Atherosclerosis is a common disease in parrots. The disease is found in all common parrot species, but especially in African Grey parrots and Amazons. It is a disease of older birds that is seen in both males and females. The most common sign is sudden death, but clinical symptoms that can be found include dyspnea, lethargy and nervous signs, such as paresis and collapses. Because the clinical signs are seldomly seen, it is difficult to diagnose atherosclerosis and therefore it is mostly an unexpected finding at necropsy. Age and species are determinants of atherosclerosis in parrots. Suggested risk factors include an elevated plasma cholesterol level, diet composition, social stress and inactivity, but research is needed to confirm this.

The effect of dietary spray-dried porcine plasma on clinical response in weaned piglets challenged with a pathogenic Escherichia coli

Weaned piglets were used to determine the effect of dietary spray-dried porcine plasma (SDPP) on the clinical response to an infection with a pathogenic Escherichia coli (E. coli) O139:K82 LT(-). The piglets were divided into two groups of 10 animals each. One group was fed the control diet containing soybean(meal) plus whey powder. The test piglets were fed a diet with 8% SDPP. Piglets were orally infected with the challenge strain on days 6 and 7 after weaning. The experimental period lasted 14 days after which the piglets were euthanised and necropsied. Faecal samples were collected daily for bacteriological analysis. Segments of jejunum, caecum and rectum were removed for bacteriological analysis post mortem. Feed intake and weight gain, faecal and condition scores and body temperature were measured daily. In the control and SDPP groups, 6 and 7 piglets died from diarrhoea. The average daily feed intake (ADFI) and average daily gain (ADG) were substantially higher in the SDPP group than in the control group. SDPP-fed piglets generally had a more favourable faecal score and a healthier appearance than did the control piglets. The faecal excretion of E. coli O139:K82 was similar for control and test piglets. There were no diet effects on the E. coli O139:K82 counts at different sites of the intestine. In this experiment, the inclusion of SDPP at an economically acceptable percentage in the diet could not prevent piglet losses due to challenge with a pathogenic E. coli, but improvements of ADG, ADFI and faecal and condition scores were achieved.

Blood sampling from the retro-orbital plexus, the saphenous vein and the tail vein in rats: comparative effects on selected behavioural and blood variables:

We compared the behaviours of rats, and measured various blood parameters, after three blood sampling techniques: orbital puncture while they were under diethyl-ether anaesthesia, blood collection by tail vein puncture under O2-N 2O-halothane anaesthesia and puncture of the saphenous vein without anaesthesia. Twelve rats were subjected to the three treatments according to a Latin square design. After each treatment, the behaviour of the rats was automatically monitored using the so-called LABORASTM method, which discriminates between grooming, locomotion and inactivity in rats. Based on excitation scores and urine production, it was found that induction of diethyl-ether anaesthesia combined with orbital puncture caused more distress than did the other two blood sampling techniques. The three techniques had no differential effects on the behaviours of grooming, locomotion and inactivity. Collecting 0.5 ml of blood by orbital puncture was ± 7 times faster than doing so by saphenous vein puncture and ± 15 times faster than collecting blood by tail vein puncture while the rats were under O2-N 2O-halothane anaesthesia. The levels of some haematological and plasma variables differed significantly between the three blood collection techniques. These observations may help to select the most appropriate technique of blood sampling with respect to anticipated discomfort in the animals.

Supplemental vitamin A enhances the recovery from iron deficiency in rats with chronic vitamin A deficiency

Studies with anaemic children and pregnant women from areas where vitamin A deficiency is endemic have shown a beneficial effect on Fe status of supplemental vitamin A in addition to Fe supplementation. This suggests a relationship between vitamin A and Fe status, which we attempted to mimic in rats with anaemia and chronic vitamin A deficiency. Male rats were fed on Fe-adequate diets (35 mg Fe/kg) containing different levels of vitamin A (1200, 450, 150, 75 and 0 retinol equivalent (RE)/kg feed) until they were 5 weeks old. These diets were identical to the diets fed to their mothers. Then the young male rats were transferred to diets containing the same levels of vitamin A but no added Fe. After another 2 weeks the rats were repleted with Fe (35 mg/kg feed) without or with vitamin A to a level of 1200 RE/kg feed. Increased vitamin A intake by the groups previously fed on diets with either 0 or 75 RE/kg produced a reduction in blood haemoglobin concentration, packed cell volume and erythrocyte count. In the group which had been fed on the diet without vitamin A, supplemental vitamin A raised mean cell volume, plasma Fe concentration and total Fe-binding capacity. Vitamin A supplementation during the period of Fe repletion produced a decrease in splenic and tibia Fe concentration, the effect being greater with increasing severity of previous vitamin A deficiency. The paradoxical effect of supplemental vitamin A on haemoglobin, packed cell volume and erythrocyte count can be explained by a decrease in the degree of haemoconcentration. Thus, the positive effect of supplemental vitamin A seen in humans is also observed with rats under controlled experimental conditions. We speculate that supplemental vitamin A during Fe repletion contributes to optimum erythropoiesis and Fe mobilization when baseline vitamin A status is impaired.

The effect of replacing nonstructural carbohydrates with soybean oil on the digestibility of fibre in trotting horses

The hypothesis tested was that the intake of extra fat at the expense of an isoenergetic amount of nonstructural carbohydrates reduces fibre utilisation in horses. In a crossover trial with feeding periods of 42 days each, 6 mature trotting horses (age 4-12 years, bodyweight 340-476 kg) were given either a control or test diet. The test concentrate was formulated to contain 37% of net energy in the form of soybean oil. The control concentrate contained an isoenergetic amount of corn starch plus glucose. The concentrates were fed in combination with the same amount of hay so that the control and test diet contained 25.13 and 86.66 g crude fat/kg dry matter, respectively. Apart from the amounts of fat and nonstructural carbohydrates, the 2 diets were identical. The test diet reduced the apparent total tract digestibilities of crude fibre, neutral and acid detergent fibre by 8.0 (P = 0.007), 6.2 (P = 0.022) and 8.3 (P = 0.0005) percentage units, respectively. It is suggested that a high fat intake by horses may increase the amount of fat entering the large intestine to levels that depress fermentation by cellulolytic bacteria. The observed interaction between fat content of the diet and fibre utilisation may have consequences for practical horse feeding in that calculating the energy content of test diets on the basis of feedstuff tables leads to overestimating the amount of energy provided by the high-fibre ingredients of the diets.

Stimulatory effect of an anion(chloride)-rich ration on apparent calcium absorption in dairy cows

Abstract The question addressed was whether an anion(chloride)-rich ration raises apparent calcium absorption in dairy cows. In a 24 × 24-day cross-over study with six non-pregnant, non-lactating, multiparous cows, the dietary cation-anion balance [mEq (Na + + K + ) − (Cl − + S 2− )] of the anion-rich and control ration were −170 and +276 mEq/kg dry matter. The two rations essentially differed with regard to their chloride contents. The anion-rich ration significantly reduced the blood base excess, caused a drop in urinary pH from 8.68 to 7.97, and significantly raised the urinary excretion of calcium from 0.8 to 11.6% of intake and the percentage apparent absorption of calcium from 3.4 to 9.5%. The raised absorption of calcium after feeding the anion-rich ration accounted for approximately 60% of the elevated urinary excretions of this mineral. The urinary output of hydroxyproline and the activity in plasma of alkaline phosphatase were unchanged by the anion-rich ration, suggesting that the extra urinary calcium did not originate from an increased bone resorption.

Effect of dietary protein source on feed intake and small intestinal morphology in newly weaned piglets

An experiment was designed to study the effect of dietary protein source on feed intake and on small intestinal morphology in newly weaned piglets. In total, 108 piglets were used, without access to creep feed during the suckling period. Piglets were weaned at 27 days of age. They were fed ad libitum one of two iso-nitrogenous experimental diets, which differed in their protein composition and contained either skim milk powder (SMP) or hydrolysed feather meal (FM), the latter component having low ileal protein digestibility. Diets contained equal amounts of indispensable amino acids. On day 4 postweaning, 18 piglets with a similar high feed intake were selected within each dietary treatment and sampled for small intestinal morphology on days 4, 7, or 14 postweaning. The dietary protein source did not affect feed intake during the first three days after weaning. From days 0 (day of weaning) to 2, the mean feed intake increased from 28.9 (S.D. 45.2) to 202.1 (S.D. 129.9) g day−1 piglet−1. In the second week, the feed intake of the selected piglets receiving the SMP diet was higher (P<0.05) than that of the piglets receiving the FM diet. Villus height and crypt depth were significantly higher for the piglets fed the SMP diet when compared to those fed the FM diet. It is concluded that SMP had a positive effect on villus height, this effect being mediated through its high degree of ileal protein digestibility rather than through its stimulatory effect on feed intake.

Iron status in rats fed on diets containing marginal amounts of vitamin A

Severe vitamin A deficiency in rats is known to cause anaemia associated with growth retardation and impaired water retention. However, study of the effect of marginal vitamin A intake is of more interest because such intake may mirror the situation in humans in many developing countries. Therefore, in two experiments, the effect of marginal vitamin A deficiency on Fe status was investigated in male rats. After 28 d of feeding either low- or high-vitamin A diets (0 or 120 v. 1200 retinol equivalents/kg feed), body weight and feed intake were not influenced by the level of vitamin A in the diet. Liver weight was lowered by vitamin A deficiency. Water intake was not influenced in rats fed on a low-vitamin A diet. Plasma retinol concentrations were decreased in rats fed on diets low in vitamin A. Marginal vitamin A deficiency produced slightly lower blood haemoglobin concentrations; it did not systematically affect packed cell volume. The concentration of Fe in liver was significantly higher when diets low in vitamin A were fed, but hepatic Fe mass was not affected. Significantly lower Fe levels were observed in femurs of rats with vitamin A deficiency. The effects on liver and femur Fe concentrations were seen with diets adequate in Fe but not with diets deficient in Fe. The efficiency of apparent Fe absorption was significantly increased by low intakes of vitamin A, provided that the dietary Fe concentration was adequate. It is speculated that depressed uptake of Fe by bone marrow is the primary feature of altered Fe status in rats with marginal vitamin A deficiency.

Sterol balance and cholesterol absorption in inbred strains of rabbits hypo- or hyperresponsive to dietary cholesterol

In 2 inbred strains of rabbits with high or low response of plasma cholesterol to dietary cholesterol, excretion of steroids in the feces and efficiency of cholesterol absorption were determined. Rates of whole-body cholesterol synthesis, measured as fecal excretion of bile acids and neutral steroids minus cholesterol intake, were similar in hypo- and hyperresponders fed a low-cholesterol (8 mumol/100 g) diet. Transfer of the rabbits to a high-cholesterol (182 mumol/100 g) diet caused an increase in fecal bile acid excretion in hypo- but not in hyperresponders. Dietary cholesterol did not affect neutral steroid excretion in either rabbit strain. Hyperresponders tended to accumulate more cholesterol in their body than did hyporesponders. After the rabbits were switched back from the high- to the low-cholesterol diet, rates of whole-body cholesterol synthesis were significantly higher in the hypo- than in the hyperresponders. With the use of the simultaneous oral administration of [3H]cholesterol and beta-[14C]sitosterol, hyperresponders were found to absorb significantly higher percentages of cholesterol than hyporesponders. It is concluded that the differences in stimulation of bile acid excretion after cholesterol feeding and the efficiency of cholesterol absorption are important determinants of the phenomenon of hypo- and hyperresponsiveness in the 2 inbred rabbit strains.