Immunolocalization of the Cholesterol Transporters ABCA1 and ABCG1 in Canine Reproductive Tract Tissues and Spermatozoa

The mammalian sperm membrane undergoes cholesterol efflux during maturation and fertilization. Although ATP‐binding cassette (ABC) transporters are known to transport cholesterol through cell membranes in other organs, their presence in canine testis, epididymis and sperm has not been proven to date. Hence, the aim of the present study was to localize the ABC transporters ABCA1 and ABCG1 in canine testicular and epididymidal tissue as well as in spermatozoa membranes. To this end, semen samples from 12 dogs as well as testicles and epididymides of four young and healthy dogs were prepared for immunohistochemistry, respectively. Capacitation and acrosome reaction (AR) were induced in aliquots of the semen samples before immunostaining to assess changes in the expression of ABCA1 and ABCG1. Evaluation by confocal microscopy revealed the presence of both ABCA1 and ABCG1 in canine testicles and of ABCA1 in the epididymides. In spermatozoa, only ABCA1 immunoreactivity was detected, mainly in the region of the acrosome and midpiece. After induction of capacitation, ABCA1 signal persisted in the acrosome but disappeared after AR, indicating a loss of ABCA1 with the loss of the acrosome. We conclude that ABCA1 and ABCG1 are expressed in canine testis, whereas only ABCA1 is expressed in epididymis and spermatozoa membrane, both transporters probably contributing to the regulation of membrane cholesterol content.     

Inter‐related effects of dietary fat and protein level on growth performance in rabbits

Isoenergetic substitution of dietary corn oil for dietary carbohydrates enhances growth in rabbits. It was hypothesized that identical amounts of metabolizable energy in the form of corn oil are more effective than those of carbohydrates in reducing protein catabolism and thus sparing it for growth, which would imply that the fat effect is greater on a marginal than normal protein diet. Young growing rabbits were fed semi‐purified diets either relatively high (21.6 energy % protein) or low in casein (13.0 energy % protein) to which extra corn oil (21.1 instead of 5.3 energy %) was added at the expense of an isoenergetic amount of corn starch and dextrose. The addition of corn oil to the diet with 21.6 energy % protein indeed increased weight gain, but the addition to the diet with 13.0 energy % protein left weight gain unchanged. These results refute our hypothesis, because the low‐protein intake was not limiting growth. The enrichment of the high‐protein diet with extra corn oil did not affect nitrogen retention, whereas urinary nitrogen excretion was increased. These observations also are at variance with the idea that additional fat would spare nitrogen for growth.     

Dietary lactulose decreases apparent nitrogen absorption and increases apparent calcium and magnesium absorption in healthy dogs

To study the effect of lactulose on the route of nitrogen excretion, we fed six healthy, adult dogs on diets containing either 0, 1 or 3 g lactulose/MJ metabolizable energy according to a 3 × 3 Latin square design. The results were analysed to identify statistically significant linear trend effects of lactulose. Faecal pH was significantly lowered by lactulose. Faecal ammonium and nitrogen excretion tended to be raised by lactulose feeding whereas urinary urea excretion was significantly reduced. Lactulose feeding significantly lowered apparent nitrogen digestibility. It is concluded that lactulose feeding shifts nitrogen excretion from urine to faeces in dogs which may be beneficial for liver patients. The data are in line with the concept that lactulose stimulates bacterial growth in the colon which in turn enhances faecal nitrogen excretion and lowers the entry of colonic ammonia into the bloodstream, leading to a lesser workload for the liver and less urinary nitrogen excretion. Lactulose consumption was also found to produce a dose-dependent increase in the apparent absorption of calcium and magnesium, but not phosphorus.     

Body composition and selected blood parameters in mice fed a combination of fibre and conjugated linoleic acid

Feeding mice conjugated linoleic acid (CLA) reduces body fat. Soluble fibre decreases apparent lipid digestibility. The objective of the present study was to examine whether a combination of dietary CLA and soluble fibre would further decrease the proportion of body fat than a diet with CLA alone. Therefore, we fed mice diets with CLA and different amounts of Nutrim, containing 10% soluble fibre. CLA was added to the control diet at the expense of high oleic acid sunflower oil (HOSF) component and Nutrim was added at the expense of an isoenergetic combination of starch, dextrose and cellulose. The diets were fed for 28 days. Weight gain after 28 days was less in CLA-fed animals than in HOSF-fed animals. Both CLA and Nutrim increased the body water content. CLA reduced total body fat and epidydymal fat but Nutrim did not. No interaction of CLA and fibre was detected. We, therefore, must conclude that under the present experimental conditions dietary CLA and fibre do not interact to reduce body fat deposition.     

The influence of dietary linoleic and alpha-linolenic acid on body composition and the activities of key enzymes of hepatic lipogenesis and fatty acid oxidation in mice

We have recently suggested that feeding the C18 polyunsaturated fatty acid, alpha-linolenic acid (ALA), instead of linoleic acid (LA) reduced body fat in mice. However, the difference in body fat did not reach statistical significance, which prompted us to carry out this study using more animals and diets with higher contents of ALA and LA so that the contrast would be greater. The diets contained either 12% (w/w) LA and 3% ALA or 12% ALA and 4% LA. A low-fat diet was used as control. The diets were fed for 35 days. The proportion of body fat was not influenced by the type of dietary fatty acid. Plasma total cholesterol and phospholipids were significantly lower in ALA-fed mice than in mice fed LA. Activities of enzymes in the fatty acid oxidation pathway were significantly raised by these two diets when compared with the control diet. alpha-Linolenic acid vs. LA did not affect fatty acid oxidation enzymes. In mice fed the diet with LA activities of enzymes of de novo fatty acid synthesis were significantly decreased when compared with mice fed the control diet. alpha-Linolenic acid vs. LA feeding did not influence lipogenic enzymes. It is concluded that feeding mice for 35 days with diets either rich in LA or ALA did not significantly influence body composition.     

The current status and outlook for insecticide,acaricide and anthelmintic resistances across the Australian ruminant livestock industries: assessing the threat these resistances pose to the livestock sector

The Australian ruminant livestock industries are faced with the need to control parasitic infectious diseases that can seriously impact the health of animals. However, increasing levels of resistance to insecticides, anthelmintics and acaricides are substantially reducing the ability to control some of these parasites. Here we review the current situation with regard to chemical resistances in parasites across the various sectors of the Australian ruminant livestock industries and assess the level of threat that these resistances pose to the sustainability of these sectors in the short to long terms. We also look at the extent to which testing for resistance occurs across the various industry sectors, and hence how well-informed these sectors are of the extent of chemical resistance. We examine on-farm management practices, breeding of parasite-resistant animals, and non-chemical therapeutics that may act as short to long term means to reduce the current reliance on chemicals for parasite control. Finally, we look at the balance between the prevalence and magnitude of current resistances and the availability and adoption rates of management, breeding and therapeutic alternatives in order to assess the parasite control outlook for the various industry sectors.     

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.     

Habitual diet and ascorbic acid status in Sudanese camels

There is suggestive evidence that a low status of ascorbic acid in camels enhances their risk for infectious diseases. This study was carried out to find clues as to the role of diet in affecting ascorbic acid status. In a crossover trial with feeding periods of 3 weeks each, six camels (Camelus dromedarius) were fed either a composite of their habitual diet or alfalfa. The simulated habitual diet contained grass (hummra), Acacia mellifera and Blepharis persica. The habitual diet significantly lowered ascorbic acid concentrations in plasma and leukocytes. It is concluded that camels kept on natural desert vegetation may not have optimal disease resistance due to a diet-induced low ascorbic acid status.     

Cerebellar cortical abiotrophy in Wiltshire sheep

AIM: To investigate the nature of a neurological disease in Wiltshire sheep.

METHODS: Three affected lambs were examined, humanely killed and necropsied. Selected neurological tissues were examined by light and electron microscopy.

RESULTS: Primary neurological lesions were confined to the cerebellum and were characterised by loss of Purkinje cells and the presence of large hypertrophied dendrites of surviving Purkinje cells. These contained stacks of smooth endoplasmic reticulum. There was hyperplasia and cell swelling of Bergmann glia. Mild Wallerian-type degeneration affected white matter in the cerebellum and spinal cord.

CONCLUSION: The cerebellar lesions were of a degenerative and reactive rather than hypoplastic nature. These, and the history, suggest a genetic cause with putative inheritance as an autosomal recessive trait. Accordingly, the disorder is described as a cerebellar abiotrophy.