Geert Janssens

Food Allergy in Dogs and Cats: A Review

Food allergy (FA) is defined as “all immune-mediated reactions following food intake,” in contrast with food intolerance (FI), which is non-immune-mediated. Impairment of the mucosal barrier and loss of oral tolerance are risk factors for the development of FA. Type I, III, and IV hypersensitivity reactions are the most likely immunologic mechanisms. Food allergens are (glyco-)proteins with a molecular weight from 10–70 kDa and are resistant to treatment with heat, acid, and proteases. The exact prevalence of FA in dogs and cats remains unknown. There is no breed, sex or age predilection, although some breeds are commonly affected. Before the onset of clinical signs, the animals have been fed the offending food components for at least two years, although some animals are less than a year old. FA is a non-seasonal disease with skin and/or gastrointestinal disorders. Pruritus is the main complaint and is mostly corticoid-resistant. In 20–30% of the cases, dogs and cats have concurrent allergic diseases (atopy/flea-allergic dermatitis). A reliable diagnosis can only be made with dietary elimination-challenge trials. Provocation testing is necessary for the identification of the causative food component(s). Therapy of FA consists of avoiding the offending food component(s).

The effects of dietary fibre type on satiety-related hormones and voluntary food intake in dogs.

Depending on type and inclusion level, dietary fibre may increase and maintain satiety and postpone the onset of hunger. This 7-week study evaluated the effect of fibre fermentability on physiological satiety-related metabolites and voluntary food intake (VFI) in dogs. Sixteen healthy adult dogs were fed a low-fermentable fibre (LFF) diet containing 8.5 % cellulose or a high-fermentable fibre (HFF) diet containing 8.5 % sugarbeet pulp and 2 % inulin. Large intestinal fibre degradation was evaluated by apparent faecal digestibility of nutrients and faecal SCFA and NH3 concentrations. Postprandial blood samples were obtained to determine postprandial plasma glucose, insulin, total peptide tyrosine-tyrosine (PYY), total glucagon-like peptide-1 (GLP-1) and total ghrelin concentrations. At the end of the study, the dogs were given a single meal of a dry dog food to determine VFI. Dogs fed the HFF diet had a significantly higher large intestinal fibre degradation and production of SCFA compared with the dogs fed the LFF diet. The HFF-fed dogs tended (P = 0.058) to show a lower VFI at the end of the study. No treatment effects were found for postprandial plasma glucose, PYY, GLP-1 and ghrelin responses. The concentrations of these metabolites could not be related to the observed difference in VFI. The inclusion of fermentable fibre in canine diets may contribute to the prevention or mitigation of obesity through its effects on satiety. The underlying mechanisms require further investigation.

The use of markers to determine energy metabolizability and nutrient digestibility in avian species

Apart from elimination of errors in obtaining exact measurements of feed intake and total faeces output in the traditional total collection method, the use of markers to determine nutrient digestibility of feeds in animal species would fit into animal welfare considerations. The external marker chromic oxide has been the prominent marker in the 1960s to evaluate metabolizable energy content of feeds for poultry. A preliminary feeding period of 5 days and collection of a sample representing day and night excreta over a 24 hour period have been suggested as protocol to get reliable results with the use of chromic oxide as marker. However, difficulty in obtaining repeatability between laboratories because of the analytical assay for chromic oxide, variability in results, incomplete and inconsistent recovery in excreta, and hazardous possibilities, resulted in replacement of the chromic oxide marker technique with the method of total excreta collection. Although titanium dioxide, which can be analysed by an accurate and simple colourimetrical assay, has been used in several studies in poultry, only one study has evaluated this marker for recovery (98%) in excreta. The internal marker, acid-insoluble ash, which also could present an external marker when the internal content is aided with the use of siliceous substances, is gaining popularity in recent times, although most studies presented higher digestibility values with this marker in avian species than those derived through the total excreta collection method. Lack of standardisation of analytical assays could partly explain the latter phenomenon. Although crude fibre has presented recovery rates of near 100% in excreta of laying hens and turkeys, fear of possible digestion of this substance by cecal microflora has prevented the further utilisation of this substance as marker. Lignin, determined by digestion in 72% sulphuric acid, presented recovery rates of 99 and 98% in chickens and ostriches, respectively, and similar (P>0.05) results than the total collection method in partridges. The elimination of the use of markers to determine energy metabolizability and nutrient digestibility with avian species have been based on a small number of studies conducted mainly before 1965, and extrapolation of results obtained with other animal species.

The effect of weight loss by energy restriction on metabolic profile and glucose tolerance in ponies

UNLABELLED In nine initially obese ponies, a weekly weight loss according to 1% of their ideal body weight was evaluated for its impact on insulin sensitivity and metabolic profile. Weight loss was obtained solely through energy restriction, initially at 70% of maintenance energy requirements, but to maintain constant weight loss, feed amount had to be decreased to 50% and 35% of maintenance energy requirement during the course of the trial. An oral glucose tolerance test (OGTT) was performed at weeks 0, 10 and 17. Fasted blood samples were taken on weeks 0, 3, 10, 17 for analysis of triglycerides (TG), non-esterified fatty acids (NEFA), creatine phosphokinase (CPK), lactate dehydrogenase (LDH), T(3), T(4) and leptin. Total average weight loss was 18.2%. When the OGTT was performed at weeks 0, 10 and 17, ponies had lost 0.22%, 9.9% and 16.3% of their initial weight respectively. Weight loss was associated with a decreased AUC for glucose and insulin. Moreover, greater % weight loss was associated with a significantly lower glucose peak and a lower area under the curve (AUC glucose). The lower glucose response after an OGTT in lean ponies was not the result of an increased insulin secretion, but an improved insulin sensitivity. Restricted feeding led to mobilization of TG and NEFA and to a reduced basal metabolism, with lower LDH, CPK, T(3) and leptin. IN CONCLUSION in obese Shetland ponies, weight loss at a rate of 1% of ideal body weight per week through restricted energy intake, ameliorated insulin sensitivity.

Dietary macronutrients, endocrine functioning and intermediary metabolism in broiler chickens pair wise substitutions between protein, fat and carbohydrate

Abstract Three pens of male broiler chicks were raised under standard conditions and fed from 7 to 42 days of age three isocaloric diets each with 15.8; 19.6 and 19.5% of CP; and 51, 51, and 44% of CHO; and 6.5; 3.0 and 7.7% of fat, and designated as the low protein (LowCP), low lipid (LowL) and low carbohydrate (LowCHO) diets, respectively. Body weights and feed intake were monitored weekly and blood samples were collected at the same time for posterior analysis of hormone and metabolite content. Chickens fed the LowCP diet were characterized by a reduced body weight gain and feed intake and poorer feed conversion efficiency compared to those fed the LowL and LowCHO diets, which were very similar in this respect. Plasma corticosterone and glucose levels and creatine kinase activity were not significantly changed by diet composition. LowCP chickens were characterised by the lowest plasma T 4 and uric acid levels (indicative for reduced protein breakdown and lower protein ingestion) but highest plasma triglyceride levels (congruent with their higher fat deposition) compared to the LowL and LowCHO chickens. LowL chickens had on average higher plasma T 3 and free fatty acid levels compared to the LowCP and LowCHO chickens. In conclusion, a limited substitution of carbohydrate for fat in iso-nitrogenous, iso-energetic diets has no pronounced effects on plasma hormone and metabolite levels, except for the elevation in T 3 (may enhance glucose uptake) and free fatty acid levels in the plasma of the chickens fed the LowL diet. The protein content of the diet has a greater impact on zootechnical performance, and underlying endocrine regulation of the intermediary metabolism compared to the dietary lipid and CHO fraction.

The effects of inulin supplementation of diets with or without hydrolysed protein sources on digestibility, faecal characteristics, haematology and immunoglobulins in dogs

Dogs with food allergy are often treated by giving a diet with hydrolysed protein sources. Prebiotics might also be successful in prevention and treatment of allergic disease through their effect on the colonic microflora, analogous to studies on probiotics in allergic children. The present study was set up to investigate the effect of supplementing inulin (IN) to commercial hypoallergenic dog diets on apparent nutrient digestibility, faecal characteristics, haematology and Ig in dogs. Supplementation of 3 % IN did not affect faecal pH, food and water intake and urine production. Compared with the intact protein diet with a limited number of ingredients (L), the diet with a hydrolysed protein source (H) resulted in an increased water intake (P<0.001), which could be due to the osmotic effect of free amino acids. Faeces production was increased by IN due to increased faecal moisture content. Increased faeces production on the H diet was mainly due to a higher DM excretion. Subsequently, the apparent digestibility coefficient (ADC) of DM was lower in the H diet group. A similar result was noted for ADC of diethyl ether extract and crude ash. The ADC of crude protein was higher in the H diet group, whereas IN decreased the ADC of crude protein. Differences in the ADC of crude protein among the different diets disappeared after correction for a higher faecal biomass, except for the dogs fed the L+IN diet. Total faecal IgA concentrations were lower in the H group (P<0.05) because of lower antigenic stimulation of hydrolysed protein, which implies that hydrolysed protein is really hypoallergenic. The present study indicates that the use of hydrolysed protein diets for canine food allergy treatment can affect digestibility and that combination with IN affected apparent protein digestibility but not IgA response.

A methodology for the calculation of farm level nitrogen and phosphorus balances in Flemish agriculture

Abstract Since the early 1990s, Flemish agriculture has been confronted with serious nutrient problems. Recently, the Flemish Government started encouraging farmers to take responsibility for the manure problem. This was done by giving them the choice between a manure administration system, based on fixed standards, or a nutrient balance system. In this project a methodology for the composition of nutrient balances at farm level in Flanders was developed. This methodology defines input–output models for the different sectors (cattle, pigs and poultry) and fixes rules on how to determine quantities and nutrient contents for several products. In addition, nutrient flows were followed during 1 year on 40 Flemish farms in different sectors and a mineral balance was calculated for each of them. Four major restrictions to the accurate calculation of farm level nutrient balances were identified: (1) the wide variability that is allowed between actual and reported nutrient composition of concentrated feed; (2) the estimates of the amount and composition of manure; (3) the assessment of changes in standing stock on the farm between the beginning and end of the reporting period and (4) the accuracy of the data supplied by the farmers.

Performance and meat quality of organically versus conventionally fed and housed pigs from weaning till slaughtering

The effects of organic nutrition on growth performance, meat and carcass traits in either a conventional or an organic housing unit from weaning till slaughtering were evaluated in terminal crossbreeds of a paternal line and a maternal 3-way crossbreed of Seghers hybrid. All pigs were reared in a conventional way from birth till weaning (4 weeks). One week after weaning they were moved to either a conventional or an organic barn. Eight pens of 4 pigs (2 barrows and 2 gilts) were held in both housing types. The study started when the pigs reached the age of 10 weeks. Half of the groups in each barn received a conventional diet, and the other half received an organic diet. Both feeds were isocaloric, neither of them contained antibiotic growth promoters. Three-phase feeding was applied. The organic housing led to a higher feed intake throughout the experiment (P<0.001), which resulted in a faster growth (P<0.001) but a lower meat percentage (P<0.05). Organic nutrition did not affect growth performance and carcass quality. Neither organic nutrition nor housing led to relevant differences in meat quality traits.

Considerations on the performance of immunocastrated male pigs

With the ongoing social pressure on surgical castration of pigs, an increase in the population of pigs that are either not castrated or immunocastrated (IC) can be expected. In both cases, their nutrient requirements and performance will differ from surgically castrated pigs and will require changes in their management. Immunocastration is performed by giving two injections of a modified gonadotrophin-releasing hormone component along with an adjuvant, at least 4 weeks apart. This paper describes the reported differences in growth performance and carcass quality of IC male pigs in comparison with boars (BO) and barrows (BA). Theoretically, IC pigs remain physiologically boar until the second vaccination and therefore, growth may be comparable with BO until this second vaccination. From then on, IC male pigs consume more feed than BO and grow faster when fed ad libitum. IC showed a faster growth and better feed conversion ratio than BA. When fed restrictedly, BO grow faster and more efficiently than BA and IC. IC have a lower carcass yield than BA and BO, whereas meat percentage is intermediate.

Nutrition of the domestic pigeon ( Columba livia domestica )

Despite the use of pigeons (Columba livia domestica) since 2500 BC by man for meat production, ornamentals, sports and experimental animals, limited information is available on their nutrient requirements and feeding. This could partly be attributed to the rearing of growing chicks (squabs) to mature body weight at 28 days by the parents. Squabs have an extraordinary high rate of maturing (0.1466 to 0.1945 g/d) in comparison to other domesticated avian species such as poultry (0.0450 g/d) and quail (0.077 to 0.097 g/d). This growth rate is achieved by regurgitation of a holocrine substance (crop milk) by both parents, formed in response to prolactin secretion and triggered by brooding. Crop milk consists primarily of protein (11.0 to 18.8% on as is basis) and fat (4.5 to 12.7% on as is basis), and lacks significant levels of carbohydrates. Furthermore, adult pigeons are mainly fed mixtures of whole grains. Special feeding characteristics inherent to the pigeon thus prevent extrapolation of nutrient requirements determined with other avian species. A dietary crude protein content of between 12 and 18%, and metabolizable energy (ME) content of around 12 MJ/kg, based on production of offspring, is recommended for feeding of adult pigeons. Apparent metabolizable energy, corrected for nitrogen retention (AMEn) for maize (14.76 MJ/kg), barley (12.36 MJ/kg), sorghum (13.87 MJ/kg) and peas (14.01 MJ/kg) did not differ substantially from values derived for poultry. Pigeons could utilize lipids better than carbohydrates as energy sources. Feed additives and suggestions for future research are discussed.