Articles 41-50

Long-term consumption of an acidifying diet affects acid-base status and bone density in cats

G.L. Czarnecki-Maulden, D.G. Chausow, C.J. Cupp

Nestle Purina Product Technology Center, St Joseph, Missouri, USA

The use of dietary modifications to control the formation of struvite uroliths is common. While acidic urine pH can prevent struvite stone formation and is an integral component in management of diet-associated feline lower urinary tract disease, there are problems associated with overuse of acidifiers. Over acidification can result in chronic metabolic acidosis and lower calcium and potassium balance (Ching et al, 1989). Although moderate urinary acidification resulted in decreased calcium and phosphorus balance, there was no effect on indices of bone formation (Fettman et al, 1992). The effect of longer-term, sustained acidification on bone density or bone content has never been reported. The purpose of this trial was to determine whether cats can adapt to chronic consumption of an acidifying diet and whether such diets cause changes in acid-base status and bone density. Two groups of five adult cats each were fed an extruded dry diet which was designed to produce either a moderately acidic urine pH (control diet; pH approximately 6.2-6.4) or a more acidic urine pH (test diet; pH <5.9) for two years. The urine pH produced by the test diet was below typical recommendations for control of struvite production. Body composition and bone density were non-invasively determined by DEXA. Blood pH, ionized calcium, and bicarbonate were measured as indicators of metabolic acidosis. A total daily urine collection was done to determine urinary calcium excretion. Urine pH was lower in cats fed the test diet (5.7) than in cats fed the control diet (6.3). Cats fed the test diet showed no clinical signs of metabolic acidosis; however, blood bicarbonate and pH were significantly lower and blood ionized calcium was significantly higher in cats fed the more acidifying diet. Urinary calcium excretion was significantly greater in cats fed the test diet. Body fat and lean muscle mass were unaffected by acidification. However, bone mineral density, bone mineral content, and total bone calcium were significantly lower in cats fed the more acidifying diet. In
conclusion, long-term consumption of an acidifying diet resulted in sub-clinical metabolic acidosis and adversely affected bone mineralization. Diets designed for urinary pH modification should be thoroughly evaluated for effects on metabolic acidosis. Long-term use of supplemental urinary acidifiers should be discouraged in cats consuming diets designed for control of struvite urolith formation.

Ching S.V. et al., 1989. J Nutr 119:902-915.
Fettman M.J. et al., 1992. Am J Vet Res 53:2125-2135.

Nutritional disorders of skeleton in emus and rheas

Petra Wolf 1 , Norbert Kummerfeld 2 and Josef Kamphues 1

1 Institute of Animal Nutrition,
2 Clinic of Companion Birds, School of Veterinary Medicine Hannover, Bischofsholer Damm 15, D-30173 Hannover

Keeping of emus (Dromaius novaehollandiae) and rheas (Rhea americana) in European environmental conditions has often been discussed. The local climate and areas available for grazing and activity do not favour birds which originated from South America (rhea) or Australia (emu). Furthermore there are risks for animals’ well-being, due to a lack of suitable experience and species-specific complete diets not being continuously available. Home-mixed diets are fed, which are often unbalanced, occasionally resulting in nutritional disorders of the skeleton. The following case reports describe problems caused by faults in feeding, particularly relating to mineral supply.

Case 1:
Due to a supply shortage, an owner of a small zoo fed emus a home-mixed diet (ingredients: piglet pellet, rabbit pellet and a mineral product rich in protein, CaCO3). The hatched emu chickens adapted very quickly to this diet and showed high growth rates in the first weeks of life. At the age of 3-4 weeks, 13 of 37 chicks showed a reluctance to rise or move. One week later these chicks showed ataxic moving activities, and slight thickening of the distal tibiotarsus and proximal tarsometatarsus which increased in the following 14 days. At the same time, the long bones developed rotational deformities (bones turned outwards and caused a ‘paddling’ movement).

Nutritional history:
In a critical examination of mangers, a macroscopic difference between the offered feed (pelleted) and the refusals (white-grey, fines) could be observed. Crude fiber and starch of the refusals were lower, but crude ash and calcium contents were higher compared to offered ration. Blood chemistry data showed slightly lower mineral contents and X-rays confirmed the bad posture of the legs.

Due to the different types of prepared feedstuffs in the home-mixed ration (pellets plus meal), the ingredients were not mixed well and the emus could selected the preferred pelleted components and refused the mineral supplement. This selective ingesting behaviour, the high growth rate of emu chicks and the insufficient mineralization of skeleton encourages the occurence of the observed clinical signs (perosis).

Case 2:
3 of 15 young rheas (3 months) showed unhealthy postures of the neck vertebral column. The ‘diet’ was based on corn, pelleted alfalfa, apples, lettuce and white bread in the first 8 weeks of life; afterwards a complete pelleted diet was fed.

Clinical history:
The X-ray of vertebral column showed complete healed up fractures of individual vertebrae.

Nutritional history:
Before feeding the complete diet the owner observed selective ingestion of corn and white bread, while the other components were refused. The preferred components are characterized by low mineral contents (especially calcium, copper).

Due to insufficient mineralization of the skeleton and a high mechanical stress (rough handling to applicate a deworming) fractures of the vertebral column occurred. Once fed the complete diet, these fractures healed due to the pelleted diet’s improved mineral balance.

Diurnal variation in concentrations of various markers of bone metabolism in goat and sheep

A. Liesegang 1 , M-L. Sassi 2 , J. Risteli 2 , M. Wanner 1

1 Institute of Animal Nutrition, University of Zurich, Switzerland
2 Department of Clinical Chemistry, University of Oulu, Finland

It is known that goat and sheep differ in their metabolism of calcium during gestation and lactation. This study was performed to evaluate if goat and sheep differ in circadian rhythm of selected markers of bone metabolism. Twelve 1-year-old female goats and sheep were used in this study. Blood and urine samples were obtained in the morning before goats and sheep were fed and then at 2-hour intervals for 24 hours. Concentrations of osteocalcin (OC) and carboxyterminal telopeptide of type-I collagen (ICTP) were measured in serum using radioimmunoassay. Concentrations of bone-specific alkaline phophatase (bAP) and degradation products of C-terminal telopeptid of type I collagen (CL) were analyzed with an enzymeimmunoassay in serum. All bone marker concentrations were significantly higher in goats than in sheep. OC concentrations in goat decreased during the day, increased thereafter and reached values similar to those obtained before feeding. The ICTP concentrations slowly decreased in goats until 4 pm, increased again, and returned to prefeeding values thereafter. The concentrations in sheep increased continously, but not significantly, towards the morning sampling. The CL concentrations increased in both species during the night, but started to decrease to levels as at the beginning of the testing at 6am. The bAP concentrations decreased from noon to 12pm in goat. Changes in the concentrations of bone markers were mainly observed in goats in this study, although all animals were fed with the same diet according to the requirements. As documented for bone resorption and formation in other species, circadian rhythms were evident for concentrations of ICTP, CL, bAP and OC. From this study, it can be concluded that goat have physiologically a higher bone turnover than sheep, because the bone marker concentrations were always higher.

Urinary acidifying effect of dietary calcium chloride in fattening pigs

G.P.J. Janssens, V. Debal, S. Millet, M. Hesta and R.O.M. De Wilde

Laboratory of Animal Nutrition, Ghent University, Belgium

Environmental pollution from pig husbandry is a major concern in most countries with intensive pig production. Especially ammonia emission from animal husbandry has been named as one of the main threats of ecosystems throughout Europe. Lowering the dietary electrolyte balance (dEB) can exert a faecal and urinary acidification. This should reduce the conversion of NH4+ into NH3 in manure. The present trial tried to demonstrate the action of dietary calcium chloride (CaCl2) supplementation on ammonia emission in fattening pigs. In the first period a low dietary protein and a moderate dietary protein level were offered to two pigs. Urine was collected in three ways; 1) directly (“uncontaminated”=UC); 2) after having passed the slatted floor (“slightly contaminated”=SC); 3) faeces where added to the urine (“highly contaminated”= HC). In the second and the third period, these collections were performed after dietary addition of 1% and 2% coated CaCl2, respectively. The dEB (Na + + K + - Cl - , in meq/kg) shifted in these three periods from +250 over +100 to –50 meq/kg. A pH drop was noted from 7.2 over 6.3 to 5.7. Slight faecal contamination of urine increased pH by 0.5. Further contamination with faeces had no supplementary effect on pH. Dietary protein level did not alter urinary pH. Based on these preliminary data, CaCl2 is a dietary additive that can likely to reduce ammonia emission from pig manure.
pH UC SC HC 0%
CaCl2 7.2 7.31 7.30 1%
CaCl2 6.3 7.15 7.05 2%
CaCl2 5.7 6.36 6.36

Effect of exercise on apparent digestibility in horses – a review

S. Van Weyenberg, M. Hesta, S. Millet, G.P.J. Janssens

Laboratory of Animal Nutrition, Ghent University, Belgium

Most digestibility studies in horses have been conducted with idle horses confined to metabolism stalls. The results of these studies are used for all horses, including the performance horse. Duren (1990) measured blood flow distribution during exercise in ponies. He proved that blood flow is shunted away from the gastrointestinal tract during exercise. Exercise also reduced mean retention time, so less opportunity for enzymatic digestion and microbial fermentation. (Orton et al., 1985)

The question left was:
what is the effect of exercise on nutrient digestibility? It was Olson (1955) who first looked at this. He suggested that light work may improve apparent digestibility of dry matter, energy and crude protein and heavy work would have the opposite effect. Orton et al (1985) concluded that exercise increased the apparent digestibility. Their horses were trotted each morning for 1 h at 12 km/h. The same results were found by Pearson (1991) for donkeys. The animals walked for 4 hours at 3.6 km/h and all the digestibility coefficients of the diet increased in exercised donkeys. Pagan et al (1998) reported that apparent digestibility decreased when horses worked for 4 weeks 40 min/day at an average speed of 20 km/h. He also looked at bioavailability of minerals. The potassium (K) uptake as well as calcium (Ca) and magnesium (Mg) uptake decreased. Only the availability of sodium (Na) increased with exercise. The same results for Ca and Mg were found by Meyer et al (1992). However, his horses did light work (100 min-12 km/h) compared with those of Pagan.

On the basis of this review it can be concluded that light work and heavy work have opposing effects on apparent digestibility of dry matter, energy and crude protein. It is not clear what the effect of exercise is on mineral availability and whether this effect is the same for all minerals. It may depend on the horse’s requirements; for example, horse sweat contains 3 times more Na than K (Snow et al.,1982). Logical questions which follow are: - at what level of exercise intensity and duration would one expect to negatively influence nutrient digestibility? - what would be the effect on mineral availability? - what is the cause of all this? Level of feed? intake, mean retention time, water intake, blood flow, changing metabolic requirements? Further research is necessary to answer these questions.

Duren S., 1990. Proceedings, Kentucky Equine Research 1997 Equine Nutrition Conference
Meyer H. et al., 1992. Journal of Equine Veterinary Science 12(4) : 233-239
Olsson N. et Ruudvere A., Nutrition Abstract Review 25 : 1-18
Orton R. et al., 1985. Equine Veterinary Journal 17(5): 386-390
Pagan J. et al., 1998. Journal of Nutrition 128 : 2704S-2707S
Pearson R. et al., 1991. Equine Veterinary Journal 23(5) : 339-343
Snow D. et al., 1982. The Veterinary Record 110: 377-384

The effect of beefhide strips on digestibility and dental calculus in dogs

C. J. Cupp, G.L. Czarnecki-Maulden

Nestle Purina Product Technology Center, St Joseph, Missouri, USA

Control of calculus deposits on the teeth of pets may play a significant role in the prevention of periodontal disease. Studies have shown that the administration of beefhide to dogs on a daily basis has a beneficial effect on both calculus removal and calculus buildup (Lage et al, 1990; Goldstein et al, 1993 and 1994). The amount of rawhide offered to the dog on a regular basis is critical to dental efficacy, but could have nutritional implications. Two dental efficacy studies were conducted to assess buildup of calculus over different time periods (1 month, 3 months) in dogs consuming beefhide strips according to package directions (2 strips per day) along with standard dry dog food. A clean tooth model was used in both trials, and different groups of dogs were evaluated for the two trials. Results showed a 27% reduction in calculus for the dogs fed beefhide strips for one month, and a 44% reduction in calculus for the dogs fed beefhide for three months. In both studies, dogs in the control groups consumed standard dry dog food alone. All dogs maintained body weight over the course of the studies. Digestibility of beefhide was determined in a separate study. Zero, 10 or 20% ground rawhide was added to a nutritionally complete wet dog food. The diets were fed to six dogs each for 10 days. Fecal collection for digestibility determination was conducted on days 5 to 10 of the trial. The digestibility of the rawhide was calculated by regression analysis. Results of digestibility testing showed 77% dry matter digestibility, 87% nitrogen digestibility, 91% fat digestibility and 86% energy digestibility. Metabolizable energy of the beefhide was determined to be 3.97 kcal/gram. In conclusion, the administration of beefhide to dogs significantly slows the accumulation of dental calculus deposits when fed on a daily basis. Digestibility of beefhide is high and must be considered a contribution to caloric intake. Administration should not exceed the label recommendations of two strips per day (approximately 28 grams or 111 kcal per day).

Lage, Arthur; Lausen, Niels; Tracy, Ronald; Allred, Elizabeth. 1990. JAVMA 197(2):213-219.
Goldstein, Gary S; Czarnecki, Gail; Venner, Marsha. 1993. Proceedings Veterinary Dentistry: 29.
Goldstein, Gary S; Czarnecki, Gail; Venner, Marsha. 1994. Abstract and poster presentation, ACVIM Forum.

Feeding and nutrition practice in 82 Hanoverian horse breeding farms during breeding season

S. Winkelsett 1 , M. Granel 1 , M. Coenen 1 , I. Vervuert 1 , A. Borchers 1 , O. Distl 2 , E. Bruns 4 , B. Hertsch 5 , L. Christmann 3

1 Institute of Animal Nutrition,
2 Department of Animal Breeding and Genetics, School of Veterinary Medicine Hannover, D-30173 Hannover,
3 Hanoverian Breeders Association, D-27283 Verden,
4 Department of Animal Breeding and Genetics, D-37075 Göttingen,
5 Clinic for Horses, D-14163 Berlin

There is little information about common feeding practice on German warmblood stud farms. Creep-feeding of mares and their foals during the winter in particular, varies enormously between the different farms. In order to produce healthy sport horses, it is necessary to begin feeding according to the nutrient requirements for a growing horse early in life. The purpose of this study was to evaluate feeding regimens in growing horse diets. This investigation was part of a larger project in which growth rates, feeding, housing, and genetics were evaluated with special reference to the development of osteochondrosis in foals.

From March to October 2001, monthly feeding practice of several breeding farms (n=82) with 629 mares and their foals, was recorded. Feed samples were taken and analyzed for crude nutrients and minerals. In addition, height and weight of the growing foals were estimated (refer to the presentation by Vervuert et al.).

On almost all farms suckling foals were not fed separately from their dams. Forty farms fed traditional rations composed of varying combinations of oats, barley or pelleted feed, and hay or haylage. Forty breeding farms fed traditional rations as well, but fortified with feedstuffs such as coarse mix or a special concentrate mix for weanlings which were given to the mares as well. Most of the stud farms fed the horses twice daily with no difference between traditional and fortified feeding practice. Fifty-eight stud farms fed additional minerals. Only one stud farm fed hay or haylage to their mares and foals without any concentrate or minerals. In another breeding farm, mares and foals were fed exclusively with hay, sugar beet pulp, and minerals. All mares and foals had regularly access to pasture from May. During this period there was no additional feeding on thirty breeding farms. Mineral contents of the various feedstuffs are shown in Table 1 below.

Traditional feedstuffs (grains and roughage), as well concentrates form common feeding practice on German stud farms. Suckling foals are not fed separately from their dams. During the winter months when horses are stabled adequate nutrient intake is expected in most cases. On pasture, without additional feeding, an inadequate supply of minerals is possible.

Table 1. The mineral contents of the feedstuffs.
feedstuff n Ca P Zn Cu g/kg dry matter mg/kg dry matter
grass 137 3.4±0.7
hay 71 4.9±1.3
haylage 52 5.1±1.4
61 20.5±12.1
coarse mix 25 13.2±7.7

Zinc intoxication in budgerigars (Melopsittacus undulatus)

Petra Wolf 1 , Cristiane Haupt 2 and J. Kamphues 1

Institute of Animal Nutrition, School of Veterinary Medicine Hannover, Bischofsholer Damm 15, D-30173 Hannover,
2 Clinic for Companion Animals, Waldfriedstr. 10, D-60528 Frankfurt

Zinc intoxication in most domestic animals is well documented, while only a few reports in pet birds have been published (all from the USA). Furthermore, there is only one published experimental study, in adult cockatiels (Nymphicus hollandicus). Cases of zinc intoxication in psittacines in Europe were documented by Dorrestein et al. (2002). However, it seems that zinc intoxications are probably not uncommon in avaries, especially in newly erected aviaries (‘new wire disease’). The symptoms are not obvious and many birds may die before the real diagnosis is made.

Case report:
The owner of a flock of 6 budgerigars bought a new aviary (200 x 100 x 200 cm) with a thermal galvanized wire mesh. Two months later one of the budgerigars showed health disorders in form of ataxia, tiredness and yellow-coloured feces. The budgie dropped repeatedly from the seat. Hepatomegaly can be seen by radiography. Three weeks later another budgerigar showed comparable symptoms. Ten weeks after being kept in the new cage a third bird was ill with similar symptoms of regurgitation of a colourless mucus and diarrhea. Two weeks later, another bird showed vomitus and a strong loss of plumage. Within three months all budgerigars were ill (increased body mass losses, vomitus, convulsions, ataxia, disorders of the central nervous system, feather losses, diarrhea, paralysis), and two of them died. However, after applications of Ca-EDTA and the moving the budgerigeras to another cage no further health disorders occured.

Nutritional history:
The budgerigars were fed a commercial seed mixture, equivalent to conditions in the other cage without clinical signs.

Examination of the birds:
No gross pathological signs could be observed at necroscopy. No parasites were found. The microbiological investigation found no unusual organisms. The practitioner suspected a zinc intoxication. Therefore the livers of the two budgerigars that died were analyzed for zinc levels (Table 1) using atomic absorption spectrometry (after wet ashing procedure).

The observed zinc levels in liver tissue were lower than comparable data in other animals (cattle, pig, horse, dog etc.) and possibly indicate a special sensitivity and a low limit of tolerance of pet birds towards zinc (specific for these bird species?).

DORRESTEIN, G. M., VAN DER HAGE, M., KIK, M. and BERENDSEN, M. (2002): Zinc intoxication in two psittacine flocks. Proc. of the DVG-Tagung, Munich, 21.-22.2.2002, pp. 125-133
REECE, R.L., DICKSON, D.B. and BURROWES, P.J. (1986): Zinc toxicity in aviary birds. Aust. Vet. J. 63,199

Table 1: Zinc levels in cases of an intoxication and physiological levels in liver of pet birds
Zn-level in liver tissue (mg/kg DM) physiological status intoxication
Kind author(s)
50.5 ± 12.7*
(37.6 – 70.5) n=10
(Melopsittacus undulatus)
* own results
57.9 ± 34.5
(28.1 – 156) n=14
179 ± 73.7
monk parakeet
(Myiopsitta monachus)
Dorrestein et al. 2002
42.5 ± 8.90*
(37.5 – 50.2) n=5
(Agapornis roseicolli)
Reece et al. 1986
38.9 ± 22.2
(12.0 – 115) n=77
150 ± 37.0
(Ara chloroptera, Ara macao)
Dorrestein et al. 2002

Distinct weight loss and elevated hepatic enzymes in horses caused by straw contaminated with Deoxynivalenol (case report)

Annette Zeyner 1 , U. Fischer 2 , Andrea Lindner 3

1 Albrecht-Daniel-Thaer-Institute of Agricultural Sciences, Faculty of Veterinary Medicine, University of Leipzig, Germany,
2 Practical Veterinarian, Leipzig, Germany,
3 Biocheck GmbH, Leipzig, Germany

The possibility of an intoxication has to be regarded in all cases of health disorders with unknown etiology. For this, information about the nutrition should be as precise as possible. In many cases it may additionally be necessary to include special methods of feed analysis.

Case report:
In February 2002, about the half of 104 predominantly Warmblood-type riding horses in a stable in the middle of Germany suddenly lost weight. With some animals this was associated with poor performance. Individual horses fell ill with recurrent cough. In March nine of the affected horses (adults: 2 studs, 7 geldings) were subjected to a clinical and clinical-chemical examination which included haematological (haemoglobin; packed cell volume; erythrocytes: count, morphology and indices; white blood cells: total and differential count) and biochemical (in the sera: total protein, urea, creatinine, calcium, inorganic phosphorus, magnesium, total bilirubin, alkaline phosphatase, aspartate aminotransferase, alanine aminotransferase, g-glutamyl transferase [GGT], glutamic acid dehydrogenase [GDH], creatine kinase, lactate dehydrogenase) parameters. The clinical examination did not indicate any specific illness. Laboratory analysis revealed a marked elevation of liver enzyme activity (GDH 163±108 U/l, GGT 151±58.7 U/l). Total bilirubin was normal. Two horses particularly affected were treated with Amynin (two times every 5 days).

Nutritional history:
All horses received whole oats and barley (1:1), a pelleted mixed feed and meadow hay. The horses had been fed this diet for several months before the health disorders were established. The bedding consisted of wheat straw. Only a few horses got wooden shavings. None of these horses fell ill. The provenance of all the straw used was uniform. After the wheat was harvested, the straw was stored as round bales (each about 300 kg) in two barns and the remainder on the field without any protection against the weather. Initially the horses got straw from a barn. Since this barn was destroyed in October 2001 straw from the field was given thereafter. Apparently no hygienic problems existed with the feed used except of the straw that was stored in the field. The surface of the bales was partly mouldy. All feedstuffs were subjected to ELISA to identify selected Fusarium mycotoxins (T-2-Toxin, Zearalenone, Fumonisin, Deoxynivalenol [DON]). The analysis revealed high DON concentrations (0.5-2.7 ppm) in the straw that was stapled on the field but not in the straw from the barn. Since this was discovered (April 2, 2002) only straw from the barn was used. Subsequently the horses slowly gained weight and the general condition became progressively better. Clinical-chemical controls occurred in April 16 and May 30, 2002. Accordingly GDH (2.8±4.3 U/l) gradually dropped to physiological values (< 8 U/l). GGT was markedly decreased (50±19 U/l) but the normal range (< 25 U/l) was obtained in only one horse.

Assessment and conclusion:
Changes in the horses weight and liver enzyme activities were obviously connected with the use and elimination, respectively, of the DON enriched straw. A recommendation for the DON limit in horse feed does not exist. Ration calculation showed that the DON concentration was clearly lower than the limits recommended for other farm animals (Anon, 2000). This may indicate a particularly high sensitivity of equines to DON. However, there may have been an additional aggravating mechanism, as yet unrecognised.

Anon, 2000. DLG-Mitteilungen 8/00

Undesirable substances in feed – an overview

Josef Leibetseder

Institute of Nutrition, University of Veterinary Medicine Vienna

Substances and products are called undesirable in animal nutrition if they are disadvantageous for the target animals, pose a risk for human health and are dangerous for the environment. Most of the individual European States established legal regulations of this matter. The European Communities entered into force the first Directive in 1974 (74/63/EEC) and the last one in 1999 (Council Directive 1999/29/EC). The following refers mainly to the latter directive, although it is currently under revision. The directive consists of 18 Articles and four Annexes. Annex I, divided in three parts, sets the maximum content of undesirable substances (Substances, Products, Botanical impurities) in feeding stuffs and feed materials. In Annex II feed materials containing undesirable substances are listed which can be used in animal nutrition only under certain conditions. Annexes III and IV have only administrative relevance. In addition to the definitions, the directive obliges the Member States (MS) to make the international directive national law. MS shall prescribe that feed materials may only be put into circulation within the Community if they are sound, genuine and of merchantable quality. MS shall prescribe that substances and products listed in Annex I shall be tolerated in feeding stuffs only under conditions set out therein and that feed materials listed in Annex II may be put into circulation only if their content of the undesirable substance or product mentioned in the Annex does not exceed the maximum level laid down in that Annex.

The Directive also regulates the conditions feed material can be used in animal nutrition if the content of undesirable substances exceeds the maximum permissible level. They may restrict the use of such feed materials to certain manufacturers of compound feedingstuffs. Where a MS has detailed grounds for establishing that a substance constitutes a danger to animal or human health or the environment it may provisionally reduce the content or prohibit that substance in feed. It shall immediately inform the other MS and the Commission. MS shall take all necessary measures to control feedingstuffs officially. The Directive also regulates the measures to be taken. The Standing Committee on Feedingstuffs shall deliver its opinion about the Commission draft of measures. Annexes shall be reviewed and amended periodically, according to the scientific development.

COUNCIL DIRECTIVE 1999/29/EC of 22 April 1999 on the undesirable substances and products in animal nutrition.