scope:

Introduction

The maximum immission values (MI values) for aluminium presented below are intended to protect farm animals. Maximum immission values were derived from long-term aluminium exposure experiments in order to determine the dose-timeresponse relationships in farm animals and farmed game animals. MI values can only be established for animal species for which experiments were carried out. However, since all investigated species responded uniformly to aluminium burden in the feed, goats, farmed game, and various poultry species can be expected to react in a similar way as cattle, pigs, and hens to aluminium exposure [1; 21; 38].

In general, results from aluminium toxicity studies can not be compared, because various aluminium compounds were applied for different periods of time [30]. Farm animals tolerated sparingly soluble aluminium compounds (aluminium phosphate and oxide) in much higher concentrations than soluble aluminium compounds (alums, aluminium sulphate, chloride, and nitrate). An amount of 1,6 g Al/kg (dry mass) applied as aluminium phosphate or aluminium oxide induced no visible effects in chicks and sheep [10; 33]. However, administration of aluminium oxide to sheep over a period of two years doubled the aluminium content in kidneys, tripled the content in liver and ribs, and increased the content in the cerebrum sixfold [10]. An uptake of 1530 mg aluminium from the soil did not reduce the feed intake of dairy cows, but it did so in case of cows that had been administered the same amount of aluminium in the form of aluminium citrate [4]. When assessing the observed effects obtained with different aluminium compounds it must be taken into account that these effects can also be triggered - for a significant part - by the anions taken up simultaneously [30].

An increased uptake of aluminium (see Table 1) can lead to chemical interactions with calcium, magnesium, phosphate, iron, and zinc [30]. The measured levels of these elements is significantly reduced in farm animals, game (deer), and farmed game (fallow-deer) so that the effects caused by an excess of aluminium can also be attributed to the secondary effects of a deficiency in these essential macronutrients and trace elements [10].

The aluminium supply to the fauna, including farm animals, is so abundant that no aluminium-related deficiency symptoms, as were observed in goats under aluminium-depleted diet (6,5 mg/kg dry mass of fodder versus control animals fed with 38 mg/kg dry mass) [6; 8; 9; 10; 27] are to be expected.

As a rule, aluminium consumption by ruminants varies between 30 mg and more than 500 mg/kg dry mass [10], between 10 mg and 50 mg/kg dry mass in monogastric species [27], and can reach up to 600 mg/kg dry mass in beef steer [29].