In a series of feeding trials with veal calves, the effect of dietary Cu levels on the Cu concentration in calf livers was investigated. The examined rations contained per kg of dry matter (DM) 2, 6, 8, 10 and 30 mg of Cu. The copper was added as sulfate. Up to a live weight of 100 kg, the ration was composed of whole milk upgraded with minerals and vitamins. This ration was supplemented with a milk replacer once the calves had reached 100 kg. In addition to the feeding trials, 40 calf livers were bought from several slaughter houses across Switzerland and the corresponding Cu contents were analysed. With a dietary Cu level of 2, 6, 8, 10 and 30 mg per kg of DM, the average Cu concentrations of the corresponding livers were 52 ± 17 mg, 97 ± 18 mg, 170 ± 19 mg, 178 ± 35 mg and 389 ± 108 mg on a fresh matter basis. The coefficient of variation varied between around 10 % and 35 % for a comparable Cu supply. There exists a close relationship between the dietary and hepatic Cu concentration (R2 = 0.804). The Cu content of the slaughter house livers averaged 63 ± 79 mg per kg of FM. Only 5 % of the liver samples surpassed 250 mg Cu per kg of FM. These 250 mg Cu per kg of FM is the concentration which is under discussion as a possible threshold value for the animals and food hygiene reasons.
Pontiggia A., Münger A., Ammer S., Philipona C., Bruckmaier R. M., Keil N.M., Dohme-Meier F.
Even in temperate climate zones, an increase in the ambient temperature and solar radiation can cause heat stress in grazing dairy cows. Agroscope studied the physiological changes in cows caused by increasing heat load.
Lazzari G., Münger A., Heimo D., Seifert S., Camarinha-Silva A., Borda-Molina D., Zähner M., Schrade S., Kreuzer M., Dohme-Meier F.
In dairy cows, herbage-based diets often lead to increased nitrogen excretion. Tanniferous sainfoin and extract of acacia can reduce nitrogen excretion from urine and thus ammonia volatilization from slurry.
Excessive nitrogen inputs from the air lead to over-fertilisation of sensitive ecosystems. Continuous feeding optimisation can make an important contribution to reducing ammonia losses and thus nitrogen inputs.