[Influence of milk-fat substitute feeding on the metabolism in calves].

Investigations were made to study the effect of milk fat substitutes ("Laktin", "TZS-60") on the metabolism of 3 and 5-weeks-old calves. "Laktin" is prepared from lard and hydrogenated soya and fish oil; additionally, it contains lecithin, monoglycerides, antioxidants, vitamins and antibiotics. "TSZ-60" is a preparation containing starch and colloidal silicic acid as carrier material mixed with 60% of coarsely powdered fat (particle sizes ranging from 50 to 200 mum), which in turn, is supplemented with vitamins and antibiotics. The kinds of "Laktin" used in the present trial contained 95%, 58%-98% or 90% of fat while "TSZ-60" contained 59.4%. Both the 3-weeks-old and the 5-weeks-old calves digested the "Laktin" fat more efficiently than the kind of fat contained in "TSZ-60" ("Laktin": 94.3% to 97.3% of fat; "TSZ-60" 71.8% to 90.5%). As a consequence of this, the "Laktin"-fed calves exhibited a higher rate of nitrogen utilization and nitrogen retention. According to the results obtained in the present trial "Laktin" should be given in daily doses of 219 g (an amount corresponding to 7 litres of milk with a milk fat content of 3.13%) while "TSZ-60" should be fed in daily amounts of 245 g (corresponding to 7 litres of milk with a milk fat content of 2.1%). Higher doses ("Laktin": 323 g/day: "TSZ-60" 335 g/day) would have a detrimental effect on the metabolism of the calves. Apart from this, it was not found that higher doses would help to reduce the protein consumption of the animals.