ChileanJAR

An experiment was carried out at La Platina Regional Research Center, Santiago, Chile, in order to evaluate: 1) the inclusion and effects of feeding rumen non-degradable (by-pass) fat on composition of mi/k and yield in cows fed with it; 2) Productive response of cows fed only young alfalfa soiling plus by-pass fato Twenty four high yielding Holstein Friesian cows were allotted to the following treatments: T₁ = young alfalfa soiling plus concentrate (and minerals) and 600 g of by-pass fat; T₂ =young alfalfa soiling plus concentrate (and minerals) and 1,000 g of by-pass fat; and T₃ =young alfalfa soiling plus 1,600 g of by-pass fat (and minerals). Milk yield and food intake were controlled daily whereas protein, mi/k fat, total solids, solids notfat and body weight were controlled weekly. Blood biochemical parameters (BU N, GGT, triglicerides) were measured monthly. The results obtained were the following: milk yield (L/day): T₁ =31.25a; T₂ =29.25a and T₃ =29.25a; milk fat (%): T₁ =2.46a; T₂ =2.65a and T₃ =2.67a; dry matter intake (kg/animal/day): T₁ =23.5a; T₂ =23.2a and T₃ =20.6b; food conversion (kg D.M./L milk/day): T₁ =0.73ab; T₂ =0.74a and T3 = 0.64b. No significant differences were found (P > 0.05) in Iive weight variation among treatments. It can be concluded that the addition of by-pass fat shown a better response (feed efficiency and feeding cost) when it was included as the only energy complement to rations of young alfalfa soiling. The remarkable facts of the three results are: the highly positive effect of combining alfalfa soiling with fat instead of concentrate; contrary to Iiterature, a high content of fat in the diet did not produce any negative effect; either in the mi/k yield or in the milk components; likewise body weight and biochemical blood parameters were not effected; the daily milk yi