Modulação do perfil de ácidos graxos do leite de vacas por meio da adição do lignosulfonato e da extração do grão de canola

Abstract

The purpose of this work was to evaluate the supply of processed canola grain on milk production, composition and fat acid profile and nutritional parameters of Holstein cows. The evaluated treatments were: ground canola (GC), extruded ground canola (EC), ground canola with lignosulfonate (GCL) and extruded ground canola with lignosulfonate (ECL). Eight cows, allotted in a double Latin square, with four treatments and four periods with 21 days each one, were utilized. The forage/concentrate relationship was 57/43. Milk production was 18.80, 19.51, 18.64 and 19.01 kg/day for GC, EC, GCL and ECL, respectively, and did not have any difference for the evaluated processing (P>0.05). The treatments did not affect milk physic-chemical composition, however the extrusion resulted in low milk fat concentration because the increase of 18:2 10t 12c isomer concentration, responsible for lipogenic active reduction on mammary gland. The canola processing altered the milk fat profile, where the extrusion increased 18:1 11t and 18:2 10t 12c, and provided reduction of the fatty acids 18:3 n-3, 22:4 n-6 and 22:5 n-3, decreasing n-3 and n-6 concentration, but increasing n-6/n-3 relationship. The processing did not affect the saturated, unsaturated, polyunsaturated and 18:2 9c 11t isomer on milk fatty acids concentration. The nutritional parameters evaluated were intake, nutrients digestibility, ruminal parameters, blood components, in situ degradability and canola protein and carbohydrate fractions. The treatments did not influence (P>0.05) DM, CP, NDF and ADF intake, however, it was verified a high EE and NSC intake (P<0.05) for extruded and extruded with lignosulfonate treatments, respectively. The total apparent digestibility of DM, OM and NSC was low (P<0.05) for lignosulfonate treatments, however, differences were not verified (P>0,.5) among others treatments. For ruminal components and blood parameters, was not observed any difference among evaluated diets, however, theprocessing of canola ground modified the DM and CP degradability parameters. The DM effective degradability at 2% and 5% passage rate did not show differences among evaluated treatments, but verified a reduction in the effective degradability at 8% passage rate for extruded treatments. The CP effective degradability was not different for the processing used in this research. This oilseed had high protein ?B2? fraction, but presented low carbohydrate "C" fractions. The processed canola grain supply for lactating cows modified the milk fat acid profile, however, did not altered the nutritional parameters.