Qualidade do leite de vacas em pastagem suplementadas com monensina e concentrado peletizado contendo linhaça

Abstract

This trial aimed to evaluate tlie production, composition and fatty acid profile of miik blood parameters and to determine the intake and digestibility of DM and nutrients from cows kept at pasture and fed with concentrate ration containing ground flaxseed, pelieted or not, with or without added sodium monensin. It was used four multiparous Holstein cows, averaging 186 (±9.7) days in milk and 515 (±36.4) kg of body weight, assigned in a Latin Square design 4x4 with the followig treatments: concentrate ration without monensin; concentrate ration with monensin; pelleted concentrate ration without monensin; pelieted concentrate ration with monensin. The animais were kept at Cynodon pasture and housed twice a day for feeding and miiking. The milk samples were composed propotionaliy according to the production of each animal in the morning and afternoon. To determine the dry matter intake (DM1) and nutrient of the concentrate ration were recorded daily the amount of offered and ieftovers food. The chromium oxide (Cr203) was used as an extermal marker, being supplied twice a day, totaiing 10 g per animal per day. The faeces samples were collected twice a day from the cows rectum, and then they were dried, grounded and composed on basis in the dry weight. There were no significant differences in the production and composition milk among the evaluated treatments. The mean of fat corrected milk yield (3.5% FCM) was 11.44 kg/day (P>0.05). In the fatty acids (FA) proflie, the C18:0 concentration decreased (P.<0.05) in miik from cows feed pelleted ration. The ievels of CLA were 47% higher in rations with monensin addition, and 70% higher for the peiieted ration. The pelieted ration decreased (P<0.05) milk concentration of saturated FA, and increased (P<0.05) 25% of polyunsaturated FA and 15% of monounsaturated FA. Textural properties of butter was not modified with the treatments, but the butter samples tended to be iess adhesive with the pelleted ration. There was no significance (P>0.05) in DM1 and nutrient forage and concentrate ration, except the ether extract (EE) intake that was reduced (P<0.05), as well as total intake and intake as a function of the body weight, with average values 0.31 kg/day, 0.43 kg/day and 0.09%, respectively. The nutrients and DM digestibility did not differ (P>0.05). There was a trend (P=0.08) for pelleted ration to increase digestibility of OM, with average 71.25% vs 68.20% for those not pelleted. The pelleted treatments increased DM digestibility (62.90% to 65.55%), the protein digestibility (68.84% to 70.78%) and EE digestibility (85.17% to 85.8%). The blood parameters did not differ. Both, pelleting rations and monensin addition, had not effect on nutrient intake from cows kept in pasture, and consequently the nutrients digestibility. Milk fatty acids profile was affected more by the heat processing than by the monensin addition ou absence in the concentrate ration.