Effects of a novel heat-treated protein and carbohydrate supplement on feed consumption, milk production, and cheese yield in early-lactation dairy cows

摘要

Protein is an expensive component of the dairy cowdiet, and overfeeding protein can have adverse economicand environmental impacts. Our objective wasto maintain milk production and components whiledecreasing dietary crude protein (CP) through useof a heat-treated, rumen-resistant sugar amino acidcomplex (SAAC) as the Schiff base, as an addition tolow-protein diets. Dietary treatments included a negativecontrol [NC, 146 g of CP/kg of dry matter (DM)],a positive control (PC, 163 g of CP/kg of DM), andthe NC supplemented with SAAC in lieu of some barleygrain (SAAD, 151 g of CP/kg of DM). Diets werefed to 30 multiparous Holstein-Friesian dairy cows forthe first 50 d postpartum. Dry matter intake (DMI)was determined daily. Milk yield and content of fat,protein, lactose, and casein were recorded weekly fromwk 2 to 7 of lactation. The fixed effects of treatment,week, treatment × week, month of calving, and BCS atcalving, and a random effect of cow, were analyzed usingthe MIXED procedure of SAS (SAS Institute Inc.,Cary, NC). The SAAD treatment had greater energycorrectedmilk yield than did NC. The PC treatmenthad greater DMI than did NC, and SAAD tended tohave greater DMI than did NC. We found significanttreatment effects for fat percentage and yield. The NCand SAAD treatments had higher fat percentages thandid PC, and SAAD had a higher fat yield than did theNC and PC treatments. Treatment effects were foundfor casein yield and percentage. We discovered a treatmenteffect for protein percentage and yield. The PCtreatment had higher protein percentage than did NCand SAAD. The PC treatment had a higher proteinyield than did NC, and analysis revealed no differencein protein yield between PC and SAAD. The SAADtreatment had higher total milk solids than did the NCtreatment. Lactose yield tended to be higher in PC thanin NC, and no differences were found between PC andNC and SAAD treatments. The PC treatment had ahigher casein percentage than did NC and SAAD; however,the SAAD and PC treatments had higher caseinyields than did NC. The PC treatment had a highercasein: fat ratio than did the NC and SAAD treatments.The NC and SAAD treatments had higher Cheddarcheese yields than did PC. We found no treatment ×week interactions for any parameter. Supplementinglow-protein dairy cow diets with a heat-treated, rumenresistantSAAC caused beneficial effects by improvingmilk components and increasing cheese yield to levelssimilar to those found when feeding expensive and environmentallydamaging high-protein diets.