Effetto dell’introduzione nella dieta di foraggi a basso input in sostituzione al silomais sulle prestazioni produttive e sulla qualità del latte di bovine di razza Pezzata Rossa

The substitution of corn silage in dairy cows’ diets is considered crucial for the economic and environmental sustainability of the livestock sector due to its price fluctuation, high irrigation water requirements and susceptibility to mycotoxin contamination. However, knowledge about the effects of using alternative crops to replace corn silage on milk yield and composition remains limited. In a herd of 29 Italian Simmental cows raised in a free stall farm of Northern Italy, 6 animals in the lactation phase (Days in Milk - DIM: 145 ± 80 d; Parity: 3.2 ± 1.7; Milk yield: 24.7 ± 4.7 kg/d) were selected for the entire duration of the trial. The study consisted in four consecutive periods using four isonitrogenous and isoenergetic diets: a control diet (CTR), a diet based on corn silage (P1) being replaced by sorghum-soy silage (P2), and then by sorghum silage (P3). The duration of each period was of 21 days, with transition periods of 12 days in between to gradually change the diet. Milk yield was obtained and samples were analyzed for chemical composition and coagulation properties for each individual cow at the last week of each period. For the statistical analysis, a mixed model was applied, using the cow, diet and parity as fixed effects and the days in milk as a covariate. Milk yield (25.6 ± 6.09 kg/d) was not affected by the diets. The fat content was similar for the CTR and P2 groups, but higher than P1 and P3 (4.21, 3.94, 3.24 and 3.48% resp.; P<0.01). While, non-adverse effects on any of the other parameters (protein: 3.6%, casein index: 78.3, urea: 26.6 mg/100ml, lactose: 4.5%, Somatic Cell Score: 3.4, RCT: 20 min, k20: 7.0 min, a30: 23.1mm, a45: 24 mm, a60: 20.8 mm in average) were observed. To conclude, the use of low-input forages maintained the high standards of the breed and could potentially reduce the reliance over corn silage in dairy cows’ diet. Specially, the replacement of corn silage with sorghum-soy silage had increased the fat content in milk without affecting milk yield or any other milk quality parameters suggesting to be a potential alternative crop for dairy cows. Furthermore, this study offers perspectives for more efficient and environmentally friendly dairy cattle farming.