Assessment of blood and productive parameters in mid-lactation dairy cows fed different diets: replacement of corn silage with triticale silage

Corn crops require large amounts of resources that affect the environmental sustainability of dairy cow farming systems. The aim of the study was thus to investigate the effects of the replacement of corn silage (CS) with triticale silage (TS) by evaluating blood and productive parameters. The study lasted 7 weeks and involved two groups of 20 Italian Holstein Friesian dairy cows that were homogeneous in terms of parity (3 +/- 1.5), days in milk (DIM) (150 +/- 85.0), and daily milk production (26 +/- 4.6 kg). Chemical analysis of feeds was carried out weekly. Dry-matter intake was estimated daily. At the beginning and end of the trial, haematological, metabolic, and immunological parameters were analysed. At the same, time body weight and body condition score were measured. Milk characteristics were also analysed weekly. Statistical analysis was performed by ANOVA on data of the second sampling, and a non-parametric test was performed to analyse BCS. Regarding the haematological parameters in the two groups, only lymphocyte values were not in the normal range (2.86 and 2.50 x 10(9) L for CS and TS, respectively). Metabolic parameters were in the normal range except for blood ureic nitrogen (BUN; 13.65 and 14.04 mg dL(-1)), non-esterified fatty acids (NEFAs; 21.40 and 31.93 mu mol L-1), and Cl (91.99 and 93.50 mmol L-1). Hair cortisol was low (0.94 and 0.91 pg mg(-1)), indicating the absence of stress signs, as confirmed by the results of other immunological parameters (serum lysozyme (SL), bactericidal activity (SBA), haptoglobin (HP), and oxygen free radicals (OFRs)). Statistical differences were not found either for haematological or biochemical parameters. The total replacement of CS with TS did not affect milk yield and composition. In conclusion, the replacement of CS by TS did not give rise to significant modifications in the parameters investigated and did not alter the health status of the animals, thus suggesting the feasibility of its introduction into the diet of mid-lactation dairy cows.