ترکیب شیمیایی، تجزیه‌پذیری ماده خشک و پروتئین خام سیلاژ یونجه عمل آوری شده با اسیدهای فرمیک و سولفوریک و تأثیر آن بر عملکرد گاوهای هلشتاین تازه‌زا

This study was conducted to investigate the effect of formic and sulphuric acids on chemical composition, dry matter (DM) and crude protein (CP) degradability of alfalfa silage and its effect on early lactating Holstein cow as three trials. In the first trial, chopped alfalfa (22 and 33% DM) was ensiled with three levels of formic acid (0.0, 15 and 20 ml/kg DM) and two levels of sulphuric acid (0 and 4 ml/kg DM). In the second trial, DM and CP degradability coefficients of silages (Treatment 1: without acid Treatment 2: 15 ml formic acid + 4 ml sulphuric acid per kg DM) and alfalfa hay (Treatment 3) were determined using nylon bag technique in two cannulated steers. In the third trial, silages (treatments 1 and 2) were replaced with 50% of alfalfa hay in the early lactation Holstein cow diet (11 cows, 19 ± 8 days in milk). Diets were fed for 49 days. Dry matter intake, milk production and milk composition were evaluated. Blood metabolites were determined in weeks 4 and 6. Effect of wilting on pH was significant (p<0.05). Quickly degradable fraction (a) of DM was similar in both silages (0.35) but was higher (0.5) for hay rather than the silages. Slowly degradable fraction (b) of DM of the acid - treated silage was higher compared with the hay (0.39 and 0.32, respectively). Fraction (a) of CP in acid treated silage was less than the control silage and hay (0.46, 0.57 and 0.57, respectively). Fraction (b) of CP in acid - treated silage was less compared with the control silage and hay (0.41, 0.28 and 0.35, respectively). There were no significant differences between the treatments on the cow’s performance. However, time effect on milk fat and solid non-fat was significant (p<0.01). Blood glucose concentration before feeding with treatment 2 was significantly higher (p<0.01) than cows feeding with treatment 1.