تأثیر جایگزینی جو با ضایعات ماکارونی بر تولید و ترکیب شیر در گاوهای شیرده

In order to determine the effects of using macaroni wastes instead of barley on dry matter intake (DMI), milk yield and composition, and nutrient digestibility, eight lactating Holstein cows (4 primiparous and 4 multiparous) in midlactation were used in a 44 Latin square design. The experimental periods were 21 d with 16 d for adjustment and 5 d for data collection. Treatments included a control diet (1) and diets 2, 3, and 4 containing 15, 30, and 45% macaroni wastes, respectively, which were fed three times a day as total mixed rations. During the last 5 days of each period, feed and fecal samples were taken for determination of DMI and apparent digestibilities and milk samples for fat, protein, lactose, and solids no fat (SNF). During the last day of collection period, urine samples were collected 3 and 5 h postfeeding for pH determination. The results showed no significant differences among experimental traits in either primiparous or multiparous, and across all cows. Milk yield and efficiency of feed conversion were nonsignificantly higher for diets 2, 3, and 4 compared with control cows. Compared to the control diet, DMI, fat, protein and SNF percentages did not significantly decrease in diets 3 and 4. From the results of this expriment, it may be concluded that replacing barley with macaroni wastes up to 45 percent could increase energy intake without any adverse effects on milk production and composition or on metabolic function in midlactating dairy cows.