At the present time in Iran , Feedstuffs are not enough to meet nutrient requirements of farm animals. Lack of metabolizable energy, crude protein, and total phosphorus are 24.52, 19.14, and 24.74%, respectively .Thus , use of nonconventional feedstuffs in the ration of animis is important .The objective of this research was to evaluate nutritional value of the olive meal and proper use level of it in the ration of lactating cows. 12 lactating Holstein cows in their second pariety were used in a change over deseign. The cows were fed four isonitrogenous and isocaloric rations for 112 days in three periods (each 28 days / period). The rations consisted of ,0,8,16 and 24% level of olive meal on a dry basis , which are named rations 1 to 4 respectively. Milk production (kg) was recorded daily and samples were taken Daily milk yield for each cow was recorded and weekly milk composition once per week for determination of its composition was measured. The results show that means milk yield (kg) and fat percentges were 22.50 3.56, 3.54 0.72; 22.22 3.95, 3.49 0.58; 22.55 2.79, 3.2 0.53; and 22.70 2.02 and 3.25 0.32, for rations 1 to 4, respectively .The means of protein; lactose and total solids were 3.09 0.29, 4.70 0.17 and 12.10 0.83 (rationl)3.11 0.21 , 4.7 0.19; 12.13 0.87 (ration 2); 3.16 0.28, 4.73
0.23 and 11.75 0.97(ration3) and for 3.14 0.10, 4.77 0.16 and 11.85 0.42(ration
4). No significant differences were obserned either in milk yield or its composition statistically, thiugh feed intake were incrased as the percent olive real was raised . However, as far as the cost of milk production is concerned under the experimental method in this study the use of olive meal as a feed ingrediend can not be economicaly recomended.
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