عملكرد گاوهاي دوشا تغذيه شده با جيره فرموله شده با نرم افزارهاي جيره نويسي اسپارتن و سيستم كربوهيدرات و پروتئين خالص كرنل

The comparison of performance of lactating dairy cows fed rations, formulated by spartan dairy ration balancer and Cornell Net carbohydrate and protein system

The purpose of this experiment was to make a comparison of performance of lactating dairy cows fed rations, formulated by Spartan (1) and CNCPS (2). The 16 lactating dairy cows (8 cows in second and 8 cows in third) with DIM=55 ± 33, body weight = 622 ± 42Kg, milk yield =31 ± 1/8 Kg/day), assigned in a randomized completely block design in individual pen. The cows fed individually with the formulated rations as TMR for 90 days after 15 days adaptation period. The milk yield of cows that fed ration 1 and 2 were 31.34 and 31.4 Kg/d, milk fat were 3.35% and 3.25% and milk protein were 2.91% and 3.01% respectively, there were no significant difference between two groups as far as mentioned traits (p>0.05). There were not any significant differences for pregnancy rate (P>0/05). The average DMI for rations 1 and 2 were 22.5 and 22.34 Kg/day is considered, respectively (p>0.05). Average daily crude protein intake of the rations while that was 3625 and 3470 g/d respectively, that was significantly different (p<0.05).However the CNCPS predicted a lower requirement of protein than Spartan for lactating dairy cows while that It was enough to support milk production such Spartan ration of this experiment did. The cost of each Kg feed per milk yield for rations 1 and 2 were 1380 and 1250 respectively, (p<0.05). the result showed that the CNCPS formulated a cheaper ration than Spartan that also it can be recommended to dairy farms as far as milk profit considered (p<0.05).