Effects of Different Protein and Energy Levels in Mixed Feed on Growth Performance and Reproduction Characteristics of Heifers.

Background: In this study, the effects of different protein and energy levels in mixed feed on growth performance and reproduction characteristics of heifers were investigated. Method: The material of the study consisted of 36 Holstein Friesian (black pied) breed cattle at the age of 6 months and average live body weight of 156.65 kg and the experiment was continued for 8 months. During the experiment, four different feeds containing 16% CP - 2500 kcal / kg ME for the 1st group, 16% CP - 2700 kcal / kg ME for the 2nd group, 18% CP - 2500 kcal / kg ME for the 3rd group, 18% HP - 2700 kcal / kg ME for the 4th group were given at 1.5% of the live weight of heifers. (Where CP and ME stand for Crude Protein and Metabolizable Energy, respectively). As roughage, an equal amount of straw and alfalfa hay mixture was given. Result: As a result of this study, the effects of the different protein levels on live body weight and body measurements (body length- BL, withers height-WH, hip height-HH, hip width-HW, body depth-BD, chest girth-CG) were not found significant (P> 0.05). Similarly, the effects of different energy levels on body weight and body measurements (P> 0.05) and protein X energy interaction in terms of live body weight and size were also not found significant (P> 0.05). Regarding the reproductive properties, the differences between the groups in terms of the effect of different protein and energy levels on the first estrus age were found statistically significant (P <0.05). As a result of the analysis made in terms of heifers age during the first insemination, the difference was found to be statistically significant (P <0.05). The effect of different protein and energy levels on the conception rate in the first insemination was found significant (P <0.05). As a result, it was concluded that affordable mixed feed combinations can be used within the limits of mixed feed combinations containing 2500-2700 kcal / kg ME and 16-18% CP, which were given in the investigation; however, low energy-high protein combinations would give more positive results considering their effects on the reproductive performances and conception rates at first insemination. [ABSTRACT FROM AUTHOR]