ABSTRACT
To study the relationship between body condition, milk yield and reproductive perfomance of highly producing dairy cows under local conditions, a number of 287 Holstein-Friesian cows, in their 1[st] to 5[th] lactation were used. Animals were grouped according to their milk production and fed on a total mixed ration according to NRC 1989. All cows were evaluated subjectively for body condition score [BCS] at calving and at service. Linear regression coefficient of interval from calving to 1[st] estrus [Y1] on peak milk yield/kg/day [X1] was significant [P < 0.01]. The resulting equation was Y1=16.37+0.7X1. Cows with higher peak milk yield showed a significant long interval to 1[st] detected estrus. No significant linear regression was found between milk yield/kg during current lactation and reproductive traits. Linear regression coefficient of interval from parturition to 1[st] detected estrus [Y1] on BCS at calving up to score 4.0 [X2] was significant [P < 0.01]. The resulting equation was Y1=90.52-20.68 X2. Cows with high BCS at calving up to score 4.0 had significantly [P < 0.05] shorter interval to 1[st] detected estrus. Meanwhile, linear regression coefficient of days open [Y2] or number of services/conception [Y3] on BCS at service [up to score 3.5] [X3] was also significant. The resulting equations were Y2 = 293.59 - 66.47 X3 and Y3=5.13-1.056 x 3, respectively. Both days open and number of services/conception were significantly improved as BCS at service was increased up to 3.5. The present work revealed that, reduced fertility in highly producing cows is not directly related to increased milk yield but rather to loss of weight and body condition. It is worthy to mention that the equations used here are helpful to predict the reproductive perfomance of a given cow by means of peak milk yield and/or BCS