Pubertal growth and reproductive performance of Horro Heifers as affected by plane of nutrition

The effect of nutrient supplementation on growth and reproductive performance was studied on sixty Horro heifers age of 18 months and weighing on average 105 kg. The heifers were stratified to four treatment groups of planes of nutrition using a CRD design. Heifers kept on grazing alone (T1) had daily growth rate of 88 g up to first heat and 95 g up to conception. As a result the late age at first heat was 47 months, conception at 50 months, and first calving at 59 months. In heifers receiving 0.3 to 1.4 kg of Rhodes hay at the rate of 0.4 kg per 100 kg body weight (T2), the daily growth rate was 121 g up to first heat, and 124 g up to conception, and hence relatively reduced age at first heat (38 months), conception (44 months), and first calving (53 months) were achieved. In heifers receiving 1.3 to 2.7 kg concentrate and 0.6 to 1.2 kg Rhodes hay at the rate of 1.1 and 0.5 kg per 100 kg body weight (T3), respectively in proportion of 69:31, the daily growth rate of 292 g up to first heat, and 268 g up to conception were achieved. The result obtained indicated significant reduction in age at first heat (28 months), conception (33 months), and first calving (42 months). The heifers in treatment 4 (T4) receiving 1.9 to 3.6 kg concentrate and 0.6 to 1.6 kg Rhodes hay at the rate of 1.4 and 0.5 kg per 100 kg body weight, respectively in proportion of 72.28 grew daily at the rate of 331 g up to first heat, and 317 g up to conception. The age at first conception (31 months) and age at first calving (40 months) was not significantly different from the third treatment. Therefore based on the current study T3 is the ideal level of feeding for Horro heifers through pubertal growth to age at first calving. Furthermore, the result indicated that feeding management can significantly reduce age at heat, Conception and calving in heifers. Therefore future study should include post weaning management (pre-pubertal) of replacement heifers to their reproductive age as it is expected to further reduce age at first calving thereby increases the number of calves born per individual cows and the lifetime productivity of the animal.