Productive and reproductive characteristics of heifers depending on the way of rearing at a younger age
2006
Lidzhi, K. (Institut po Zhivotnovadni Nauki, Kostinbrod (Bulgaria)) | Gorinov, Ya. (Institut po Zhivotnovadni Nauki, Kostinbrod (Bulgaria))
The study was carried out on a group of 56 heifers. All animals were reared under controlled productive conditions from 6 months of age to their calving. In the beginning of the experiment three groups of 25 calves were formed which were equalized by the analogous method for sire parentage, age and weight: group I - free stall under a three-wall shed on deep litter; group II - indoor group free stall with individual beds, and group III - indoor groop free stall. After the first calving the cows were reared indoors being tied with a walking yard and the nutrition level was according to the milk production of the animals. The health status of the animals at a younger age was a considerable factor (P0.001) concerning the reproduction age and level of production, while the rearing manner was of importance for the live weight of heifers (P0.001), the duration of the lactation period (P0.01) and the service period (P0.05). The heifers which at a youn ger age had been reared in a group free stall under a three-wall shed on deep litter were equalized on production capacity and reproductive quality. The animals which had been reared in a free stall with individual beds for rest reached a significantly higher live weight as heifers, but had decreased milk production and low relative milk yield. The female calves and breeding heifers which had been reared in an indoor group free stall had an average productivity at their first lactation close to those reared on deep litter but the distance in productive abilities reached 1298.83 kg of milk. The breeding animals which had suffered an illness in their younger age were included in reproduction despite the rearing regime at a significantly higher age. They had highly significant lower production levels and their age at the second calving was higher (P0.01-P0.001).
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