Productive Performances of Crossbred Dairy Cattle at Holetta Agricultural Research Center

摘要

This study was conducted to evaluate the productive performances of crossbred dairy cattle at Holetta research center dairy farm. A total of 6685 performance records were used and analyzed to determine the effect of period of calving, season of calving, parity and genetic group. The parameters used us indicator of productive performances were Lactation milk yield (LMY), daily milk yield (DMY) and lactation length (LL). The GLM procedure of SAS 2004 software was used for analysis. The overall least square means and standard errors for Lactation milk yield (LMY), daily milk yield (DMY) and lactation length (LL) were ÷ 2204.05 ± 21.12 kg, 6.88 ± 0.05 kg and 326.69 ± 2.03 days, respectively. Result of fixed effect analysis indicated that calving period, genetic group and parity were significantly (p0.001) influenced all productive traits. LMY, DMY and LL were sensitive to seasonal variation. Comparisons among the crosses revealed a clear-cut difference among the genetic groups. Milk production in the ?rst generation crosses increased more compared to second generations. There were marked decline in performance among 50% F 1 (Borena dam x Holstein Friesian sire), F 2 (F 1 dam x F 1 sire) and F 3 (F 2 dam x F 2 sire) from 2203kg of milk to 1697 and 1522 kg, respectively. The 75% first generation was superior LMY compared with other genetic groups and produced about 34.2 %, 74.3%, 94.3% and 45.9% more milk than 50% F 1, F 2, F 3 and 75% second generations, respectively. The higher milk yield of 75% first generation and 50% F 1 crosses from other genetic groups could be associated with higher heterosis effect in F 1 , higher milk gene in 75% and longer lactation length. Based on the productive performances evaluation, the results of LMY, DMY and LL of higher grades ( 50%) in the present study revealed that performances were continued to increase with increasing proportion of exotic genes.