Authors : Nazir Ahmad , M. Syed , M. Farooq , S.I. Shah and R. A. Gill
Abstract: Information on production and reproduction traits from 1982 through 1992 of imported anf farm-born Holstein cattle maintained at Government Cattle Breeding and Dairy Farm, Harichand, Charsadda were collected to investigate lactation length, dry period and persistency of lactation and some of the factors affecting these traits. Overall mean lactation length, dry period and persistency of lactation was 315.46?3.62 days (coefficent of variation, 29.88%), 134.47?5.65 (coefficient of variation of 93.38%) and 90.5?0.01%, respectively. The lower and upper limits of 95% confidence interval for lactation length, dry period and persistency of lactation were 308.3, and 315.46 days, 123.30 days, and 45.65 days and 89.75%, and 90.82%, respectively. Imported cows had longer length of lactation and shorter dry period than in farm-born cows while persistency of lactation was same. Year and season of calving had a significant (P<0.01) effect on lactation length, dry period and persistency of lactation. Lactation length was found significantly (p<0.01) correlated with age at first calving (r=-0.20), milk yield per day of age at second calving (r=0.26) and lactation yield (r=0.69). Dry period had a significant (p<0.01) correlation with age at second calving (r=0.43), calving interval (r=-0.78) and lactation yield (r=-0.13). Persistency of lactation had a significantly (P<0.01) negative correlation with puberty age (r=-0.23). Efforts should be made to achieve optimal lactation lengths, shorter dry periods and appropriate calving interval by improving reproductive efficiency of the herd. Protection of animals from extreem of hot climates, availability of green fodder and possibilities of voluntry culling should be sorted out to aviod further deterioration in genetic potentials of the progeny.
Nazir Ahmad , M. Syed , M. Farooq , S.I. Shah and R. A. Gill , 2003. Lactation Yield, Length and Persistency of Lactation in Holstein Cows under the Subtropical Environment of North West Frontier Province (NWFP) . Journal of Animal and Veterinary Advances, 2: 548-553.