INFLUENCE OF GENETIC AND ENVIRONMENTAL FACTORS ON LACTATION COMPONENTS AND PRODUCTION PERFORMANCE OF HOLSTEIN FRIESIAN CATTLE IN BALOCHISTAN
Published: November 20, 2011
By: A. Nawaz, A. H. Nizamani, I. B. Marghazani, Nasrullah, A. Fatih
Summary
Data on 100 Holstein-Friesian cows for a period of 15 years (1988-2002) were analyzed using least squares and maximum likelihood methods. Lactation
components such as lactation length, peak yield, milk yield, and age at calving averaged 319±56, 474±42 liters, 3661±785 liters, 1963±636 days respectively. The h2s estimates were 0.49, 0.29, 0.32 and 0.535 for lactation length, peak yield, milk yield and age at calving respectively. Seasonal effects revealed that there is no influence of season of calving on lactation components. Summer, Autumn, Winter and Spring had lactation length 323±50, 317±49, 313±56 and 321±55 days, monthly peak yield 477±77, 472±70, 466±53 and 482±73 liters, and milk yield 3685±766, 3593±817, 3645±677, 3724±864 liters, respectively. Parity-wise (1st, 2nd, 3rd, 4th and 5th), average lactation length was, 312±51, 319±59, 337±55, 311±50 and 318±54 days, monthly peak yield 470±81, 464±69, 481±79, 475±68 and 480±57 liters, and milk yield, 3657±786, 3740±813, 3938±750, 3486±645, 3484±670 liters, respectively. Positive correlations were observed between lactation length and peak yield (0.56), lactation length and milk yield (0.693, peak yield and milk yield (0.38), and peak yield and age at calving (0.11), while negative correlation was recorded between milk yield and age at calving (-0.171) and lactation length and age at calving (-0.104). The regression coefficient
between lactation length and peak yield (0.04), lactation length and milk yield (0.05), peak yield and milk yield (0.03), and peak yield and age at calving (0.94) was positive, while negative correlation was recorded between milk yield and age at calving (-0.13) and lactation length and age at calving (-0.01).
Key words: Genetics, environment, lactation performance, Friesian, Balochistan
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