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Researcher Vikram
Advisor Vinayak, A. K.
Source KrishiKosh-Indian National Agricultural Research System
Content type Text
Educational Degree Master of Science (M.Sc.)
Publisher LUVAS
File Format PDF
Language English
Subject Domain (in DDC) Natural sciences & mathematics ♦ Animals (Zoology) ♦ Specific topics in natural history
Subject Keyword Additive Correction Factors ♦ Milk Yield ♦ Multiplicative Correction Factors ♦ Heritability ♦ Murrah Buffaloes ♦ Animal Genetics and Breeding ♦ Age and Parity Adjustment Factors For Milk Production In Murrah Buffaloes
Abstract The data on performance records of 1637 buffaloes, progeny of 180 sires; calved during the year 1993 to 2012, maintained at Animal Farm section, CIRB, Hisar, were analyzed by least squares method using mixed model comprising of sire effect as random, period of calving, season of calving and parity as fixed effect and lactation length as covariate. The additive and multiplicative correction factors for age at calving were developed by using the same model after replacing parity effect from age groups. The efficiency of adjustment factors for milk production up to fifth lactation records were compared by different methods. The overall least squares means for total lactation milk yield (TLMY), 305 days or less milk yield (305DMY), peak yield (PY), lactation length (LL), dry period (DP), service period (SP) and calving interval (CI) were 2182.82 ± 20.19 kg., 2060.93 ± 20.22 kg., 10.08 ± 0.96 kg., 311.68 ± 3.35 days., 173.34 ± 5.59 days, 187.10 ± 5.91 days., 479.47 ± 4.88 days, respectively. The heritability estimates of TLMY, 305DMY, PY, LL, DP, SP and CI were 0.471 ± 0.085, 0.507 ± 0.087, 0.520 ± 0.088, 0.357 ± 0.095, 0.230 ± 0.075, 0.297 ± 0.080 and 0.273 ± 0.078, respectively. The genetic correlation coefficients between TLMY/305DMY, TLMY/PY, and 305DMY/PY were 0.956 ± 0.016, 0.931 ± 0.04 and 0.874 ± 0.046, respectively. The high genetic correlations of PY with TLMY and 305DMY suggested that peak yield may be the best trait to be taken in to selection criteria for improvement of milk production in Murrah buffaloes. Multiplicative and additive adjustment factors for age at calving were equally effective on the basis of Fvalue, phenotypic correlation and repeatability. Additive correction factor ranged from -121.592 (AG1) to 504.49 (AG24), whereas multiplicative correction factor ranged from 0.79 (AG17) to 1.06 (AG1). Additive correction factors were found to be more effective when compared on the basis of means and R2 values, while multiplicative correction factors were more effective in retaining similar CV (0/0) in different age groups as that of uncorrected data. As far as comparison among both the age correction factors is concerned it may be concluded that both ACF and MCF were equally efficient for correcting milk yield for age at calving . The additive correction factors for parity ranged from 0.00 (L1) to 339.17 (L5), whereas multiplicative correction factor ranged from 0.84 (L4) to 1.00 (L1). Both the parity correction factors were equally effective on the basis of F-value and CV (0/0).while, multiplicative correction factor were more efficient in retaining almost constant least square means. As far as comparison among both the correction factors is concerned both additive and multiplicative parity correction factors were equally efficient when age is expressed in terms of parity. Hence either of these methods may be preferred in sire evaluation programmes to obtain accurate estimates of sire’s breeding values and to increase efficiency of selection.
Educational Use Research
Education Level UG and PG
Learning Resource Type Thesis
Size (in Bytes) 630.05 kB