Lactation pattern of dairy cattle in a multibreed dairy population in central Thailand | เธฅเธฑเธเธฉเธเธฐเธเธฒเธฃเนเธซเนเธเธฅเธเธฅเธดเธเธเนเธณเธเธกเนเธเธเธฃเธฐเธเธฒเธเธฃเนเธเธเธกเธซเธฅเธฒเธเธซเธฅเธฒเธขเธเธฑเธเธเธธเนเนเธซเนเธเธซเธเธถเนเธเนเธเนเธเธเธ เธฒเธเธเธฅเธฒเธเธเธญเธเธเธฃเธฐเนเธเธจเนเธเธข
2008
Amena Seangjun(Kasetsart University. Bangkhen Campus, Bangkok (Thailand). Faculty of Agriculture. Department of Animal Science) E-mail:[email protected] | Skorn Koonawootrittriron(Kasetsart University. Bangkhen Campus, Bangkok (Thailand). Faculty of Agriculture. Department of Animal Science) E-mail:[email protected]
Monthly tested-day samples (5,713 records) of 520 dairy cattle raised by 108 farmers in Central Thailand were used to study characteristic of lactation pattern, which were initial yield (INT), peak yield (PEK), days in peak (DIP), persistency (PST), and 305-d milk yield (MY). Breed groups were classified by Holstein fraction as BG1 (Holstein) BG2 (0.9687 LT= H LT 1.00) BG3 (0.9375 LT= H LT 0.9687) BG4 (0.875 LT= H LT 0.9375) and BG5 (0.50 LT= H LT 0.875). The studied model was multiple-trait animal model that has contemporary group (i.e., herd x year x season), calving age, breed group, and heterosis being as fixed effects, and the random effects were animal and residual. Variance and covariance components were estimated using Average Information-Restricted Maximum Likelihood procedure and then those estimates were used to obtain heritability and genetic correlation. The results revealed that cows in this population has 14.90 +- 6.22 kg for INT, 18.58 +- 5.67 kg for PEK, 40.75 +- 32.93 days for DIP, 6.62 +- 0.88 for PST, and 4,056.98 +- 1,261.58 kg for MY. Herd x year x season had influence on lactation pattern (P LT 0.01) except for DIP (P GT 0.05). Breed group had influenced only on INT (P LT 0.01). Cows in BG1, BG2, BG3, and BG4 had similar lactation pattern but different from BG5 especially for INT and PEK. Heterosis occurred from mating between sire and dam of dairy cattle had influence on INT (P LT 0.01) and PEK (P LT 0.05). Heritability estimates were 0.06 for INT, 0.08 for PEK, 0.01 for DPI, 0.11 for PST, and 0.14 for MY. Genetic correlations between MY and INT, PEK, DIP, and PST were 0.32, 0.32, 0.05, and 0.08 respectively. These results implied chance to increase milk production by improving some traits of lactation pattern (i.e., INT and PEK) from genetic selection and farm management.
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