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Asian-Australas J Anim Sci > Accepted Articles
DOI: https://doi.org/10.5713/ajas.19.0798    [Accepted] Published online February 25, 2020.
Genetic parameters for milk yield in imported Jersey and Jersey-Friesian cows using daily milk records in Sri Lanka (R)
Amali Malshani Samaraweera1,3,*  , Vinzent Boerner1  , Hewa Waduge Cyril4  , Julius van der Werf2  , Susanne Hermesch1 
1Animal Genetics & Breeding Unit, a joint venture between NSW Department of Agriculture and University of New England, University of New England, Armidale 2351, NSW, Australia
2School of Environmental and Rural Science, University of New England, Armidale 2351, NSW, Australia
3Uva Wellassa University, Badulla 90000, Sri Lanka
4National Livestock Development Board, Narahenpita 00500, Sri Lanka
Correspondence:  Amali Malshani Samaraweera, Tel: +61267735159, Fax: +61267733266, Email: asamaraw@myune.edu.au
Received: 15 October 2019   • Revised: 4 December 2019   • Accepted: 6 February 2020
Estimate genetic parameters for milk yield traits using daily milk yield records from parlour data generated in an intensively managed commercial dairy farm with Jersey and Jersey-Friesian cows in Sri Lanka.
Genetic parameters were estimated for first and second lactation predicted and realized 305-day milk yield using univariate animal models. Genetic parameters were also estimated for total milk yield for each 30-day intervals of the first lactation using univariate animal models and for daily milk yield using random regression models fitting second-order Legendre polynomials and assuming heterogeneous residual variances. Breeding values for predicted 305-day milk yield were estimated using an animal model.
For the first lactation, the heritability of predicted 305-day milk yield in Jersey cows (0.08 ± 0.03) was higher than that of Jersey-Friesian cows (0.02 ± 0.01). The second lactation heritability estimates were similar to that of first lactation. The repeatability of the daily milk records was 0.28 ± 0.01 and the heritability ranged from 0.002 ± 0.05 to 0.19 ± 0.02 depending on day of milk. Pearson product-moment correlations between the bull EBVs in Australia and bull EBVs in Sri Lanka for 305-day milk yield were 0.39 in Jersey cows and -0.35 in Jersey-Friesian cows.
The heritabilities estimated for milk yield in Jersey and Jersey-Friesian cows in Sri Lanka were low, and were associated with low additive genetic variances for the traits. Sire differences in Australia were not expressed in the tropical low-country of Sri Lanka. Therefore, genetic progress achieved by importing genetic material from Australia can be expected to be slow. This emphasizes the need for a within-country evaluation of bulls to produce locally adapted dairy cows.
Keywords: Dairy Cattle; 305-Day Milk Yield; Daily Milk Yields; Random Regression; Heritability; Tropical Climate

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