A comparison of different measures of persistency with special respect to variation of test-day milk yields |
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| Affiliation: | 1. Institut für Nutztierwissenschaften, Abteilung Tierzucht, Universität für Bodenkultur, Gregor-Mendel-Strasse 33, A-1180 Wien Austria;2. Zentrale Arbeitsgemeinschaft Österreichischer Rinderzüchter, Gumpendorferstrasse 15/II/2, A-1060 Wien Austria;1. Centre for Genetic Improvement of Livestock, Department of Animal Biosciences, University of Guelph, Guelph, ON, Canada, N1G 2W1;2. Department of Animal Sciences, Purdue University, West Lafayette, IN 47907;3. Canadian Centre for Swine Improvement Inc., Ottawa, ON, Canada, K1A 0C6;4. Institute of Genetics, Vetsuisse Faculty, University of Bern, 3001 Bern, Switzerland;1. Cátedra de Producción de Leche, Facultad de Ciencias Agropecuarias, Universidad Nacional de Córdoba, Córdoba 5000, Argentina;2. Consejo Nacional de Investigaciones Científicas y Técnicas, Córdoba 5000, Argentina;3. Intensive Livestock Industries, NSW Department of Primary Industries, Elizabeth Macarthur Agricultural Institute, Menangle NSW 2568, Australia;4. Cátedra de Estadística y Biometría, Facultad de Ciencias Agropecuarias, Universidad Nacional de Córdoba, Córdoba 5000, Argentina;5. Department of Animal Science, University of California, Davis 95616;6. Dairy Science Group, School of Life and Environmental Sciences, Faculty of Science, The University of Sydney, Camden NSW 2570, Australia;1. Department of Agronomy, Food, Natural Resources, Animals and Environment, University of Padova, Viale dell’Università 16, 35020 Legnaro, Padua, Italy;2. School of Agriculture and Environment, Massey University, Private Bag 11 222, Palmerston North 4442, New Zealand;1. Université Paris-Saclay, INRAE, AgroParisTech, UMR GABI, 78350 Jouy-en-Josas, France;2. Université Paris-Saclay, INRAE, AgroParisTech, UMR MoSAR, 75005 Paris, France;1. Department of Biotechnology, GLA University, Mathura, Uttar Pradesh, 281406, India;2. Department of Pathology, Deen Dayal Upadhyay Pashu Chikitsa Vigyan Vishwavidyalaya evam Go Anusandhan Sansthan, Mathura, Uttar Pradesh, India;3. Animal Health Division, Central Institute for Research on Goats, Mathura, Uttar Pradesh, India;4. Department of Pathology, Veterinary College, Mhow, Indore, Madhya Pradesh, India;5. Amity Institute of Microbial Technology, Amity University, Jaipur, Rajasthan, India;6. National Centre for Veterinary Type Cultures, ICAR-National Research Centre on Equines, Hisar, India;1. Departamento de Zootecnia, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil;2. Embrapa Gado de Leite, Juiz de Fora, MG, Brazil |
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| Abstract: | Six measures of persistency of milk yield were compared by estimation of heritabilities, genetic correlations and the amount of concentrates required by cows with high and low persistency.Persistency was expressed as ratio between different parts of the lactation (P2:1 and P3:1), as a ratio between maximum test-day milk yield and mean test-day milk yield and as the standard deviation of the test-day milk yields of a lactation. The investigation was based on 39 349 first, 23 910 second and 13 651 third lactation records of Simmental cows from the region of Lower Austria.The heritability estimates ranged from 0.12 to 0.18 for measurements including the first 200 days of lactation and from 0.17 to 0.22 when the whole 305-day lactation was included. The largest values were found for the standard deviation of test-day milk yields (305 days); 0.21, 0.22 and 0.22 for the first, second and third lactation, respectively. Genetic correlations between lactations were high for all measures of persistency, ranging from 0.79 to 0.95. Highly persistent cows required between 69 and 161 kg less concentrate than cows with a poor persistency to produce 5500 kg of milk. The difference was generally larger when the grouping was performed on measures including 305 days of lactation vs. measures including only earlier parts of the lactation; 161 kg was found for P3:1. |
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