BeefxDairy breeding values
NAV breeding values for AI beef bulls evaluated on their crossbred offspring from dairy cows (so called BeefxDairy or BxD breeding values) can be used by dairy farmers to select beef bulls across breed for producing crossbred calves that are easily born and have a good growth and carcass quality. Crossbred calves included in the evaluation are from purebred Holstein, Jersey and RDC cows. Up to eight single BxD breeding values can be published for each bull if the publication rules are fulfilled. The single breeding values are combined with economic weights into one of two sub-indices, Birth or Growth, which are further combined into the Nordic BeefxDairy Index (NBDI).
For the breeding values and indices to be published two publication criteria have to be fulfilled;
- A required level of reliability of breeding values for each trait group
- A one-time fee for the AI bull payed by the bull owner/importer of semen. The fee system was introduced 1st of January 2020. Currently, the fee is 1300 euro per bull and NAV will contact owner/importers to bulls that have high enough reliability to be published.
4 breeding values for calving traits: Calf survival and calving ease based on cows in 1st and later lactations, respectively. All four breeding values can be published if the bull has a minimum reliability of 50 for breeding value for either calf survival or calving ease in later lactations. Information of calf size is used as an indicator trait in the evaluation (only available from Denmark).
3 combined breeding values for carcass traits: Daily carcass gain, carcass conformation score and carcass fat score. Carcass gain is based on combining breeding values for bulls and heifers with short (<550 days) and long fattening period, respectively, with equal weights. Conformation and fat score are based on combing breeding values for bulls and heifers with equal weights. All three breeding values can be published if the bull has a minimum reliability of 50 for breeding value for carcass conformation score.
3 breeding values for youngstock survival: Early period, late period and youngstock survival, a combination index based on equal weights of both first breeding values, Breeding value for early period is based on the survival of bull’s progeny between day 1 to day 30 and the late period is based on the survival of bull’s progeny between day 31 to day 200. All three breeding values are published when bull’s reliability for late period is 50 % or it has at least 500 offspring or published breeding values for calving and growth traits.
Gestation lenght, cow describes bull’s calves gestation lenght when the dam is calved at least once. Breeding values for gestation lenght are expressed in days and as a deviation from a standard dairy gestation length mean fixed at 280 days. Breeding values for gestation length, cow are published if the beef bull has got official breeding values for calving traits and reliability for gestation length is higher than 50%.
Nordic BeefxDairy Index
The Nordic BeefxDairy Index (NBDI) describes a beef bull’s economic value based on genetic potential for producing crossbred beef-dairy offspring that give the farmers the best economy. It is currently composed of two sub-indices, Birth and Growth. The length and intensity of the rearing affects the economic values of the growth traits. Each bull gets different values both for the sub-index Growth and for the total merit index NBDI depending on rearing period short (<550 d) or long (>550d). In general, short rearing period is applied in Denmark and long rearing period in Finland and Sweden.
Birth index includes two breeding values, calf survival and calving ease in later lactations, combined with economic weights.
Growth index, short or long, includes three breeding values, daily carcass gain, carcass conformation score and carcass fat score, combined with economic weights.
NBDI, short or long, includes birth index and growth index, short or long, combined with economic weights. How the different breeding values are combined into NBDI is the result of thorough economic calculations and expectations on future production conditions and price relations.
Making the decisions of which AI beef bull to use in your dairy herd based on NBDI gives crossbred calves that are easily born and with good growth and carcass quality. It gives progress in all included traits. With NBDI you are breeding for improved profit.
NAV BxD breeding values were first published in December 2018 and replaces earlier national breeding values for beef bulls evaluated on dairy cows that have been available nationally in Denmark and Sweden, respectively. From 2019 and onwards BxD breeding values are published four times a year in connection to NAV evaluations for dairy (February, May, August and November). NBDI and sub-indices for Birth and Growth were first published in November 2019. The newest results can be viewed at the web page NAV Beef Search.
The search page contains all publishable breeding values and other relevant information for the AI beef bulls included in the evaluation. The user has to select the appropriate rearing period (short or long) to get the result. By default the results will show beef sires of all breeds born in all countries and be sorted on NBDI. However, it is possible to set the search criteria to create top lists of your preference and also to search for individual bulls.
NAV BxD breeding values and sub-indices are standardized to an average breeding value of 100 and a standard deviation of 10. NBDI is standardized to an average breeding value of 0 and a standard deviation of 10.