Main Article Content
16 526 records of the calving interval (CI) and the milk yield accumulated up to 305 d (MY305) of 5 881 Mamb? de Cuba cows (? Holstein ? Zebu), were used. The records were from four cattle units and 171 herds. The records corresponded to the period of 1981- 2006.
An univariate animal model was used, including as fixed effects the combination herd-year-calving period of four months; calving age, as
linear and quadratic covariable, and as random effects the animal, the permanent environment and the residuals, to estimate the heritability
and the repeatability of the CI. A bivariate animal model was applied to estimate the genetic and environmental correlation between the CI
and the MY305. The estimates of heritability and repeatability for the CI were of 0.06 ? 0.01 and 0.20 ? 0.01, respectively. The phenotypic
trend for the CI was of 3.13 ? 1.12 days.year-1 and the genetic trend of -1.53 ? 0.16 days.year-1. The genetic and environmental correlations between the CI and the MY305 were of 0.72 ? 0.06 and 0.01 ? 0.01, respectively. It was concluded that the increase in the phenotypic trend for the CI in the Mambi de Cuba cattle was explained by environmental causes and not by the deterioration in the genetic merit. The correlation between the CI and the MY305 was opposite, thus, the increment in the capacity of milk yield of the cows will reduce the reproductive efficiency of the herd.
Key words: Mambi de Cuba cattle, calving interval, genetic parameters, genetic trends, correlation with the milk yield.
Those authors that have publications with this journal accept the following terms:
1. They will retain their copyright and guarantee the journal the right of first publication of their work, which will be simultaneously subject to the License Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) that allows third parties to share the work whenever its author is indicated and its first publication this journal. Under this license the author will be free of:
- Share — copy and redistribute the material in any medium or format
- Adapt — remix, transform, and build upon the material
- The licensor cannot revoke these freedoms as long as you follow the license terms.
Under the following terms:
- Attribution — You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use.
- NonCommercial — You may not use the material for commercial purposes.
- No additional restrictions — You may not apply legal terms or technological measures that legally restrict others from doing anything the license permits.
2. The authors may adopt other non-exclusive license agreements to distribute the published version of the work (e.g., deposit it in an institutional telematics file or publish it in a monographic volume) whenever the initial publication is indicated in this journal.
3. The authors are allowed and recommended disseminating their work through the Internet (e.g. in institutional telematics archives or on their website) before and during the submission process, which can produce interesting exchanges and increase the citations of the published work. (See the Effect of open access).