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- Corrales, Roldan, et al.
(författare)
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Birth weight, reproduction traits and effects of inbreeding in Nicaraguan Reyna Creole cattle
- 2011
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Ingår i: Tropical Animal Health and Production. - : Springer Science and Business Media LLC. - 0049-4747 .- 1573-7438. ; 43, s. 1137-1143
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Tidskriftsartikel (refereegranskat)abstract
- Reyna Creole cattle in Nicaragua comprise about 650 purebred animals, and the breed has been shown to have a high level of inbreeding. To characterize the breed, as basis for a conservation program, information from two herds on birth weight (BW, n = 1097), age at first calving (AFC, n = 449) and calving interval (CI, n = 1,347) was analysed. Overall averages were 27.8 kg for BW, 37.4 months for AFC and 424 days for CI. Large differences between the herds were observed for all traits. Thus, there would be opportunities for management interventions to improve reproduction results. The heritability for BW was 0.34. For CI, the heritability of 0.20 and the additive genetic standard deviation of 36 days were comparatively high values. No genetic variation was found in AFC. Estimated inbreeding effects were associated with large standard errors due to the small size of the data and incompleteness of pedigrees. Nevertheless, significant effects were shown of dam inbreeding level on all traits. For each percentage of increased inbreeding, BW decreased by 0.06 kg, AFC increased by 3.5 days and CI increased by 1.4 days. The effects of the inbreeding level of the individual itself were not significant. The relatively good reproduction traits of Reyna Creole cattle shown in this study, despite high inbreeding levels, will be supplemented with a characterization of milk production traits.
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| 2. |
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| 3. |
- Corrales, Roldan
(författare)
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Population structure and phenotypic characterization as a basis for conservation and sustainable use of Reyna Creole Cattle in Nicaragua
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The Reyna Creole cattle in Nicaragua is a local breed originating from the Bos taurus cattle brought to Latin America during the Spanish colonization in the fifteenth century. Reyna Creole cattle are today found in five herds. The primary use of the breed is to produce milk. The breed comprises about 650 purebred female animals. The main objective of the thesis was to characterize the population structure and productivity in terms of milk production and some reproduction traits, and to discuss options for conservation and improvement of the breed. The inbreeding level was 13% on average, primarily due to use of individual bulls for long periods. An effective population size of 28 to 46 animals was estimated, showing that the Reyna Creole cattle breed is endangered, close to critical status. Average birth weight was 27.8 kg, age at first calving 37.4 months and calving interval 14.0 months. Large differences between herds were observed for all traits. Heritabilities were 0.34, zero and 0.20 for the respective trait. Average lactation yield for 534 Reyna cows with 1,750 lactations was 1,319 kg with large variations between herds and time periods. Test-day records on milk yield and fat and protein contents were collected monthly during one year for three Reyna herds and two herds with crossbred cows. Commercial dairy breed crosses had the highest production, and Reyna the lowest, but large differences were noted in management between the herds. The heritability for lactation yield in Reyna cattle was 0.18. Large variation between and within the Reyna herds suggest good opportunities to increase productivity of the Reyna breed by improving management and breeding strategies. It is proposed to keep all females in the herds, develop mating plans and to apply a recording scheme for keeping pedigrees and records on reproduction and milk production traits. Only young bulls, selected from the best cows for milk production and calving interval, are proposed to be used for 1-2 years each to manage inbreeding and keep generation intervals short.
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| 4. |
- Corrales, Roldan, et al.
(författare)
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Population structure of Reyna Creole cattle in Nicaragua
- 2010
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Ingår i: Tropical Animal Health and Production. - : Springer Science and Business Media LLC. - 0049-4747 .- 1573-7438. ; 42, s. 1427-1434
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Tidskriftsartikel (refereegranskat)abstract
- Reyna Creole cattle originated from Bos taurus cattle brought to Latin America during the Spanish colonization in the fifteenth century and are the only remaining local breed in Nicaragua. However, the current genetic status of this breed is unknown. Therefore, the population structure of three recorded Reyna Creole herds in Nicaragua was studied to estimate their level of inbreeding, effective population size, and generation intervals. Data from 2,609 animals born between 1958 and 2007 were analyzed. A pedigree completeness index higher than 0.8 was required to obtain reliable estimates of the level of inbreeding, and this criterion was met for 367 animals (14%) in two herds. The average level of inbreeding was 13.0%, with values ranging from 0% to 43.8% for individual animals. One of the herds had an average inbreeding level of 21.6%, primarily due to long periods in which the same bulls were used for mating, leading to excessive frequencies of matings between closely related animals. The effective population size differed between years and ranged from 28 to 46 animals, showing that the Reyna Creole cattle breed is endangered, close to critical status. The average generation interval was 6.9 years with values as high as 19.1 years for some sires that were used for artificial insemination over a long period of time. Due to the high level of inbreeding and small population size, urgent actions are required for the development of a breeding program to protect the breed and support its sustainable utilization.
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