An effective rotational mating scheme for inbreeding reduction in captive populations illustrated by the rare sheep breed

Within breeds and other captive populations, the risk of high inbreeding rates and loss of diversity can be high within (small) herds or subpopulations. When exchange of animals between different subpopulations is organised according to a rotational mating scheme, inbreeding rates can be restricted. Two such schemes, a breeding circle and a maximum avoidance of inbreeding scheme, are compared. In a breeding circle, flocks are organised in a circle where each flock serves as a donor flock for another flock, and the same donor–recipient combination is used in each breeding season. In the maximum inbreeding avoidance scheme, donor¿recipient combinations change each year so that the use of the same combination is postponed as long as possible. Data from the Kempisch Heideschaap were used with computer simulations to determine the long-term effects of different breeding schemes. Without exchanging rams between flocks, high inbreeding rates (>1.5% per year) occurred. Both rotational mating schemes reduced inbreeding rates to on average 0.16% per year and variation across flocks in inbreeding rates, caused by differences in flock size, almost disappeared. Inbreeding rates with maximum inbreeding avoidance were more variable than with a breeding circle. Moreover, a breeding circle is easier to implement and operate. Breeding circles are thus efficient and flexible and can also be efficient for other captive populations, such as zoo populations of endangered wild specie

Perspectives of genomics for genetic conservation of livestock

Genomics provides new opportunities for conservation genetics. Conservation genetics in livestock is based on estimating diversity by pedigree relatedness and managing diversity by choosing those animals that maximize genetic diversity. Animals can be chosen as parents for the next generation, as donors of material to a gene bank, or as breeds for targeting conservation efforts. Genomics provides opportunities to estimate diversity for specific parts of the genome, such as neutral and adaptive diversity and genetic diversity underlying specific traits. This enables us to choose candidates for conservation based on specific genetic diversity (e.g. diversity of traits or adaptive diversity) or to monitor the loss of diversity without conservation. In wild animals direct genetic management, by choosing candidates for conservation as in livestock, is generally not practiced. With dense marker maps opportunities exist for monitoring relatedness and genetic diversity in wild populations, thus enabling a more active management of diversity

Hoornloze koeien in aantocht

Hoornloosheid komt bij enkele koeienrassen voor. Om het in de huidige melkkoe in te fokken, zou een fokprogramma hulp kunnen bieden. De veehouderij vindt gebruik van zo'n programma prima, de gemiddelde burger is daar wat terughoudender in en ook meer verdeeld

Grassland Bird Nest Predation and Artificial Nest Use

Grassland bird conservation should be a priority in the northeastern United States because many grassland species have declined since 1966. During 2004 and 2005, I examined rates of depredation on artificial grassland bird nests in two cool season grasslands, I (98 ha= large) and C (8.5 ha= small), at Iroquois National Wildlife Refuge (INWR). I established 50 m by 50 m gridded study plots in each grassland. One artificial nest was randomly placed in each grid section, and baited with a House Sparrow (Passerdomesticus) egg; half of the nests also received a clay egg to aid in identification of nest predators. Concurrently, I searched for and monitored real nests of Savannah Sparrows (Passercu/us sandwichensis) and Bobolinks (Dolichonyx oryzivorus). Vegetation measurements included percent cover, total hits of vegetation on a narrow aluminum rod and Robel pole scores. I trapped small mammals to determine small populations of species that potentially depredate nests, and I used characteristic bite marks left in the clay eggs to identify nest predators. The larger I field consistently exhibited a greater proportion of successful nests than the smaller C field. Daily survival rates of artificial nests averaged 0.914. The most frequently identified small mammal nest predator, based on clay egg bite mark identification, was Microtus pennsylvanicus, which was also the most frequently caught small mammal. In I field successful nests had significantly greater cover, higher Robel scores, and higher total hits of vegetation. In C field, there was a trend towards greater cover being related to greater nest success. Binomial logistic regression suggested that for nests in I field, year and the year*Robel interaction significantly affected nest success: 2004 nests, and those with higher Robel scores, were more successful: Year*distance to forest edge and year*cover interactions approached significance; nests placed in 2004 that were further from the forest edge and with more cover tended to be more successful. ln C field, year and distance to nearest hedgerow were the most important variables, although neither was significant and only year approached significance; nests in 2004 tended to be more successful than in 2005. Results from my study support much published data, and indicate that grassland bird nest success is greater in larger fields. Although artificial nest success increased with vegetative cover and density, these results should not be taken to indicate that managers should attempt to increase grassland density and height too much; common grassland birds in the Northeast nest preferentially in relatively low vegetation ( \u3c1 m high). My data is consistent with results from other studies that suggest that when managing for grassland birds, one should focus on not mowing too frequently, and not mowing until after nestlings have left the nest by mid July. Ideally, grassland habitat patches should be greater than 50 ha (125 acres) in size, with shapes that minimize edge effects. Leaving some dry vegetation litter that can subsequently serve as cover may be beneficial as well (Swanson 1998)

Selection for scrapie resistance decreased inbreeding rates in two rare sheep breeds in the Netherlands

An attempt to balance selection intensity and conservation of genetic diversity was made in the national program for breeding for scrapie resistance in the Netherlands. The ARR allele is associated with resistance to scrapie. In the Netherlands a breeding program was started on a voluntary basis in 2001 and starting 2004 the use of ARR/ARR rams was obligatory. In some rare breeds there were so few ARR/ARR rams that the risk of high inbreeding and associated loss of genetic diversity would be unacceptably high. Based on computer simulations predicting the inbreeding rates for several breeds exemptions on the obligatory breeding program were allowed. In this paper the ARR frequencies and associated inbreeding rates are analyzed as an indication of loss in genetic diversity during the years of scrapie selection in two breeds: the “Zwartbles schaap” (Black-blazed sheep) and the “Melkschaap” (Friesian-Zealand Milksheep)

Selectie tegen gevoeligheid voor scrapie met behoud van genetische variatie = Selection against scrapie susceptibility while maintaining within breed genetic variation

National legislation to breed for scrapie resistence was changed in 2007. The obligatory use of ARR/ARR rams was suspended in that year. Breeding for scrapie resistance is, however, still stimulated and not suspended. In this report a general advice on how to continue breeding for scrapie resistance is presented. A one day meeting on breeding in small breeds of sheep and goats provided further information and attracted much interest. A specific analysis was carried out for 2 small Dutch sheep breeds, the Black blazed sheep (Zwartbles) and the Dutch Milksheep (Melkschaap

Wenselijkheid en mogelijkheden voor het fokken van hoornloze koeien : fase 2 = Desirability and opportunities for breeding polled cattle : phase 2

Alternatives for dehorning are being sought in a set up of a breeding program taking into account demands of farmers, breeding organizations and society. This entailed balancing the speed of fixation of polledness, genetic gain in other traits and inbreeding rates. Risks have been investigated and several scenario's will be presented

Huidige staartlengte bij Clun Forest, Hampshire Down en Suffolk: startpunt voor fokken van kortere staarten

Since 2008 there is in the Netherlands a ban on tail docking in sheep. Three breeds from English origin are exempted temporarily. Mean tail length of lambs and estimated heritability are determine