Progress 09/01/04 to 08/31/06
Outputs
Holstein cattle that carry and express the Slick hair gene along with normal-haired siblings were produced in about 20 herds in Puerto Rico and additional animals were born in a large Florida dairy through the use of semen collected from upgraded Holstein bulls that were heterozygous for this dominant gene. Studies conducted in a south Florida dairy suggest that slick-haired cows maintain significantly lower rectal temperatures and respiration rates than their normal-haired siblings. A preliminary study of the sweating rates of slick and normal-haired siblings along with normal-haired contemporary Holsteins indicated a significantly higher sweating rate for the slick-haired cows along all groups had relatively low sweating rates under the high ambient humidity of this farm in southern Florida. It is possible that under environments with lower humidities that the impact of higher sweating capacities could be much greater. Another study of young Holstein bulls (87.5%
Holstein) with and without the Slick hair gene under a grazing system showed the same lower respiration rates of the slick-haired bulls which also tended to have lower rectal temperatures (neither group was highly heat-stressed). The slick-haired bulls also grazed longer during the morning hours and began grazing again earlier during the afternoon than did their normal-haired siblings. The slick-haired bulls also gained more during the grazing trial than did their normal-haired siblings. An important part of this overall study will be the evaluation of the fertility and milk yield of cows with and without the Slick hair gene in Florida and Puerto Rico but insufficient data is available to date to make a valid evaluation of these traits. Data from another research study involving slick-haired cattle in Venezuela showed that the slick-haired cows milked 1000 kg more than their normal-haired sisters while at the same time calving back 42 days quicker in a semi-arid environment. In order
to develop genetic markers to distinguish between cattle that are homozygous from those that are heterozygous for the Slick hair gene it is necessary to locate the mutation responsible for this condition in the bovine genome. A DNA pooling study followed by individual genotyping and interval mapping has been used to confirm the location of the gene to BTA20. Two point linkage analysis indicated that the location of the peak was closer to 55 cM than 60 cM predicted from multipoint analysis on the same data. Further inspection of the haplotypes in all of the eight sires and their grand-daughters revealed the presence of a tightly conserved haplotye block at markers DIK2416 and NRDIKM023. The results indicate the localization of the slick gene to a 1.4 cM interval and should enable its utilization for identifying homozygous breeding stock. Identification of a useful marker for the Slick hair gene will not only aid in the development and use of slick-haired Holsteins but should also be
useful to breeders of Senepol and other slick-haired breeds used in other parts of the world.
Impacts
As the world warms and attempts are made to produce milk and other products from cattle under increasing heat stress, it will be very useful to incorporate a gene which reduces heat stress both for the physical well-being of the cattle as well as to reap the economic benefits associated with reduced stress. Such benefits would be due to a higher feed efficiency and increased embryo survival rate from late May through September and for longer periods of time in Puerto Rico and other more tropical areas.
Publications
- Chase, C.C., Jr., M. Mariasegaram, J.X. Chaparro, T.A. Olson, R.A. Brenneman, and R.P. Niedz. 2006. Maping the locus causing the slick phenotype in Senepol-derived cattle. (Abstract presented at the Plant and Animal Genome XIV Conference, San Diego, California, January 14-18, 2006.)
- Mariasegaram, M., C.C. Chase, Jr., J.X. Chaparro, T.A. Olson, and R.P. Niedz. 2006. Interval mapping confirms Slick hair gene localization to bovine chromosome 20. (Abstract presented at the Plant and Animal Genome XIV Conference, San Diego, California, January 14-18, 2006.)
- Olson, T. A., C.J. Lucena, C.C. Chase, Jr., and A.C. Hammond. 2003. Evidence of a major gene influencing hair length and heat tolerance in Bos taurus cattle. J. Anim. Sci. 81:80-90.
- Olson, T.A., C.C. Chase, Jr., M. Mariasegaram, C. Lucena and E. Godoy. 2006. A history of the evaluation of the Slick hair gene. Invited presentation given at the Southern Section meetings of the American Society of Animal Science to be held in Orlando, FL February 4-8, 2006. An abstract will be published in the J. Anim. Sci.
- Olson, T.A., C.C. Chase,Jr., C. Lucena, E. Godoy, A. Zuniga, and R. J. Collier, 2006. Effect of hair characteristics on the adaptation of cattle to warm climates. 8th World Congress on Genetics Applied to Livestock Production, August 13-18, Belo Horizonte, MG, Brasil.
|
Progress 10/01/04 to 09/30/05
Outputs
Cows sired by 75% Holstein:25% Senepol bulls, and thus 7/8 Holstein in breed composition, began to calve for the first time at McArthur Farms in south Florida and also at the Dairy Research Unit of the University of Florida. These cows were approximately 50% slick-haired and 50% normal-haired. Most of these cows calved from October through March and, thus, not at the time when they would have most benefited from increased heat tolerance. Data collected during the summer months of 2005 on these cows in south Florida indicated that the slick-haired cows did maintain lower rectal temperatures and lower respiration rates. The slick-haired cows also had higher sweating rates than did their normal-haired paternal half sisters. Preliminary analyses of their milk yield, however, did not demonstrate that this was translated into higher milk yields or reproductive rates as has been indicated by a major study involving cattle with the Slick hair gene in Venezuela. Semen has been
collected from additional slick-haired Holstein bulls (now with higher genetic potential for milk yield and some possibly homozygous for the Slick hair gene) and is being utilized in several herds throughout the state of Florida. Additional 15/16 Holstein calves with the Slick hair gene and sired by the highest TPI (Type-Production-Index) bull in the Holstein breed in 2004 were produced via both embryo transfer and artificial insemination programs. In Puerto Rico, additional calves were born from slick-haired Holstein bulls in a number of private dairies and the oldest of the heifers born previously were inseminated. Also, efforts were made to utilize superovulation and embryo transfer to produce progeny (using semen from elite registered Holstein bulls) of slick-haired Holstein cows apparently derived from upgrading to Holstein of slick-haired Puerto Rican criollo cows. Unfortunately these procedures were not successful and will be repeated. We were able to locate the genomic
location of the Slick hair gene on Bovine Chromosome 20 as a result of research associated with this project. Subsequent research should allow us to identify very closely linked markers that will be useful in identifying sires that are homozygous for this dominant gene and, as a result, will only sire slick-haired, heat tolerant progeny.
Impacts
The effect of heat stress in southern areas of the U.S. and throughout the subtropical and tropical areas of the world limits the use of the superior genetics of registered Holstein cattle as such animals are not adapted to the high heat, humidity and external parasites of these regions. The slick hair gene has previously been shown to allow cattle to maintain lower body temperatures while under heat stress. We expect that this ability, when transferred into high-producing Holstein cows, will allow them to produce more milk with greater efficiency of production while under heat stress. We also expect that slick-haired cows will have a higher embryo survival rate while under heat stress.
Publications
- Chase, C.C., Jr., M. Mariasegaram, J.X. Chaparro, T.A. Olson, R.A. Brenneman, and R.P. Niedz. 2006. Maping the locus causing the slick phenotype in Senepol-derived cattle. (Abstract to be presented at the Plant and Animal Genome XIV Conference, San Diego, California, January 14-18, 2006.)
- Mariasegaram, M., C.C. Chase, Jr., J.X. Chaparro, T.A. Olson, and R.P. Niedz. 2006. Interval mapping confirms Slick hair gene localization to bovine chromosome 20. (Abstract to be presented at the Plant and Animal Genome XIV Conference, San Diego, California, January 14-18, 2006.)
- Olson, T.A., C.C. Chase, Jr., M. Mariasegaram, C. Lucena and E. Godoy. 2006. A history of the evaluation of the Slick hair gene. (Invited presentation to be given at the Southern Section meetings of the American Society of Animal Science to be held in Orlando, FL February 4-8, 2006. An abstract will be published in the J. Anim. Sci.)
|
Progress 10/01/03 to 09/30/04
Outputs
The process of generation of slick and normal-haired sibling heifers continued during the past year in both Florida and in Puerto Rico. Approximately 200 heifers have been born from Holstein cows and sired by predominantly Holstein sires (75% and greater)that are heterozygous for the slick hair gene have been born at McArthur Farms in southern Florida. Approximately half of these heifers are slick-haired and half are normal-haired. The oldest of these heifers have begun to calve during the late summer and early fall and production, reproduction and health data are beginning to be collected on these cows. Thirty-nine heifers from this south Florida herd were transferred to the Dairy Research Unit (DRU) of the University of Florida where more intense evaluation of their heat tolerance relative to normal-haired Holsteins will be conducted. Five slick-haired, seven-eigths Holstein heifers from the DRU group were superovulated and had embryos collected from them which
subsequently were transferred into recipient females. A group of 11 ET calves were born in the spring of 2004 which included red and white, slick-haired bulls and heifers that may be homozygous for the slick hair gene. Also, slick-haired, fifteen-sixteenths Holstein calves were born sired by BW Marshall, an elite Holstein sire. In Puerto Rico about 60 heifer calves have been born to date sired by three-quarters Holstein, slick-haired bulls in various herds. In addition, seven slick-haired Holstein cows have been assembled in the University of Puerto Rico herd from private herds. A slick-haired son of one of these cows has been identified for future use in both Florida and Puerto Rico. Data from Venezuela relevant to this study has been analyzed during this period. Approximately 100 slick-haired 75% Holstein: 25% Carora first lactation cows were compared with approximately 100 normal-haired first lactation cows of the same breed composition and age, sired by the same registered
Holstein bulls, and from the same Carora X Holstein F1 dams. The slick-haired females produced approximately 1000 liters more milk and calved back approximately 40 days earlier than their normal-haired siblings.
Impacts
The effect of heat stress in southern areas of the U.S. and throughout the subtropical and tropical areas of the world limits the use of the superior genetics of registered Holstein cattle as such animals are not adapted to the high heat, humidity and external parasites of these regions. The slick hair gene has previously been shown to allow cattle to maintain lower body temperatures while under heat stress. We expect that this ability, when transferred into high-producing Holstein cows, will allow them to produce more milk with greater efficiency of production while under heat stress. We also expect that slick-haired cows will have a higher embryo survival rate while under heat stress.
Publications
- No publications reported this period
|
|