Genomics: The new tool for the 21st Century
NEW DNA TEST COULD PROVIDE KEY TO PROFIT "Testing for the leptin gene in livestock is a new cutting edge proposition associated with DNA gene markers. The IGENITY-L™ test, provided by Merial, allows producers to utilize yet another tool in beef production to improve carcass merit. “Leptin is a protein produced in white fat tissue and the more leptin produced, the stronger the signal is sent to the brain to reduce appetite,” Tate says. “The leptin protein is directly related to appetite, energy utilization and fat deposition.” (Clifford, 2005).
RFI (Residual Feed Intake) tests for feed efficiency in animals. For example: If Bull A eats less and gains the same as Bull B then Bull A will have a negative RFI number and is considered more feed efficient. "An efficient bull will pass on superior genetics for feed efficiency to his progeny, which will be realized as feed savings for calves in the feedlot and for replacement heifers entering the cowherd." (From: http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/agdex10861).
The Effect of Leptin on Average Daily Gain and Feed Efficiency:
The particular gene being examined produces leptin, which is associated with appetite. Cattle with the fully mutated form of leptin (genotype TT) put on weight faster than those with the slightly mutated form (genotype CT) which put on weight faster than those with the non mutated form of leptin (genotype CC). (From: http://www.innovationplace.com/thescene/news/56.html)
Yield Grade:
Although the results vary in terms of the proportion that grade AAA or higher, the trend has always been the same: TT cattle have a much higher chance of AAA, or in the USA system "choice".
(DNA Studies Genes Affecting Meat Quality in Beef Cattle. Department of Animal and Poultry Science, University of Saskatchewan, Available at: http://homepage.usask.ca/~schmutz/leptin.html)
Milk Production:
Prior research indicates that a SNP at position 305 of exon 2 in the leptin gene affects milk production in dairy cows. Dairy cows with at least one copy of the T allele have been shown to have higher milk production than CC cows. If that effect carries over to beef breeds, it is reasonable to expect that CT and TT beef cows will wean heavier calves than CC beef cows. We tested this hypothesis for a herd of mixed breed cows using anova. Results indicated that both crossbred CT and TT beef cows wean significantly heavier beef calves than CC crossbred beef cows. (Anim Genet. 2008 Jun;39(3):284-6. doi: 10.1111/j. The impact of a leptin gene SNP on beef calf weaning weights. DeVuyst EA, Bauer ML, Cheng FC, Mitchell J, Larson D.)
The Effect of Leptin on Lactating Beef Cows and Calf Weaning Weights:
NEW DNA TEST COULD PROVIDE KEY TO PROFIT "Testing for the leptin gene in livestock is a new cutting edge proposition associated with DNA gene markers. The IGENITY-L™ test, provided by Merial, allows producers to utilize yet another tool in beef production to improve carcass merit. “Leptin is a protein produced in white fat tissue and the more leptin produced, the stronger the signal is sent to the brain to reduce appetite,” Tate says. “The leptin protein is directly related to appetite, energy utilization and fat deposition.” (Clifford, 2005).
RFI (Residual Feed Intake) tests for feed efficiency in animals. For example: If Bull A eats less and gains the same as Bull B then Bull A will have a negative RFI number and is considered more feed efficient. "An efficient bull will pass on superior genetics for feed efficiency to his progeny, which will be realized as feed savings for calves in the feedlot and for replacement heifers entering the cowherd." (From: http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/agdex10861).
The Effect of Leptin on Average Daily Gain and Feed Efficiency:
The particular gene being examined produces leptin, which is associated with appetite. Cattle with the fully mutated form of leptin (genotype TT) put on weight faster than those with the slightly mutated form (genotype CT) which put on weight faster than those with the non mutated form of leptin (genotype CC). (From: http://www.innovationplace.com/thescene/news/56.html)
- Leptin positive animals finish for slaughter approximately 37 days faster and had an ADG of 3.323 compared with non-positive animals that had an ADG of 2.937.
- Leptin positive animals also exhibit a greater feed efficiency (6.4) compared to non-positive animals (8.2). (Quantum Management Protocol)
Yield Grade:
Although the results vary in terms of the proportion that grade AAA or higher, the trend has always been the same: TT cattle have a much higher chance of AAA, or in the USA system "choice".
(DNA Studies Genes Affecting Meat Quality in Beef Cattle. Department of Animal and Poultry Science, University of Saskatchewan, Available at: http://homepage.usask.ca/~schmutz/leptin.html)
Milk Production:
Prior research indicates that a SNP at position 305 of exon 2 in the leptin gene affects milk production in dairy cows. Dairy cows with at least one copy of the T allele have been shown to have higher milk production than CC cows. If that effect carries over to beef breeds, it is reasonable to expect that CT and TT beef cows will wean heavier calves than CC beef cows. We tested this hypothesis for a herd of mixed breed cows using anova. Results indicated that both crossbred CT and TT beef cows wean significantly heavier beef calves than CC crossbred beef cows. (Anim Genet. 2008 Jun;39(3):284-6. doi: 10.1111/j. The impact of a leptin gene SNP on beef calf weaning weights. DeVuyst EA, Bauer ML, Cheng FC, Mitchell J, Larson D.)
The Effect of Leptin on Lactating Beef Cows and Calf Weaning Weights:
|
Spring
Initial Cow Body Wt (lbs) Fall Final Cow Body Wt (lbs) Change in Cow Body Wt (lbs) Calf Weaning Wt WPDA lbs/day TT positive calves wean off extra (lbs) |
CC
1369 1410 41 603 2.95 |
CT
1334 1397 63 614 2.95 |
TT
1322 1400 78 634 3.02 +31 |
(Quantum Management Protocol)
*Quantum Genetics: 25th International Alltech Animal Health and Nutrition Symposium, May 18, 2009
*Quantum Genetics: 25th International Alltech Animal Health and Nutrition Symposium, May 18, 2009
Residual Feed Intake Research:
RFI = The difference between actual intake and expected intake given the animal's level of performance - negative values imply greater efficiency.
- Herd, R. M. & Arther, P. F. (2014). Psychological basis for risidual feed intake. Journal of Animal Science. Available: https://www.animalsciencepublications.org/publications/jas/pdfs/87/14_suppl/0870064
- Beef Cattle Research Council - Genetic Improvements in Feed Efficiency. Available: http://www.beefresearch.ca/research-topic.cfm/genetic-improvements-in-feed-efficiency-57?language=&print
- Residual Feed Intake: a System for Efficiency. Available: http://www.thebeefsite.com/articles/1675/residual-feed-intake-a-system-for-efficiency/
Research on Leptin:
- Buchanan, F.C., A. G. Van Kessel, C. Waldner, D. A. Chris-tensen, B. Laarveld and S. M. Schmutz. 2003. “An Association Between a Leptin Single Nucleotide Polymorphism and Milk and Protein Yield,” Journal of Dairy Science 86: 3164-3166.
- Bullinger, J. R., DeVuyst, E. A., Bauer, M. L., Berg, P. T. and Larson, D. M. 2006. An economic analysis of genetic information: Leptin genotyping in fed cattle. Agribusiness & Applied Economics Report No. 581
- DeVuyst, E.A., M. Bauer, Fu-Chih Cheng, J. Mitchell and D. Larson, 2008. “The Impact of Leptin Gene SNP 305 on Beef Calf Weaning Weights,” Animal Genetics 39:284-286.
- DeVuyst, E.A., J. Bullinger,, M. Bauer, P. Berg and D. Larson. 2007. “An Economic Analysis of Genetic Information: Leptin Genotyping in Fed Cattle,” Journal of Agricultural and Resource Economics 32(2): 291-305
- DeVuyst, E. A. The Economics of Gene Testing Cattle. Available: http://pods.dasnr.okstate.edu/docushare/dsweb/Get/Document-5557/AGEC-255web.pdf
- Department of Animal Science, University of Saskatchewan (nd). DNA Studies of Leptin and Meat Quality (2006) Available at: http://homepage.usask.ca/~schmutz/leptin.html
- T. W. Geary, E. L. McFadin, M. D. MacNeil, E. E. Grings, R. E. Short, R. N. Funston and Leptin as a predictor of carcass composition in beef cattle. Available at: http://jas.fass.org/content/81/1/1.full.pdf+html
- Mitchell, Clifford (2005) NEW DNA TEST COULD PROVIDE KEY TO PROFIT. Cattle Today. Available at: http://www.cattletoday.com/archive/2005/September/CT418.shtml
- Mitchell, J., E.A. DeVuyst, M.L. Bauer, and D.L. Larson. 2009. “Cow-Calf Profitability and Leptin Genotyping,” Agricultural Economics, 40:113-118.
- Kononoff, P.J., H.M Deobald, E.L. Stewart, A.D. Laycock and F.L.S. Marquess. 2005.“The effect of a leptin single nucleotide polymorphism on quality grade, yield grade and carcass weight of beef cattle,” Journal of Animal Science 83: 927-932
- Herd, D.B., and L.R. Sprott. “Body Condition, Nutrition and Reproduction of Beef Cows.” Texas Agricultural Extension Service, College Station, Texas: The Texas A&M University System. "TT cattle may be ‘easier fleshing’ (apt to carry more external body fat). Cattle with greater fleshing ability are much preferred from a maternal standpoint. The amount of external fat is the primary determinant of a cows body condition score (BCS). On average, females with a higher BCS will produce heavier calves, have a shorter calving interval, and more longevity"