Wednesday, October 25, 2017

Coat Color Matters

From the Oct-Nov 2017 Beef Route Letter

It is one of the great ironies of the current club-calf scene, that “hair” may be the primary selection trait.
Not “beef” yield, for edible meat cuts;  not “hides” for leather;  not “bones” for fertilizer.    Just inedible and unsalable “hair coat”, so important to the final fitting process at our club shows and sales.

Why do I bring this up?    Not necessarily because of “certified Angus beef” which has created a demand for “black” cattle, earning slaughter market premiums in hopes that the promoted carcass advantages of Angus would be present.   

No, it is because of the latest trends in Genetic (genotype, genomic) DNA research.

Black coloration of cattle is due to the presence of the MC1R (Melanocortin 1 Receptor) gene, which encodes a receptor located on Chromosome 18 that is needed for black pigmentation “and also has other functions” according to two researchers at Iowa State University college of Veterinary Medicine.

Black (MCR) is always dominant to the other alleles at the E locus.   Non-black (mcr) color is recessive (which is why other breeds, red, yellow, with or without white spots turned black so easily when bred to Angus to gain that black hair coat).     Like the black hair gene, the non-black gene has other functions which the ISU-CVM research find to be very beneficial.

It seems the “non black” cattle have a gene-encoded resistance to Salmonella and E.-Coli infections.  If exposed to either of those lethal diseases, their genotypes have natural resistance;  if vaccinated against these pathogens they develop useful titres;  if treated with antibiotics they metabolize them faster (which reduces withdrawal times) and they have a higher pain threshold (less likely to go off feed when ill).

Ironically, this DNA capability is lacking in the MC1R gene which provides the black hair.   Therefore, breeding for “black” in all the non-black hair breeds has passed a latent genetic effect across 70% of the total beef cattle population in the USA.

Genomics started out as a way to predetermine genetic values from DNA samples prior to actual animal performance and subsequent data evaluation.    These uses matured fairly quickly; now the bulk of DNA research is seeking out answers to more physiological and health-related issues such as ability to get an immunity from vaccination, or response to various drug therapies for typical herd problems.

Dominant and Recessive gene activity was already known in all breeds (dominant polled vs recessive horns;  dominant black vs recessive red hair) but now we are finding cases of linkages of effects as in this occlusion between black hair and specific disease susceptibility.   

Possible benefit to non-black breeds

The popularity of non-black cattle is greatest in commercial beef production, often the range managed herds, where minimum human handling is possible.    Could better health experience be part of this ??   
The cattle industry has always included highly observant breeders alongside data driven commercial producers, with some synergy resulting (given 90% of range cattle are bred naturally, only 10% AI).

It remains for our club calf judges to open up the opportunity for good red, roan, yellow, white cattle.

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