GLOBAL - Global warming will pressure cattle productivity and welfare as heat stress becomes a growing issue, but experts are quick to note that help is at hand.
A wide variety of phenotypes exist that can abate heat stress, a risk that was costing the US cattle industry $369 million each year around 2003.
According to an Oklahoma State University literature review, research dating back decades illustrates that fatter, blacker, more excitable cattle could be bred out with beneficial impacts on heat tolerance.
These are part of an armoury of techniques cattle producers have, including the “slick hair gene”, which was mapped to chromosome 20 in Senepol cattle. Also present in the Spanish Criollo breeds, this Gene was introgressed into Holstein, among others.
Research has demonstrated the importance of hair shedding, a heritable trait, to winter coats, with cows shedding over 50 per cent of their coat before June 1 had calves weighing 11kg more than cows that did not shed their coast as quickly.
And in terms of body condition score (BCS), one score can mean a ten per cent change in stress level.
- Dark skin has 93 per cent thermal absorption, compared to non-pigmented skin at 43 per cent, which is why dark cattle so readily seek shade.
- Excitable animals have been found to be 3.2 per cent more stressed than calmer counterparts, with weight gain suffering as a result.
- Incorporating Bos Indicus genetics increases heat tolerance at some loss to performance.
- Herefords sweat more and have higher rectal temperatures than Brahmans.
- Crossing Bos Indicus genetics into a cow herd is a weapon against the heat and has the “added bonus” of maternal heterosis which can provide dramatic improvements in lowly heritable traits like fertility.