Back in 2006 on a field trip to Venezuela, it was observed that some Carora cows were not making use of the available shade and were happily grazing in the direct sun and considerable heat and humidity. On closer investigation, these cows were also producing sustainable and profitable yields. The following year a similar observation was made in Costa Rica with dairy cattle derived from the Senepol. These cattle were exhibiting exceptional heat tolerance and solid performance.
A few years later, the opportunity to infer heat tolerance into temperate dairy cattle began in earnest using the Senepol breed of tropical cattle. Over the following years the specific marker was identified and introgression of the Slick gene was possible to achieve purebred, heat tolerant dairy type cattle, as you see presented here. The work refining and developing the breadth and depth of herd and bloodlines continues using natural breeding.
Thermo Regulatory Genetics Limited (TRG) was formed in 2018. The company purchased the breeding programme from Dairy Solutionz (NZ) Limited and has injected capital to globalize the tropical bull team. The 250 animal NZ breeding nucleus, consisting of animals milked in New Zealand since 2011, spans several different bloodlines from US Holstein, to Crossbreed to Jersey. This allows for the development and selection of the best fit genetics for the farming systems and relative degree of heat stress of our tropical farming clients.
The Slick gene is present in several dairy clusters around the world, across NZ, the USA, Costa Rica, Venezuela, Colombia, Puerto Rico, Philippines, Thailand, Vietnam, Tanzania and Mozambique. Thermo Regulatory Genetics Limited has lead the development of the Slick nucleus in many of these markets and offers an outcross for those with established herd momentum.
Thermo Regulatory Genetics Limited owns the world's first Homozygous dairy cross breed bulls born in 2015, Pathos, Eros and Himeros, and owns the world's largest and most diverse Homozygous bull team genotypes for future farmer confidence in the breeding development.
Here's some of the supporting science and background behind Slick genetics:
The Senepol was observed to be as heat tolerant as Brahman (Bos Indicus) cattle (Hammond et al, 1994); (Olson et al, 1997). The root cause of the heat tolerance has more recently been identified as the Slick gene by Littlejohn et al (2014), which has been the topic of significant scientific interest since. Huson (2014) suggests the dominant mutation was originally derived from the Criollo breeds, and is present in the Senepol, the Carora, and the Romosinuano.
Dikmen et al (2012, 2013) found that regulation of body temperature is heritable in Holsteins. Dikmen et al (2014) also concluded Holsteins with slick hair have superior thermoregulatory ability compared with non-slick animals.
Littlejohn et al (2014) identified the specific prolactin receptor PRLR base deletion at exon 10, for which LIC has a patent pending. The newly developed DNA test clearly allows the identification of progeny with the gene introgression, allowing the development of DNA proven homozygous bulls to transmit the heat tolerance to 100% of their progeny.
The difficulty previously for breeders was in identifying which of their progeny were carriers of the Slick gene, beyond the phenotypic slick coat, and differentiating those that were homozygous from heterozygous. Recent research has moved on to quantifying its impact on productivity and value to the farmer. The first quantification of the Slick introgression to Holstein value came from Dikmen et al (2014) at the University of Florida, where the Slick versus wild type milk improvement in the summer was recorded as 4 liters per day.