Global warming is a concern that affects all of mankind; recently, this has been extended to cattle-kind as well. Compounded by the intensification of production and increase in cattle population, the effect of heat stress on cows has become one of the most pressing concerns of the dairy industry. Ironically, this problem is one of their own making: cattle ranching has played no small part in increasing deforestation and greenhouse gas emissions.
More susceptible to heat stress due to their selectively bred higher milk yields, New Zealand cows have already become heat stressed for 20% of their milking time. This halves yields, as their immediate coping mechanism is to reduce DMI, decreasing the availability of nutrients used for milk synthesis. Furthermore, it also reduces fertility, an issue as dairy cows need to have a calf every year or so to maintain milk production.
A cow with grey patches instead of black has been created using CRISPR genome editing to reduce the heat absorption of cows. Goetz Laible at AgResearch in New Zealand used CRIPSR to change a gene called PMEL, which is involved in pigmentation, to one more similar to Highland beef cattle with lighter coats. Other teams are creating more heat-tolerant cattle with a gene variant for shorter hair.
The future looks bright and somewhat cooler for cattle, but the cause of the issue should be addressed: livestock farming produces about 18% of global emissions. Instead of editing the genomes for pigmentation, perhaps the genomes of bacteria that produce methane inside the cows should be edited instead.
