Shedding light on dairy cow weight and the beef potential of progeny
The lack of knowledge on how selecting solely for smaller dairy cows impacts upon the beef merit of their resulting progeny has been narrowed through the publication of a recent paper in the Journal of Dairy Science.
Across the world, breeding for heavier dairy cows is often penalised on environmental or maintenance cost grounds through breeding indexes. However, a study completed in Teagasc Moorepark, in conjunction with Munster Technological University and the Irish Cattle Breeding Federation (ICBF), examined the genetic relationship between cow size traits – namely body weight, carcass weight, body condition score, carcass conformation and carcass fatness – with a host of beef performance slaughter-related traits and age at slaughter in their progeny.
Analysing over 50,000 cow and 300,000 progeny records, the study found that selecting exclusively for lighter body weight or carcass weight cows will, on average, result in lighter prime animal carcasses of poor carcass conformation, while also delaying the age of slaughter.
The above is particularly important as more animals of dairy origin enter the beef production chain, while at the same time beef processors are setting minimum standards for carcass weights and conformation specs. Additionally, given the focus on greenhouse gas emissions from agriculture, age of slaughter considerations must also be accounted for.
Despite the negative consequences on progeny carcass performance by selecting exclusively for smaller cows, Shauna Mulhall, lead author of the study, said: “While previous studies have explored the correlations among cow body weight, body condition score and cow carcass weights, no study that we are aware of has yet specifically investigated the genetic correlations between these traits and the carcass performance of the prime animals from these cows.
“Using the national database to fill this gap in knowledge helped us understand the scope that exists to breed for lighter cows who can still produce prime animals with heavier carcasses.
“The results of this study show that selecting only for lighter cows will, on average, result in lighter and less conformed prime animal carcasses, while also delaying slaughter age.
“Given this, there is the potential to negatively affect prime animal carcass performance traits by placing an increased focus on breeding for lighter cows within the breeding indexes, thus further reducing the profit of the resulting dairy-beef calves for beef producers.”
Despite this, Shauna noted that there is scope to identify animals that excel in both suites of traits via the EBI, adding: “Being able to identify such animals is the goal of the breeding programme.”
“Selective breeding through total merit indexes like the EBI should be successful in breeding for smaller dairy cows, and desirable prime animal carcass traits concurrently. This will help to achieve a more ethical, environmentally sustainable, and economically viable dairy-beef industry.”
Also read: Tracking the changes of carcass traits in beef animals