There are “many benefits” to beef-sired heifer calves from dairy cows, according to recently-published research.
The research was carried out by Donagh Berry, a senior principal research officer and quantitative geneticist with Teagasc and Siobhán Ring, a senior research geneticist at the Irish Cattle Breeding Federation (ICBF).
The research found that benefits exist for beef-sired heifer calves in that they had, on average shorter gestation periods and easier calving.
These heifers had less calf value and their carcasses were lighter than males, but they were slaughtered notably younger than steers.
The research paper – which was published in the journal JDS Communications, an official journal of the American Dairy Science Association – said that, although interest in beef-on-dairy breeding strategies is intensifying, little is actually known of the performance difference between beef-sired male and female progeny of dairy cows.
The objective of the study was to use a large cross-sectional database – 1,390,670 animals – to investigate if performance differences existed between male and female progeny generated from beef-on-dairy mattings.
The focus of the study was on “characteristics of interest” to both dairy producers (i.e. gestation length, calving performance, perinatal mortality, and calf sale value) and beef producers (i.e. slaughter-related traits).
The research found that, while statistical differences existed between both sexes, the observed differences were not always large, with some favouring females (such as calving traits and age at slaughter), and some favouring males (such as carcass weight).
According to the study, beef-sired male calves had, on average, a 0.8 day longer gestation than their female counterparts. For dairy-sired calves, the sex difference was 1.1 days, with the advantage to females.
The odds of a difficult calving was found to be 2.2 times greater for beef-sired male calves relative to beef-sired female calves.
In terms of value, male beef-sired calves sold at auction (under 42 days of age) at an average of €32.40 more than beef-sired female calves.
Looking at carcass weight, beef-sired steers were found to have an average weight of 336.9kg, while the beef-sired bulls weighed, on average, 335.4kg.
These figured compared to a carcass weight for beef-sired females of 280kg.
Based on a 15-point conformation scale, the carcasses of bulls were one unit superior to heifers, while the carcasses of the heifers were 0.6 units superior to steers.
The heifers were slaughtered, on average, 79.1 days younger than steers, although the former were slaughtered, on average, 93.8 days older than bulls.
The research paper said: “Many benefits exist for beef-sired heifer calves in that they had, on average, shorter gestations with less expected assistance required at calving and, although their calf value was less and their carcasses were lighter than their male counterparts, they were slaughtered several months younger than steers.”