Unlike physics or chemistry, meat science can be a difficult subject in which to establish once-size-fits-all laws, theorems and formulas. Every breed is different; every animal is different; and every farm is different.
Those differences might not be better demonstrated than in a side-by-side profile of 100 finished Holstein steers and 100 finished beef steers, be it Angus or Charolais.
Dairy steers are visibly more variable in pens – in both height and weight at a similar age – and statistically more variable in their rib-eye size and marbling grade.
Holstein steers have a smaller average daily gain (13% less than beef) and gain-to-feed ratio (4% worse) when fed to similar weights, according to Dr. Ty Lawrence. Lawrence is a professor of meat science at West Texas A&M University, and a 2013 Vance 40 Under 40 awardee. His research, shared at the 2014 Vita Plus Summit in Red Wing, Minn., set out to provide a snapshot of a 2012 study using Holstein steers in a Texas feedlot.
While Holstein steer growers have an idea of what a finished animal looks like, data on how they get there individually is mostly missing. Also, despite a plethora of knowledge in dairy cows dating back more than a century, findings on how variable the breed is in height, weight gain and finishing weight are largely unknown, due to a widespread lack of tracking and research in the male side of the industry.
Holstein Association USA recognized height as an issue for the breed"s females in 2011, dictating that cows falling outside the height range of 56 to 62 inches at the spine would have 0.4 points deducted from their final classification score.
"Statistics show the Holstein breed is getting taller, and we're seeing where it's causing dairymen to have to remodel the stalls in their tiestall and freestall barns to accommodate larger cows," stated Holstein"s director of type evaluation, John Connor, at the time.
This translates to similar problems on the less-tracked male side of the industry, to the point that Tyson Foods banned steers over 58" tall at the hip on June 7, 2013, Lawrence said. Holsteins in Texas feedlots are often sorted by height, with those at risk of breaking the limit sent to Wisconsin where the dairy-focused plants can handle them. Due to rail-to-floor height in processing plants, carcasses from steers over 58" tall risk dragging on the floor at the plants, a food safety issue. Their massive size also creates handling issues for workers, slowing the plant and costing productivity.
Based on Lawrence"s study, Holstein steers are likely to reach a hip height of 58" or greater at about 460 days and 1,425 lbs.
Determining end points
The West Texas A&M research team first selected 135 Holstein steers at about the same weight – +/- 35 lbs. of 886 lbs. – at 180 days on feed. All of the cattle received Revalor-XS implants and were on a typical Texas feedlot diet including steam-flaked corn.
Lawrence"s team began selecting 10 cattle for slaughter at 254 days on feed, slaughtering 10 more every 28 days while the rest of the steers were weighed. When cattle were slaughtered, the team calculated all yield, feed efficiency and weight traits you would expect. But, they also followed the carcasses through to meat grade, rib fat depth, and gastrointestinal fill. They also had the ability to track how often and how much the steers ate using GrowSafe feeding scales.
Two of the biggest surprises to the industry might be that accepted beef industry constants could be way off for dairy steers.
Lawrence found the steers to have between 12% and 18% gastrointestinal (G.I.) fill as percent of live weight. The typical G.I. discount for steers is 4%, meaning Holstein feeders may be getting 8% to 14% free at slaughter.
"We are going to be feeding bigger Holsteins," Lawrence told those in attendance at the Vita Plus Summit.
The other discrepancy was a much lower rib-eye area-to-hot carcass weight ratio: 1.12 to 1.44, compared to the beef industry standard of 1.8.
From day 254, the Holstein steers took 125 days to increase 1 yield grade unit (starting at an average of 3.0); 166 days to go from marbling USDA Select to USDA Choice; and deposited an additional 0.10 inch of back fat every 91 days.
In Lawrence"s opinion, these steers on this diet would have been best harvested at 394 days on feed, and at 1,600 lbs. Using those two guidelines, feeders would be past discount triggers for lightweight carcasses and select marbling, but before heavyweight carcasses and the worst yield grades – 4 and 5.
"Whether you're forward contracting, using a formula, or a negotiated grid, we're probably maximizing revenues at 394 days on feed," Lawrence explained.
It should be noted that this study was just one set of cattle on one diet in one location. However, with numbers so far from what we know as standard, dairy producers should want to know more about a sector that may contribute up to 20% of their revenue.