From the time dairy farm neighbors began to hold informal contests to compare cattle, the goal has been to raise and show the ideal dairy cow that’s profitable for the farm. Today, opinions vary regarding the level of emphasis for conformation, selection and culling strategy. Some believe conformation doesn’t matter at all, and cows should be bred solely for production. Others believe conformation improves profitability, and some select based on potential show ring performance.
Dr. Jeff Bewley, analytic innovations scientist at Holstein Association USA, said judging contests and the show ring have refueled the “best cow” discussion. But what makes a cow profitable, and is it measurable?
“Linear type classification programs are designed to quantify physical conformation,” said Bewley. “As a breed, Holsteins have improved dramatically over the last century. As that has happened, the emphasis on conformation has changed quite a bit.”
Bewley has proof that conformation matters. It comes from a study designed to assess the relationships between conformation and linear traits with economically important outcomes including first lactation energy corrected milk (ECM), lifetime ECM, somatic cell score and longevity.
For the study, classification scores from the Holstein Association were used for linear classification. The first classification score for a cow in her first lactation was used for the analysis. “That was to eliminate the bias toward animals scored only because they needed to be scored to improve their score,” said Bewley. “We used official DHIA records for production and culling data and included only cows that were born after January 1, 1990.”
Cows in the study had lactations starting between Jan. 1, 2000 and Aug. 27, 2021. For lifetime production analyses, only data from the first six lactations were used.
“We only looked at cows calving for the first time before January 1, 2016 for lifetime analyses because we needed to give those animals enough time to express their lifetime production,” said Bewley. “We included only animals that had complete 305-day lactations for 305-day milk analyses.”
Only first lactation records with age at first calving between 18 and 35 months were included, and lactation records with milking frequencies greater than 3x were excluded.
“That left us with about one million cows in almost 5,500 dairies for the data set,” said Bewley. “We only included a cow in the final data set if she had at least five herdmates in that herd, year and season of calving.”
These criteria ensured sufficient comparable cows in the herd for comparisons in the statistical analysis and removed the potential for preferential bias.
Statistical analysis showed a stepwise increase in ECM, and lifetime ECM was even more impressive.
“The difference between the highest and lowest scoring animals is almost 30,000 pounds,” said Bewley. “At $20 per hundredweight milk across those animals’ lifetime, that’s a $5,700 difference in milk revenue. Animals that were scored higher and closer to what a Holstein should look like provided a lot more milk revenue over their lifetime.”
The study analyzed the most economically important traits correlated with first lactation 305-day ECM. “Rear udder width was the most correlated with 305-day ECM,” said Bewley, “followed by dairy form (angularity), followed by udder depth – animals with deeper udders produced more milk in their first lactation. Other traits included body depth and strength, rear height, stature and foot angle.” When rear legs were viewed from the side, the ideal optimum was not too post-legged and not too much set.
Owners of dairy cattle such as these registered Holsteins can benefit from extensive research aimed at determining correlations between economically important traits and lifetime milk production. Photo by Sally Colby
Somatic cell scores (SCS) were closely related to udder traits. “Udder depth has a negative correlation with SCS, meaning animals with more shallow udders have a lower SCS,” said Bewley. “Animals with a better fore udder attachment have a better SCS, and same with udder cleft and front teat placement.”
Certain linear traits were related to culling age. Fore udder attachment was the highest-ranking trait, said Bewley, followed by rear udder height, udder depth, rear udder width, foot angle, thurl width and dairy form. “Animals need good udders, good foot angle and they need to look like dairy animals,” he said.
The study also considered lifetime ECM because the goal is high-producing animals that remain in the herd for a long time. “Rear udder height and rear udder width were most correlated with lifetime ECM,” said Bewley, “followed by fore udder attachment, dairy form, foot angle and udder cleft.”
Tall, angular animals with the best feet and legs produced the most milk in their first lactation. Following that trend, cows with higher and wider rear udders produced more milk in the first lactation. For combined udder traits, there are more differences with SCS.
“They don’t have to be fancy, perfect udders,” said Bewley, “but when udders fall apart, an increase in somatic cell score follows.”
On a lifetime basis, animals with the strongest fore udder attachments have the most lifetime ECM. Cows with low, narrow rear udders and loose fore udder attachments have lower lifetime production.
There’s still debate regarding rump angle. Bewley said the optimum is in the middle – not too much slope, but not too high with pins higher than the hooks.
“Animals with better feet and legs last longer than animals with less desirable feet and legs,” he said. “Rear leg side view animals in the middle last longer than animals in either extreme – either post-legged or sickle-legged.”
The data set for the million-cow study was for phenotypic rather than genetic relationships. “There are many other management factors that affect the outcomes from relationships,” Bewley said. “Production isn’t just about dairy form and somatic cell score isn’t just about udder cleft. A lot of other things happen on the farm beyond genetics.”
The study confirmed that conformation does matter. “I’m surprised how striking some of the relationships are,” said Bewley. “The classification system quantifies economically important differences as well.”
Because udder, feet and legs and dairy form have a clear impact on lifetime profitability, they’re the most important factors for breeding and culling decisions. Bewley said conformation traits should be considered in combination with production and fitness traits using an index such as Total Performance Index®, Net Merit or DWP$.
Both type and conformation should be considered in breeding decisions. “That doesn’t necessarily mean we’re breeding for tall show cows,” said Bewley. “I think that’s where the word ‘type’ has gotten a bit of a negative connotation. Type isn’t just about winning a show – it’s about producing functionally correct animals that stay in the herd longer and produce more milk.”
by Sally Colby
Leave A Comment