Healthy pregnant cows lead to thrifty, fast-growing calves
Raising healthy, vigorous calves is fundamentally the most important factor to the success of a dairy farm. Without a next generation of well-developed heifers ready to step in as replacements, there won’t be much profit in the future.
Environment and proper feeding programs are the vital areas that calf raisers should focus on in order for the genetic potential of calves to truly be expressed, says Jon Robison, consultant for JDR Livestock Management Services. Robison is a former dairy science professor from Fresno State University. He shared his thoughts on "Feeding Dairy Calves for Performance" during the 2014 High Plains Dairy Conference in Lubbock, Texas.
"We’ve known for a long time that future productivity of the dairy is really based upon the genetic potential of today’s offspring," Robison says. "It is important to understand the impact and significance of management. Management programs do impact genetic expression."
Life is all about development. For dairy replacement heifers there are seven critical physiological development stages that can be identified as:
"A good replacement heifer program results from understanding what the developmental process is in terms of growing a heifer," Robison says. Development and growth are not necessarily the same thing.
Growth is just the increase of cell size, often measured by weight and structural size. Growth does not automatically account for optimal tissue development. This development occurs in phases from conception to maturity. It is the differentiation and maturation of cellular tissues that are capable of expressing genetics over a period of time.
Robison adds that development can only occur if calves have the right tools, such as nutrients, environment, health protocol, etc.
"Oftentimes the development of tissue cannot be measured until we collect productive performance out of that animal, such as milk," Robison says. If opportunities are missed to properly develop tissue, a producer won’t know until it is too late.
Poor nutrition at the cow level results from deficiencies in minerals and vitamins. It has a direct effect on the development of the fetus.
In 2009, Robison was seeing a lot of differences in newborn calves from western U.S. calf ranches. Many of those calves came onto the ranches in a weak condition. He relates this change in calf development to dairymen cutting costs at a time when feed prices were high.
"They look at a bill at the end of the month and see $500 to $600 per ton for that close-up mineral pack and it gets cut out," Robison says.
If the lack of nutrients continues as the cow is coming into milk, it also impacts colostrum quality and quantity. "What we do to that cow has an impact on that calf. When we get negative production or low-quality production of colostrum, it’s an indicator that we’re not doing so good with our close-up dry cows and far-off dry cows," Robison says.
Three to four weeks prior to calving, cows begin accumulating hormones, growth factors (immunoglobulins such as IgF-I and IgF-II) and transforming factors (TGF-β1 and TGF-β2) inside the colostrum. This is a process, known as clostrogenesis, activates mammary secretory cell receptors, allowing for large amounts of milk synthesis to make up the core contents of colostrum.
Monitoring the quality and quantity of colostrum can determine how well cows are being managed and what to expect from calves. Monitoring colostrum, however, is tricky.
"Here is one of the biggest obstacles to it: Within about six to 10 hours after parturition there is a significant amount of reabsorption of those biologically active substances and even some of that antibody," Robison says. "They degrade very quickly, but they do have a very big impact on the initial start of that calf’s life."
He suggests using inexpensive tools such as a colostrometer or refractometer to measure colostrum quality.
The colostrum also needs to be harvested in a timely manner. Robison points to research conducted on seven central California dairies that determined the average first milking occurs more than nine hours after calving. That’s too late, with quality degradation falling into the extreme range.
With the long gap between calving and first milking, the average concentration of antibodies was less than 36 mg/mL, far below the recommended 50 mg/mL. The study also indicated that antibodies are inadequately transferred to calves 36% of the time.
To develop calves that will perform, Robinson says to feed a high plain of nutrition that matches the calf’s individual growth and development. "When calves are fed well, health concerns tend to be minimized so optimum growth and development are achieved," he says.