Cow health, nutrition and reproduction are key when trying to find the best options for the transition period of dairy cows. That said, there is a lot of information about nutritional strategies that can be tough to sort through.
“Nutritional strategies and feeding management during pre-calving and post-calving periods impact health, productivity and fertility of high-producing dairy cows,” says Phil Cardoso, DVM, Ph.D., associate professor at the department of animal sciences, University of Illinois.
“Cows must make ‘metabolic decisions’ about where to direct scarce resources, and in early lactation, nutrients will be directed to milk production rather than to the next pregnancy,” he says. “Changes in management systems and inadequacies in management may be more limiting for fertility of modern dairy cows than their genetics, per se.”
Cardoso says the negative energy balance (NEB) that results from inadequate transition management is the main reason behind decreased fertility in the face of increasing milk production.
A simple management technique is to watch body condition scores (BCS). Cows that lose more than one BCS unit (on a 1 to 5 scale) from dry-off to calving had a greater incidence of metabolic disorders such as milk fever and ketosis and an increased incidence of metritis and retained placenta.
“Recommendations for optimal BCS at calving have trended downward over the last two decades, and, in my opinion, a score of about 2.75 and 3 is a good goal,” Cardoso says. “However, always observe your cows’ BCS change from dry-off to calving and from calving to breeding.”
He adds that the effects of maintaining a small change in BCS is obvious, citing studies that show cows that gained or maintain a good BCS to 21 days after calving have a higher pregnancy per A.I. at 40 days than cows that lost body conditioning.
Although it is necessary to always be monitoring cows for loss of body conditioning, which may indicate the potential for negative energy balance, Cardoso says allowing drying cows to consume more than their required energy intake results in health responses typical of overly fatty cows, even if cows do not become noticeably overconditioned.
Formulating diets to meet requirements of the cows but avoid overconsumption of energy may improve outcomes of the transition period and lead to improved fertility, he says.
“Management to improve cow comfort and ensure good intake of the ration is pivotal for success,” he says. “Impacts of the transition program should be evaluated in a holistic way that considers disease occurrence, productivity and fertility.”
Cardoso says energy-controlled dry cow programs do decrease health problems – bulking up rations with fiber is the focus to limit the intake of the whole TMR by the cow. If that is accomplished, the diet will limit the intake of energy (about 15 to 16 megacalories [Mcal] per day for a typical Holstein) but meet the requirements for protein, minerals and vitamins.
He adds that in addition to feeding nutritionally complete diets, it is essential to make sure the TMR is well-processed so that cows do not sort the bulkier ingredients. Inadequate processing or trying to side feed bulky forage such as straw leads to some cows eating too much and some consuming too little.
Formulation and delivery of appropriate diets that limit total energy intake but also provide proper intakes of all other nutrients before calving can help lessen the extent of NEB after calving.
Dairy producers should target 1,200 grams per day of metabolizable protein during the dry period (especially pre-fresh).
“Proteins are made of amino acids,” he says. “The importance of amino acids has been getting a closer look by researchers. Recent studies have shown that rumen-protected methionine and lysine added to the diet of Holstein cows during the transition period and early lactation improves health, milk yield and the survival rate of pre-implantation embryos.”
Kelli Boylen is a freelancer based in northeast Iowa.
Cardoso’s recommendations include:
- Manage dietary ingredients for:
–Adequate crude protein (about 13 percent for dry cows and 16 percent for lactating)
–Metabolizing methionine in TMR (30 grams per day for dry cows and 46 grams per day for lactating)
–Metabolizing lysine in TMR (84 grams per day for dry cows and 129 grams per day for lactating)
- Achieve a pregnancy rate of greater than 20 percent. Aim for more than 25 percent and a conception rate at first A.I. of more than 40 percent.
- Reduce embryonic death to less than 15 percent. Aim for less than 10 percent.