Successful management of cows through transition is a hot topic among both producers and researchers. Producers know smooth transition means making sure to cover the basics. With the basics covered, the next step is to optimize nutrition. Nutritional management of cows through transition must start during lactation. It requires a good reproduction program and a nutrition plan to manage body condition gain through late lactation.
Research shows that overconditioned cows have lower dry matter intake (DMI) through the dry period than cows at a more moderate body condition score (BCS).
In order to achieve a target BCS 3 – and maintain this score through late lactation – it may be necessary to feed a diet with lower, or less fermentable, starch levels and more highly digestible neutral-detergent fiber (NDF) than cows would be fed near peak lactation.
This dietary strategy should maintain milk production while minimizing weight gain by shifting nutrients away from body condition gain and toward the mammary gland to support milk production. If goals for maintaining condition can be met leading into the dry period, then cows may be more likely to maintain DMI through the dry period.
During the dry period, maintenance of DMI through the period is likely more important than total DMI. A recent University of Illinois summary of seven studies compares controlled-energy versus high-energy diets during the prepartum period.
The summary suggests that controlled-energy diets during the dry period can limit body condition mobilization postpartum, lower plasma non-esterified fatty acids (NEFA) postpartum and increase plasma glucose concentration after calving – all suggestive of an improved metabolic state.
Adequate glucose precursors
Following calving, cows have increased glucose demand to support milk production. Therefore, it is important to offer a diet that provides adequate production of glucose precursors, such as propionate (the major glucose precursor).
Propionate is the end product of starch fermentation in the rumen, and its production varies based on the fermentability of the starch in the diet. For example, high-moisture corn has much higher ruminal fermentation than dry-ground corn.
It is important for DMI to increase during early lactation in order to support rumen health and function, energy balance and milk production. However, there is little research on how starch fermentability affects DMI during the fresh period.
Researchers have reported that steam-flaked corn tended to reduce DMI following calving compared to dry-cracked corn. Additionally, recent studies at Michigan State University using a ruminal propionate infusion model found that propionate depressed DMI by reducing meal size during the fresh period in cows that were mobilizing body condition.
Starch fermentability
One idea has been to feed higher-starch diets during the fresh period if the starch fermentability of the diet is low. Recently, different research groups have been investigating high-starch versus low-starch diets fed to fresh cows where the primary starch source was dry-ground corn. However, results of these studies have been contradictory.
For example, in one experiment, cows receiving a low-starch diet (21 percent) tended to have higher intake than cows fed a medium-starch (23.2 percent) or high-starch (25.5 percent) diet. Conversely, other researchers reported that cows fed a high-starch diet (26.2 percent) had higher DMI (as a percentage of bodyweight) than cows fed a low-starch (21.5 percent) diet.
There are several possible explanations for the differences in the responses to these dietary treatments. In these two experiments, the diets fed during the dry period varied in starch concentration (13.5 percent versus 17.4 percent, respectively).
Cows fed higher starch during the dry period responded better to higher-starch diets during the fresh period. Also, during the fresh period, there were differences in dietary NDF concentration due to the amount of straw included in the diet, which may have affected the response to the starch level as well.
Transition in practice
Based on the research with propionate infusions and the limited research with feeding studies, we can make a few recommendations for feeding practices for fresh cows.
• Ensure there is adequate feedbunk space for all cows, and they cannot easily sort the ration.
• Maintain rumen fill by providing a high-fill (high-forage fiber) diet which helps to buffer the rumen (by stimulating rumination) and prevent displaced abomasums.
• Limit the fermentability of the fresh cow diet to maximize intake.
Large amounts of starch sources, such as dry-ground corn, are better than high-moisture corn because they produce less propionate in the rumen while still providing adequate glucose precursors through post-ruminal digestion.
Keep in mind that adequate starch concentration is essential in the diet of the fresh cow. Dry corn sources allow for higher starch intake – and propionate production – compared to high-moisture corn.
Transition basics
Before fine-tuning nutrition, be sure to cover the basics of transition cow management:
• Do not overcrowd dry cows or fresh cows. Target 80 percent stocking density on stalls. Remember that cows need adequate space at the feedbunk as well; 30 inches of space per cow is ideal. Target a minimum of 3 linear inches of water space per cow and, if possible, provide multiple sources.
• Be aware of cow flow through your close-up and fresh cow pens, and plan labor and facility resources to accommodate periods with higher-than-average calvings.
• Manage springing heifers and mature cows in separate prefresh and postfresh pens, if possible. Younger cows are at a disadvantage when competing for resources such as stalls and feedbunk space.
• Limit the number of pen moves within 10 days of calving. Longer pen stays and weekly pen entries are less disruptive and help reduce stress.
• Have a thorough fresh cow evaluation program in place. Train employees to identify diseases and treat cows appropriately. Lock up cows no longer than one hour and make fresh feed available at all times.
• Keep fresh cows in the fresh pen until they are healthy and eating well, and milk production is increasing steadily.
The fresh diet is more filling than the lactation diet. So, in order to avoid limiting their energy intake, switch cows to the lactation diet when fill becomes limiting. The transition period can vary from cow to cow and may depend on her metabolic status through the transition.
A target of 14 days in the fresh pen is an attainable goal for most cows, although some cows may be ready to move sooner, and some may require more time in the fresh pen. PD
Thomas Oelberg has a Ph.D. in dairy nutrition from Ohio State University and is employed by Diamond V as a dairy technical service specialist based in Minnesota. He can be contacted by email .
Sarah Stocks
Consultant
Barton & Kiefer Nutrition Group
