The more dairy researchers learn about transition health, the more they realize its critical impact on milk production, return to fertility and culling risk.
Stephen LeBlanc, professor of population medicine at Ontario Veterinary College at the University of Guelph, Ontario, Canada, said the relationship between transition cow metabolism and subsequent disease, production and reproduction is striking.
LeBlanc explained that non-esterified fatty acid (NEFA) levels reflect how much stored fat is being mobilized by fresh cows, while ß-hydroxybutyrate (BHB) levels indicate how efficiently the liver is processing fatty acids (a measurement of ketosis).
“High NEFA (> 0.4 mmol/L) in the last seven to 10 days before expected calving is associated with two to four times greater risk of left displaced abomasum (DA); double the risk of retained placenta; double the risk of culling in the first 60 days in milk; and 2.4 lb./day less milk production in the first four months of lactation,” LeBlanc said. Similarly, he said subclinical ketosis (BHB > 1.2 mmol/L) in the first or second week after calving is associated with three to eight times increased risk of left DA; three times greater risk of metritis; and four to six times greater risk of clinical ketosis.
“It also is worth emphasizing that health in the weeks before and after calving influences reproduction at least two months later,” he added.
LeBlanc said several on-farm tests now are available to monitor BHB levels in blood, urine and milk. NEFA monitoring must be done in an off-farm lab but also can be a valuable, ongoing assessment. He emphasized the importance of working with the herd veterinarian and nutritionist for monitoring and interpreting these levels, while keeping in mind the two, distinct objectives of such monitoring:
(1) To evaluate success of the management and nutrition program at the herd or group level; and
(2) To identify individual cows at high risk for disease, with the goal of early intervention to prevent clinical disease.
In addition, monitoring clinical disease records, feed intake, milk production, body condition score (BCS) and postpartum uterine health all can be useful in detecting shifts in herd health and flagging individual cows at high risk of disease.
LeBlanc emphasized the common denominator of the entire transition cow complex is management to support desired cow behaviors and feed intake. Herd-wide management steps he advises to maximize intake and support every cow include:
- Feed for 2% to 5% leftover total mixed ration daily.
- Provide at least 30" of bunk space per cow or four cows per five headlocks.
- Keep stocking density in free stall barns at 85% or lower, or provide at least 120 sq. ft. of bedded pack per cow.
- Build facilities with stall and feeding capacity for 140% of the average monthly number of calvings.
- Separate first-calf heifers from older cows if possible (without violating the goals above).
- Minimize time in individual calving pens to 24 hours or less.
- Provide heat abatement when temperature-humidity index is 68 or above.
- Aim for a BCS of 3.0 to 3.5 at calving.
- Feed to provide but not exceed maintenance energy requirements from dry-off to close-up.
- Provide fresh water ad lib from two watering sources per pen, providing at least 4" of trough space per cow.
“Our focus should be on minimizing the nutritional, housing, social and environmental factors that may impair feed and resting access for all or some postpartum cows,” LeBlanc concluded.