by Michael F. Hutjens
The author is a professor emeritus of animal sciences at the University of Illinois, Urbana.
At the ADSA (American Dairy Science Association) meeting, transition cow research abstracts were prevalent. Several abstracts are listed below with a brief summary, a take-home message developed by myself, and the researcher's contact if reader's desire more information.
Measuring milk ketone levels
Research summary: A study of 356 cows in five Canadian herds with in-line milk testing technology was conducted to measure subclinical ketosis (SCK). The threshold level of beta hydroxy butyric acid (BHBA) ranged from 1.2 to 1.7 mmol/liter. Third-lactation cows with greater than 1.7 mmol/liter produced 5,511 pounds less milk compared to mature cows with lower levels of BHBA. Across farms, elevated BHBA (greater than 1.4 mmol/liter) for mature cows were associated with higher milk yield. No differences were observed in second-lactation cows or first-lactation cows.
Take-home message: At the farm level, milk BHBA data, along with milk records, can be used to refine the effectiveness of treating cows with elevated BHBA across various lactation numbers. High-producing cows mobilize body weight to support milk production in early lactation. On-farm milk testing will enable early detection of cows that have greater ketosis and fatty liver risks while achieving optimal milk production. Regional DHI testing labs can provide this data.
Contact author: V.R. Osborne, University of Guelph, Ontario, Canada; email: email@example.com
Rumination in transition cows
Research summary: A total of 339 cows in four Canadian herds were monitored for rumination activity and SCK from 14 to 28 days after calving. BHBA levels over 1.2 mmol/liter were considered SCK. Cows were grouped by health status - H cows (139 cows with no SCK), subclinical ketosis - SCK cows with no other health problem (97 cows) and subclinical ketosis with one or more health problems - SCK+ (53 cows).
Monitored health problems included milk fever, metritis, retained placenta and mastitis. First-lactation cows ruminated 409 minutes per day on average, while second and greater lactation cows averaged 459 minutes per day. Cows with SCK averaged 25 minutes less than healthy cows. SCK+ cows averaged 44 minutes less compared to healthy cows.
Comparing SCK+ to H cows, larger rumination time differences were observed one week before calving (48 minutes), one to two weeks after calving (73 minutes) and two weeks after calving (65 minutes).
Take-home message: Rumination monitoring during the transition period may allow you to intervene and reduce health risks contributing to ketosis and related disorders/diseases. Another interesting aspect in the study was that 48 percent of cows in commercial Canadian herds were healthy, while 18 percent of cows had ketosis and other metabolic challenges.
Contact author: S. LeBlanc, University of Guelph, Ontario, Canada; email: firstname.lastname@example.org
Ketosis tool based on milk data
Research summary: Blood samples for BHBA and milk records from 658 Holstein cows in 10 Wisconsin herds were analyzed to determine if milk components could be used to evaluate cows' ketosis status. The model accurately predicted SCK for 88 percent for second- and greater lactation cows from five to 11 days after calving, 83 percent of first-calf heifers from 12 to 20 days after calving and 97 percent of first-lactation cows from five to 20 days in milk.
Take-home message: The model may be a useful way to predict BHBA based on milk components and cow test day information. This diagnostic tool could provide dairy managers with a tool to monitor herd level ketosis risk and prevalence using DHI records and data.
Contact author: G.O. Oetzel, University of Wisconsin, Madison; email: email@example.com
Regional early-lactation diseases and disorder
Research summary: Researchers assessed 16 herds with 10,959 cows for their incidences of retained placenta, metritis, subclinical ketosis, mastitis, lameness and left displaced abomasum. Four regions in the U.S. were summarized: Midwest (six herds), Southeast (one herd), Northeast (four herds) and Southwest (five herds). Two seasonal effects were also evaluated: warm season from May to August (WS) and cool season from October to January (CS). Table 1 summarizes the results.
The regional effect on disease was only significant for lameness. Season of calving was associated with all diseases and disorders in the risk assessment.
Take-home message: The study provides regional benchmarks and differences for dairy managers to measure their herd risks and opportunities. Readers should study the data, as seasonal effect and regional differences are interesting and valuable to interpret.
Contact author: J. Fetrow, University of Minnesota, St. Paul; email: firstname.lastname@example.org
Impact of RP methionine
Research summary: Eighty-one multiparous (second and greater lactation) Holstein cows were fed rumen-protected (RP) methionine at 0.08 percent of the ration dry matter or rumen protected choline at 15 grams or 60 grams of product per cow per day. Treatment groups were control (no methionine or choline), added methionine, added choline, and both methionine and choline (MIX). Dry matter intake, milk yield and milk protein percentage were higher for methionine-supplemented and MIX cows compared to other groups.
No differences were measured on milkfat percentage, blood ketones and NEFA (nonesterified fatty acids). Liver function and immune status (inflammation and oxidative stress) were also measured in a second abstract with 48 multiparous Holstein cows. Methionine and MIX had positive effects on reducing inflammation and oxidative stress compared to other treatments. A third abstract using 40 multiparous Holstein cows evaluated the liver metabolism using methionine and choline. The data reflected the high demand for methionine compared to control cows during early lactation.
Take-home message: The role of methionine goes beyond its main nutritive role as an essential amino acid (it is considered first limiting in most dairy rations). Immunity and health improvements along with gene expression aspects are of interest. The role of a methyl donor from methionine, choline, folate and betaine continue to be studied.
Contact authors: J.K. Drackley and F.C. Cardoso, University of Illinois, Urbana; emails: email@example.com, firstname.lastname@example.org
Impact of dry period energy on glucose metabolism
Research summary: Eighty-four cows were divided into three groups: Control diet (C) at 100 percent of energy requirement (C), high energy at 150 percent of energy required (H), or intermediate energy with the control diet fed for the initial 28 days of the dry period and 125 percent of energy requirement until calving (I). Table 2 summarizes the results.
Group H had greater fat mobilization and more ketosis with lower blood glucose and higher glycogen compared to other groups. This shift did not impact glucose tolerance test results.
Take-home message: Energy intake prior to calving can have a significant impact on cow health and metabolic disorders. These metabolic changes may reflect why these cows are at risk for these health and production problems. Body condition score and dry matter intake are additional risk factors.
Contact author: T.R. Overton, Cornell University, Ithaca; email: email@example.com
Calcium bolus near calving
Research summary: Thirty-eight French Holstein cows were monitored in three commercial herds. Control cows did not receive boluses, while the treatment cows received two boluses at calving and two more boluses 12 to 18 hours after calving. Four boluses provided 65 grams of calcium (from calcium propionate and calcium formate sources), 5 grams of magnesium, 4,000 IU of vitamin E, 50,000 IU of vitamin D and 12 grams of niacin.
Supplemented cows had 8.7 mg/L of blood calcium compared to control cows at 7.9 mg/L 12 hours after calving. The prevalence of hypocalcemia (less than 8.0 mg/L) decreased from 37.5 percent in the control cows compared to 7.1 percent in the supplemented cows.
Take-home message: Blood calcium levels at calving are critical for smooth muscle contraction in the uterus, digestive tract and mammary gland teat end, especially in older cows. Several boluses are commercially available. Determine the level of calcium being delivered and the source of calcium as some calcium sources are more biologically available. The boluses may deliver other important nutrients to fresh cows but will also increase the cost per cow per day. Be a detective when selecting and comparing boluses.
Contact author: R.P. Dagorne, Neolait, Yffiniac, France