The Manager - November 2022
Jason Oliver joins Dairy Environmental Systems program at PRO-DAIRY
Jason Oliver, PhD, joins the PRO-DAIRY team as Senior Extension Associate of the Dairy Environmental Systems program.
What can milk constituents tell us about cow calcium status?
Jackson Seminara, David Barbano, and Jessica McArt
Dairy cows respond to the challenges of the transition period in ways that are both dynamic and cow specific. This is especially true for the challenge of maintaining calcium balance immediately following calving. With the onset of lactation, cows begin secreting copious amounts of calcium in their milk, to the extent that their dietary intake cannot compensate for the loss of this essential mineral. Cows must coordinate a response to this challenge to maintain calcium balance, and those that fail to do so often develop milk fever, or clinical hypocalcemia. While this is certainly an important disease, prepartum diet management, and well-established treatment protocols minimize the impact that milk fever has on cows and herds. For cows that do not develop milk fever, individual dynamic responses to the early lactation calcium challenge are varied. These individual responses can be identified by measuring blood calcium at one and four days in milk (DIM), such that the dynamics of calcium at and between these timepoints can classify individual cows into one of four “calcium dynamic groups.” Each group is associated with different health and production outcomes that, for the sake of this article, we consider: worst, at risk for negative health outcomes and producing the least milk; bad, at risk for negative health outcomes but producing decent to appreciable amounts of milk; good, consistently healthy and producing average amounts of milk; and excellent, consistently healthy and producing exceptional amounts of milk.
Should you delay oral calcium bolus supplementation for fresh cows?
Claira Seely and Jessica McArt
Subclinical hypocalcemia (SCH) is an invisible threat to both the dairy cow and producer. As nearly 45 percent of multiparous cows experience SCH during the early lactation period, producers can implement dietary strategies such as feeding negative dietary cation anion difference (DCAD) rations in the late dry period or administering prophylactic calcium treatments to fresh cows to minimize the risk of SCH. Although negative DCAD rations have successfully reduced the incidence of clinical milk fever, many cows still experience SCH after calving. For this reason, it is commonplace to administer supplemental calcium at calving to help maintain blood calcium concentrations. Despite the widespread use of oral calcium boluses, their impacts on production and health are variable. Large-scale field studies show that when high-producing or lame cows are given calcium boluses after calving, they produce more milk and experience less disease than cows of similar status not given a bolus. However, low-producing cows and primiparous cows are negatively impacted by calcium bolus administration.
Feeding calcium and dietary cation-anion difference in the close-up period: How much is enough?
Geneva Graef and Thomas Overton
The transition period is a tumultuous period for a cow and those of us trying to manage them. During this time cows are particularly prone to mineral and metabolic imbalances that can leave them more susceptible to diseases as well as lower milk production and poorer reproductive performance. Of particular concern is the issue of calcium (Ca). At and around calving calcium is in high demand for fetal development, birth, and lactation, while leaving enough for a cow’s normal physiologic needs. Fortunately we can prepare the cow to improve her chance of success through this transition period by managing the dietary cation-anion difference (DCAD) in the close-period to improve her calcium metabolism around and after the time of calving. This allows her to more efficiently use calcium stores rapidly when she needs it most. There are also some strategies to consider when managing dietary Ca. When it comes to either Ca or DCAD feeding, the question always returns to, if we choose one or both strategies, how much is enough?
What is the impact of subclinical hypocalcemia diagnosed at four days in milk on reproductive outcomes?
Claira Seely and Jessica McArt
While often undiagnosed due to the absence of clinical signs and the price tag associated with collecting blood samples required for diagnosis, subclinical hypocalcemia (SCH) affects nearly 45 percent of multiparous dairy cows. Traditionally, one day in milk (DIM) was thought to be the opportune time to diagnose SCH; however we have recently discovered that decreases in blood calcium occurring at four DIM are more closely associated with lower milk production, reduced feed intake, and an increased risk for additional disease development. Although we understand the negative effects of SCH, particularly episodes occurring at four DIM, on future health and milk production, its effect on reproductive success is largely unknown. Results from past reports are inconsistent, likely due to the range of days in which SCH was diagnosed, as well as the variation in calcium cutpoints used for diagnosis. As successful and efficient reproduction is critical for the success of dairy operations, we were interested in exploring the association of SCH occurring at four DIM with the odds of pregnancy to first service and the time from calving to pregnancy.
Methionine and omega-3 fatty acid feeding for transition cows
Joseph McFadden and Tanya France
The transition period, characterized as the three weeks pre- through three weeks postpartum, is a critical life event for the dairy cow. Around calving, cows involuntarily reduce feed intake; however nutrient demands increase to support fetal growth and milk production. A systemic inflammatory response also occurs at calving which can increase the risk for developing metabolic diseases. For example, the development of fatty liver is a common condition for the transition cow. Milk loss from health incidences particularly in the first 21 days in milk are major contributing factors for economic loss in the dairy industry. Because of these challenges, nutritional strategies are implemented with the goals of improving health and milk production in the transition cow. Methionine (Met) and omega-3 fatty acid (n3 FA) feeding have received attention due to their health benefits.
Leaky gut and the warning signs of heat-stressed dairy cattle
Ananda Fontoura and Joseph McFadden
Since pre-industrial times, global surface temperatures have risen considerably and most of the warming occurred in the past 40 years. Reflective of this global trend, temperatures in the United States northeast region have also increased, and projections indicate additional warming that can reach up to 40.6°F by 2100, and estimate an increase in the intensity and frequency of extreme heat weather events, and a decrease in the intensity and frequency of cold extremes for North America. If these predictions come to fruition, higher occurrence of periods of extremely high temperatures will most likely affect both animal and human health, and will increase the incidence of heat-related illnesses. Due to this, heat stress will likely become more prevalent in the future. And indeed, the effects of climate change on production systems have often been highlighted as one of the main challenges currently faced by crop and animal-based systems. This is important to United States dairy systems because of the inherently increased heat production of highproducing dairy cows, which makes them more sensitive to warmer climates and heat fluctuations. Therefore, a better understanding of the mechanisms by which heat stress compromises the production of dairy products is important because it will allow us to develop heat stress alleviation therapies.
Implementing selective dry cow therapy on farms across New York state
Tracy Potter, Amber Forrestal, Michael Capel, and Daryl Nydam
Selective dry cow therapy (SDCT) is an effective way to use antimicrobials judiciously on dairy farms while decreasing treatment costs and maintaining herd health. In the Netherlands it has been enforced since 2014 and the national somatic cell count (SCC) has decreased. As of 2022 the European Union banned prophylactic use of antibiotics in animal source food production. Each year legislation with similar rules is proposed in New York state but has not yet passed. Many on-farm randomized trials in the USA, some conducted in NYS, show that when SDCT is implemented well, it does not detrimentally impact udder health. SDCT provides a way to save on treatment costs and ease product allocation when antibiotics are on backorder. However, adoption of the practice has been slow in the USA. To improve the adoption of this practice in New York, we formed a team of veterinarians to help interested dairy producers and their herd veterinarians (with financial reimbursement for their time) to implement SDCT successfully. Not all farms are a good fit for SDCT. Herds that wish to employ this management practice should already have good udder health (e.g. bulk tank SCC less than 250,000 cells/mL), control of contagious mastitis pathogens (e.g. Strep ag and Staph aureus), and routine detection of clinical mastitis cases. An in-depth discussion between the herd veterinarian and farm stakeholders before adoption is necessary. This discussion should include current practices (e.g. appropriate use of teat sealants), data available to make the selection process (e.g. DHIA test data), best practices for dry-off and dry pen management (e.g. SOPs for excellent hygiene during the dry-off procedure), and how to monitor progress going forward.