By Adrian A Barragan
It is well known that the period encompassed between three weeks before and after calving, known as the transition period, is one of the most challenging times for dairy cows. During this period cows experience a drop in dry matter intake, an increase in nutrient demands and depression of the immune system functions (LeBlanc, 2010). On top of these challenges, cows suffer systemic stress and inflammation during the days before and after calving (Comline et al., 1974; Uchida et al., 1993).
An increased inflammatory or stressful response after calving has been associated with an increased risk of developing infectious and metabolic diseases. In one study, where 67 dairy cows were sampled from 21 days before calving until 21 days after calving, authors reported that cows that developed mild (red-brownish watery foul smelling discharge without fever) and severe (red-brownish watery foul smelling discharge with fever) clinical metritis between 3 and 21 days after calving had higher systemic inflammation in the first days after calving compared to cows that did not develop clinical metritis. Similarly, in another study, author reported that cows that developed subclinical or clinical (milk fever) hypocalcemia had higher stress at calving compared to cows that did not develop this disease (Horst and Jorgensen, 1982). Now the million-dollar question is: Why did these cows have higher stress and inflammation around calving compared to their pen mates? Although this question still remains unanswered, the most likely explanation may be related to management. Different management practices before calving, such as overstocking, commingling first lactation cows with older, and high number of pen moves, may increase stress and inflammation in the more susceptible animals within the group.
Regardless of the origin of these systemic responses, proactive dairy researchers have focused their efforts on developing strategies to decrease inflammation after calving in order to improve cow health and performance during the lactation period. The most common approach proposed has been treating cows (e.g., drenches, boluses, injectable [SC, IV]) after calving with anti-inflammatory drugs known as non-steroid anti-inflammatory drugs or NSAIDs. The first strategy worth discussing, basically because it is a treatment regime that used flunixin meglumine which is the only FDA approved drug to treat inflammation in lactating dairy cattle, is the one proposed by Dr. Duffield and collaborators (Newby et al., 2017). In this large study, researchers explored two treatment strategies: the first one included administering a first dose of flunixin meglumine at the beginning of calving (i.e., observation of the water bag or feet of the calf outside the vulva) and a second dose 18-36 h later, and the second strategy consisted of administering a first dose immediately after calving and a second dose 24 h after. In the first strategy, authors reported that treated cows had 26.3% higher stillbirth incidence compared to the placebo group; while in the second strategy authors reported that treated cows had higher incidence of retained placenta, postpartum fever and metritis, and decreased milk yield compared to placebo cows. The study authors concluded that the used of flunixin meglumine after calving was not recommended in dairy cattle. A possible explanation for the results reported by the previous study is that flunixin meglumine is a potent anti-inflammatory drug that may have greatly decreased or totally inhibit inflammation after calving; while dairy cows rely on inflammatory processes after calving to detach and expel the placenta and to achieve normal uterine involution. That is why we talk about modulating the inflammatory response instead of inhibiting it.
The next strategy that will be discussed in this article is the use of aspirin products to modulate inflammation after calving. The first topic to mention about this approach is that aspirin products are not approved to be used in lactating cattle, even under extra label use rules (ELDU; Smith et al., 2008), and therefore, their use in dairy farms is controversial. Nevertheless, it is an attractive alternative due to their short milk and meat withhold, low cost and easy administration. Research studies that used aspirin products to modulate inflammation after calving have reported fairly consistent positive results on cow performance. These studies have tested different strategies that varied on the length of treatment administration (2 days [Barragan et al., 2017; Barragan et al., 2020], 3 days [Carpenter et al., 2016], 5 days [Bertoni et al., 2004], 7 days [Farney et al., 2013]), treatment frequency (every 12 h [Barragan et al., 2017], daily [Bertoni et al., 2004; Farney et al., 2013; Carpenter et al., 2016; Barragan et al., 2020]), and type of aspirin product used (sodium salicylate [Farney et al., 2013; Carpenter et al., 2016], acetylsalicylic acid [Barragan et al., 2017; Barragan et al., 2020]). As a summary, most of the studies found an increase in milk production in multiparous cows but not in primiparous cows, and the studies that treated cows for more days (5-7 days) found negative effects of treatment on the metabolic status of cows (i.e., lower body condition and higher concentration of ketone bodies). A recent study, performed by our lab (Barragan et al., 2020), assessed an applicable and simple treatment approach and found not only benefits on milk production but also on cow metabolic status, prevention of uterine diseases and cow fertility. This approach consisted of treating cows with aspirin boluses (200 mg/kg; 4 boluses of 480 grains) at calving and 24 h later. Our results showed that second and greater lactation cows treated with this strategy produced 3.6 lbs/d more milk during the first 60 days in milk compared to multiparous cows that remained untreated. Furthermore, all treated cows (first lactation cows and older) had lower concentration of ketone bodies at 14 days in milk, lower incidence of clinical metritis and endometritis, and required 20 days less to become pregnant when compare to untreated cows.
When managing transition dairy cows, the main goal must be focused on providing a comfortable environment (facilities, diet, animal handling) to decrease stress and inflammation around calving. Although this is achievable in most modern dairy farms, often management can fail, or due to financial situations management cannot be improved in the short term (e.g., building new facilities). In those scenarios, proactive and applicable strategies to modulate inflammation can help dairy producers to improve cow health and performance while the management is adjusted.Source : psu.edu