Randomized clinical trial evaluating the effects of administering acidogenic boluses at dry-off on udder health, milk yield, and herd removal

Acidogenic boluses can mitigate potential negative effects of high milk yield at dry-off on udder health. This randomized controlled trial aimed to investigate the effect of administering acidogenic boluses at dry-off on dry period intramammary infection (IMI) dynamics and on milk production parameters, somatic cell count linear score (LSCC), clinical mastitis (CM), and herd removal in the next lactation. A total of 901 cows from 3 dairy farms were randomly allocated to a control (CON, n = 458; no administration of acidogenic boluses at dry-off) or treatment group (TRT, n = 443; administration of 2 acidogenic boluses at dry-off). Quarter milk samples were collected at dry-off and after calving and submitted for bacteriological milk culture. The effects of treatment on the presence of quarter-level postpartum IMI, cure of existing IMI, and acquisition of new IMI, and on the prevalence of cow-level high LSCC (LSCC ≥4) in the first 30 days in milk (DIM) were analyzed using mixed effects logistic regression. Mixed linear regression was used to analyze cow-level milk production parameters (i.e., milk yield, fat corrected milk, fat and protein yield, and LSCC) in the first 90 DIM and until 300 DIM. For CM and herd removal, Cox proportional hazard regression models were used. In addition to treatment group, lactation group at dry-off, presence of high LSCC in the last test-day, average milk yield in the week before dry-off, presence of CM in the lactation of enrollment, and biologically relevant interactions were offered in all models. There was no evidence of a difference in IMI dynamics or in milk, fat corrected milk, protein or fat yields in the subsequent lactation between groups. The TRT group had a lower LSCC in the first 2 mo postpartum compared with the CON group (2.58 ± 0.3 vs. 2.92 ± 0.3 and 2.42 ± 0.3 vs. 2.81 ± 0.3, for first and second month postpartum). The prevalence of high LSCC in the first 30 DIM was 9.1% lower in the TRT compared with the CON group (16.3% vs. 25.5%; risk difference: -9.2; 95% confidence interval [CI]: -15.8, -2.5). Cows in the TRT group exhibited reduced hazards of CM in the subsequent lactation compared with cows in the CON group (hazard ratio: 0.75; 95% CI: 0.63, 0.89) as well as a reduced hazard of herd removal (hazard ratio: 0.82, 95% CI: 0.77, 0.88). The administration of acidogenic boluses as a component of dry-off management is a promising approach to maintain good udder health and reduce the hazard of CM and herd removal during the subsequent lactation.

Graduate Student Literature Review: The challenge of drying-off high-yielding dairy cows

The cessation of lactation (i.e., dry-off) in dairy cattle is an area of research that has received much focus in recent years. The dry period is necessary to optimize tissue remodeling of the mammary gland, but represents a stressful event, incorporating several changes in daily routine, diet, and metabolism. Moreover, the high milk yields achieved by modern cows in late gestation exacerbate the need for relevant manipulations in the days around dry-off, as excessive accumulation of milk might jeopardize the success of the dry period, with potential negative effects on future lactation. Production levels over 15 kg/d are an additional risk factor for udder health, delay mammary involution, and worsen metabolic stress and inflammatory responses. Furthermore, the pressure to reduce antibiotic usage in farm animals has resulted in increased attention on the dry period, given that historically most dairy cattle were provided prophylactic intramammary antibiotic treatment at dry-off as a means to reduce the risk of intramammary infections in the subsequent lactation. Several strategies have been proposed over the years to cope with these challenges, aiming to gradually reduce milk yield before dry-off, promoting at the same time the start of mammary involution. Among them, the most common are based on feed or nutrient restriction, a decrease in milking frequency, or administration of prolactin inhibitors. These practices have different capacities to reduce milk yield through different mechanisms and entail several implications for udder health, animal welfare, behavior, endocrine status, metabolism, and inflammatory conditions. The present review aims to provide a comprehensive overview of the dry-off phase in high-yielding cows and of the impact of high milk production at dry-off, and to describe possible strategies that might be implemented by farmers and veterinarians to optimize this critical phase in an integrated way.

A randomized clinical trial evaluating the effects of administration of acidogenic boluses at dry-off on rumination and activity behavior in the 14 subsequent days

Elevated milk production at dry-off can lead to increased udder pressure and, in turn, increased stress due to pain and discomfort, affecting natural behaviors. Administering acidogenic boluses at dry-off acts by inducing temporary and mild decreases in blood pH. This decreases dry matter intake, reduces milk yield, and increases cow comfort by lessening udder pressure. The objective of this study was to assess the effect of oral administration of acidogenic boluses at dry-off on total daily activity (TDA) and total daily rumination (TDR) behaviors in the first 2 wk of the dry period. This randomized clinical trial was conducted on a single farm and cows were randomly assigned to either treatment (TRT; n = 30) or control (CON; n = 34). The TRT group received 2 acidogenic boluses at dry-off and the CON group received no intervention. All cows received dry-cow therapy (intramammary antibiotic and internal teat sealant). The TDA and TDR data from 7 d before to 14 d after dry-off were measured using ear-mounted activity monitors. Analyses were performed using linear mixed-effects models with repeated measures. We observed a similar TDA in both groups throughout the study follow-up period. Overall, cows in the TRT group spent 17 min/d less time active than cows in the CON group in the first 2 wk after dry-off with the greatest difference observed on the second day of the dry period (TRT = 395 min/d; 95% CI: 370 to 420 vs. CON = 428 min/d; 95% CI: 404 to 451). The TRT group had lower TDR in the first 24 h after bolus administration (TRT = 437 min/d; 95% CI: 414 to 461 vs. CON = 488 min/d; 95% CI: 466 to 510) when compared with the CON group, but no differences were observed when comparing both groups in the 13 subsequent days. Our results indicate that administering acidogenic boluses at dry-off slightly decreased TDA during the first 2 wk of the dry period and decreased TDR on the first day after administration.

A randomized controlled trial assessing the effect of intermittent and abrupt cessation of milking to end lactation on the well-being and intramammary infection risk of dairy cows

The objectives were to compare the effects of an intermittent milking schedule with a thrice daily milking schedule during the final week of lactation on the well-being, udder health, milk production, and risk of culling of dairy cows. We hypothesized that cows subjected to an intermittent milking schedule would experience less udder engorgement and pain, lower concentrations of fecal glucocorticoid metabolites (11,17-dioxoandrostanes; 11,17-DOA concentration) after dry-off, lower risk of an intramammary infection during the dry period, higher milk production and lower somatic cell count in the subsequent lactation, and lower culling risk compared with herd mates milked 3 times daily and dried off by abrupt cessation. In a randomized controlled field study, Holstein cows (n = 398) with a thrice daily milking schedule were assigned to treatment and control groups. The treatment consisted of an intermittent milking schedule for 7 d before dry-off (gradual cessation of milking, GRAD). Gradual-cessation cows were milked once daily until the day of dry-off, whereas cows in the control group (abrupt cessation of milking, APT) were milked 3 times daily until the day of dry-off. Udder firmness and pain responses of the udder 3 d after dry-off, as well as the percentage change in fecal 11,17-DOA concentration (3 d after dry-off compared with the dry-off day), were used to assess the well-being of the animals. Compared with cows in the GRAD group, the odds [95% confidence interval (CI)] of udder firmness were 1.55 (0.99-2.42) for cows in the APT group, and the odds of a pain response were 1.48 (0.89-2.44) for cows in the APT group. The least squares means (95% CI) of the percentage change in 11,17-DOA concentration were 129.3% (111.1-150.4) for the APT group and 113.6% (97.5-132.4) for the GRAD group. Quarter-level culture results from the periods before dry-off and after calving were compared, to assess the likelihoods of microbiological cure and new infection. Cows in the APT group had lower odds of a new intramammary infection in the dry period [odds ratio, 95% CI: 0.63 (0.37-1.05)], whereas we observed no meaningful differences in the microbiological cure likelihood among groups. The least squares means (95% CI) for somatic cell counts (log₁₀-transformed) were 4.9 (4.8-5.0) in the APT group and 4.9 (4.8-5.0) in the GRAD group. The odds (95% CI) of clinical mastitis in the first 30 d postcalving were 1.32 (0.53-3.30) in the APT group compared with the GRAD group. We observed no meaningful differences in milk production at the first test date postcalving or the culling risk among groups. We conclude that the gradual-cessation protocol tested herein failed to significantly improve animal well-being, udder health, milk production, and survival in the tested study cohort. However, the observed differences in udder firmness, as well as the numerical differences in udder pain and the percentage change in fecal 11,17-DOA concentrations suggest that this line of research may be useful. Future research is needed to develop drying-off strategies that are appropriate for lowering milk production at the end of the lactation and improve animal well-being without compromising udder health.

Effects of dietary and milking frequency changes and administration of cabergoline on clinical udder characteristics in dairy cows during dry-off

We investigated the effects of 2 diet energy densities [normal lactation diet (NORM) vs. energy-reduced diet (REDU), both fed for ad libitum intake] and 2 daily milking frequencies [twice (2×) vs. once (1×)] during 1 week before the dry-off day, as well as effects of an injection of either a dopamine agonist [cabergoline (CAB); Velactis, Ceva Santé Animale, Libourne, France; labelled for use only with abrupt dry-off, e.g. no reduction in diet energy density or milking frequency before the last milking] or saline (SAL) following the last milking, on clinical udder characteristics of Holstein cows. During a week before and after the last milking, the following measures were recorded: palpation-based udder firmness and soreness; image-based hock-hock distance; responsiveness to mechanical udder stimulation and degree of udder fill measured with a dynamometer. Before the last milking, REDU cows displayed lower odds of having a firm udder and lower degree of udder fill, as well as lower responsiveness to mechanical udder stimulation, than NORM cows. After the last milking, REDU cows displayed shorter hock-hock distance compared with NORM cows. The effects of milking frequency on the clinical udder characteristics were unclear. Within 24 h following injection, CAB cows showed lower odds of having a firm udder, shorter hock-hock distance, and lower degree of udder fill than SAL cows, irrespective of treatment group before dry-off. In this study, reducing diet energy density prior to dry-off, and to some extent administering the dopamine agonist cabergoline after the last milking, resulted in fewest clinical udder changes.

Dry-off and dairy cow udder health and welfare: Effects of different milk cessation methods

The cessation of milking at the end of lactation is a routine management practice in dairy herds, and the importance of the dry period for milk production and udder health, has long been recognized. Among countries and herds, drying-off practices differ and include various milk cessation methods, such as changes in milking frequency and in feeding, the use of antibiotic dry cow therapy and teat sealants, and changes in housing. Published studies reporting methods of stopping milk production are scarce, and there are no uniform recommendations on optimal procedures to dry cows off for good udder health, cow welfare, and milk production. This review describes methods to stop mik production to prepare cows for the dry period and their effects on mammary involution, udder health, and dairy cow welfare. Milk yield at dry-off (the final milking at the end of lactation) is important for rapid involution, which stimulates the immune system and promotes good udder health and cow welfare. Based on the findings of this review, gradual cessation of milking over several days before the final milking can effectively reduce milk yield at dry-off and accelerate mammary gland involution while maximizing cow comfort and welfare. Data from this review indicate a target production level of 15 kg/day of milk or less at dry-off.