Randomized field trial on the effects of body weight and short transport on stress and immune variables in 2- to 4-week-old dairy calves.

BACKGROUND: Whether underweight calves respond differently to transport stress, enhancing their disease risk, is currently unknown. OBJECTIVE: To determine the effects of low body weight and transport stress on immune variables. ANIMALS: Twenty-one 2- to 4-week-old male Holstein calves, housed on a commercial farm. METHODS: Randomized clinical trial. Full factorial design with 4 treatment groups: low body weight (≤46 kg)/no transport (LOWCON); low body weight/transport (LOWTRANS); normal body weight (>46 kg)/no transport (NORMCON), and normal body weight/transport (NORMTRANS). Transport duration was 2 hours. RESULTS: Transport significantly increased serum cortisol concentration (77.8 µg/mL; 95% confidence interval [CI], 37.8-131.6; P < .001), interleukin (IL)-17A (344.9 pg/mL; 95% CI, 32.2-556.5; P = .04), and tumor necrosis factor-α (TNF-α) (218.2 pg/mL; 95% CI, 32.5-368.3; P = .03) production after lipopolysaccharide (LPS) stimulation. Body weight did not affect any of the studied variables. However, the interaction of transport and body weight was significant. LOWTRANS calves showed increased monocyte count (2.0 × 109 /L; 95% CI, 0.6-4.2; P < .05) and interleukin IL-17A production (106.0 pg/mL; 95% CI, 4.2-306.9; P = .03) compared to normal weight calves and increased TNF-α production (275.6 pg/mL; 95% CI, 2.6-463.0; P = .02) compared to LOWCON calves in unstimulated peripheral blood mononuclear cells (PBMCs) after transport. CONCLUSION AND CLINICAL IMPORTANCE: These findings contribute to our understanding of increased disease susceptibility of underweight calves when transported. Gamma globulin concentration was identified as important interfering factor in studies on immune variables in neonatal calves.

Integrating fasciolosis control in the dry cow management: the effect of closantel treatment on milk production.

The liver fluke Fasciola hepatica is a parasite of ruminants with a worldwide distribution and an apparent increasing incidence in EU member states. Effective control in dairy cattle is hampered by the lack of flukicides with a zero-withdrawal time for milk, leaving the dry period as the only time that preventive treatment can be applied. Here, we present the results of a blinded, randomized and placebo-controlled trial on 11 dairy herds (402 animals) exposed to F. hepatica to 1) assess the effect of closantel treatment at dry-off (or 80-42 days before calving in first-calving heifers) on milk production parameters and 2) evaluate if a number of easy-to-use animal parameters is related to the milk production response after treatment. Closantel treatment resulted in a noticeable decrease of anti-F. hepatica antibody levels from 3-6 months after treatment onwards, a higher peak production (1.06 kg) and a slightly higher persistence (9%) of the lactation, resulting in a 305-day milk production increase of 303 kg. No effects of anthelmintic treatment were found on the average protein and fat content of the milk. Milk production responses after treatment were poor in meagre animals and clinically relevant higher milk production responses were observed in first-lactation animals and in cows with a high (0.3-0.5 optical density ratio (ODR)), but not a very high (≥ 0.5 ODR) F. hepatica ELISA result on a milk sample from the previous lactation. We conclude that in dairy herds exposed to F. hepatica, flukicide treatment at dry-off is a useful strategy to reduce levels of exposure and increase milk production in the subsequent lactation. Moreover, the results suggest that treatment approaches that only target selected animals within a herd can be developed based on easy-to-use parameters.