Lameness prevention
Claw horn lesions (CHL) are reported as the most common cause of lameness in intensive dairy systems. Despite their prevalence, the underlying pathological mechanisms and preventive strategies for CHL remain poorly understood. Recent advances have pointed to the role of inflammation in disease aetiopathogenesis. Moderating inflammation from first calving may lead to long-term benefits and a viable intervention for treating and preventing disease. Wilson et al (2022) (Journal of Dairy Science10.3168/jds.2021-21329) conducted a 34-month randomised controlled trial to investigate the effects of routine treatment with ketoprofen at calving and during treatment for lameness, on the future probability of lameness and culling, caused by exposure to normal farm conditions. A cohort of dairy heifers were recruited from a single, commercial herd between January 2018, and June 2020, and randomly allocated to one of four treatment groups before first calving. The lactating herd was lameness scored every 2 weeks on a 0 to 3 scale using the adapted Agriculture and Horticulture Development Board (AHDB) lameness scoring system (see full paper for details), to identify animals that became lame (single score ≥2a) and hence required treatment. Animals in group 1 received a therapeutic trim and a hoof block on the sound claw (if deemed necessary) every time they were treated for lameness. Animals in group 2 received the same treatment as group 1 with the addition of a 3-day course of ketoprofen (single dose daily) every time they were treated for lameness. Animals in group 3 received the same treatment as group 2 with the addition of a 3-day course of ketoprofen (single dose daily) starting 24 to 36 hour after each calving. Animals in group 4 received a 3-day course of ketoprofen (single dose daily) every time they were identified with lameness. No therapeutic trim was administered to this group, unless they were identified as severely lame. Animals were followed for the duration of the study. Probability of lameness was assessed by a lameness outcome score collected every 14 days. Data on culling were extracted from farm records. One hundred thirty-two animals were recruited to each group, with data from 438 animals included in the final analysis. Compared with the control group (group 1), animals in group 3 were less likely to become lame (odds ratio: 0.66) and severely lame (odds ratio: 0.28). Furthermore, compared with group 1, animals in groups 2 and 3 were at reduced risk of culling (hazard ratios: 0.55 and 0.56, respectively). The lameness effect size identified was large. If repeatable, this study is very significant in the context of lameness prevention.
Colostrum at pasture
This observational study by Mason et al (2022) (Journal of Dairy Science10.3168/jds.2021-21460) assessed serum total protein (STP) in calves born at pasture and left to suckle their dams for up to 24 hours. It also investigated failure of passive transfer (FPT) of immunity once calves had been provided with colostrum from the farmer and some factors that may contribute to the risk of FPT. Over 2 years, eight farms (four in the North Island, four in South Island of New Zealand) were involved in an observational study where cows and calves were observed for 24 hours a day for 2 weeks per farm. Observers recorded the time from birth to first suckling, number of suckling events, time of calf removal from the dam, and ambient temperature. Calves were blood sampled on arrival at housing, before receiving colostrum from the farmer (day 1), and again 2 days later to test for STP concentration. On day 1, 689 calves had blood samples collected, at a median of 11.5 (interquartile range 5.6 to 19.2) hours post-birth. Of these, 283 calves (41.1%; 95% confidence interval (CI) 37.4 to 44.9%) had STP >52 g/litre (proportion by farm ranged from 10 to 78%). On day 3, 680 blood samples were collected, of which 16.0% (95% CI 13.5 to 19.0) had FPT (STP ≤52 g/litre) with proportion by farm ranging from 2.5 to 31.6%. The FPT risk at day 3 in calves that did not suckle before housing was 2.91 (95% CI 2.04 to 4.13) times the risk in calves that suckled. For every hour longer post-birth that it took for a calf to have its first suckling event, odds of FPT at day 3 increased by 1.21 (95% CI 1.08 to 1.36) times, and compared with calves that only suckled once, calves that suckled 2, 3–5, or >5 times had 0.42 (95% CI 0.15 to 0.99), 0.35 (95% CI 0.15 to 0.76), and 0.10 (95% CI 0.005 to 0.47) times the odds of FPT, respectively. For every 1-percentage-point increase in the Brix % of the colostrum, the odds of FPT decreased by 33% (95% CI 24 to 42). There were very large between-farm variabilities for rates of suckling, colostrum feeding, and FPT risk that require further investigation for calves born at pasture.
Readers may also be interested in an invited review entitled The importance of colostrum in the newborn dairy calf by Lopez and Heinrichs (2022) (Journal of Dairy Science10.3168/jds.2020-20114). The importance of discussing colostrum with clients never goes away!