By Penn State Extension Veterinarian Robert Van Saun, DVM
With reproductive performance in dairy herds declining and cow culling rates increasing, newborn calf survival is critical component to maintaining some financial stability and profitability for dairy herds. The most recent National Animal Health Monitoring System (NAHMS) report has shown a decline in dairy calves alive at 48 hours from 93.4% to 86% compared to the 1996 report. This loss accounts for stillborn and postnatal calf mortality. Average stillborn loss for the dairy industry according to the 2007 NAHMS study is 8.1% with a slightly higher rate (8.9%) reported in smaller dairy herds (< 100 cows) typical of Pennsylvania. Stillbirth rates are greater for heifers compared to older cows and rates have increased in both groups over the past years.
Although stillborn births in beef herds are lower than dairy herds, still-birth losses are significant. Stillbirths in beef cattle are reported to be in the order of 3.5%. All beef cattle studies indicated a strong association between dystocia and stillbirth occurrence. This is supported by significant associations between parity status, dam and sire breeds, calf sex (or more importantly birth weight), and mal-presentations with stillbirth occurrence.
Difficult calving is often the primary cause, but only accounts for approximately 50% of stillbirth causes according to two different studies in dairy cattle. Other congenital, infectious, nutritional, and management factors can contribute to stillborn occurrence. Infectious causes of stillbirth might result from specific agents, namely Bovine Virus Diarrhea (BVD), leptospirosis, Infectious Bovine Rhinotracheitis (IBR), and Neospora caninum, or non-specific bacterial agents. Studies evaluating stillbirth causes have concluded that stillbirth is the result of an interaction of multiple factors. A missing piece of the stillbirth puzzle, dam and calf nutritional status, has not been adequately investigated relative to stillbirth incidence. Nutritional deficits might directly result in death or induce a state of immune incompetence predisposing the fetus/neonate to infectious agents. Similar to what occurs in abortion diagnostics, a significant proportion of stillborn cases (>30%) have no clear diagnosis for causation and may be accounted for if nutritional status is better evaluated.
To address these gaps in our understanding of stillbirth problems, an initial 6 month survey study will be undertaken at Penn State University. We will be contacting producers and veterinarians willing to participate in the study by submitting dairy and beef calves that have died within 6 hours of birth for full diagnostic evaluation. All stillborn calf submissions will have a comprehensive questionnaire completed addressing calving numbers, nutrition, management, and maternity practices for the farm and specific situation. Submitted calves will have complete necropsy with histopathologic assessment of key organs for evidence of disease pathogenesis. Microbiologic diagnostics addressing important pathogens (IBR, BVD, Leptospirosis, Neospora, Bacteriology) will be completed. Concentration of 9 essential minerals and vitamins A and E will be determined by ICP/MS and HPLC, respectively, in liver samples submitted for nutritional analyses. Results of this preliminary study should provide useful information as to prevalence of stillborn calves and potential causes in dairy and beef herds in Pennsylvania. Additionally, some information as to potential risk factors leading to stillbirths can be identified, thus providing producers with suggestions for changes to minimize stillborn losses. If you have dairy and/or beef clients in Pennsylvania that would be interested in participating in this study contact Dr. Robert Van Saun at the Penn State Veterinary Extension office (814-863-2160). We are planning on starting the research in January, 2013.
Source: Penn State Extension