Interactions among factors affecting stillbirths in Egyptian buffaloes (Bubalus bubalis)

In buffaloes, stillbirth (SB) is a major source of reproductive and economic losses. Hence, the objectives of this study were: 1) investigating the relationship between potential risk factors (body condition score [BCS], gestation period, calving season, calf sex, and dam parity) and SB occurrence in Egyptian buffaloes; and 2) identifying blood metabolites, the redox status, and immune-inflammatory attributes in calves that may be related to SB. The incidence of SB was 6.64%. Among the evaluated risk factors, BCS was a significant risk factor for SB. There was a 73.7% lower odds (lower odds odd ratio, OR = 0.246) of SB for dams with a gestation length ≥ 305 days, compared to those with a gestation length < 305 days. The risk of SB decreased steadily with increasing dam parity. The odds of SB were 2.48 times higher in male calves compared to female calves. In comparison to the spring season, the probability of SB doubled during the summer season. Calf blood serum analysis showed that SB-born calves had higher blood biochemical and cytokines alterations than normal-born calves. On the other hand, immunoglobulins and glutathione peroxidase were significantly lower in SB-born calves. Our results indicated that factors related to the induction of inflammation and/or disrupted immune system responses, such as obesity, high temperature, and oxidative stress, are the main evoking factors for SB in buffaloes; therefore, protective measures against SB in Egyptian buffaloes should be based on controlling these factors, either by nutritional interventions or management practices.