Effects of assisted calving and retained fetal membranes on milk production in the smallholder farming system

The impact of assisted calving, retained fetal membranes (RFM) and calf sex on milk production in small-scale dairy systems remains unknown. This study evaluated their impact on early lactation milk production and standardized 305-day yield (305MY) using 279 lactation records from 23 farms over 18 months. Variables analyzed included assisted calving, RFM, calf sex, and lactation number, with milk production at 30 days and 305MY as response variables. General Linear Models were used for statistical analysis, with significance at P < 0.05, and trends at P < 0.1. Lactation number significantly affected early lactation milk production (P = 0.023), with RFM showing a trend toward significance (P = 0.078). Cows without RFM produced 21.8 ± 0.8 kg/day, while those with RFM produced 18.6 ± 1.7 kg/day. Assisted calving significantly affected 305MY (P < 0.05), with cows not requiring assistance having higher yields compared to those needing assistance. Interactions between assisted calving and lactation number (P = 0.099), as well as RFM and calf sex (P = 0.060), approached significance. In cows that did not require assisted calving, no significant differences in 305MY were found based on lactation number (P ≥ 0.05). However, in cows that required assisted calving, significant differences in 305MY (P < 0.05) were observed between first and third or higher lactations, with second-lactation cows having average values. Additionally, cows without RFM that gave birth to female calves had higher 305MY compared to cows with RFM or those that gave birth to male calves with RFM or without RFM. In conclusion, RFM reduces early lactation milk production by approximately 3.2 kg/day, and assisted calving impacts 305MY by about 1,069 kg/lactation.