[Influence of feeding rumen-protected choline to transition dairy cows. Part 2: Health and reproduction]

OBJECTIVE: To determine the effects of rumen-protected choline (RPC) on health and reproduction in dairy cows. MATERIAL AND METHODS: A total of 298 primi- and multiparous German Holstein cows of a high-production dairy herd (average daily milk yield: 32 l) were assigned randomly to a control or treatment group and were hand fed with 0 or 60 g/d of RPC as ReaShure®, respectively, from 21 days before expected calving to 21 days post partum (p. p.) as a top dressing. Health data was analyzed for the incidence of fever within the first 10 days in milk (DIM) as well as the incidence of diseases and the culling rate within the first 200 DIM. Reproduction data were evaluated in terms of the calving data, uterine involution on days 10, 21 and 42 p. p., uterine cytology at day 42 p. p., progesterone concentrations during weeks 3 and 5 p. p. and certain fertility measures. In the statistical analysis, it was differentiated between the control and treatment groups and between primi- and multiparous animals, and their interactions were analyzed. RESULTS: The treatment group had less cows with subclinical endometritis, higher sickness rates after day 100 p. p., lower numbers of stillbirths and more cyclic cows in week 5 p. p. compared to the control group (p  <  0.05). Primipara in contrast to multipara had fever more frequently, higher rates of subclinical ketosis p. p., metritis and lameness, higher numbers of sick cows in the first 30 DIM, higher rates of stillbirths and dystocia, showed impaired involution of the uterus on day 10 p. p., fewer animals were cyclic during week 5 p. p. and less animals were culled (p < 0.05). Statistically significant interactions indicated that more heifers of the treatment group were lame, more heifers of the control group developed fever and subclinical endometritis, cows of the treatment group suffered more metritis and were sick more often in the first 30 DIM, and cows of the control group had more dystocia (p < 0.05). CONCLUSION: Overall, supplementing RPC had only minor effects on the health status and reproduction. Further research in other dairy herds should focus on this topic.