The article “Effects of nutrition on the fertility of lactating dairy cattle” by Rodney et al. (2018) main focus was to examine diet modifications in early lactation for their impact upon artificial insemination pregnancy rates and calving-to-pregnancy intervals in dairy cows. The article also discovered several possible causes for the wide range of responses. Rather than focusing on the differences between individual dietary treatments, the goal was to determine the impact of nutrition on reproduction. The authors employed the more conventional way of looking at differences between treatments and their reference treatment in an experiment for the article.
Rodney et al. (2018) state that lactating dairy cows have a complicated reproductive disease linked to increased milk output and intensification of production. Genetics and the environment have changed dramatically in the previous several decades, making it impossible to pinpoint the exact cause of infertility decline. According to the article, the heritability of reproductive problems is low, even though genetic selection for a higher milk supply may have contributed to some of the historical declines in infertility. As a result, Rodney et al. (2018) argue that this shows that the drop previously seen was mostly due to environmental factors such as changes in feeding, housing and herd management and their interactions with genetics.
As per the authors, endogenous bodily tissue reserves have a role in the number of nutrients used for reproduction. The nutrient depletion hampers reproduction in milk secretion and the utilization of resources for maintenance and development. Rodney et al. (2018) clarify that nutrient balance is determined by the difference between food intake and expenditure, and endogenous resources are depleted if the balance is negative. Infertility has been studied extensively about a woman’s energy balance. Dietary management during lactation and milk production are two important factors that influence the duration and severity of the first locational negative energy balance. Calculated energy balance was, as expected, linked favourably to an increase in the number of pregnant animals and a decrease in the time between calving and pregnancy (Rodney et al., 2018).
The authors conclude that higher milk output cows are less fertile and that breeding for higher milk production can lower fertility. Although this data set did not include genetic variations, we were able to identify correlations between enhanced milk fat and protein production and shorter calving to pregnancy intervals. In this final model, milk protein yield was more important than the invariable model.
The authors conducted research that used 118 diets and 39 experiments to examine the relationship between dietary components and production outputs, the likelihood of service, and the time to conception. According to previously disclosed procedures, the dietary data were collected using feed data from the trials and the CPM-Dairy feed bank and calibrated these according to tested data from the previously reported experiments (Rodney et al., 2018). Despite the rigour used in diet extraction and the adoption of the CPM model, there were limits to the estimations of dietary components. The limitations or inaccuracies in the model included; differences in diet composition and timing; and feed.
This article provides numerous noteworthy results for future research into the effects of transition diet on fertility. The authors show that feeding cows during the transition phase may significantly impact their reproductive performance. In the end, the number of well-described diets that could be included in the study was much less than we had anticipated. Due to the limited number of effective treatments and the diverse ways cattle responded to different treatments, it is clear that more concentrated field trials are needed to understand better the effects of food on reproduction and the interactions between various dietary components.
Rodney, R. M., Celi, P., Scott, W., Breinhild, K., Santos, J. E. P., & Lean, I. J. (2018). Effects of nutrition on the fertility of lactating dairy cattle. Journal of dairy science, 101(6), 5115-5133.