Surrogates of Long-Term Vitamin D Exposure and Ovarian Cancer Risk in Two Prospective Cohort Studies

Experimental evidence and ecologic studies suggest a protective role of vitamin D in ovarian carcinogenesis. However, epidemiologic studies using individual level data have been inconsistent. We evaluated ultraviolet (UV)-B radiation, vitamin D intake, and predicted plasma 25-hydroxyvitamin D [25(OH)D] levels as long-term surrogates of vitamin D exposure within the Nurses’ Health Study (NHS) and NHSII. We estimated incidence rate ratios (RRs) and 95% confidence intervals (CIs) for risk of overall ovarian cancer and by histologic subtype using Cox proportional hazards models. Between 1976 and 2010 in NHS and 1989 and 2011 in NHSII, we identified a total of 1,225 incident epithelial ovarian cancer cases (NHS: 970, NHSII: 255) over 4,628,648 person-years of follow-up. Cumulative average UV-B exposure was not associated with ovarian cancer risk in NHS (Ptrend = 0.08), but was associated with reduced risk in NHSII (highest vs. lowest category RR = 0.67; 95% CI: 0.50, 0.89; Ptrend < 0.01). When stratified by histologic subtype, UV-B flux was positively associated with risk of serous tumors in NHS (Ptrend < 0.01), but inversely associated in NHSII (Ptrend = 0.01). Adjusted for confounders, ovarian cancer risk was not associated with vitamin D intake from food or supplements or with predicted 25(OH)D levels. Our study does not strongly support a protective role for vitamin D in ovarian cancer risk

Net benefits of smallholder dairy cattle farms in Senegal can be significantly increased through the use of better dairy cattle breeds and improved management practices

Senegal, located in West Africa, is an example of a low-to middle-income country where the govern-ment has prioritized improving livestock production self-sufficiency, with a strong focus on dairy. Among other initiatives, the use of exotic dairy cattle has been promoted, despite no evidence for the potential liveli-hood benefits (or otherwise) to smallholder farmers on adopting the new genetics. The current work fills this evidence gap by performing a farm-level economic study comparing the keeping of different breed and cross-breed types of dairy cattle under different management levels. Data for the study were obtained by monitoring 220 smallholder dairy cattle farms, with a combined cattle population of about 3,000 animals, over an almost 2-yr period. Findings of the study suggest that the most net-beneficial and cost-beneficial dairy cattle enterprise that could be used by the smallholder farmers was to keep crossbred indigenous zebu by exotic Bos taurus animals under management standards that are consid-ered good compared with local standards. This dairy enterprise type was 7.4-fold more net beneficial and had a 1.4-fold more favorable cost-benefit ratio than the traditional system of keeping indigenous zebu animals under poor (low-input) management. Interestingly, the keeping of (near) pure B. taurus dairy cattle resulted in the highest milk yields and thus benefit from milk, but was not the most net beneficial due to the high costs of keeping these animals, particularly in terms of feed. We also found that increasing the managementlevel of any of the breed or cross-breed types under consideration, including the indigenous zebu animals, resulted in an increased net benefit of 2.2-to 2.9-fold. Results of this economic analysis are discussed as part of a broader trade-off analysis, resulting in recommendations to strengthen the Senegal dairy sector. The combined intervention of improved dairy cattle genetics and management is considered a promising intervention to improve livelihoods of the rural poor as well as livestock production self-sufficiency for Senegal; some other system constraints are addressed.Peer reviewe