Differences in nutrient use efficiency and food-feed competition among Chinese dairy farms

With rapid intensification and a decoupling of animal and crop production, Chinese dairy farmers are increasingly relying on the import of high-quality feed, while facing difficulties to return the animal manure to the fields. This leads to high environmental losses of nutrients such as nitrogen (N) and food-feed competition. To provide guidance towards a sustainable dairy sector within a circular food system, this study explores differences in N use efficiency (NUE) and food-feed competition between major farm types in North-Central China. From October to December 2020, a farm survey was conducted among 48 dairy farms in Henan. Herd size ranged from 115 to 4,289 heads and 52% of the farms were landless. Data on farm characteristics were collected to calculate the NUE and human-edible protein conversion ratio (HePCR). NUE was defined as the ratio of aggregated N inputs and outputs (i.e. meat and milk) at farm level, while NUEM also considered a fraction of 48% of the N in exported manure as a valuable output, to account for the amount that ended up in crop products when used as fertilizer. HePCR was defined as the amount of protein in feed that is potentially edible for human over that in milk and meat. Three major farm types were identified by cluster analysis, varying in herd size and milk yield. Typologies include (A) large-scale farms (≥1,309 heads) with high yielding cows (9.5 ton/cow/yr); (B) small and medium-scale farms (170-1,022 heads) with medium to high yielding cows (8.6 ton/cow/yr); (C) small-scale farms (≤485 heads) with low yielding cows (5.2 ton/cow/yr). Preliminary results showed that the average NUE was 19% (A), 20% (B) and 14% (C). The average NUEM was 29% (A), 30% (B) and 34% (C). The HePCR varied from 0.9-3.1 for typology A, from 0.4-3.2 for B, and from 1.1-4.5 for C. Overall, farm type B performed better both in terms of NUE and feed-food competition, mainly owing to its moderate concentrate usage and relatively higher milk yield. Differences in NUE and NUEM show the importance of recycling manure by recoupling animal and crop production. With most of the farms having a HePCR>1.0, effort should be made to improve utilization of by-products and human-inedible biomass as dairy cattle feed.