1AGIR,Université de Toulouse,INPT,INP-PURPAN,INRA,31320 Auzeville,France.
2Université de Perpignan,IUT,F-66962 Perpignan,France.
Animal. 2018 Aug;12(8):1642-1651. doi: 10.1017/S1751731117002993. Epub 2017 Dec 4.
Given the very recent investment in research on organic rabbit production, many knowledge gaps remain. Simulation models based on data from experiments and farms may help generate general principles for organic rabbit production. Our goals were to (i) develop a model to simulate intake regulation and growth of rabbits raised on pastures, (ii) validate this model under a diversity of conditions and (iii) conduct a simulation experiment to predict the potential to decrease the supply of complete feed by increasing the grazing area per rabbit. The model developed (PASTRAB) simulates organic rabbit fattening on pastures in four main submodels that represent dynamics of (i) herbage standing biomass, fill and feed values; (ii) intake of herbage, complementary feed (i.e. complete pellets, cereal-legume grain mixtures) and hay as regulated by herbage allowance, fill and feed values of feedstuffs and rabbit physiological parameters; (iii) conversion of rabbit intake into live weight gain; and (iv) rabbit mortality. The model also calculates gross margin per rabbit sold. Model accuracy was assessed by considering the fit between observed and predicted herbage intake, which was low, with a relative root mean square error (rRMSE) of 51% and 66% on grass-based and legume-based pastures, respectively. However, the standard deviations of observed herbage intake were similar to the root mean square error of predicted herbage intake, indicating that it would have been difficult to improve model calibration. The fit between observed and predicted rabbit live weight was acceptable, with an rRMSE of 11% and 10% for grass-based and legume-based pastures, respectively. Simulated scenarios showed that a decrease in complementary feed combined with an increase in the grazing area per rabbit had little impact on average daily growth and gross margin per rabbit but increased herbage use efficiency. With 90 g of complementary feed per day and grazing of 0.4 m²/rabbit per day, herbage use efficiency was 22%, with average daily growth of 21.6 g/day and gross margin of 18.80 €/rabbit. With no complementary feed and grazing of 1.2 m²/rabbit per day, average daily growth decreased (19.2 g/day), but herbage use efficiency reached 100% and gross margin reached 19.20 €/rabbit. We used PASTRAB in participatory workshops with farmers so that the latter could explore adaptations to their current practices. Overall, farmers considered the model predictions realistic, and some of them decided to adapt some of their management practices immediately after the workshops.
鉴于最近对有机兔生产的研究投入，许多知识空白仍然存在。基于实验和农场数据的模拟模型可能有助于为有机兔生产生成一般原则。我们的目标是：(i) 开发一种模拟在牧场上饲养的兔子的采食调节和生长的模型；(ii) 在多种条件下验证该模型；(iii) 进行模拟实验，以预测通过增加每只兔子的放牧面积来减少全价饲料供应的潜力。所开发的模型（PASTRAB）模拟了在四个主要子模型中有机肉兔在牧场上育肥，这四个子模型代表了（i）牧草立生物质、填充和饲料值的动态；（ii）根据牧草供给量、饲料的填充和饲料值以及兔子生理参数，对牧草、补充饲料（即全颗粒、谷物-豆类混合饲料）和干草的采食调节；（iii）兔子采食量转化为活体重增加；以及（iv）兔子死亡率。该模型还计算了每只出售兔子的毛利润。通过考虑观察到的和预测的牧草采食量之间的拟合度来评估模型的准确性，结果表明牧草采食量的拟合度较低，分别为 51%和 66%，适用于基于草的牧场和基于豆科植物的牧场。然而，观察到的牧草采食量的标准偏差与预测的牧草采食量的均方根误差相似，表明很难提高模型校准的精度。观察到的和预测的兔子活体重之间的拟合度是可以接受的，基于草的牧场和基于豆科植物的牧场的相对均方根误差分别为 11%和 10%。模拟场景表明，减少补充饲料并增加每只兔子的放牧面积对平均日增重和每只兔子的毛利润影响不大，但会提高牧草利用效率。每天用 90 克补充饲料，每只兔子放牧 0.4 平方米/只，牧草利用率为 22%，平均日增重 21.6 克/天，毛利润为 18.80 欧元/只。如果没有补充饲料，每只兔子每天放牧 1.2 平方米/只，平均日增重（19.2 克/天）下降，但牧草利用率达到 100%，毛利润达到 19.20 欧元/只。我们在与农民的参与式研讨会中使用了 PASTRAB，以便后者能够探索对其当前做法的调整。总体而言，农民认为模型预测是现实的，其中一些农民在研讨会后立即决定调整他们的一些管理做法。
