Sentence:  On both sampling occasions, the odour threshold concentration of exhaust air from the house fitted with <WSD>mini-cup</WSD> drinkers was substantially less than that from the house equipped with conventional 'bell' drinkers—see Fig. 1. The rationale for fitting mini-cup drinkers was that it was thought that the <WSD>mini-cup</WSD> drinkers would reduce water wastage and hence improve the litter conditions. 
Meaning of the word marked with <WSD> tags:  extra-small cup