2x2x2 factorial design with the factors of breeds; Murrah x swamp crossbreds and swamp buffaloes, non and feed supplementation, and work and non-work, was used in this study. Sixteen Murrah x swamp crossbreds and 16 swamp buffaloes were randomly allotted into 8 treatment combinations. The study period was 6 nonths; however, the animals in the working groups only started plowing at the beginning of week 5 and finished at the end of the experimental period. It was found that the average daily gain of Murrah x swamp crossbreds was not significantly different from that of swamp buffaloes. With out regard to other factors, the feed supplemented group gained more weight than the non-feed supplemented (P0.01), while the working and non-working groups were not statistically different in growth rate. No interaction among factors was found. For plowing ability, the crossbreds, the non-supplemented and supplemented groups could plow an area of 0.23 rai (0.09 acre) per hour while swamp buffaloes, the non-supplemented and supplemented groups, could plow 0.24 rai (0.10 acre) and 0.30 rai, (0.12 acre) respectively (P0.01). For the speed of plowing, the crossbreds, the non-supplemented and supplemented groups, could travel 40.71 and 48.42 metres per minute, respectively (P0.05) while the swamp buffaloes, the non-supplemented and supplemented groups, could travel at a speed of 43.86 and 53.32 metres per minute, respectively (P0.05). Within the non-feed supplemented groups, crossbred and swamp buffaloes could plow the area of 0.23 rai (0.09 acre) and 0.24 rai (0.10 acre) per hour, respectively (P0.05). Within the feed supplemented groups, the crossbred and swamp buffalo could plow the area of 0.23 rai (0.09 acre) and 0.30 rai (0.12 acre) per hour, respectively (P0.01). As for the speed of plowing, the performance of all the groups was not significantly different, i.e. 40.71, 48.42, 43.86 and 53.32 m/min for crossbred non-supplemented, crossbred supplemented, swamp non-supplemented and swamp supplemented groups, respectively (P0.05). However, the supplemented groups could plow faster than the non-supplemented ones (P0.05).

Infestation by leeches (Hirudinia sp.) was observed in Murrah buffaloes of Song Be, Vietnam, mostly during the humid-hot season. Percentage incidence of attachment was about 31.14, 22.75, 15.75, 10.78, 7.19, 5.39, 4.19 and 2.99 in the region of udder and teats, inguinal region, vulva and vagina, nasal cavity, lips and chin, base of the ears, naval region and neck and brisket, respectively. After blood sucking for different periods, mean body weight of leeches was 338.12, 291.85, 245.51, 204.17, 139.53, 118.82, 103.80 and 98.73 g in the corresponding order of attachments. The body weight of partly and fully fed leeches ranged from lowest 12 g detached from neck and brisket region to highest 517 g fallen after full feeding from the udder and teats.