Author : Weerasak Wongsrikeao

Summary : Three studies were conducted at the Department of Animal Science, University of the Philippines Los Baños (UPLB) in Los Baños, Laguna, and at the Department of Animal Science, Central Luzon State University (CLSU), Muños, Nueva Ecija, to find out the effect of PGF2a or norepinephrine on estrus, ovulation, and pregnancy in the Philippine carabaos and Murrah buffaloes. The results of study showed that 20, 25, and 30 mg PGF (subscript 2 (a) ) given on day 12 or day 16 (but not day 6) of the estrous cycle in carabaos significantly induced estrus (P<0.05) within five days post-treatment. However, 30 mg PGF (subscript 2 (a) ) gave the best response with induced estrus occurring three or four days after treatment. The duration of estrus, ovulation time, and length of subsequent estrous cycle were normal as compared with those of the control carabaos. In study 2, however, carabaos failed to show significant response (P>0.05) to 2.5, 5.0, or 7.5 mg norepinephrine treatment on day 6, 12, or 16 of the estrous cycle based on the interval between treatment to estrus occurrence, duration of estrus, ovulation time, and the length of subsequent estrous cycle. In study 3, a single injection of 30 mg PGF (subscript 2 (a) ) on the day 12 of the estrous cycle or two injections of 30 mg PGF (subscript 2 (a) ) 12 days apart were effective in synchronizing estrus in carabaos and Murrah buffaloes, with pregnancy rate comparable to that of the control animals.