Effect of feed supplementation, body condition and oestrus timing on the mounting activity of Brahman heifers at grazing in the humid tropics of Mexico
The effects of supplementation (SUP), body condition (CC) and oestrus timing (SINC) on mating activity were evaluated in 90 cycling Brahman heifers (diagnosis by ultrasonography). During 110 d prior to SINC, 45 animals received SUP (concentrated feed at a rate of 1% of live weight daily), the same number remained without SUP. For the SINC, Norgestomet was applied to 40 heifers (20 with and 20 without SUP) by subcutaneous implantation for 9 d and Norgestomet and estradiol valerate by intramuscular route. The other 50 animals (25 with and 25 without SUP0 did not receive SINC. After removing the implant, the mounting activity was observed in the pasture for 100 continuous hours. Neither the SUP nor the CC (which varied between 3.0 to 4.0 in the scale from 0 to 5) affected (P> 0.05) the variables studied. The interval between removal of the implant and the start of the activity of performing and receiving mounts was 36.1 ± 10.1 and 41.1 ± 8.4 h, respectively. The correlation between the The time of implant removal and the start of the activity were r = 0.3 and r = 0.5, respectively. The activity of mounting lasted longer and the number of mounts performed was higher (P <0.05) in SINC females than in those without SINC (10.0 ± 4.5 vs. 5.4 ± 5.1 h and 16.0 ± 8.0 vs. 8.2 ± 4.8, respectively) but the SINC did not alter (P> 0.05) the duration of receiving mounts or the number of mounts received. ) the duration of riding and the number of riding performed (r = 0.70). the intensity of riding and receiving m ontas was not affected by (P> 0.05) by the SINC, being the means 1.7 ± 0.6 and 1.8 ± 0.7 montas / h, respectively.
Copyright (c) 1997 Rodolfo Soto-Camargo, Carlos S. Galina, Ivette Rubio, Epigmenio Castillo, Hector Basurto
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