The effect of hay quality on the onset of puberty and subsequent reproductive
performance was evaluated in 51 3/4 Hereford x 1/4 Angus (HA) heifers and 47 3/4
Hereford x 1/4 Brahman (HB) heifers. Two qualities of alfalfa hay were fed ad
libitum. along with an average of 3.1 lbs/hd/day of ground sorghum grain.
HB heifers were heavier and carrying more backfat and body condition (P<.05)
at the start of the experiment and they maintained their weight advantage through
out the experiment. A higher (P<.05) percent of the UB heifers reached puberty by
14 and 15 months of age and became pregnant during a 45 day artificial insemination
breeding period. HA heifers reached puberty at a lighter (P<.05) average weight.
Heifers fed high quality alfalfa hay were heavier (P<.05) by the start of the
breeding season and were carrying more (P<.05) backfat and body condition. A
higher percent (P=.08) of the heifers receiving higher quality hay reached puberty by
16 months of age and a higher (P=.10) percent became pregnant during the breeding
period.
Heifers inseminated at their pubertal estrus had lower (P=.04) first service
conception rates than heifers inseminated at their second or later estruses (52% vs.
88%).
