A note on versions:The version presented here may differ from the published version or from the version of record. If you wish to cite this item you are advised to consult the publisher's version. Please see the repository url above for details on accessing the published version and note that access may require a subscription.For more information, please contact eprints@nottingham.ac.uk 3215 INTRODuCTIONBreeding bulls in Australia are commonly fed high-energy diets before sale, generally in the form of grain. These diets previously have been shown to negatively affect sperm quality in bulls (Coulter phenomenon has been associated with increased adipose tissue deposition in the scrotal neck, impairing thermoregulation via the pampiniform plexus (Kastelic et al., 1996). Elevation of testicular tem--duction and sperm viability (Vogler et al., 1993). However, anecdotal evidence from veterinary practitioners and semen morphology laboratories suggests that sperm production can be affected early in the sale preparation process, before fat deposition occurring (P. McAuliffe, personal communication). The rapid introduction of diets containing readily fermentable carbohydrates may precipitate ruminal acidosis AbSTRACT: Breeding bulls are commonly fed high-energy diets, which may induce subacute rumiGertrudis bulls (age 20 ± 6 mo) were used to evaluate the extent and duration of effects of SARA on semen quality and the associated changes in circulating hormones and metabolites. The bulls were relocated and fed in yards with unrestricted access to hay and daily individual concentrate feeding for 125 d before SARA challenge. Semen was collected and assessed at 14-d intervals before the challenge to ensure acclimatization and the attainment of a stable spermiogram. The challenge treatments consisted of either a single oral dose of oligofructose (OFF; 6.5 g/kg BW) or an equivalent sham dose of water (Control). Locomotion, behavior, respiratory rate, and cardiovascular and gastrointestinal function were intensively monitored during the retained for VFA, ammonia, and lactate analysis. After the challenge, semen was then collected every third day for a period of 7 wk and then once weekly until 12 wk, with associated blood collection for FSH, testosterone, inhibin, and cortisol assay. Percent normal sperm decreased in bulls dosed with OFF after the challenge period (P -lenge. There was a corresponding increase in sperm defects commencing from 16 d after challenge. These included proximal cytoplasmic droplets (P P = 0.01), and vacuole and teratoid heads (P -ity after challenge were associated with lower serum testosterone (P P cortisol in OFF bulls tended to be greater (P = 0.07) at 7 d after challenge. This study shows that SARA chalpreclude bulls from sale as single sire breeding animals 3 mo after the event occurred.

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