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- Title
Relationships between feed efficiency, scrotal circumference, and semen quality traits in yearling bulls.
- Authors
Hafla, A. N.; Lancaster, P. A.; Carstens, G. E.; Forrest, D. W.; Fox, J. T.; Forbes, T. D. A.; Davis, M. E.; Randel, R. D.; Holloway, J. W.
- Abstract
A meta-analysis was conducted to examine phenotypic relationships between feed effi-ciency, scrotal circumference, and semen quality traits in yearling bulls. Data evaluated were obtained from 5 postweaning trials involving Angus (n = 92), Bonsmara (n = 62), and Santa Gertrudis (n = 50) bulls fed diets that ranged from 1.70 to 2.85 Meal ME/kg DM. After an adaptation period of 24 to 28 d, feed intake was mea-sured daily, and BW was measured at 7- or 14-d intervals during the 70- to 77-d trials. Ultrasound carcass traits (12th-rib back fat thickness, BF; LM area, LMA) and scrotal circumference (SC) were measured at the start and end of each trial. Semen samples were collected by electroejaculation within 51 d of the end of the trials when the age of bulls averaged from 365 to 444 d and were evaluated for progressive sperm motility and mor-phology. Residual feed intake (RFI) was calculated as the difference between actual DMI and expected DMI from linear regression of DMI on ADG and midtest BW0 75, with trial, trial by ADG, and trial by midtest BW0 75 as random effects. Across all studies, bulls with low RFI phenotypes (<0.5 SD below the mean RFI of 0) consumed 20% less DM and had 10% less BF but had similar ADG, SC, and semen quality traits com-pared with high-RFI bulls (>0.5 SD above the mean RFI of 0). Gain to feed ratio was strongly correlated with ADG (0.60) and weakly correlated with initial BW (-0.17) and DMI (-0.26). Residual feed intake was not correlated with ADG, initial age, or BW but was cor-related with DMI (0.71), G:F (-0.70), and BF (0.20). Initial SC (-0.20), gain in SC (-0.28), and percent nor-mal sperm (-0.17) were correlated with G:F, but only sperm morphology was found to be weakly associated with RFI (0.13). These data suggest that RFI is not phe-notypically associated with SC or spenn motility but is weakly associated with sperm morphology.
- Subjects
CATTLE feeding &; feeds; BULLS; SEMEN analysis; ANIMAL carcasses; SPERM motility; PHENOTYPES
- Publication
Journal of Animal Science, 2012, Vol 90, Issue 11, p3937
- ISSN
0021-8812
- Publication type
Article
- DOI
10.2527/jas.2011-4029