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1262
Effect of pre- and postnatal trace mineral (TM) source on Angus and Brangus heifer growth and reproductive performance

Thursday, July 21, 2016: 4:30 PM
151 E/F (Salt Palace Convention Center)
Deborah M. Price , Department of Animal Sciences, University of Florida, Gainesville, FL
Meaghan M O'Neil , Department of Animal Sciences, University of Florida, Gainesville, FL
Wayne B Watson III , Department of Animal Sciences, University of Florida, Gainesville, FL
Roger West , College of Veterinary Medicine, University of Florida, Gainesville, FL
Dr. Owen Rae , College of Veterinary Medicine, University of Florida, Gainesville, FL
Dr. Max Irsik , College of Veterinary Medicine, University of Florida, Gainesville, FL
Matt Hersom , Department of Animal Sciences, University of Florida, Gainesville, FL
Joel V. Yelich , Department of Animal Sciences, University of Florida, Gainesville, FL
Audio File Recorded Presentation (mp4)
Abstract Text:

A 2 by 2 factorial design evaluated reproductive performance in Angus (n = 40) and Brangus (n = 40) heifers born to cows supplemented with either inorganic (n = 40, 20/breed) or organic (n = 40, 20/breed) TM sources. The TM was initiated 82 ± 2 d pre-calving and resultant calves were weaned, and blocked by maternal TM source, age, sire, and weaning BW, and randomly assigned to 10 pens (5 pens/TM) for a 168 d development period. On d 161 and 168, blood samples were collected to determine pubertal status (puberty = progesterone ≥ 1.5 ng/mL at one of two samples). A BW, BCS (Scale 1-9), and reproductive tract score (RTS, 1-5) were recorded and heifers were sorted by breed and TM source into 4 pastures (1 pasture/TM×breed) on d 168 for a 72 d natural service breeding season.  Pregnancy was determined by ultrasound on d 51 of breeding season and 28 d after bull removal. The TM supplement was pen fed 3 d/wk at 0.4 kg•454 kg BW-1•heifer-1•d-1 as a pellet during development and as loose mineral during breeding (88.8 g•heifer-1•d-1). Heifer was the experimental unit and analysis utilized PROC MIXED for BW, BCS, and RTS data and PROC GLIMMIX for pregnancy and pubertal status. Fixed effects included TM, breed, and interaction. On d 168, inorganic (328 ± 5 kg) and organic (339 ± 5 kg) did not differ (P > 0.05) in BW or BCS (5.4 ± 0.1). Heifer RTS tended (P = 0.10) to be greater for organic (3.3 ± 0.1) than inorganic (3.0 ± 0.1) and greater (P ≤ 0.01) in Brangus (3.4 ± 0.1) than Angus (2.9 ± 0.1) on d 168. Pubertal status did not differ (P > 0.05) on d 168 for TM (Inorganic, 20%=4/20; Organic, 20%=4/20) and breed (Angus, 20%=4/20; Brangus, 20%=4/20). On d 51 of breeding, pregnancy rates did not differ (P > 0.05) between inorganic (45%=18/40) and organic (63%=25/40) but were greater (P ≤ 0.05) in Brangus (65%=26/40) than Angus (43%=17/40).  Final breeding season pregnancy rates did not differ (P > 0.05) between inorganic (87.5%= 35/40) and organic (95%=38/40), or between Angus (93%=37/40) and Brangus (90%=36/40). The TM source affected RTS but not pubertal status at the start of breeding season in yearling Angus and Brangus heifers. Additionally, TM source did not influence pregnancy rates to a natural breeding.

Keywords:

trace minerals, heifers, pregnancy rate

See more of: Production, management and the environment: Reproduction
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