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ARS Home » Plains Area » Miles City, Montana » Livestock and Range Research Laboratory » Research » Publications at this Location » Publication #321170
Title: Effect of supplemental trace mineral level and form on peripubertal bulls

Author
item Geary, Thomas
item KELLY, WHISPER - World West Sire Services
item SPICKARD, D - World West Sire Services
item LARSON, C - Zinpro Corporation
item GRINGS, E - South Dakota State University
item ANSOTEGUI, R - Montana State University

Submitted to: Animal Reproduction Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/15/2016
Publication Date: 4/6/2016
Citation: Geary, T.W., Kelly, W.L., Spickard, D.S., Larson, C.K., Grings, E.E., Ansotegui, R.P. 2016. Effect of supplemental trace mineral level and form on peripubertal bulls. Animal Reproduction Science. 168:1-9.

Interpretive Summary: Our goal was to determine if puberty and fertility in bulls was affected by specific minerals in their diet. Fifty beef bulls were fed one of five diets that differed in amount and type of mineral. Mineral treatments were: 1) 1x sulfate form (1S); 2) 1x complexed form (1C); 3) 1S + 1C (2SC); 4) 1S + 2x 1C (3SCC); and 5) 3x 1S (3S). Each 1x supplementation level contained 360 mg zinc, 125 mg copper, 200 mg manganese and 12.5 mg cobalt. Liver biopsies were collected on d -21 and d 100 to measure mineral content. Fertility measures and blood samples were collected on d –14, 14, 42, 70, and 98. All bulls had inadequate copper, but adequate zinc in livers on d -21. All except two bulls had adequate manganese in their liver on d -21. Following 100 d on treatment, liver zinc levels decreased and liver copper levels increased in bulls regardless of treatment. Day 100 liver zinc levels were similar across treatments, but liver copper concentrations were greater in 3SCC and 3S bulls compared to 1C and 1S bulls, whereas 2SC bulls were intermediate. On d 42, more bulls fed complexed trace minerals (1C, 2SC, 3SCC; 79%) were pubertal compared to those fed only sulfate trace minerals (1S, 3S; 47%). Bulls fed complexed minerals tended to reach puberty after fewer (P = 0.11) days on treatment (43.9 d) than bulls fed only sulfate minerals (58.5 d). We conclude that recommendations for zinc may be inadequate for young bulls. Supplementing complexed copper and zinc to bulls may lower the age at puberty, however, no differences in semen measurements were observed.

Technical Abstract: The objectives were to determine if different supplemental trace mineral levels and /or forms (sulfate and metal amino acid complexes) influence age at puberty, semen quality, endocrine status and scrotal circumference in peripubertal bulls. Fifty crossbred, peripubertal bulls were blocked by age (258 ' 8.9) and scrotal circumference and assigned to one of five treatments: 1) 1x sulfate form (1S); 2) 1x complexed form (1C); 3) 1S + 1C (2SC); 4) 1S + 2x 1C (3SCC); and 5) 3x 1S (3S). Each 1x supplementation level contained 360 mg Zn, 125 mg Cu, 200 mg Mn and 12.5 Co. Liver biopsies were collected on d -21 and d 100, and were analyzed for Zn, Cu, and Mn. Scrotal circumference, semen, and blood samples were collected on d –14, 14, 42, 70, and 98. Semen was collected by electroejaculation and spermatozoa evaluated for morphology and motility. All bulls were deficient in Cu yet adequate in Zn on d -21. All animals except 2 were adequate in Mn. Following 100 d on treatment, liver Zn concentrations decreased (P < 0.01) and liver Cu concentrations increased (P < 0.01) in bulls regardless of treatment. Day 100 liver Mn concentrations were not different (P > 0.10) across any treatments or when compared to d -21. Day 100 liver Zn concentrations were similar (P = 0.50) across treatments, but liver Cu concentrations were greater (P = 0.07) in 3SCC and 3S bulls compared to 1C and 1S bulls, whereas 2SC bulls were intermediate. On d 42, more (P = 0.03) bulls fed complexed trace minerals (1C, 2SC, 3SCC; 79%) were pubertal compared to those fed only sulfate trace minerals (1S, 3S; 47%). Bulls fed complexed minerals tended to reach puberty after fewer (P = 0.11) days on treatment (43.9 +_ 5.7 d) than bulls fed only sulfate minerals (58.5 +_ 6.7 d). We conclude that NRC recommendations for Zn may be inadequate for peripubertal bulls. Supplementing complexed Cu and Zn to prepubertal bulls may lower the age at puberty, however, no differences (P > 0.41) in semen characteristics were observed at one year of age.